Optical coupler capable of achieving isolation and / or polarization management comprising a molded optical interposer and a PIC and 2 polarization selective elements

Abstract

This invention describes an apparatus that implements efficient coupling between a photonic integrated circuit (PIC) and a second optical element such as an optical fiber or laser, while allowing for efficient polarization management and / or optical isolation. It enables the packaging of a PIC with a large number of single-mode optical fibers and allows for input and output coupling of light with arbitrary polarization. The apparatus includes a glass insert containing at least one polarization-selective element and a pair of lenses that transform the beam profile between the second optical element and the polarization-selective coupler on the PIC. The invention also includes a method for manufacturing a component-based subassembly using wafer-level high-precision glass molding and one or more surface treatments such as thin-film coating.

Description

Background Technology

[0001] While traditional network topologies employ a tree architecture, where data traffic between access nodes must traverse several layers, topologies implemented in newer data centers are typically based on a spine-leaf architecture, connecting top-of-rack (TOR) switches (leaves) to multiple or all backbone nodes, significantly reducing latency and improving network reliability. Due to the resulting high port counts and increased distances, and also due to the proportionally increasing number of servers, these architectures require cost-effective, high-bandwidth optical interconnects over distances of 500 meters or more. Therefore, the industry is currently undergoing a paradigm shift from traditional multimode vertical-cavity surface-emitting laser (VCSEL) technology to single-mode-based optical technologies. This facilitates the use of photonic integrated circuit (PIC) technologies such as silicon photonics, which feature complex optical circuitry capable of implementing, for example, wavelength division multiplexing or polarization multiplexing data encoding. 400G transceivers with 100Gb / s per carrier or per fiber as defined by the IEEE P802.3bs standard are being implemented using external modulation and PIC technologies.

[0002] As a further trend, electronic-photonic co-packaging in data center switches is being actively researched as a means to reduce power consumption. This brings further challenges to optical packaging, as a very large number of optical fibers must be packed into a single package.

[0003] In the following text, PIC refers to a chip that includes optical components that emit or receive light from or to the chip, and PIC can refer to a chip that includes waveguides connected to modulators, photodetectors, multiplexers, or other on-chip optics. However, it can also refer to a chip that includes an array of surface-emitting single-mode VCSELs or large-area detectors. PIC can also be an electro-photonic integrated circuit (EPIC) that includes both photonic and electronic devices. In its most general form, PIC can refer to any chip having photonic devices that emit or receive light.

[0004] In single-mode optical systems, efficient coupling of light between individual optical elements is a significant challenge, requiring precise spatial and angular alignment of the two components. Furthermore, polarization management during the assembly of single-mode optical systems is another major challenge, as standard single-mode fibers do not maintain a predetermined polarization, and integrated components are typically designed for higher performance when used with single polarization. Finally, the lasers used in optical systems often need to be isolated from back reflections to operate stably. This presents a further challenge, as isolators are typically implemented using discrete components assembled as part of the optical package.

[0005] Generally speaking, single-mode fiber coupling technology can be divided into three categories:

[0006] - Couple the optical fiber directly to a surface-transmitting / receiving, mode-matched transmitter or receiver;

[0007] - Couple the fiber directly to a pattern-matched edge transmitter or receiver;

[0008] - Use imaging optics to indirectly couple optical fibers to surface or edge transmitters or receivers for mode conversion.

[0009] For the first two coupling techniques, single-mode fiber is directly coupled to optical components such as a PIC. Mode matching is achieved, for example, by using a mode-matched surface-emitting grating coupler or an adiabatic tapered waveguide as an edge coupler on the PIC. Alternatively, an insert waveguide-based component can be used to adiabatically transform the PIC's mode to the fiber mode. In this case, the coupling scheme can conceptually be viewed as a series of direct couplings between several optical components. This coupling scheme is characterized by the light being guided within the waveguide of the insert, rather than propagating as a free beam unrestricted by guidance within the waveguide (as described below in the insert). In these direct coupling schemes, the mode profile size is on the order of a few micrometers, and the beam path between elements is short, even zero, when the optical components are directly attached to each other. Alignment tolerances vary with the mode profile; therefore, when attaching single-mode fiber, alignment tolerances can reach several micrometers. However, these coupling schemes do not add any optical functionality to the system beyond mode transformation. That is, polarization separation, wavelength filtering, routing, or optical isolation must be implemented elsewhere in the optical system. If implemented on a PIC, on-chip polarization management might require redundant components if the two polarizations are handled separately, or combining the two polarizations on the PIC could significantly increase the complexity of the optical system and associated control systems. In particular, recombining two arbitrary polarizations typically requires photonic subcircuits with at least two phase shifters. While applying control signals to the two phase shifters to recombine the two polarizations at system startup is a manageable problem, the phase shifters may reach their compliance limits due to the polarization of the incident light drifting over time, leading to unacceptable service interruptions.

[0010] The third approach is currently primarily used for high-priced, small-to-medium-sized products, such as in high-value telecommunications applications. Here, discrete optical elements, such as lens arrays, prisms, or polarizing beam splitters, are assembled on an optical testbed subassembly that images (transforms) the optical mode of the emitting element (e.g., laser diode, PIC, or fiber) into the optical mode of the receiving element (e.g., photodiode, PIC, or fiber). Due to the stringent tolerances required for beam path alignment and optical element alignment, polymer-based couplers used in multimode systems cannot be used in single-mode optical systems while maintaining reasonable yields. Furthermore, due to the beam path length, the angular alignment tolerances of individual elements are significantly more stringent, and, with current state-of-the-art assembly techniques, only continuous active assembly of precision-manufactured elements can produce reasonable results. To maintain sufficient manufacturing precision, such elements are typically manufactured by grinding, polishing, or grayscale lithography followed by etching. The complexity of the assembly process makes this coupling and technology a major cost driver, currently limiting its commercial application to high-priced applications.

[0011] However, external imaging systems are compatible with adding other optical functions (such as polarization management, wavelength management, or optical isolation) to coupler subassemblies. The key challenge, then, is to integrate as many functions as possible into as few components as possible, and to maintain extended free beam paths within each component rather than between components to facilitate assembly.

[0012] Common manufacturing techniques used to manufacture discrete optical components include:

[0013] - High-precision grinding and polishing of individual components;

[0014] - High-precision glass molding of single or multiple components;

[0015] - High-precision etching using 3D grayscale mask technology.

[0016] While the first method yields the best results in terms of optical performance, it is also the most expensive and is only used for high-end applications, such as large-diameter lenses for astronomical systems. The last method is based on high-resolution lithography and 3D resist exposure. It offers the highest spatial resolution and allows multiple high-resolution optical elements, such as gratings or lens arrays, to be fabricated in parallel at the wafer scale. However, high-resolution lithography typically requires a flat substrate. Furthermore, fabricating 3D surfaces (such as lens surfaces) requires significant process development and cannot be easily transferred to other geometries; its achievable range remains very limited.

[0017] High-precision molding technology combines the advantages of the other two manufacturing techniques, increasing production volume while offering high design flexibility. Here, the glass preform, typically a planar wafer-shaped substrate with optical-grade top and bottom surface quality, is heated to its glass transition temperature (T0). c The process involves compression between one or two molds, which can be manufactured using high-precision grinding, milling, and cutting, or a combination thereof, providing very high shape accuracy and flexibility for the resulting 3D surface. Since the molds can be reused thousands of times and can be recoated with hardened materials to extend their lifespan, the costs associated with precision grinding can be spread across a large number of molded preforms and manufactured parts.

[0018] Furthermore, multiple instances of the same or different geometries can be manufactured in parallel using a single molding process applied to wafer-shaped preforms. Since glass molding is a reproducible manufacturing technique, it offers high throughput, with each production tool capable of producing hundreds of thousands to millions of parts per year, depending on the size of the molded part. A wide variety of glass substrates are available, ranging from low-temperature glass with a Tc of approximately 450°C to pure silica substrates with a Tc of 1100°C, and a wide range of coefficients of thermal expansion, facilitating reliable assembly with other building blocks made of different materials. The process is available in two versions: (1) isothermal glass molding, in which both the mold and the glass preform are preheated to the same temperature, and (2) non-isothermal glass molding (NGM), in which only the glass preform is heated above its glass transition temperature, while the mold remains significantly cooled. This allows for reduced process time, resulting in higher throughput than the isothermal process. However, it is also more susceptible to the effects of tension and localized shrinkage caused by temperature gradients, making the process less precise and potentially less reliable than the isothermal process. While glass molding technology has been used for many years to manufacture lenses for applications such as lighting, it has only recently reached the level of precision and resolution required to achieve single-mode coupled devices. Even now, certain dimensions, such as the precise distance between the top and bottom molds, and thus the distance between the top and bottom surfaces of the molded part, remain critical and affect the overall tolerances of the manufactured parts. Furthermore, lenses can be manufactured with greater precision if the optical axis of the lens is at a small angle along or relative to the pressing axis—that is, in the case of molded wafer-shaped preforms, if the optical axis of the lens is nearly perpendicular to the surface of the glass wafer. A range of + / -30° relative to this direction can generally still be manufactured with good yields. These constraints and tolerances need to be incorporated into the inserter design to obtain usable parts. Nevertheless, this manufacturing scheme offers more flexibility than grayscale lithography because other features, such as reflective facets, can be manufactured directly alongside the lens. This capability will be fully utilized below to add functionality to glass-molded inserters.

[0019] Functions such as polarization management or optical isolation require polarization-selective elements, which can be implemented on a glass-molded insert as polarization-selective elements located at the boundary or between dielectric materials. Several classes of such polarization-selective elements exist that affect the reflectivity or transmittance of the boundary between two dielectrics (including air, vacuum, and glass), causing light at the boundary to be transmitted, reflected, scattered, or absorbed according to its polarization. In the following text, if one polarization is reflected while another is transmitted or filtered out, these polarization-selective elements will be further referred to as polarization-selective reflectors; if one polarization is transmitted while another is filtered out, they will be further referred to as polarization-selective filters.

[0020] 1. Polarization-selective elements based on metal surface gratings. An electric (E-) field oriented along the same axis as the grating induces a current in the metal wire, resulting in significant absorption (filtered polarization), while an electric field oriented perpendicular to the grating passes through with significantly reduced absorption (transmission polarization). Careful design of the density and size of the metal grating is required to achieve sufficient contrast between transmission and filtered polarization. In particular, very fine and potentially expensive photolithography is necessary. As a significant advantage, the polarizer's function remains constant over a wide range of wavelengths and incident angles.

[0021] 2. Polarization-selective transmission / reflection elements based on dielectric surface gratings. These polarizers operate based on the different scattering behaviors of light, depending on whether they have parallel or perpendicular electric field alignments relative to the in-plane translation axis of a (1D) grating or the lattice vectors of a 2D grating. While one polarization is scattered to the side or reflected (filtered or reflected polarization), another polarization passes through (transmitted polarization). These types of polarizers require very precise control of the grating size within tens of nanometers and are typically optically narrow. Furthermore, the incident angle is usually limited to a narrow range.

[0022] 3. Polarization-selective transmission / reflection elements based on typical multilayer dielectric thin-film stacks, which reflect (reflected polarization) or transmit (transmitted polarization) light according to its polarization. These multilayer stacks are easier to fabricate and are widely used in polarization beam splitter cubes (PBS). They utilize different reflection coefficients at the interface of two dielectric materials, depending on whether the E-field is perpendicular (s-polarized) or parallel (p-polarized) with respect to the plane of incidence. Specifically, the reflection coefficient for p-polarized light becomes zero at Brewster's angle, defined as the angle of incidence arctan(n' / n), where n is the refractive index of the incident / reflected dielectric material and n' is the refractive index of the transmitted dielectric material. S-polarization reflection is improved by having multiple dielectric boundaries and associated constructive superpositions of individual reflection phases. This can be used to design thin-film stacks that allow p-polarized light to pass through and reflect s-polarized light. Therefore, these polarizers require an angle of incidence tilted relative to the surface normal of the stacked layers. The reflection of s-polarized light is enhanced by stacking multiple layers, trading reduced optical bandwidth for enhanced contrast between transmitted and reflected polarization. This configuration, also known as the MacNeille configuration, is used for Brewster angle polarization beamsplitters. As a drawback, if the target is a specific angle of incidence (typically 45° relative to the surface normal of the thin-film stack, measured inside the polarization beamsplitter), this limits the refractive index of the cubic substrate material to match a value that depends on the refractive index of the materials used in the thin-film stack. For example, if the thin-film stack is formed using two materials with alternating refractive indices n1 and n2, the glass substrate of the PBS should preferably have a verified n...G 2 =2n1 2 n2 2 / (n1 2 +n2 2 The refractive index n G Another approach, known as a planar polarizer, does not require the incident angle to be precisely within the Brewster angle of the thin-film stack, thus relaxing design constraints. It relies on the correlation between the spectral width of the high-reflectivity wavelength range (its stopband) of the quarter-wavelength stack and the intensity of the reflectivity at the interface between the thin films. When the wavelength of light is in the high-reflectivity range of one polarization but near the edge, it can already be in the high-transmittivity range of another polarization, thus producing the desired polarization selection. As a drawback, this configuration, which relies more on thin-film interference effects, can have a narrower bandwidth unless they are optimized to support a wider wavelength range, in which case the selectivity between the two polarizations (extinction) may be affected. Polarizers based on dielectric thin-film stacks retain light in the available beam in the blocked polarization because it is reflected in a different predetermined direction than the transmitted polarization (reflected polarization). Thin-film stacks can be fabricated by successive dielectric coatings, also known as thin-film coatings.

[0023] The three types of polarization-selective elements described above belong to the general category of surface treatments at the interface of dielectric materials or between dielectric materials.

[0024] Polarization-selective elements can also be implemented in the PIC as polarization-selective couplers. These couplers couple light into the PIC based on its polarization, and further couple it to other optical devices on the PIC, such as waveguides, modulators, multiplexers, etc., or discard or reflect the light back. Therefore, these polarization-selective couplers can function as both coupling elements and on-chip polarization filters. Similarly, polarization-selective couplers can emit light from the PIC under a single polarization.

[0025] A single-polarization grating coupler, composed of an array of gratings, is a coupling device that allows coupling of light on and off a PIC to achieve single polarization, typically but not always having an E-field polarization oriented along the principal axis of the grating. This grating coupler allows coupling light from a waveguide to a beam emitted from the surface of the PIC, or capturing a beam incident on the surface of the PIC and coupling it to a waveguide. While many figures illustrate configurations with single-polarization grating couplers, these are merely examples of surface-emitting polarization-selective PIC couplers. Therefore, these figures are also intended to represent more general configurations, including universally polarization-selective surface-emitting / receiving couplers (hereinafter simply referred to as surface-emitting couplers for simplicity).

[0026] Another example of a polarization-selective coupler is a waveguide edge coupler, which is combined with an on-chip element to allow light to be coupled to and from the edge of the PIC, the on-chip element allowing one polarization to pass through and reflect, couple out, or otherwise discard another polarization. This polarization filter can be implemented, for example, in the form of a corrugated waveguide. Since the integrated waveguide can be made highly birefringent (i.e., having different effective refractive indices for the two polarizations) for example by selecting a non-square rectangular cross-section, the corrugation can be fabricated to have very different properties depending on the polarization of the light, so that it only reflects or couples out one polarization while allowing the other to pass through. Which polarization is transmitted and which is discarded can be selected by adjusting the periodicity of the grating or the cross-section of the waveguide. Polarization sensitivity can also be implemented in other ways; for example, the waveguide corrugation can be replaced by a polarization-selective reflector, which takes the form of a thin-film coating deposited on the edge of the PIC on top of the edge coupler interface. This thin-film coating is also part of the PIC.

[0027] For the sake of brevity, the combination of an edge coupler or other coupler with insufficient polarization sensitivity and an on-chip polarization-selective element is also referred to hereinafter as a polarization-selective coupler, even if other optical elements are inserted between them, because the required optical work can still be achieved. A coupler or a combination of a coupler and another on-chip device (resulting in significant polarization-dependent insertion loss) is further referred to as a polarization-selective coupler. Furthermore, from a polarization management perspective, couplers following a PIC subsystem (whose intended function is only achieved for one polarization, further referred to as a polarization-selective subsystem) face the same challenges as polarization-selective couplers, as the intended function is not achieved for the other polarization. Similarly, when the direction of light travel is reversed, light emitted from a polarization-selective subsystem via a PIC coupler has only one polarization. Therefore, for the sake of brevity, couplers before / after a polarization-selective subsystem are also referred to as polarization-selective couplers, even if the coupler itself is not polarization-selective. The terms PIC subsystem and photonic subcircuit are used interchangeably herein.

[0028] If the two polarizations are not handled separately, an additional loss exceeding 3 dB for one polarization significantly impacts the performance of links with non-polarization-maintaining fibers; therefore, from a polarization management perspective, this is considered a polarization-selective coupler. Some applications even require polarization-dependent losses of no more than 1 or 2 dB. If used in optical isolators, an additional loss exceeding 10 dB for one polarization allows for substantial optical isolation; therefore, from an optical isolation perspective, it is considered a polarization-selective coupler. For some applications, an additional loss as low as 5 dB may be acceptable.

[0029] One embodiment of an optical isolator comprises a Faraday rotator (e.g., made of garnet material to which a permanent magnetic field is applied due to the magnetization of the garnet, or made of an additional magnet) placed between two polarization-selective elements. The Faraday rotator rotates the polarization of transmitted light in a non-reciprocal manner; that is, when light passes through the material in one direction, its polarization rotates in that direction, and when light passes through the material in another direction, its polarization rotates in the same direction (with the same chirality), rather than rotating back. Therefore, the isolator operates as follows:

[0030] In the direction of transmission, the first polarizer transmits light with a predetermined polarization. Then, a Faraday rotator is designed to rotate the polarization by 45° in one direction (rotation angles without a prefix can generally refer to either direction of rotation). The second polarizer is then aligned accordingly to allow the light to pass through.

[0031] Conversely, light from the other direction is blocked by the isolator. Alternatively, it may not match the passing polarization of the second polarizer and be directly blocked by it. Conversely, if it matches the second polarizer, it will be rotated 45 degrees by the Faraday rotator. Due to the non-reciprocal nature of the Faraday rotator, this becomes blocked polarization of the first polarizer and terminates, so the light is also filtered out at this point.

[0032] While this baseline configuration allows light to pass through in only one polarization direction, many configurations exist that allow both polarizations to pass through in the forward (passing) direction. For example, this would be achieved in the following (preferred embodiment C) by: implementing a first polarizer with a polarization-selective reflector and further processing the two polarization-dependent beam paths; efficiently creating two such isolators in a glass-molded optical insert structure combined with a polarization-selective coupler on the PIC, each isolating one of the two polarizations.

[0033] Optical isolation is typically used at the output of a laser to prevent operational instability caused by light being reflected back into the laser cavity under poorly controlled conditions. The isolator can be placed immediately after the laser, or in some cases, at a distance after the laser but still within the transmitter subsystem, for example, at the output of a PIC to which the laser is coupled via another (input-) port. This is acceptable because the laser's sensitivity to back reflection increases with distance from the back reflection source, making back reflections occurring downstream in the optical link (e.g., at the receiver or at insertion devices such as optical switches or add-drop multiplexers) more critical.

[0034] In some cases, if another device already possesses sufficient polarization sensitivity, one of the two polarization-selective elements does not need to function as a separate device. For example, a laser, through the design of its cavity or its gain medium, can exhibit sufficiently high suppression of a second polarization. In this case, the laser is also considered a polarization-selective element of the isolator. Summary of the Invention

[0035] The invention described herein enables single-mode coupling with advanced functionalities, such as polarization management and / or optical isolation, using low-cost micro-optical devices. These micro-optical devices can be manufactured via glass molding and implemented as inserts for precision glass molding. In particular, the parallel molding of multiple parts using preforms in the shape of molded glass wafers, along with wafer-level surface treatments (e.g., thin-film coating, metal deposition, or micropatterning) and wafer-level assembly of the micro-optical devices, makes it possible to reduce manufacturing costs.

[0036] This invention includes an optical assembly in which a (typically single-mode) device on a PIC, such as a single-mode waveguide or a single-mode laser, is coupled via a glass insert to a (typically single-mode) second optical element, such as a glass fiber or laser. The glass insert includes at least one lens (typically two lenses) that allows matching of beam profiles between the PIC and the second optical element (or vice versa if the propagation directions are reversed). The PIC includes at least one polarization-selective coupler, and the glass insert includes at least one polarization-selective reflector or polarization-selective filter. In some embodiments, a Faraday rotator is also inserted into the beam path and can be attached to the glass insert or to the PIC. In summary, these elements enable not only low-loss optical coupling but also polarization management and / or optical isolation. Because the PIC and the second optical element can be located adjacent to lenses on the optical insert, the free beam path can be primarily located within the insert, thus facilitating assembly as previously described. Because the PIC and / or the second optical element can be attached to the mechanical contact facet / attachment interface of the glass inserter, the angle of the beam emitted from or received by the PIC or the second optical element can be well controlled.

[0037] This invention also includes a method for manufacturing glass inserts based on high-precision glass molding technology, comprising wafer-level manufacturing, surface treatment, and pre-assembly of component blocks. The insert geometry and assembly process are optimized to minimize sensitivity to manufacturing tolerances, particularly the precise distance between the top and bottom molds used to form the component blocks. A wide range of functions and different inserts can be achieved using a single or a few component block types.

[0038] Since polarization-selective surface treatments applied to glass inserters are typically applicable to a limited range of k-vectors (the angle of incidence determined after Fourier decomposition), it is advantageous to collimate or nearly collimate the beam (reducing the diffraction angle compared to the beam emitted or received by the PIC and the second optics). This is why, from the perspective of the beam path, it is advantageous for the glass inserter to include at least two lenses with polarization-selective surface treatments inserted therebetween. Possible polarization-selective surface treatments include metallic gratings, dielectric gratings, or thin-film coatings as described above. In the following text, describing the beam as collimated in the sense of having a significantly narrower k-vector distribution than the beam emitted / received by the PIC and the second optics can also mean nearly collimated. Essential collimation can mean that the beam's diffraction angle is less than half that of the beam emitted / received by the PIC and the second optics. It can also mean that the full width at half maximum (FWHM) of its k-vector distribution is less than half that of the beam emitted / received by the PIC and the second optics. Detailed Implementation

[0039] Detailed description of the invention (device)

[0040] The present invention includes a micro-optical component, which may be made of molded glass, interchangeably referred to as a glass inserter or optical inserter

[300] , having at least one polarization-selective reflector or polarization-selective filter

[310] implemented by processing of internal or external surfaces, and a photonic integrated circuit (PIC)

[100] including at least one polarization-selective coupler

[110] . The glass inserter is capable of coupling light to or from a second optical element

[200] between polarization-selective couplers on the PIC.

[0041] Figure 1(a) illustrates an embodiment in which the second optical element

[200] is implemented by a glass optical fiber

[201] and the polarization-selective coupler

[110] is implemented by a single-polarization, single-mode VCSEL

[111] . A VCSEL is considered a polarization-selective coupler if it emits a single polarization and rejects reflections in other polarizations through its cavity and gain medium design. More conventionally, the polarization-selective coupler referred to below can also be a device that couples light to or from the waveguide

[120] of a PIC

[100] in a polarization-selective manner, which may be a single-mode waveguide. Such a polarization-selective coupler is, for example, a single-polarization grating coupler

[112] or an edge coupler

[113] , which can be implemented in combination with additional polarization-selective elements

[130] such as waveguide corrugations

[131] or thin-film coatings

[132] applied to the PIC. The glass inserter

[300] includes two lenses [320A] and [320B] and a polarization-selective reflector

[310] . The PIC, the glass inserter, and the optical fiber together form an optical subassembly, which is further attached to a printed circuit board (PCB) that includes other components (FIG. 1(b)), such as electronics, like transimpedance amplifiers (TIAs) or modulators or laser drivers, and edge connectors, such as quad small form factor (QSFP) connectors. The optical fiber may be attached to a standard fiber optic connector, such as a multi-fiber MPO connector. In the figures, PCB represents a printed circuit board, PSM represents parallel single-mode, WDM represents wavelength division multiplexing, OI represents an optical inserter, and SM represents single-mode. In other embodiments of the invention, instead of the polarization-selective reflector

[310] or in addition to the polarization-selective reflector

[310] , the inserter may also include a simple reflector

[330] or a wavelength-selective reflector

[340] .

[0042] Figure 2 Different configurations of the beam path between the polarization-selective coupler

[110] and the second optical element

[200] are shown. Light from the second optical element is collimated using a first lens [320A] and guided to the polarization-selective reflector or filter

[310] of the glass inserter

[300] . This element separates the beam into one of two beams according to its polarization and guides at least one beam with a single polarization to a second focusing lens [320B], which focuses the light onto the polarization-selective coupler

[110] on the PIC. The device can also operate with the beam path reversed, i.e., light emitted from the polarization-selective coupler

[110] of the PIC is coupled to the second optical element

[200] using the glass inserter

[300] . An exemplary polarization of the beam

[400] is shown in... Figures 2 to 6The arrows are indicated by double dashed arrows superimposed on the beam path. These are merely exemplary—generally, it is important that when several beams are present, they are orthogonal to each other and that they correspond to the transmission or filtering / reflection polarization of the polarization-selective filter or reflector

[310] . For the purpose of illustrating possible implementations, they are generally shown as polarized, which would be necessary if the polarization-selective element on the optical insert were to be implemented as a polarization-selective filter or reflector using a thin-film coating in a MacNeille configuration. The arrows also indicate the path of light propagation.

[0043] Figure 2 The difference between the configurations shown in (a)-2(d) lies in whether the beam is received / emitted from / from the edge of the PIC, or from / from the top surface of the PIC. Both configurations are practically significant because they correspond to different types of PIC couplers, each with its own advantages and disadvantages. For example, grating couplers emit light from the top surface of the PIC at an angle typically within + / -30° from the normal to the surface and belong to the category of surface-emitting couplers. Their advantage lies in the ability to perform wafer-level probing and sorting of the PIC before it is diced into dies, but they are also limited by the range of operating wavelengths. Edge couplers, on the other hand, are broadband but more difficult to probe at the wafer level. They may also lead to more complex assembly because the edge of the die provides a smaller attachment surface, and the emitted / received beam typically has a smaller lateral dimension than that for grating couplers, resulting in tighter alignment tolerances.

[0044] The differences between these configurations also lie in whether the angle at which the second optical element

[200] emits / receives the beam is substantially perpendicular to the surface of the PIC (e.g., within an angle range of + / -30° relative to the surface normal), or whether the direction of the second optical element

[200] emits / receives the beam is substantially parallel to the surface of the PIC (e.g., within an angle range of + / -30° relative to a direction parallel to the surface). This has significant practical implications because current form factors of electro-optic transceivers typically specify that the fiber optic termination is at the connector at the edge of the module. In this case, it is advantageous to route the light out, as shown in configurations (b) and (c). On the other hand, an emerging trend for optical communications in data centers is to co-package electronic switching structures with electro-optic transceivers. This removes the inserted printed circuit board signal trace and reduces electronic signal attenuation and distortion between the switching chip and the electro-optic module. Consequently, the power consumption associated with electronic data transmission between the electro-optic transceiver and the switching structure can be reduced. However, this requires densely packaged optical fibers to access such co-packaged optics. For example, a 12.8Tb / s switching chip requires 32 modules, each transmitting and receiving at 400Gb / s. If each fiber transmits at 100Gb / s in one direction, this corresponds to a total of 256 fibers. Such a large number of fibers can be packed into a 2D array of 16×16 fibers, tightly packaged in 4×4mm blocks with a pitch of 250μm. However, this requires the fibers to exit from the top of the package. In this case, the configurations shown in (a) and (d) are advantageous.

[0045] In configurations (a) and (b), a polarization-selective PIC coupler

[110] emits / receives a beam from / to the top surface of the PIC; that is, it is a surface-emitting coupler and may be a single-polarization grating coupler

[112] . In configurations (c) and (d), a polarization-selective PIC coupler emits / receives a beam from / to the edge of the PIC and may be an edge coupler

[113] combined with a polarization-selective element

[130] such as a corrugated waveguide

[131] inside the PIC, or a surface treatment applied to the edge of the PIC in the form of, for example, a thin-film coating

[132] . In all four configurations, a pair of lenses [320A], [320B] image the beam from the PIC

[100] to the second optical element

[200] or from the second optical element

[200] to the PIC

[100] . A polarization-selective reflector or filter

[310] is applied to the outer or inner surface of the glass inserter and allows one polarization to propagate from a polarization-selective coupler on the PIC to a second optical element, or from a second optical element to a polarization-selective coupler on the PIC. The other polarization is routed away or absorbed, either discarded or routed elsewhere, such as to another coupler on the PIC. A polarization-selective reflector

[310] can also be used to combine two beams with different (orthogonal) polarizations (e.g., beams emitted by two polarization-selective couplers of the PIC or beams emitted by a second optical element and a third optical element) into a single beam.

[0046] Configurations (a) and (c) are characterized in that the selected polarization is transmitted through a polarization-selective reflector or filter

[310] , while configurations (b) and (d) are characterized in that the selected polarization is reflected by a polarization-selective reflector

[310] .

[0047] The following describes the correspondence between Figures 3 to 34. Figure 6 Four preferred embodiments of the present invention are described below. A method for manufacturing and assembling the optical glass insert

[300] is then described.

[0048] A: In the first preferred embodiment depicted in Figure 3(a), the device couples two polarizations from the second optical element

[200] to two different couplers [110A], [110B] on the PIC

[100] . This functionality is advantageous, for example, in a receiver that receives light from a standard single-mode fiber

[201] , in which the polarization of the light has been scrambled or the data is encoded with two polarizations. Besides the device described herein, a dual-polarization coupler can also be used on the PIC. However, such couplers tend to have higher insertion loss, suffer from higher polarization-dependent loss (PDL), and impose more limitations on manufacturing techniques. Alternatively, the device described herein can be used to transmit light from the PIC

[100] into the fiber

[201] . In this case, the light will be polarized in the fiber depending on which PIC coupler it is emitted from. Such functionality is advantageous, for example, in a dual-polarization transmitter using dual polarization as independent communication channels (e.g., using dual-polarization quadrature phase-shift keying or DPQPSK), in which data is encoded in each communication channel.

[0049] Preferred embodiments include micro-optical devices made of glass, namely glass inserters

[300] and PICs

[100] . The glass inserter includes a first lens [320A], a second lens [320B], a third lens [320C], a first polarization-selective reflector

[310] , and a second reflector

[330] that may be polarization-selective or non-polarization-selective. While a polarization-insensitive reflector can fulfill the function required by element

[330] , only one polarization passes through it, so a polarization-selective reflector that reflects said polarization can also be used. This may be advantageous in some manufacturing processes by reducing the number of different surface treatments that must be applied. For example, in the variant shown in Figure 3(b), elements

[310] and

[330] need to reflect the same polarization, so in principle they can be obtained through the same surface treatment.

[0050] The PIC

[100] includes a first polarization-selective coupler [110A] and a second polarization-selective coupler [110B], each polarization-selective coupler coupling light between waveguides [120A], [120B] and free-space beams [400A], [400B] on the PIC, wherein the polarizations of the two free-space beams coupled by the two polarization-selective couplers have polarizations that are substantially orthogonal (opposite) to each other. This can be achieved, for example, by orthogonally oriented the polarization-selective couplers [110A], [110B] to each other on the surface of the PIC, as shown in Figures 3(a) and 3(b) for the case of a surface emitter / receiver. Typically, the angle of the out-of-plane beam can be perpendicular to the surface of the PIC (i.e., along the surface normal) or can deviate from that axis by up to 30°.

[0051] Even if light leaves or enters the surface-emitting PIC coupler at an angle relative to the surface normal of the PIC, if the optical axis of the lens is along the surface normal and if the surface-emitting coupler is centered relative to the lens (i.e., on their optical axis), the collimated beam generated by the lenses [320B] and [320C] inside the optical inserter

[300] will ultimately propagate along the direction of the surface normal. Embodiment AD can be implemented in this way. Similar considerations apply to the second optical element

[200] if it emits or receives light at a smaller angle relative to a direction parallel to the PIC surface / relative to the optical axis of the lens [320A], as depicted in FIG3(a). This would be the case, for example, if the second optical element

[200] is a glass fiber

[201] with end-faced polished at an angle. If the fiber core at the end facet is centered relative to the lens [320A] (i.e., on the optical axis of the lens), and the optical axis of the lens [320A] is parallel to the surface of the PIC, then the collimated beams [400A] and [400B] generated by the lens [320A] inside the optical inserter

[300] will be parallel to the surface of the PIC. Figures 2 to 6 The direction of the beam shown can also deviate from the direction inside the depicted inserter, for example, by a maximum deviation of 20°.

[0052] The polarization-selective reflector

[310] combines the two beams [400A], [400B] before routing them to the second optical element

[200] (when coupling light from the PIC to the second optical element), or splits the two beams [400A], [400B] so that they can be independently routed to the two polarization-selective couplers [110A], [110B] (when coupling light from the second optical element to the PIC). Generally, all coupling schemes described herein can operate in either direction.

[0053] Therefore, the difference between the two coupling schemes lies in the direction of light travel: for the first coupling scheme, the light from the second optical element

[200] has two possible polarizations, namely, the electric field can be oriented along a plane perpendicular to the insert cross section shown in FIG. 3(a) (further referred to as s-polarized light), or it can be oriented parallel to that plane (further referred to as p-polarized light). In FIG. 3(a), the beam [400A] is exemplarily shown as s-polarized, while the beam [400B] is exemplarily shown as p-polarized. The light is collimated using the first lens [320A] and directed to the first polarization-selective reflector

[310] of the glass insert

[300] . Here, light with one polarization, such as s-polarized light, is reflected to the second lens [320B] and focused onto the polarization-selective coupler [110A] on the PIC, thereby coupling to the waveguide [120A] on the PIC. Light with another polarization, such as p-polarized light, is transmitted through a polarization-selective reflector

[310] , guided to a second reflector

[330] , reflected at the second reflector

[330] to a third lens [320C], and focused onto a second polarization-selective coupler [110B] on the PIC, and coupled to another waveguide [120B] of the PIC. This coupling scheme can be used, for example, to couple two polarizations propagating in a single-mode fiber

[201] to the PIC

[100] , where polarization is uncontrolled within the fiber, or to encode data independently on two communication channels.

[0054] In the second coupling scheme, the propagation directions of the light are opposite. Therefore, light from the two PIC couplers [110A], [110B] is coupled to a second optical element

[200] , such as an optical fiber

[201] , where the polarization depends on which polarization-selective coupler [110A], [110B] the light was emitted from. This coupling scheme can be used, for example, at the output of the PIC to couple light from a transmitter circuit that performs polarization multiplexing (encoding data onto two polarizations) into a single-mode optical fiber.

[0055] As an advantage of the configuration shown in Figure 3(a), this configuration relies on orthogonally oriented surface emitter / receiver couplers [110A], [110B] on the PIC, so that the light coupled to the waveguides [120A], [120B] of the PIC ultimately has the same polarization inside the PIC

[100] , even though it has orthogonal polarization in the free-space beam between the PIC and the second optical element

[200] . This is helpful for PIC design because components inside the PIC can all be designed for the same polarization. When using surface emitter couplers, preferred embodiments of AD can all be configured in this way. When using edge couplers, it may be necessary to implement (typically reciprocal) polarization rotators inside the PIC to obtain the same polarization thereafter inside the PIC.

[0056] The configuration shown in Figure 3(a) can be based on Figure 2 The different configurations shown are generalized. For example, polarization-selective couplers [110A] and [110B] can be edge couplers, in which case the glass inserter

[300] can be placed on one side of the PIC, as shown in Figure 3(c). As shown in Figure 3(b), light can also be coupled to the second optical element

[200] and coupled from the second optical element

[200] in a direction substantially perpendicular to the surface of the PIC, which can be easily achieved by moving the position of the lens [320A] and reorienting the orientation of the grating couplers (surface emission couplers) [112A], [112B], indicating that the orientation of the surface couplers (and the PIC in general) must be designed in conjunction with the optical inserters to match each other's requirements.

[0057] When used in an etch-coupled configuration, the preferred polarization of the polarization-selective coupler can be determined, for example, by changing the grating period in the waveguide cross section or the corrugated waveguide

[131] , thereby verifying the Bragg condition for the rejected polarization. This is illustrated exemplary in Figure 3(c), where the periodicity of the corrugations [131A] and [131B] is shown to be different.

[0058] In this preferred embodiment, polarization management is achieved by utilizing a polarization-selective reflector

[310] on the glass insert and by orienting or adjusting polarization-selective couplers [110A], [110B] on the PIC according to the received or transmitted polarization. Thus, polarization management is distributed across the PIC and the glass insert. Here, polarization management refers to polarization multiplexing and / or demultiplexing (also known as demultiplexing).

[0059] B: In the second preferred embodiment depicted in Figure 4, the device implements an optical isolator. An optical isolator is a non-reciprocal optical device that transmits light in one direction (through direction) and blocks light in the opposite direction (blocking direction). Here, the optical isolator consists of a Faraday rotator

[500] embedded between two polarization-selective elements

[110] ,

[310] , which transmit light of one polarization and block or reroute light of another polarization. By adding a Faraday rotator in the beam path between the polarization-selective reflector or filter

[310] of the optical inserter

[300] and the polarization-selective coupler

[110] of the PIC

[100] , the single-mode coupling device enhances the optical isolation function. The device can be used at the output of the transmitter PIC to protect the upstream laser from back reflections occurring downstream of the transmitter (e.g., in an optical fiber or receiver). By integrating the optical isolator into the fiber coupler, the assembly cost of the laser sub-assemblies can be significantly reduced, thereby significantly reducing the assembly cost of the entire transceiver system. In particular, this allows for the integration of flip-chip or heterogeneous lasers without sacrificing isolation. Since the optical path length between the laser and the fiber coupler is typically relatively short, approximately a few millimeters or centimeters, this is acceptable in terms of maintaining stable, low-noise laser operation. The device can also be used at the input of a transmitter PIC to couple a laser into the PIC, again isolating the laser from back reflection. In this case, the direction of the light is reversed relative to that depicted in Figure 4(a) (and the rotation direction of the Faraday rotator is reversed, or the orientation / configuration of the polarization-selective coupler is changed to interchange the through and blocking directions of the isolator). As already mentioned, the coupling scheme described here can be used in either direction, where, in the case of optical isolation, small adjustments as described above are necessary due to the non-reciprocal nature of the beam path.

[0060] Preferred embodiments include micro-optical elements made of glass, namely a glass inserter

[300] , a PIC

[100] , a second optical element

[200] , and a Faraday rotator

[500] . The glass inserter includes a first lens [320A], a polarization-selective reflector or filter

[310] , and a second lens [320B]. The PIC includes a polarization-selective coupler

[110] that couples light from a preferred polarization to a waveguide

[120] on the PIC. When light is coupled to or from the PIC through the surface of the PIC, as shown in FIG4(a), the orientation of the polarization-selective coupler

[110] must be selected according to the operating direction of the isolator, as described below. In the case of an edge-emitting coupler, as shown in FIG4(b), the coupler must be adapted to be selective for the target polarization. The Faraday rotator element

[500] may be integrated into or attached to the inserter

[300] , or may be integrated into or attached to the PIC

[100] . It may also be a separate element placed anywhere in the beam path between the polarization-selective reflector or filter

[310] of the inserter

[300] and the polarization-selective coupler

[110] of the PIC

[100] .

[0061] Two coupling schemes are described, differing only in the direction of light travel: For the first coupling scheme, (i) light from the second optical element

[200] is first collimated using a first lens [320A] and directed toward a polarization-selective reflector or filter

[310] . (ii) The polarization-selective reflector or filter now either reflects (Fig. 4(a)) / transmits (Fig. 4(b)) the beam or discards it, depending on the beam's polarization. In cases where the second optical element

[200] only supports single polarization, such as in some semiconductor lasers, in the coupling scheme depicted in Fig. 4(a) where the beam is reflected, the polarization-selective reflector

[310] can be replaced by a polarization-insensitive reflector

[330] . In the case of the direct coupling scheme depicted in Fig. 4(b), the polarization-selective filter

[310] can also be simply omitted. In this case, the first polarization-selective element is effectively moved to the second optical element

[200] . (iii) The light is then focused by the second lens [320B] of the optical inserter

[300] onto the polarization-selective coupler

[110] of the PIC

[100] so that it couples all or part of the light into the PIC waveguide

[120] . The Faraday rotator

[500] is designed to rotate the polarization of the beam by 45° in a non-reciprocal manner.

[0062] Light reflected directly from the coupling interface of the PIC retains its polarization. Since the polarization-selective coupler

[110] produces only beams with a fixed polarization consistent with the target polarization of the incident beam, light coupled into the PIC and reflected back from devices inside or behind the PIC also retains its initial polarization. The polarization of the light returning from the PIC and propagating in the opposite direction is again rotated by the Faraday rotator

[500] in a non-reciprocal manner by 45°. In the case where a polarization-selective reflector or filter

[310] has been implemented, its performance is now switched: if it reflects (Fig. 4(a)) / transmits (Fig. 4(b)) the beam in (ii), it is now discarded due to the polarization switching. In other words, if the element

[310] is a polarization-selective reflector, the transmission and reflection performance are exchanged for the reflected return beam. Therefore, the reversed optical path takes a different path than the forward optical path, and the beam is not coupled back to the second optical element

[200] . If the second optical element

[200] only accepts single polarization and no polarization-selective reflector or filter

[310] is implemented, the reflected light is routed back to the second optical element

[200] . However, since the second optical element

[200] only supports single polarization, the light is now rejected by it, thus still achieving optical isolation. Therefore, in all cases, the second optical element

[200] efficiently isolates the light from reflections occurring at or after the PIC

[100] . This coupling scheme can be used, for example, to couple a laser directly to the PIC or to couple a laser to the PIC using an optical fiber between the laser and the coupling device (an extension of the device described as preferred embodiment C also supports lasers connected via non-polarization-maintaining optical fibers).

[0063] For the second coupling scheme corresponding to the passage direction from the PIC

[100] to the second optical element

[200] , light from the PIC is coupled out of the PIC through a polarization-selective coupler

[110] with a single polarization. This polarization is rotated 45° by a Faraday rotator

[500] , collimated by a second lens [320B], and guided to the polarization-selective reflector or filter

[310] of the inserter

[300] . The light is then focused by the first lens [320A] of the inserter

[300] onto the coupling interface of the second optical element

[200] and coupled to the second optical element

[200] .

[0064] For example, if the second optical element includes an optical fiber in which polarization is scrambled, the light reflected from the second optical element

[200] can have either of two polarizations. However, in both cases, it is prevented from coupling back into the PIC: either light has the correct polarization that will be routed back to the polarization-selective coupler

[110] via the polarization-selective reflector or filter

[310] and the two lenses [320A] and [320B]. The rotation of the Faraday element is chosen such that the light then has orthogonal polarization relative to the light coupled by the polarization-selective coupler

[110] , thus preventing the light from being coupled back into the PIC. Alternatively, the light has another polarization, so that the polarization-selective reflector

[310] does not couple it back into the polarization-selective coupler

[110] and again prevents the light from being coupled back into the PIC. Thus, isolation is also achieved here, because the light reflected from the second optical element

[200] is not coupled back into the PIC

[100] regardless of its polarization. This coupling scheme can be used, for example, to couple the PIC to an optical fiber at the output of the transmitter's optical path to efficiently isolate the transmitter and its light source from back reflections occurring in other optical fibers and / or other optical circuits implemented downstream of the transmitter.

[0065] For embodiment A, the configuration shown in FIG4(a) representing coupling to and from the PIC via the top surface of the PIC can also be extended to a configuration in which light is coupled to and from the PIC via the edge of the PIC (FIG4(b)). In this configuration, the polarization sensitivity of the edge coupler

[113] can be obtained, for example, by waveguide ripples

[131] or by a thin film coating

[132] , the period of which is adjusted according to the polarization to be transmitted or reflected. In FIG4(b), the polarization of light at the edge coupler interface is preferentially along the x- or y-direction, as shown, because these correspond to polarizations typically preserved by waveguide modes. This facilitates, for example, the design and fabrication of the ripples

[131] . Due to the 45° rotation caused by the Faraday rotator

[500] , the surface normal of the polarization-selective reflector or filter

[310] preferentially follows the x- or y-direction in the coordinate system shown in the figure. or Direction. In other words, in order to adjust the Faraday rotator, the optical insert

[300] has been relative to... Figure 2 The configuration shown in (c) is rotated by + / -45° with the z-axis as the rotation axis.

[0066] In this preferred embodiment, optical isolation is achieved by utilizing a polarization-selective reflector or filter

[310] on the glass insert

[300] and by orienting or adjusting a polarization-selective coupler

[110] on the PIC

[100] according to the received or transmitted polarization. Thus, optical isolation is distributed across the PIC and the glass insert.

[0067] C: In the third preferred embodiment, such as Figure 5 The depicted device combines the functions of preferred embodiments A and B, achieving both polarization-dependent routing and optical isolation. To achieve these functions, the embodiment includes a glass inserter

[300] , a PIC

[100] , and a first Faraday rotator [500A] and a second Faraday rotator [500B]. This embodiment can be used as an optical fiber coupler at the input of the PIC to connect it to a light source. It then allows coupling of both polarizations arriving from the light source into the PIC while protecting the light source from reflections from the PIC. Even if the light source is a single-polarization laser, this polarization can be scrambled in the single-mode fiber inserted between the laser and the PIC. While polarization-maintaining (PM) fiber would prevent polarization scrambling, PM fiber is more expensive to manufacture and assemble because it must be carefully aligned so that its slow and fast axes are parallel / perpendicular to the polarization orientation of the transmitted light. Alternatively, this embodiment can be used at the output of the PIC to couple it to an optical fiber. It then allows coupling of light with either polarization into the fiber as needed, for example, in a transmitter using polarization multiplexing, i.e., encoding data on both polarizations. Simultaneously, it protects the PIC and light sources integrated within or upstream of the PIC from reflections occurring after the PIC's output. In this latter case, the forward direction of the isolator is reversed compared to the former. As in preferred embodiment B, the rotation direction of the Faraday rotators [500A], [500B], or the orientation / configuration of the polarization-selective couplers [110A], [110B] and / or the polarization-selective reflectors or filters

[310] can be adjusted according to the desired direction of light travel. Figure 5 In this example, the orientation of grating couplers [112A] and [112B] has been rotated by 45° relative to FIG. 3(a) to explain the fact that the polarization of beams [400A] and [400B] is additionally rotated by 45° by Faraday rotators [500A] and [500B]. Grating couplers [112A] and [112B] remain orthogonally oriented to each other. Alternatively, one Faraday rotator can be configured to rotate the incident beam by +45°, while the other is configured to rotate the incident beam by -45°, for example, by inverting one Faraday rotator relative to the other. In that case, the two grating couplers [112A] and [112B] must be oriented parallel or antiparallel to each other.

[0068] In this preferred embodiment, optical isolation and polarization-selective routing are achieved jointly by utilizing a polarization-selective reflector or filter

[310] on the glass insert

[300] and by orienting or adjusting a polarization-selective coupler

[110] on the PIC

[100] according to the received or transmitted polarization. Thus, the optical isolation and polarization-selective routing functions are distributed across the PIC and the glass insert.

[0069] D: In Figure 6 In the fourth embodiment illustrated, the device implements single-mode coupling from the second optical element [200A] to the PIC

[100] and from the PIC

[100] to the third optical element [200B] in such a manner that the light received by the PIC

[100] and the light re-emitted from the PIC

[100] can have arbitrary polarization. Furthermore, the light can be processed on the PIC by an on-chip photonic device, electro-optic device, or optoelectronic device

[150] , regardless of the polarization. A photonic device, electro-optic device, or optoelectronic device is a device that processes light with or without transduction to or from an electrical domain, and can be, for example, a filter, wavelength division multiplexer, optical add-drop multiplexer, or electro-optic modulator. It may also include a photodetector, for example, in combination with a power monitor tap or optical add-drop multiplexer. It can be reconfigured according to an electrical control signal and can generate or convert high-speed electrical signals. Regardless of whether it involves electrical signals, it will be referred to hereinafter as a photonic device.

[0070] The device includes a molded glass inserter

[300] , a PIC

[100] having two polarization-selective couplers [110A], [110B] and a photonic subcircuit

[140] connecting the two elements, and two Faraday rotators [500A], [500B]. The photonic subcircuit

[140] is a subset of the optical circuitry on the PIC

[100] and includes one or more photonic devices

[150] .

[0071] The photonic subcircuit

[140] connects two polarization-selective couplers [110A] and [110B] via a bidirectional photonic subcircuit

[140] , such that at least a portion of the light entering the photonic subcircuit through the first polarization-selective coupler [110A] leaves the photonic subcircuit through the second polarization-selective coupler [110B], and at least a portion of the light entering the photonic subcircuit through the second polarization-selective coupler [110B] leaves the photonic subcircuit through the first polarization-selective coupler [110A]. The photonic subcircuit

[140] has at least two ports [141A] and [141B] connected via waveguides [120A] and [120B], one port connected to the polarization-selective coupler [110A] and the other port connected to the polarization-selective coupler [110B]. At least a portion of the light injected into the photonic subcircuit

[140] via one of these ports leaves the photonic subcircuit

[140] via the other of these ports.

[0072] The photonic subcircuit

[140] can further process the light, for example by modulating the amplitude and / or phase according to the data stream, by filtering it according to the wavelength, by monitoring it using a tap and a photodetector, by discarding certain communication channels according to the wavelength and then photodetecting them, or by adding certain communication channels according to the wavelength. In other words, some, but not all, of the light needs to be transmitted between the two ports [141A] and [141B] of the photonic subcircuit

[140] . Light of all wavelengths can be transmitted between the two ports [141A] and [141B], or, for example, if the optical circuit

[140] includes wavelength-selective photonic devices

[150] , only some wavelengths of light can be transmitted between the two ports [141A] and [141B].

[0073] The photonic device

[150] may also be a device having at least two ports, such that one of its ports is directly or indirectly connected to port [141A], and the other of its ports is directly or indirectly connected to port [141B]. Similarly, ports [141A] and [141B] may be directly connected to polarization-selective couplers [110A] and [110B] using waveguides [120A] and [120B], or may be indirectly connected to polarization-selective couplers [110A] and [110B], for example, via insertion devices. Two components on the PIC are considered connected if at least some light propagates from one component to the other. A direct connection refers to a direct connection using waveguides, while an indirect connection refers to a connection using one or more insertion devices. In its simplest form, the photonic subcircuit

[140] includes a two-port photonic device

[150] , a waveguide connecting a first polarization-selective coupler [110A] to a first port of the device

[150] , and a waveguide connecting a second polarization-selective coupler [110B] to a second port of the device

[150] .

[0074] The photonic device

[150] can be a bidirectional device that functions in both directions in which light can propagate through the device (from the first port to the second port or from the second port to the first port). In a preferred embodiment, the 2-port photonic device

[150] is an electro-optic modulator

[151] that modulates light entering through either of its optical ports and transmits the modulated light to the other of its two optical ports. This modulation occurs regardless of the direction in which the light travels through the device, i.e., the modulator is a bidirectional electro-optic modulator. This can be achieved, for example, if the modulator is electrically driven as a lumped element, i.e., if the modulator is small enough that the electrical signal transmitted to its active elements (phase shifter, electroabsorption section) is substantially the same throughout the device in a given time. For example, a traveling wave modulator is not a lumped element modulator and typically operates at the highest target modulation rate only when the light travels in the preferred direction. Examples of lumped element modulators are, for instance, resonant ring modulators, zigzag modulators (Mach-Zehnder modulators, whose phase shifters are zigzag-shaped to make them small enough from an electrical point of view to be lumped elements), and certain types of slow-light modulators that are compact enough to be lumped elements. A bidirectional slow-light modulator can be implemented as a resonant-assisted Mach-Zehnder modulator, in which several ring modulators are driven together according to a single data stream.

[0075] The glass insert couples the second optical element [200A] and the third optical element [200B] to the PIC

[100] , wherein two polarizations arriving from the second optical element [200A] are routed to the corresponding polarization-selective couplers [110A] and [110B] of the PIC, and light emitted from the same two polarization-selective couplers of the PIC is routed to the third optical element [200B]. Non-reciprocal polarization rotation of the Faraday rotators [500A] and [500B] is required to separate the beam paths of the two coupling schemes (second optical element [200A] to PIC

[100] and PIC

[100] to the third optical element [200B]), which are non-reciprocal. The required complex functionality of the glass insert

[300] can be achieved by adding a second layer of polarization-selective and / or polarization-insensitive reflectors to the glass insert elements on which preferred embodiments A, B, and C are based. In other words, the complex glass inserts required here can be manufactured by stacking simpler components and assembling them together, as described in more detail in the description of the manufacturing method. Figure 6 In this context, for example, a set of reflectors [310A], [310B], and [330A] can be seen on a first level, and reflectors [310C] and [330B] are stacked on a second level above the first level. Furthermore, in Figure 6In this configuration, reflectors [310A], [310B], and [330A] are oriented in one direction, for example, at -45° relative to the surface normal of the PIC or within + / -20° of that angle, while reflectors [310C] and [330B] are oriented in another direction, for example, at +45° relative to the surface normal of the PIC or within + / -20° of that angle. Here, in an equivalent (symmetrical) embodiment, +45° and -45° can be interchanged with each other.

[0076] In the following description, the beam path is described according to whether the light is polarized along s-polarization or p-polarization. In this specification, the s- and p-polarizations can be interchanged by reconfiguring the polarization-selective reflector

[310] of the inserter

[300] and the polarization-selective couplers [110A], [110B] of the PIC

[100] (depending on which polarization is transmitted or reflected / discarded) and the Faraday rotators [500A], [500B] (depending on the direction of rotation, i.e., the sign of the rotation angle). In other words, the exact nature of the two polarizations is not important, as long as they are orthogonal to each other. An exemplary selection... Figure 6 The polarization shown is used to enable the implementation of a polarization-selective reflector

[310] to operate in a MacNeille configuration.

[0077] The beam path is described as follows: A first lens [320A] collimates the two polarizations of light from a second optical element [200A] and guides it to a first polarization-selective reflector [310A]. The p-polarized light is transmitted through the polarization-selective reflector [310A] and focused by a second lens [320B] onto the first polarization-selective coupler [110A] of the PIC

[100] . A first Faraday rotator [500A] is located in the beam path of the p-polarized light, for example, between the second lens [320B] and the PIC

[100] , and rotates the polarization by 45°. The rotation direction of the Faraday rotator [500A] and the orientation of the polarization-selective coupler [110A] are configured such that the light is coupled into the PIC. S-polarized light emitted from the second optical element [200A] is reflected by the first polarization-selective reflector [310A] to the second polarization-selective reflector [310B], which reflects the s-polarized light again and routes it to the third lens [320C], which focuses the s-polarized light onto the second polarization-selective coupler [110B] of the PIC

[100] . A second Faraday rotator [500B] is placed in the beam path of the s-polarized light and rotates the polarization by 45°. The rotation direction of the Faraday rotator [500B] and the second polarization-selective coupler [110B] are configured such that the light is coupled into the PIC. The path of light emitted from the second optical element [200A], which has p-polarization, and routed to the first polarization-selective coupler [110A] constitutes the first beam [400A]. The path of light emitted from the second optical element [200A] with s-polarization and routed to the second polarization selective coupler [110B] constitutes the second beam [400B].

[0078] Light entering the PIC

[100] through the first polarization selective coupler [110A] is processed by the photonic sub-circuit

[140] and leaves the PIC through the second polarization selective coupler [110B]. On the other hand, light entering the PIC through the second polarization selective coupler [110B] is processed by the photonic sub-circuit

[140] and leaves the PIC through the first polarization selective coupler [110A].

[0079] Light emitted from the second polarization-selective coupler [110B] of the PIC

[100] is transmitted in the opposite direction through the second Faraday rotator [500B], where its polarization is rotated again by 45° in a non-reciprocal manner, converting it back to p-polarized light. The light is collimated using a third lens [320C] and guided to the second polarization-selective reflector [310B]. Here, the light is transmitted and guided to the third polarization-selective reflector [310C], where it is transmitted and focused using a fourth lens [320D] onto the coupling interface of the third optical element [200B].

[0080] Light emitted from the first polarization-selective coupler [110A] of the PIC

[100] is transmitted in reverse through the first Faraday rotator [500A], where its polarization is rotated 45° in a non-reciprocal manner, converting it back to s-polarized light. The light is collimated using a second lens [320B] and directed toward the first polarization-selective reflector [310A]. Here, the light is reflected toward a fourth (polarization-selective or polarization-insensitive) reflector [330A], at which it is reflected toward a fifth (polarization-selective or polarization-insensitive) reflector [330B], at which it is reflected again toward a third polarization-selective reflector [310C], at which it is reflected and refocused onto the coupling interface of the third optical element [200B] using a fourth lens [320D].

[0081] The path of light emitted from the first polarization-selective coupler [110A] and routed to the third optical element [200B] constitutes the third beam [400C]. The path of light emitted from the second polarization-selective coupler [110B] and routed to the third optical element [200B] constitutes the fourth beam [400D].

[0082] To better distinguish Figure 6 The beams [400A], [400B], [400C], and [400D] are represented by solid arrows with filled arrowheads. The beams [400A] and [400B] travel from the second optical element [200A], through the optical inserter

[300] , and reach the PIC

[100] . The corresponding polarizations are also represented by filled arrowheads. The beams [400C] and [400D] travel from the PIC

[100] , through the optical inserter

[300] , and reach the third optical element [200B]. The corresponding polarizations are also represented by open arrowheads.

[0083] At a more abstract level, the functions of the three polarization-selective reflectors [310A], [310B], and [310C] can be described as follows: The first polarization-selective reflector [310A] has the function of (i) separating the incident beams [400A] and [400B] emitted from the second optical element [200A] according to their polarization, sending the first incident beam [400A] to the first polarization-selective coupler [110A] and sending the second incident beam [400B] to the second polarization-selective reflector [310B]. It also has the second function of (ii) routing the first return beam [400C] from the first polarization-selective coupler [110A] to the third polarization-selective reflector [310C]. The second polarization-selective reflector [310B] has the function of (i) routing the second incident beam [400B] from the first polarization-selective reflector [310A] to the second polarization-selective coupler [110B] and routing the second return beam [400D] from the second polarization-selective coupler [110B] to the third polarization-selective reflector [310C]. The third polarization-selective reflector [310C] has the function of combining the return beams [400C] and [400D] arriving from the first polarization-selective reflector [310A] and the second polarization-selective reflector [310B], respectively, and routing them to the third optical element [200B]. Whether these functions are implemented in reflection mode or transmission mode, and whether the routing is direct or indirect, for example with an additional insert reflector

[330] , is a concrete and non-concrete implementation for the basic routing map of the beam.

[0084] The function of routing a beam from the first element to the second optical element and another beam returning from the second optical element to the third optical element is also the function of an optical circulator, which is a non-reciprocal device. Therefore, together with the Faraday rotators [500A] and [500B], the polarization-selective reflectors [310A] and [310B] each function as circulators. Furthermore, the polarization-selective reflector [310A] functions to split the beams [400A] and [400B] incident from the second optical element [200A]. The polarization-selective reflector [310C] functions to combine the returning beams [400C] and [400D] before they are routed to the third optical element [200B].

[0085] Alternative configurations can also be implemented, in which polarization-selective reflectors [310A] and [310B], together with Faraday rotators [500A] and [500B], each function as a circulator as described above, but wherein polarization-selective reflector [310A] has the additional function of combining the returned beam instead of splitting the incident beam. In this configuration, polarization-selective reflector [310C] also functions as splitting the incident beam instead of combining the returned beam. This configuration can be achieved, for example, by interchanging each other. Figure 6 The second optical element [200A] and the third optical element [200B] are used to simply reverse the direction of all beams and the rotation direction of the Faraday rotator to accommodate the reverse path. Therefore, typically two polarization-selective reflectors, together with their associated Faraday rotators, each function as a circulator. One of these two polarization-selective reflectors has the additional function of (i) splitting the incident beam according to its polarization after it has been emitted by the second optical element [200A], or (ii) combining them before sending the oppositely polarized returning beam to the third optical element [200B]. The third polarization-selective reflector has the other of the two functions (i) or (ii). Thus, four functions, namely two circulators, a polarization beam splitter, and a polarization combiner, are distributed across three polarization-selective reflectors [310A] to [310C], one of which, in addition to being part of an optical circulator, also has the dual function of combining or splitting beams.

[0086] In a preferred embodiment, all polarization-selective reflectors [310A], [310B], and [310C] are of the same type (in terms of which polarization is transmitted or reflected). In another preferred embodiment, reflectors [330A] and [330B] are also implemented with the same type of surface treatment. This greatly facilitates the manufacture of the optical insert because the same surface treatment (e.g., thin-film coating) can be used on all these reflectors. This is possible because [330A] and [330B] are required to reflect... Figure 6 The s-polarization in [310A], [310B], and [310C] is the same. In another preferred embodiment, the Faraday rotators [500A] and [500B] are of the same type. If the two Faraday rotators are oriented in the same way, such that the incident beams [400A] and [400B] both rotate in the same direction, then the single-polarization grating couplers [112A] and [112B] should preferably be orthogonally (perpendicularly) oriented to each other. If one Faraday rotator is inverted, such that one incident beam is rotated +45° and the other incident beam is rotated -45°, then the two single-polarization grating couplers should preferably be oriented parallel or antiparallel to each other.

[0087] In this preferred embodiment, bidirectional polarization-selective routing is achieved by utilizing a polarization-selective reflector on the glass insert and by orienting or adjusting a polarization-selective coupler on the PIC in conjunction with a Faraday rotator. Thus, the bidirectional polarization-selective routing function is distributed across the PIC and the glass insert. Since two polarizations are routed from the second optical element [200A] to two different polarization-selective couplers [110A] and [110B] on the PIC

[100] , and light with the same polarization emitted from the polarization-selective couplers [110A] and [110B] is later routed to different third optical elements [200B], the entire system is inherently non-reciprocal and cannot be implemented without one or more Faraday rotators.

[0088] Alternatively, different PIC configurations will be able to achieve the same or similar optical inserters

[300] as Figure 6 The same functionality is shown, but without the need for Faraday rotators [500A] and [500B]. In this PIC configuration, the two polarization-selective couplers [110A] and [110B] are each replaced by dual-polarization couplers [170A] and [170B]. The photonic subcircuit

[140] is configured to support two polarizations, i.e., the desired functionality is achieved for light of either polarization. This can be achieved using a photonic component

[150] that supports two polarizations, or by splitting the polarization within the subcircuit

[140] and by configuring two sets of photonic components

[150] , each of the two sets of components [150A] and [150B] handling one polarization. The polarization of the light can be rotated and interchanged before entering one of the components [150A] and [150B] and after leaving one of the components [150A] and [150B], so that the photonic components [150A] and [150B] can be of the same type.

[0089] The dual polarization couplers [170A] and [170B] are capable of coupling (receiving) incident light with either polarization into the waveguides [120A] and [120B], and coupling light with either polarization from the waveguides [120A] and [120B] out of the PIC (emitting). The Faraday rotators [500A] and [500B] are no longer needed and are removed. The orientation of the dual polarization couplers can be adjusted accordingly. In all other respects, the aspects previously described in Embodiment D still apply. The dual polarization couplers [170A] and [170B] are configured (oriented) such that beam [400A] is coupled to waveguide [120A] with a first polarization and beam [400B] is coupled to waveguide [120B] with a second polarization. Since beams [400A] and [400B] have opposite (orthogonal) polarizations, this can correspond to dual polarization couplers [170A] and [170B] to share a common orientation.

[0090] The light from beam [400A] propagates from the dual polarization coupler [170A] to port [141A] of sub-circuit

[140] , from port [141A] to port [141B] of sub-circuit

[140] , and from port [141B] back to the dual polarization coupler [170B]. There, it is emitted from PIC

[100] with a polarization orthogonal to the polarization of beam [400B], and corresponding to... Figure 6 The polarization of the beam [400D] (and also the initial polarization of the beam [400A]). This is because the light from beams [400A] and [400B] has orthogonal polarizations inside the PIC, and therefore, in the absence of a non-reciprocal device such as a Faraday rotator

[500] , it also needs to be orthogonal after leaving the PIC (emitted from the PIC). Similarly, the light from beam [400B] then propagates from the dual polarization coupler [170B] to port [141B] of the sub-circuit

[140] , from port [141B] to port [141A] of the sub-circuit

[140] , and from port [141A] to the dual polarization coupler [170A]. There, it is emitted from the PIC

[100] with a polarization orthogonal to the polarization of beam [400A] and corresponding to... Figure 6 The polarization of the beam [400C] (and also the initial polarization of the beam [400B]). Therefore, the light emitted from the PIC subsequently follows the same polarization as... Figure 6 The same optical path is depicted in the diagram and described above, so that it is coupled to a third optical element [200B].

[0091] The challenge associated with dual-polarization couplers [170A] and [170B] is that they need to couple two polarizations to a single waveguide [120A] or [120B], or couple two polarizations from a single waveguide [120A] or [120B], rather than coupling light to one of the two waveguides individually based on polarization, or coupling light from one of the two waveguides. This functionality can be achieved, for example, through a 1D diffraction grating (similar to a single-polarization grating coupler) from which the two polarizations are emitted at different angles, or which are incident on the 1D diffraction grating at different angles. Alternatively, the two polarizations can be emitted from or received by the dual-polarization couplers [170A] and [170B] at different locations on the coupler. Therefore, either or both of these must be considered in the optical inserter design. Finally, grating couplers can be designed to transmit / receive two polarizations at the same location and at the same angle by managing birefringence within the grating coupler, for example, by using subwavelength patterning / structure.

[0092] In this configuration of the PIC

[100] , Faraday rotators[500A] and[500B] are not required because the PIC supports two polarizations of light, one inside the waveguides[120A] and[120B] and the other inside the photonic subcircuit

[140] . This provides an additional degree of freedom for the light, which determines where the light is routed after leaving the PIC

[100] , which can be used with reciprocal optics for routing. In the previous PIC configuration, this degree of freedom was given only by the direction of light travel, since the polarization-selective couplers[110A] and[110B] receive and emit light with the same polarization. By definition, using the direction of light to determine the path followed by light is a property of non-reciprocal devices, such as those implemented by the Faraday rotator

[500] .

[0093] At a more abstract level, in this alternative embodiment that uses a dual polarization coupler to verify the functionality of embodiment D, polarization-selective reflectors [310A] and [310B] can be seen to verify the equivalent functionality of a circulator with reciprocal devices, which is obtained using switched polarizations of forward and reverse paths (beams [400A] and [400C] have opposite polarizations, and beams [400B] and [400D] have opposite polarizations).

[0094] The fourth embodiment D can be used to implement massively parallel optical processing in space close to the core of an electrical switch by using a single-mode optical fiber [201A] (an example of a second optical element [200A]) to couple a remote light source to a PIC

[100] and sending the processed light to an interconnecting optical fiber [201B] (an example of a third optical element [200B]) that is further routed to a downstream electro-optic receiver. In such a receiver, the coupling device according to embodiment A or C can be used. A transmitter using the coupling device according to embodiment D and a receiver using the coupling device according to embodiment A or C can be combined in a common PIC, a common sub-component, or a common package.

[0095] When optics are co-packaged with heat-generating electronics, remotely positioned light sources are highly advantageous because lasers suffer performance degradation at elevated temperatures. Furthermore, when electronic switches are co-packaged with other parts of the transceiver system, such as electro-optic modulators, remotely positioning the laser and connecting it to one or more optical fibers allows for replacement of a single laser in case of failure, without replacing the entire switch. Using one or more single-mode fibers to connect one or more remote lasers to the PIC, rather than polarization-maintaining fibers, is highly advantageous because it significantly reduces manufacturing costs. Co-packaging optics with high-speed electronics is also advantageous because it avoids electrical signal attenuation and distortion that would otherwise occur in the inserted printed circuit board traces. The greatest challenge lies in coupling light into and out of the PIC in a manner that is scalably parallelizable and polarization-insensitive, which is the problem addressed in this paper. Assuming a lens pitch of 250 μm in one in-plane direction (corresponding to the standard pitch between fibers in a fiber optic array) and a coupler / lens pitch of 3.5 mm in another in-plane direction (corresponding to the thickness of a typical fiber optic array), over 1000 fibers can be attached to a standard silicon photonic device with a 32 × 30 mm crosshair size, corresponding to over 500 bidirectional optical links. At current state-of-the-art data rates (50 gigabits 4-level pulse amplitude modulation, corresponding to 100 Gb / s), this would correspond to a total bandwidth exceeding 50 Tb / s, meeting the data throughput requirements of top-rack switches in data centers. Another promising application area for this packaging scheme is the massively parallel optical distribution of signals to phased array antennas, as anticipated by 5G wireless technology.

[0096] In Figures 1 to 6 and Figures 11 to 13In this diagram, the device on the PIC

[100] is shown as having an inserter

[300] or inserter component blocks

[600] ,

[700] ,

[800] ,

[900] attached to the same side (surface) of the PIC. However, a surface emission coupler can also emit / receive light through the back side of the PIC, which is opposite to the side on which the surface emission coupler is fabricated. In this case, the inserter

[300] or inserter component blocks

[600] ,

[700] ,

[800] ,

[900] will also be mounted on the back side of the PIC. While this may cause the beam emitted by the surface emission coupler to be widened due to the increased propagation distance traveled before reaching the inserter

[300] , this can be compensated for by lenses [320A], [320B] built into the inserter without requiring additional structural elements. All configurations described above and below can be generalized to surface-emitting couplers that emit or receive light from a surface located on the back side of a PIC, which is defined as opposite to the side on which couplers and other photonic devices are fabricated.

[0097] Detailed description of the invention (method)

[0098] The present invention includes a method for manufacturing the foregoing embodiments and other devices, which forms a glass inserter

[300] by assembling a plurality of identical glass-molded component blocks

[600] . More complex glass inserters

[300] can be constructed by assembling different types of component blocks

[600] ,

[700] ,

[800] ; however, the number of different types of component blocks is kept to a minimum for ease of inventory and production. In particular, the method of manufacturing the above-described embodiments AD is disclosed below.

[0099] The first type of component block

[600] is composed of... Figure 7The component block includes a facet

[601] that can serve as a mechanical contact and attachment interface when attaching another optical element such as a PIC

[100] , a laser diode, or an optical fiber

[201] (or, more generally, a second or third optical element

[200] , [200A], [200B]), precisely determining the distance between the optical element and the lens

[602] , and precisely determining the angle of the beam emitted / received by the PIC

[100] or the second or third optical element

[200] , [200A], [200B] relative to the optical axis of the lens. The component block also includes two optical facets

[603] and

[604] , which can be surface-treated, for example, with a thin-film coating, grating, metallization, or any other surface treatment described herein, to define polarization-selective or polarization-insensitive reflectors

[310] ,

[330] , polarization-selective filters

[310] , wavelength-selective filters

[340] (e.g., for implementation of wavelength division multiplexers), or to reduce reflection (anti-reflective coating). Depending on the configuration, the light beam can be reflected, transmitted, scattered, or absorbed at these optical facets in a polarization-selective or polarization-insensitive manner and in a wavelength-selective or wavelength-insensitive manner. Features

[605] and

[606] facilitate manufacture via glass molding and assembly (stacking) of the component block, as described below. The optical axis

[607] of the lens

[602] is indicated by a dashed line.

[0100] In addition, such as Figure 7 As shown in (b), the component block may have a recess

[608] formed into the facet

[601] , creating a space in which additional optical elements

[609] , such as a Faraday rotator

[500] , a birefringent plate, a polarizer, a dichroic mirror, or other wavelength-selective devices, can be inserted, such that light rays transmitted (propagated) along the optical axis

[607] of the lens are also transmitted (propagated) through the inserted optical element

[609] . The optical element

[609] may, for example, be attached to a... Figure 7 (b) shows the stepped features on the side of the recess

[608] . Figure 7(a) and 7(b) show exemplary cross-sections of such a component block

[600] without the recess

[608] and with the recess

[608] . The inserted optical element

[609] can also be a wedge-shaped or prismatic element that alters the propagation angle of the beam due to its non-parallel surface. This is useful, for example, if a PIC

[100] is later attached to a facet

[601] of the component block, where a surface-emitting or receiving polarization-selective coupler

[110] , such as a grating coupler

[112] , emits or receives the beam at an angle to the surface normal of the PIC. The inserted optical element

[609] can then be used to reorient the direction of the beam to be substantially parallel to the optical axis

[607] of the lens

[602] , or to move the axis of the beam before reaching the lens. If the facet

[601] is attached to a second or third optical element

[200] , [200A], [200B] that emits a beam of light at an angle, such as glass fiber

[201] with the end facet polished at an angle, similar considerations still exist.

[0101] In a preferred embodiment, facet

[601] is perpendicular to the axis

[607] of the lens

[602] . In a second preferred embodiment, facet

[601] forms an angle of no more than 20° with respect to a plane perpendicular to the axis

[607] of the lens

[602] . In a preferred embodiment, the first optical facet

[603] forms an angle of -45° with respect to the axis

[607] of the lens

[602] , or within + / -20° of that angle. In a preferred embodiment, the second optical facet

[604] forms an angle of +45° with respect to the axis

[607] of the lens

[602] , or within + / -20° of that angle. Positive angles are counterclockwise, while negative angles are clockwise. The axis between the center points of the two optical facets

[603] ,

[604] may be perpendicular to the axis

[607] of the lens

[602] .

[0102] The component blocks can be manufactured using a glass molding process, preferably by molding several identical or different component blocks onto a plate-shaped (wafer-shaped) glass preform

[1000] , the bottom and top surfaces of which have been pre-polished to ensure optical-grade surface quality. For example... Figure 8 As shown, component blocks

[600] ,

[700] ,

[800] can be repeated on one or more molds to form a 2D array

[1001] of the basic structure, thereby realizing multiple replicas of the same component blocks at the (glass) wafer level using a single glass molding process. These component blocks can then be later divided into individual component blocks, groups of component blocks, or smaller arrays of component blocks, for example when parallel optical transceivers (e.g., parallel single-mode PSM transceivers) or optical devices with multiple input and / or multiple output fibers (such as optical switches and routers) require an array of coupling structures. Figures 7 to 22As shown, the preferred pitch of the component blocks along the x-axis is 250 μm or 127 μm, because these correspond to the pitch between fibers in a standard fiber array. The x-axis corresponds to one of the axes parallel to the wafer surface and corresponds to the axis relative to the wafer surface. Figure 7 and Figure 20 The out-of-plane axis of the component block cross section is shown. The component block is molded using two molds [1201A] and [1201B], one mold forming the attachment interface

[601] , the lens

[602] and the optional recess

[608] , while the second mold forming the first optical facet

[603] and the second optical facet

[604] , as well as features

[605] and

[606] .

[0103] exist Figure 7 In the middle, where the two optical facets

[603] and

[604] would otherwise merge, additional small facets

[605] are provided. This facilitates the molding of the component blocks, since otherwise sharp tips would be formed where the two facets

[603] and

[604] merge. Such sharp features are difficult to manufacture with glass molding and lead to low yield and faster mold deterioration, thus reducing the number of molding steps they can be used for. In order to allow the stacking and assembly of component blocks to form composite component blocks

[900] , corresponding complementary features

[606] are provided at the base of either the optical facets

[603] or

[604] . Figure 7 In this context, the complementary feature

[606] is also shown as a small facet that can have the same width as the facet

[605] (in the y-direction, as shown). As described below, features

[605] and

[606] can also provide mechanical contact to guide the component blocks to be precisely positioned relative to each other when constructing the composite component block

[900] .

[0104] The component blocks described above can be assembled with other component blocks of the same or different types to achieve the target function in the composite component block

[900] . In the following text, the letters A, B, C, D, etc. (in...) Figures 9 to 22 The composite component blocks (in the middle) identify the individual components forming the composite component block and their corresponding features. For example, the composite component blocks enable the surface treatment of the inner surface of the assembled inserter

[300] . They also enable the formation of complex shapes that are difficult or impossible to form directly using a single molding process. For example, forming two lenses that are perpendicular to each other (such as...) Figure 9 (b) As depicted, where lenses [602A] and [602C] are oriented perpendicularly to each other, it would be difficult to manufacture in a single molding process, and even if possible, it would adversely affect yield. Furthermore, if the entire insert is formed by a single molding process, the inner surface of the composite component block

[900] (such as...) Figure 9The treatment of [603A] and [603B] in (a) to 9(d), i.e., the inner surface formed by combining the facet [603A] of component block [600A] with the facet [603B] of component block [600B], is not possible. Relying on as many component blocks of the same type as possible is beneficial for inventory, thereby reducing manufacturing costs.

[0105] In a preferred embodiment, the assembly of the component blocks is accomplished by an epoxy resin or hot-paste-based bonding process, wherein the epoxy resin can be thermosetting or UV-curing. In another preferred embodiment, the assembly is formed by welding. A metallic coating is deposited on some or all of the surface of the component blocks, where spatial selectivity is achieved, for example, through a shadow mask, and the molded glass component blocks can then be directly welded to each other to form a composite component block. The welding process can be a laser welding process, a thermal welding process, or an induction welding process. When in the beam path, the epoxy resin or other materials used for assembly are generally transparent at one or more target wavelengths and refractive indices that match the materials used to form the individual component blocks, in order to minimize optical losses due to absorption or internal reflection within the inserter.

[0106] In the following figures, the facets of the components depicted as contacting each other, or referred to as assembled, can be in direct mechanical contact with each other (after the application of surface treatments such as thin-film coatings and internal gratings, or in direct mechanical contact with the untreated surface of another component). They can also be separated by thin layers of adhesive material, such as cured epoxy. While small apertures between facets are theoretically possible, this is generally undesirable in the beam path because the interface will have significant refractive index discontinuities leading to high reflectivity, which will be further affected by high variability unless the aperture width is controlled very precisely.

[0107] The component blocks

[600] described above allow for different forms of stacking, such as Figure 9 As shown. It should be noted that there may be several arrangements for the component block

[600] , as the feature

[606] may be positioned at the base of the facet

[603] (as shown) or at the base of the facet

[604] . In addition, the lens

[602] may be positioned such that its optical axis

[607] preferably cuts the facet

[603] or facet

[604] at the midpoint of its yz plane. These figures are based on one such configuration (feature

[606] at the base of the facet

[603] , and the optical axis

[607] cutting the facet

[603] at its midpoint), but the composite component block configuration described below also applies to other arrangements of the component block

[600] .

[0108] Figure 9(a) Depicts a configuration in which two component blocks [600A] and [600B] are assembled such that their respective facets [603A] and [603B] are joined together. In this composite component block, facets / features [606A] and [605B] are also joined together. So are [605A] and [606B]. Thus it can be seen how features

[605] and

[606] of component block

[600] can act as mechanical alignment features, as they prevent sliding along the contact interface at the joint of [603A] and [603B]. Furthermore, it can be seen that the optical axes [607A] and [607B] of lenses [602A] and [602B] coincide. Together they form the optical axis [901A] of composite component block

[900] . To make the optical axes of the two lenses coincide, the position of the lens

[602] of the component block

[600] can be selected such that its optical axis

[607] intersects the facet

[603] at the midpoint of the facet

[603] in the yz plane, as shown below. Figure 7 and Figure 9 What is depicted.

[0109] It can be seen that the lens [602A] of component block [600A] and the lens [602B] of component block [600B] are located on opposite surfaces of the composite component block, i.e., they are rotated 180° relative to each other. Their optical axes [607A] and [607B] are oriented from the lens surface toward the interior of the component block, and can be oriented relative to each other at 180° or within + / - 20° of that angle.

[0110] Figure 9 (b) shows an alternative configuration in which an additional component block [600C] is added to the composite component block. This could, for example, provide an additional lens [602C] whose optical axis [607C] is orthogonal to axis [901A] or within an angle of + / -20° to said direction. Axis [607C] forms an additional optical axis [901B] of the composite component block

[900] . It intersects facets [603A] and [603B] at the midpoint of facets [603A] and [603B], at the same point where optical axis [901A] also intersects facets [603A] and [603B]. This is a necessary condition for facets [603A] or [603B] to act as mirrors to direct light beams from lens [602C] to [602A] (and vice versa). To achieve this configuration, facet [603C] of component block [600C] is combined with facet [604A] of component block [600A]. Facets [605C] and [606C] of component block [600C] are combined with side facets of component blocks [600B] and [600A], respectively, wherein the side facets of component blocks [600B] and [600A] may have already been formed during the division of the component blocks (e.g., by cutting). Not all facets are already formed. Figure 9The text is marked to avoid overloading the diagram, even though it is mentioned in this article. However, according to... Figure 7 The markers in the text can be easily identified because Figure 9 All the component blocks shown are of the same type.

[0111] It can be seen that the lens [602A] of component block [600A] and the lens [602C] of component block [600C] are oriented at 90° relative to each other. Their optical axes [607A] and [607C] are oriented from the lens surface toward the interior of the component block and can be oriented at +90° or -90° relative to each other or within + / -20° of these angles.

[0112] If the intended function is to route the light beam between lenses [602A] and [602C] via a reflector formed by facet [603A] (with or without surface treatment), and especially if the reflector is not intended to be polarization- or wavelength-selective, then from Figure 9(b) The component block [600B] is omitted in the composite component block shown. In fact, for glass refractive indices higher than 1.4142, and if the facet [603A] is at a 45° angle relative to the optical axes [901A], [901B] as described above, total internal reflection is achieved, thus a reflector will be obtained at the glass-air interface even without a surface coating. However, this also makes it difficult to implement a polarization- or wavelength-selective reflector at the facet [603A] without the component block [600B]. While polarization selectivity can still be achieved using, for example, a metal grating, a thin-film coating, which is easier to manufacture, will not work because both polarizations will be reflected at the air interface due to total internal reflection, regardless of the deposited film. Therefore, to implement wavelength- or polarization-selective reflectors

[340] ,

[310] , including the component block [600B] to prevent high refractive index contrast with air may be beneficial. In this case, the lens [602B] may not be functional. It may still be advantageous to construct a composite component block

[900] by assembling three identical component blocks

[600] to reduce the number of different parts involved in the manufacturing process. In that case, light would not reach the lens [602B] of component block [600B] under normal operation, so the lens is not needed. However, it may also be advantageous to replace component block [600B] with a component block having all the same features except for the lens. Since the lens has the finest features, molds that include the lens will be more expensive and will experience faster degradation, thus limiting the number of molding steps that a given mold can be used for. Therefore, when critical production levels have been reached, manufacturing a component block with a lens will be more expensive than manufacturing a component block without a lens. If [600B] is absent or does not include a lens, then [901A] is given only by [607A]. These considerations also apply to other configurations described below when a component block including a lens is depicted where the lens is not functionally required.

[0113] Figure 9 (c) describes another configuration, in which... Figure 9(a) Two additional component blocks [600C] and [600D] are added to the configuration shown. As previously mentioned, the lens in [600D] may or may not be functional. In the latter case, the presence of component block [600D] may be to eliminate the high refractive index contrast with air at facet [603C]. The line connecting the two points where the optical axis [607A] of lens [602A] intersects with facet [603A] and the optical axis [607C] of lens [602C] intersects with facet [603C] forms the second optical axis [901B] of the composite component block

[900] . When present, the optical axes [607C] and [607D] of lenses [602C] and [602D] coincide and form the third optical axis [901C] of the composite component block

[900] . If [600D] is absent or does not include a lens, then [901C] is given only by [607C]. For example, a beam of light can be routed from lens [602B] to lens [602A] along axis [901A], or routed from lens [602B] to [602C] along axis [901A] to facets [603B] and [603A], reflected back to axis [901B] and routed along it to facets [603C] and [603D], reflected back to axis [901C] and routed along it to lens [602C].

[0114] Because in Figure 9 In the configuration shown in (c), component blocks [600A] and [600C], as well as component blocks [600B] and [600D], are kept side-by-side as they were originally manufactured in an array

[1001] on wafer

[1000] , so they do not need to be divided into individual component blocks before assembly, but can be kept in a block of two (or more) component blocks. This facilitates the assembly of composite component blocks because fewer parts need to be manipulated.

[0115] Figure 9 (d) illustrates a configuration built on top of configuration 9(c), to which an additional component block [600E] is added to provide a lens perpendicular to the other lenses, similar to the component block added in configuration 9(b) to configuration 9(a). The optical axis [607E] of lens [602E] coincides with the optical axis [901B] of 9(c). Together they form the new optical axis [901B] of configuration 9(d). For example, a beam of light can first be routed from lens [602E] to either lens [602A] or [602C] along the optical axis [901B]. Reflection towards axis [901A] at facets [603A], [603B] will cause the beam of light to be routed to lens [602A]. Reflection towards axis [901C] at facets [603C], [603D] (if present) will cause the beam of light to be routed to lens [602C]. As mentioned earlier, this reflection can depend on polarization or wavelength.

[0116] Features

[605] and

[606] do not need to be straight facets, especially when vertical stacking is primarily desired. This is in Figure 10 As shown in the figure. They can also consist of multiple facets or curved features, that is, they can also include circular elements to facilitate manufacturing, since any type of sharp feature at the junction of different facets may be more difficult to manufacture. Figure 10 (a) shows a version of component block

[600] in which features

[605] and

[606] have been replaced by circular features (such as arcs or elliptical features) but remain complementary to each other because one has the inverted shape of the other. Figure 10 As can be seen in (b), when the two component blocks [600A] and [600B] are assembled such that their facets [603A] and [603B] are joined together, their features [605A] and [606B], as well as their features [606A] and [605B], are also joined together without creating voids between them. Alternatively, as Figure 10 As shown in (c), even more material can be removed at one or both of features

[605] and

[606] , thereby forming pores [902A] and [902B] between features [606A] and [605B] and between features [605A] and [606B] respectively when assembling the composite component block, such as Figure 10 As shown in (d). These pores can be filled with air, vacuum, or other materials, but will not mechanically prevent the stacking of the component blocks. Furthermore, features

[605] and

[606] can be configured such that they continue to function as mechanical guides for assembling the composite component block

[900] . For example, in Figure 10 In (c), feature

[606] includes an additional facet

[610] opposite to facet

[603] that performs the role. When the component blocks [600A] and [600B] are attached to each other using epoxy resin or other adhesive materials, the pores can be used to store excess epoxy resin or adhesive material without negatively affecting the optical function of the composite component blocks, since the light beam does not pass through these areas. If the features enable the component blocks to be stacked such that the optical facets to be joined together can be joined seamlessly without creating pores between the optical facets at the location where the light beam passes, then these features are referred to herein as complementary to each other.

[0117] The optical facets of the component blocks can be coated with a single-layer thin film (including metals) or a stack of thin films (particularly dielectric films) to implement polarization-selective reflectors or filters

[310] , polarization-insensitive reflectors

[330] , anti-reflective coatings, or wavelength-selective reflectors

[340] (for implementation of wavelength division multiplexing systems). Alternatively, 1D or 2D gratings can also be etched into the facets, which also allows for the implementation of polarization-selective reflectors or filters

[310] and wavelength-selective reflectors

[340] . These surface treatments can be performed on all facets of all component blocks at a time on the glass wafer level, or only on a predetermined number of facets / predetermined areas. In a preferred embodiment, this can be achieved by using appropriate masking techniques during coating deposition. Typically, this can be accomplished by selectively removing the resist layer using optical lithography (e.g., using a stripping technique). Since surface treatments via thin-film deposition (typically applied to wide areas) generally do not require the fine features achieved by optical lithography, it may be more cost-effective and therefore a preferred method to perform shadow masking during deposition by covering the molded glass wafer (or a PIC wafer on which glass component blocks have already been mounted) with a reusable mechanical mask. In a second preferred embodiment, this can also be achieved by wafer-level deposition followed by removal of the thin-film coating in the predetermined facet region using appropriate etching processes and masking techniques.

[0118] In a preferred embodiment of the manufacturing method, the assembly of the component blocks is performed at the wafer level; that is, multiple component blocks are attached to each other before assembly, either as a molded glass wafer manufactured as a whole or as a block comprising at least a few component blocks that will be assembled together before dicing / further cutting. Other elements may be attached to the wafer or wafer parts as diced component blocks or groups of component blocks still attached to each other. Since the positions of the component blocks relative to each other are very clear before dicing, this is advantageous for assembly processes such as pick-and-place assembly. Furthermore, this approach provides alignment references on the wafer or wafer parts, eliminating the need to repeatedly provide alignment references for each individual component block, thus saving space and materials.

[0119] After assembly, such as Figure 7 , Figure 9 , Figure 10 and Figures 14 to 21 The inserters or inserter sub-assemblies shown can be divided into individual inserters that perform the functions described above, or divided into 1D or 2D arrays of such inserters, which remain attached to each other and can be transferred together and attached to a PIC or other optical element. This facilitates the placement of the inserters. For example, an alignment reference can be shared for the entire array. Furthermore, in the case of active alignment, ensuring that at least two inserters are properly aligned is sufficient to guarantee proper alignment of the entire 1D or 2D array.

[0120] As for assembling component blocks into composite component blocks or complete glass inserters, the assembly of glass inserters onto the PIC can also be done before the wafer on which the PIC is manufactured is fully or partially diced, i.e., before the PIC is diced. The PIC can be manufactured using silicon photonics technology, and the inserter can be attached to the silicon photonics wafer.

[0121] This is conceptual, like Figure 11 As shown. The three PICs [100A]-[100C] remain attached to each other. Each has four surface-emitting couplers and requires an optical inserter

[300] with a cross-section along the yz plane, the optical inserter

[300] being, for example, corresponding to Figure 7 , 9 Any one of 10, 14 to 21. Each inserter

[300] has four bottom lenses

[320] that transmit light to one of the four surface-emitting couplers

[110] or receive light from one of the four surface-emitting couplers

[110] (see also...) Figure 13 There are several options for attaching the inserters [300A]-[300C] to the PICs [100A]-[100C]. They can be assembled at the (glass) wafer level, attached to each other (unsplit), and transferred together to the three attached PICs, after which the PICs and optical inserters may be diced together. Alternatively, the optical inserters can be assembled at the glass wafer level, diced, and transferred individually to the three attached PICs, after which the PICs are diced. Finally, the optical inserters can also be transferred one by one to the already diced PICs. However, wafer-level assembly is generally more efficient at high volumes.

[0122] Alternatively, component blocks [600A]-[600C] or composite component blocks [900A]-[900C] can be transferred and attached to the attached PIC assembly for further processing (such as surface treatment) and further stacking of the component blocks before dicing the PIC, instead of transferring the fully assembled inserters [300A]-[300C] to the attached PIC. For PICs manufactured using silicon photonics technology, the advantage is that process steps such as surface treatment can be performed, for example, on a 300mm wafer, allowing for the parallel processing of a large number of optical sub-assemblies. Since glass preforms are currently much smaller than silicon wafers, this increases the scale of individual process steps (such as surface treatment).

[0123] At least in the x-direction (perpendicular to) Figure 7 , 9 The plane of the figures in Figures 10 and 14 to 22) is advantageous for holding arrays because it allows the pitch of these arrays to be directly matched to the pitch of standard fiber arrays. From an assembly perspective, the inserter is in the wafer direction on the other side (by... Figures 7 to 22It would be advantageous to keep the 2D arrays (given by the y-axis) attached to each other, but if the inserters are restricted to being spaced further apart in that direction due to the thickness of the fiber array, a significant amount of glass wafer surface area could be wasted. Therefore, it might also be advantageous to segment the array in the y-direction, allowing it to be tightly encapsulated on the glass wafer, but assembled on the PIC with a larger pitch. This is in Figure 12 As shown, component blocks [600A], [600B], composite component blocks [900A], [900B], or fully assembled inserters [300A], [300B] are transferred to a PIC or a group of attached PICs before being separated from each other by a cutting line along the x-direction. Since the pitch between the groups [110A]-[110D] and [110E]-[110H] of the surface-emitting couplers in the y-direction is greater than the width of the component blocks or inserters (along the y-direction), additional spacers

[1002] must be manufactured to match the pitch on the inserter side. This results in a reduction in material and glass wafer area. If the component blocks or inserters are separated before transfer, spacers

[1002] are not needed, and glass wafer area can be saved.

[0124] When a component block

[600] or a composite component block

[900] including a component block

[600] is attached to a PIC

[100] or another optical element

[200] , [200A], [200B], the mechanical contact facet / attachment interface

[601] of the component block

[600] can also be used to seal a portion of the surface of the PIC

[100] or other optical elements

[200] , [200A], [200B], as well as the lens

[602] of the component block

[600] , to isolate it from the environment. In particular, by ensuring that the facet

[601] completely surrounds the area below the lens

[602] , and by ensuring that adhesive material / solder is applied to the facet

[601] so as to also completely surround the area below the lens

[602] , the cavity formed between the lens and the PIC

[100] is effectively sealed. Figure 13 This allows the area below the lens

[602] of the component block

[600] to be maintained in a vacuum or improved atmosphere (e.g., N2 atmosphere or different inert atmospheres containing reduced oxygen levels). This is useful, for example, in cases where a laser is also present in the cavity formed by a glass inserter, which can be added to the PIC, for example, via flip-chip attachment. Sealing also prevents dust from entering the cavity. This protects, for example, surface-emitting couplers (e.g., such as...). Figure 13 The [110A]-[110D] shown and the lenses [602A]-[602D] are protected from dust.

[0125] While the manufacturing methods described herein can produce the inserters described above, they also allow for the production of different types of inserters, such as, for example, the simpler single-mode fiber attachment inserter shown in Figure 1, which can attach a second optical element

[200] to a PIC

[100] but does not have polarization management or isolation features. It can also be used to manufacture, for example,... Figure 19 The insert shown implements wavelength division multiplexing instead of polarization management by using a dichroic mirror or other wavelength-selective reflector instead of a polarization-selective reflector. Such a wavelength-selective reflector

[340] can also be manufactured by surface treatments as described above.

[0126] Conventional alignment references defined within a glass component block can be difficult to use for verifying the alignment / overlap of the component block with other structural elements such as a PIC, since the component block is preferably made of glass, i.e., transparent. One possibility is to utilize the fact that features manufactured into the glass, such as lenses, can distort patterns located on the other side (below) of the component block if visualized (imaged) through it (from above). For example, if visualized through a lens or other shaped surface of the glass component block, an array of lines, squares, crosses, or other alignment references defined on the PIC will be distorted, as the glass component block forms optical elements according to its alignment with the PIC. For instance, a straight line intersecting the optical axis of a lens will still be imaged as a straight line, while a straight line on one side of the lens's optical axis may be imaged as a curve due to distortion caused by an imperfect lens. Obtaining a straight line can serve as a standard for proper alignment. To achieve proper alignment on two axes parallel to the PIC surface, lines in two directions can be used, which can form a cross, but can also be different lines under different lenses (or more generally under different optical elements of the glass component block). Therefore, the deformation of the alignment reference visualized by the glass component blocks

[600] ,

[700] ,

[800] , composite component blocks

[900] , or complete inserters

[300] can be used as a standard for aligning the glass component blocks

[600] ,

[700] ,

[800] , composite component blocks

[900] , or complete inserters

[300] with respect to the PIC

[100] on which the alignment reference is defined.

[0127] Alternatively, lenses or other optical elements of the glass component block can be used to image lines, crosshairs, or other alignment references on the PIC surface. If the alignment reference is centered relative to the lens, i.e., on its optical axis, the resulting real or virtual image will remain aligned in a predetermined manner relative to surrounding alignment references not imaged by the lens. These surrounding alignment references can be imaged through one or more flat surfaces of the component block, composite component block, or inserter, wherein said surfaces are preferably parallel to the surface of the PIC. On the other hand, if the lens, and therefore the component block, composite component block, or inserter, is displaced relative to the imaging alignment reference, the real or virtual image produced by the lens will be displaced relative to surrounding alignment references not imaged by the lens. Therefore, the relative alignment between an alignment reference imaged by a lens or other optical element of a glass component block

[600] ,

[700] ,

[800] , composite component block

[900] , or complete inserter

[300] and an alignment reference not imaged by a lens or other optical element can be used as a standard for aligning the glass component block

[600] ,

[700] ,

[800] , composite component block

[900] , or complete inserter

[300] with respect to a PIC

[100] on which an alignment reference is defined. The optical element of the glass component block that images the alignment reference of the PIC can be as simple as a tilted facet, which also results in a displacement of the imaging alignment reference.

[0128] The following describes the application of this manufacturing method in the manufacture of preferred embodiments A to D and in optical inserters including wavelength division multiplexing:

[0129] 1. Figure 14 The construction with is shown Figure 14 The possibility of a composite component block

[900] with the function shown in (a) is required for the preferred embodiment B represented by FIG. 4(a). In one direction, the beam

[400] is collimated by lens [320A], reflected by polarization-selective reflector

[310] if it has reflective polarization, and finally focused by lens [320B]. The direction of the beam can also be reversed, in which case [320B] is the collimating lens and [320A] is the focusing lens.

[0130] Figure 14 (b) An embodiment based on two component blocks [600A] and [600B] is shown, wherein component blocks [600A] and [600B] are configured with... Figure 9 The configuration described in (b) is arranged as follows. [600A] and [600B] are assembled by joining facets [603A] and [604B]. Facet / feature [606A] serves as a mechanical stop for aligning the two component blocks relative to each other and can be joined with, for example, the side facet of [600B] formed by cutting. Lenses [602A] and [602B] are implemented respectively. Figure 14 The functions of lenses [320A] and [320B] in (a). The beam

[400] is first delivered from lens [602A] to facet [603B], which is surface-treated to function as a polarization-selective reflector

[310] along the axis [607A] of lens [602A], which also forms the axis [901A] of the composite block. If the beam has reflective polarization, it is further routed along its axis [607B] to lens [602B], which also forms the axis [901B] of the composite block. Regarding... Figure 14 (a) The direction of light can be reversed.

[0131] Applied to Figure 14 The faceted treatment in [603B] of (b) can be, for example, a metallic grating. It can also be a thin-film coating, even in which case, as explained above, it may be difficult to achieve a polarization-selective reflector at the glass-air interface

[310] . Therefore, as already... Figure 9 As described in (b), it may be advantageous to add additional component blocks [600C] to reduce the dielectric contrast on both sides of the interface formed by joining facets [603B] and [603C] together. Mechanical stops for aligning component block [600C] with the other two component blocks are now provided by facets / features [606B] that can be joined with facets / features [606C], facets / features [605B] that can be joined with facets / features [606C], and facets / features [605A] that can be joined with the side facets of component block [600C], these facets / features being formed, for example, by cutting.

[0132] 2. Figure 15 The construction with is shown Figure 15 The possibility of a composite component block

[900] with the function shown in (a) is required for the preferred embodiment B represented by FIG. 4(b). In one direction, the beam

[400] is collimated by lens [320A], and if the beam

[400] has transmission polarization, it is transmitted by polarization-selective filter

[310] and finally focused by lens [320B]. The direction of the beam can also be reversed, in which case [320B] is the collimating lens and [320A] is the focusing lens.

[0133] Figure 15 (b) An embodiment based on two component blocks [600A] and [600B] is shown, wherein component blocks [600A] and [600B] are configured to... Figure 9The configuration described in (a) is arranged as follows. [600A] and [600B] are assembled by joining facets [603A] and [603B]. Facets / features [605A] and [606A] serve as mechanical stops to align the two component blocks relative to each other, and can be joined with facets / features [606B] and [605B] respectively. Lenses [602A] and [602B] are implemented respectively. Figure 15 Functions of lenses [320A] and [320B] in (a). The light beam

[400] is first delivered from lens [602A] to facets [603A] and [603B], one or both of which are surface-treated to function as a polarization-selective filter

[310] along the axis [607A] of lens [602A], which coincides with the axis [607B] of lens [602B] and also forms the axis

[901] of the composite block. If the light beam has transmission polarization, it is further routed to lens [602B] along axis

[901] . As previously described, the direction of the light can be reversed.

[0134] 3. Figure 16 The construction with is shown Figure 16 The possibility of a composite inserter

[900] with the function shown in (a) is that the function is shown in Figure 3(a) and Figure 5 The preferred embodiments A and C are required. In one direction, beams [400A] and [400B] with orthogonal polarization are collimated by lens [320A] and sent to polarization-selective reflector

[310] . Beam [400A] with one polarization is reflected to lens [320B] and refocused. Beam [400B] with the other polarization is transmitted to reflector

[330] , which further reflects beam [400B] to lens [320C]. It is then also refocused. As with the previous embodiments, the direction of light propagation can be reversed.

[0135] Figure 16 (b) An embodiment based on four component blocks [600A] to [600D] is shown, the component blocks [600A] to [600D] being in Figure 9 The configuration described in (d) is arranged accordingly. The assembly of components [600A], [600B], and [600D] benefits from being compatible with... Figure 14 In (c), the component blocks [600A], [600B], and [600C] are guided in a similar manner relative to the mechanical stops that are aligned with each other. Figure 14 In (c), [600C] takes the same position as [600D] here. Figure 16In (b), [600C] is attached to combine [604C] and [604D] together, wherein one side of [600B], formed by cutting, can act as a mechanical stop by forming mechanical contact with one side of [600C]. Alternatively, [600C] and [600B] can be treated as two attached component blocks

[600] that have not yet been cut to each other. This method is preferred because it facilitates handling and assembly, as one less part that must be assembled is required when constructing the composite component block

[900] . Lenses [320A], [320B], and [320C] are embodied by lenses [602A], [602B], and [602C], respectively. Facets [603B] and [603D] are combined to form a polarization-selective reflector

[310] , wherein one or both of [603B] and [603D] may be provided with appropriate surface treatment. The faceted [603C] forms a reflector

[330] and may not need to be coated, since total internal reflection is sufficient to achieve the desired reflection (for sufficiently high glass reflectivity). However, coatings such as thin film coatings or metallic coatings, even if not necessary, help to make the insert robust to dust, since light will not reach the outer surface on which dust may have deposited.

[0136] 4. Figure 17 and 18 Further variations for implementing embodiments A and C are formed, wherein light is coupled into or out of the lens from the top of the inserter rather than from the side [320A]. More specifically, Figure 17 (b) is the possibility of implementing the inserter shown in Figures 3(b) and 3(c), while Figure 18 (b) is the possibility of further variations of embodiments A and C. These composite component blocks are made of, for example... Figure 9 (c) describes the arrangement of several component blocks

[600] to form a structure. Figure 17 (a) and Figure 18 (a) Functional components and Figure 17 (b) and Figure 18 (b) The correspondence between structural elements is indicated by common symbols. For example, for Figure 16 The aspects described herein, similar to those described for polarization-selective reflectors

[310] at internal facets or reflectors

[330] at external facets, apply here. Similar to Figure 16 , Figure 17 and Figure 18 The component blocks [600B] and [600C] and Figure 18 The component blocks [600A] and [600D] can be treated as a group of undivided component blocks

[600] for easy assembly and processing.

[0137] 5. Figure 19 It shows Figure 16 The extension adds four additional component blocks to create two additional internal reflective surfaces. Furthermore, the polarization-selective reflector

[310] is replaced by a wavelength-selective reflector

[340] to implement a wavelength division multiplexer / demultiplexer (also known as a signal splitter or multiplexer).

[0138] More in detail, Figure 19 (a) describes Figure 19 Function of the composite component block

[900] shown in (b). In one propagation direction, beams [400A]-[400D], each with a different wavelength, enter the composite component block

[900] via a lens [320A], and are first collimated by the lens and sent to a first wavelength selective reflector [340A]. According to its wavelength and the wavelength selectivity of the reflector [340A], beam [400A] is reflected, sent to the lens [320B] and focused, while beams [400B]-[400D] are transmitted and sent to a second wavelength selective reflector [340B]. According to its wavelength and the modified wavelength selectivity of [340B], beam [400B] is reflected, sent to the lens [320C] and focused, while beams [400C] and [400D] are transmitted and sent to a third wavelength selective reflector [340C]. Depending on its wavelength and the further modified wavelength selectivity of [340C], the beam [400C] is reflected, sent to lens [320D] and refocused, while the beam [400D] is transmitted and sent to reflector

[330] . There, it is reflected to lens [320E] and refocused. For example, different wavelength selectivity can be achieved with thin film coatings of different compositions or layer thicknesses.

[0139] Figure 19 (a) Functional components and Figure 19 (b) The correspondence between structural elements is indicated by common symbols. For example, for Figure 16 The aspects described herein, similar to those described for polarization-selective reflectors

[310] at internal facets or reflectors

[330] at external facets, apply here, where wavelength selectivity may be more easily achieved at the internal surface. Similar to Figure 16 Component blocks [600B]-[600E] and [600F]-[600H] can be treated as a group of undivided component blocks

[600] for easy assembly and processing.

[0140] It is used as an example to illustrate that the manufacturing method described herein can be used to construct the optical inserter AD described above, but it can also be applied to other types of optical inserters, such as inserters that implement wavelength-selective routing.

[0141] 6. Figure 20 and Figure 21This demonstrates the possibility of constructing a composite component block

[900] having the features described as a preferred embodiment D and in... Figure 6 The inserter

[300] shown in the figure has the required characteristics. Figure 20 The construction is shown Figure 21 (b) Two additional types of component blocks required for the composite component block are further referred to as type II component block

[700] and type III component block

[800] . Component block

[700] may be implemented as a mirror image of component block

[600] . It includes the same basic features, namely facets

[701] , lenses

[702] , optical facets

[703] and

[704] used as mechanical contacts. In addition, it may also include facet or circular features

[705] for easy manufacture by glass molding and / or for use as mechanical stops for assembling the composite component block, as well as complementary features

[706] . Lens

[702] has an optical axis

[707] .

[0142] Component block

[700] is complementary to component block

[600] . In particular, component block

[700] is characterized in that if the optical axis

[607] of lens

[602] of component block

[600] intersects one of optical facets

[603] ,

[604] at an angle of -45° or within + / -20° of the optical axis

[607] , then the optical axis

[707] of lens

[702] intersects one of optical facets

[703] ,

[704] at an angle of +45° or within + / -20° of the optical axis

[707] . Furthermore, the component block

[700] is characterized in that if the optical axis

[607] of the lens

[602] of the component block

[600] intersects one of the optical facets

[603] and

[604] at an angle of +45° or within + / -20° of the optical axis

[607] , then the optical axis

[707] of the lens

[702] intersects one of the optical facets

[703] and

[704] at an angle of -45° or within + / -20° of the optical axis

[707] . Similar to the first type of component block

[600] , the second type of component block

[700] may also have a recess

[708] for inserting an optical element

[709] . The second type of component block

[700] may be an alternative arrangement of the first type of component block

[600] as described above.

[0143] Component block

[800] has four optical facets

[803] ,

[804] ,

[813] , and

[814] . Furthermore, component block

[800] may have two facets or circular features

[805] and

[815] to facilitate manufacturing by glass molding and / or use as mechanical stops for assembling composite component blocks. In this case, features

[606] and

[706] of component blocks

[600] and

[700] may be complementary to features

[805] and

[815] of component block

[800] . Additionally, component block

[800] may have features

[806] and

[816] that are complementary to features

[605] or

[705] of component blocks

[600] and

[700] , respectively. Features

[805] and

[815] are located at the locations where optical facets

[803] and

[804] , and optical facets

[813] and

[814] will be merged. Features

[806] and

[816] are located at the base of optical facets

[803] or

[804] and at the base of optical facets

[813] or

[814] , respectively.

[0144] Figure 21 (b) shows a composite component block

[900] that can be assembled from component blocks of types

[600] ,

[700] , and

[800] , such that the composite component block satisfies the following functional requirements: Figure 6 Requirements of embodiment D of the inserter

[300] shown. Figure 21 (b) structural components and Figure 21 (a) The correspondence between functional elements is indicated by a common label. A composite component block

[900] can be assembled from two component blocks [600A] and [600B] of type

[600] , two component blocks [700A] and [700B] of type

[700] , and three component blocks [800A]-[800C] of type

[800] . Component blocks [600A] and [600B], component blocks [700A] and [700B], and component blocks [800A]-[800C] can be treated as groups of two, two, and three undivided component blocks, respectively.

[0145] like Figure 21 As shown, in order for component blocks

[600] ,

[700] and

[800] to be assembled as intended, the features of component blocks

[600] and

[700] and the features of component blocks

[700] and

[800] need to be complementary. Specifically, the complementary feature pairs are

[605] and

[806] ,

[606] and

[805] ,

[705] and

[816] , and

[706] and

[815] .

[0146] The functionality typically required for transmission in Embodiment D, and the functionality required for receivers in Embodiments A or C, can be obtained on a common glass insert

[300] . For example, an insert

[300] supporting four parallel transmission channels (fiber optics) and four parallel receiving channels (fiber optics) can be constructed starting from a 2×8 array of building blocks

[600] that can remain attached to each other. The 2×8 array is described as being attached to the leftmost 2×2 array of the rightmost 2×2 array. A 3×4 array of building blocks

[800] can be attached, for example, on top of the leftmost array, followed by (inverted) building blocks

[700] of the 2×2 arrays stacked on top, to produce the functionality required for the transmitter (according to...). Figure 21 ). A 1×2 array or a 2×2 array of (inverted) component blocks

[600] can be attached, for example, to the top of the rightmost array to produce the functionality required by the receiver (according to Figure 17 (Or 18). This transmitter / receiver array can be extended to other port numbers.

[0147] As mentioned in the description of the prior art, one of the main sources of variation between the manufactured component blocks

[600] ,

[700] ,

[800] compared to their nominal designs is controlling the distance between the top mold [1201A] and the bottom mold [1201B] during the molding process. Figures 14 to 21 All embodiments shown have been optimized to minimize the sensitivity of the composite component block

[900] and inserter

[300] to this manufacturing parameter, i.e., their functionality can be maintained if this parameter is modified. In particular, in component block

[600] , the mechanical contact facet

[601] and lens

[602] can be defined by one mold, while the optical facets

[603] ,

[604] , faceted or circular features

[605] ,

[606] can be defined by another mold. The same applies to component block

[700] . For component block

[800] , the optical facets

[803] ,

[804] and faceted or circular features

[805] ,

[806] can be defined by one mold, while the optical facets

[813] ,

[814] and faceted or circular features

[815] ,

[816] can be defined by another mold.

[0148] Changing the distance between the top mold [1201A] and the bottom mold [1201B] of any of the component blocks

[600] ,

[700] , and

[800] will not hinder the following: Figure 9 , 10The assembly scheme shown in any of 14 to 19, 21 will not change the point at which any of the optical axes

[607] ,

[707] ,

[901] intersects the optical surfaces

[603] ,

[604] ,

[703] ,

[704] ,

[803] ,

[804] ,

[813] ,

[814] . Therefore, assuming that the optical axis is preferably perpendicular or parallel to the orientation of the mechanical contact surfaces

[601] ,

[701] , and preferably at an angle of + / -45° relative to the normals of the optical surfaces

[603] ,

[604] ,

[703] ,

[704] ,

[803] ,

[804] ,

[813] ,

[814] , the light beam will reach the lenses

[602] ,

[702] at the same point and at the same angle, regardless of the deviation in the height of the component block given by the spacing between the two molds. Therefore, these designs are insensitive to major sources of manufacturing variation, making their production simpler and more cost-effective.

[0149] This is primarily due to the fact that light propagating from the component block element formed by the top mold to the component block element formed by the bottom mold propagates in a direction substantially parallel to the surface normals of the mechanical contact facets / attachment interfaces

[601] ,

[701] for the component blocks

[600] and

[700] , and substantially parallel to the surface normals of the unmolded glass wafer surfaces for all three types of component blocks. Specifically, light propagating from the component block element formed by the top mold to the component block element formed by the bottom mold propagates in a direction substantially parallel to the direction in which the pressing of all component blocks is driven (the direction in which the top and bottom molds are pressed together during the molding process, i.e., the compression directions [1202A] and [1202B]). "Substantially parallel" here may mean within an angle of + / -20°, or within a smaller angle of + / -10° or + / -5°, to improve tolerance to height variations / obtain better performance under manufacturing differences. The compression directions [1202A] and [1202B] are generally opposite but parallel to each other.

[0150] This is Figure 22The diagram illustrates how the top mold [1201A] and the bottom mold [1201B] are pressed together along the compression directions [1202A] and [1202B] to form three component blocks [600A], [600B], and [600C]. The three component blocks can later be separated by cutting the molded glass wafer along the cutting lines [611A] and [611B]. It can be seen that the optical facets [603A]-[603C], [604A]-[604C] and facets / features [605A]-[605C], [606A]-[606C] are formed by the top mold [1201A], while the mechanical contact facets / attachment interfaces [601A]-[601C] and the lens [602A]-[602C] are formed by the bottom mold [1201B]. The component block has an optical axis [901A]-[901C] that can coincide with the optical axis of the lens (e.g., the optical axis [607A]-[607C] of the lens [602A]-[602C]). The optical axis [901A]-[901C] is followed by the beam

[400] in the manufactured component and connects the optical element formed by the bottom mold [1201B] to the optical element formed by the top mold [1201A], here the lens [602A]-[602C] and the optical facet [603A]-[603C]. Importantly, the optical axis [901A]-[901C] is parallel to the compression directions [1202A], [1202B], or within the angular tolerances described above.

[0151] Mark reference list

[0152] 100: PIC

[0153] 110: Polarization Selective Coupler

[0154] 110A: First polarization-selective coupler

[0155] 110B: Second polarization-selective coupler

[0156] 111: Single-mode, single-polarization VCSEL

[0157] 112: Single polarization grating coupler

[0158] 112A: First single-polarization grating coupler

[0159] 112B: Second single-polarization grating coupler

[0160] 113: Edge Coupler

[0161] 113A: First edge coupler

[0162] 113B: Second edge coupler

[0163] 120: Waveguide

[0164] 120A: First Waveguide

[0165] 120B: Second Waveguide

[0166] 130: Polarization Selective Element

[0167] 130A: First polarization-selective element

[0168] 130B: Second polarization-selective element

[0169] 131: Waveguide ripples

[0170] 131A: First waveguide ripple

[0171] 131B: Second waveguide ripple

[0172] 132: Thin film coating

[0173] 132A: First thin film coating

[0174] 132B: Second thin film coating

[0175] 140: Photonic Sub-circuit

[0176] 141: Optical Port

[0177] 141A: First optical port

[0178] 141B: Second optical port

[0179] 150: Photonic, electro-optical, or optoelectronic devices

[0180] 151: Bidirectional electro-optic modulator

[0181] 160: Cutting line

[0182] 170: Dual polarization coupler

[0183] 170A: First dual polarization coupler

[0184] 170B: Second dual polarization coupler

[0185] 200, 200A: Second optical element

[0186] 200B: Third optical element

[0187] 201: Glass optical fiber

[0188] 300: Glass / Optical Insert

[0189] 310: Polarization-selective reflector or filter

[0190] 310A: First polarization-selective reflector or filter

[0191] 310B: Second polarization-selective reflector or filter

[0192] 310C: Third polarization-selective reflector or filter

[0193] 320: Lens

[0194] 320A: First lens

[0195] 320B: Second lens

[0196] 320C: Third Lens

[0197] 320D: Fourth Lens

[0198] 330: Reflector

[0199] 330A: Fourth Reflector

[0200] 330B: Fifth Reflector

[0201] 340: Wavelength-selective reflector

[0202] 400: Beam

[0203] 400A: First Beam

[0204] 400B: Second Beam

[0205] 400C: Third Beam

[0206] 400D: Fourth Beam

[0207] 500: Faraday Rotator

[0208] 500A: The First Faraday Rotator

[0209] 500B: Second Faraday Rotator

[0210] 600: Component block / Type 1 component block

[0211] 601: Faceted surface, mechanical contact / attachment interface

[0212] 602: Lens

[0213] 603, 604: Optical facets

[0214] 605: Prevents sharp-pointed facets or rounded features

[0215] 606: Features complementary to 605

[0216] 607: Optical axis of the lens

[0217] 608: Recess for inserting optical elements

[0218] 609: Inserted optical elements

[0219] 610: Additional facets

[0220] 611: Cutting line

[0221] 700: Type II component block

[0222] 701: Faceted surface, mechanical contact / attachment interface

[0223] 702: Lens

[0224] 703, 704: Optical facets

[0225] 705: Prevents sharp-point facets or rounded features

[0226] 706: Features complementary to 705

[0227] 707: Optical axis of the lens

[0228] 708: Recess for inserting optical elements

[0229] 709: Inserted optical elements

[0230] 800: Type III component block

[0231] 803, 804: Optical facets

[0232] 805: A facet or rounded feature to prevent sharp points, a feature complementary to 606.

[0233] 806: A faceted or rounded feature to prevent sharp points, a feature complementary to 605.

[0234] 813, 814: Optical facets

[0235] 815: A faceted or rounded feature to prevent sharp points, a feature complementary to 706.

[0236] 816: A faceted or rounded feature to prevent sharp points, a feature complementary to 705.

[0237] 900: Composite component block

[0238] 901: Optical Axis

[0239] 902: Porosity

[0240] 1000: Glass wafer, preform

[0241] 1001: 1D or 2D array of molded component blocks

[0242] 1002: Spacer

[0243] 1100: (Any type of) component block

[0244] 1101: Faceted surface, mechanical contact / attachment interface

[0245] 1102: Lens

[0246] 1103: Optical facet

[0247] 1107: Optical axis of the lens

[0248] 1201A: Top mold

[0249] 1201B: Bottom mold

[0250] 1202A: Compression direction of the top die

[0251] 1202B: Compression direction of the bottom mold

Claims

1. An optical inserter [300] comprising a first lens [320A], a second lens [320B], and a first polarization-selective reflector [310A], the optical inserter [300] coupling light from a second optical element [200A] to or from a photonic integrated circuit (PIC) [100] to the second optical element [200A], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the second lens [320B], from the second lens [320B] to the first coupler [110A], or in the reverse order. Light is coupled from the second optical element [200A] to the first coupler [110A] for one polarization, and to the second coupler [110B] of the photonic integrated circuit [100] for another polarization, or Light is coupled from the first coupler [110A] to the second optical element [200A] with one polarization, and from the second coupler [110B] of the photonic integrated circuit [100] to the second optical element [200A] with another polarization, or Light is coupled from the second optical element [200A] to the first coupler [110A], and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A]. Light is coupled from the first coupler [110A] to the second optical element [200A], and the photonic integrated circuit [100] is isolated from reflections occurring at or after the second optical element [200A]. The optical inserter [300] includes at least a first Faraday rotator [500A], and the optical inserter includes a third lens [320C] and a fourth lens [320D], as well as a second polarization-selective reflector [310B] and a third polarization-selective reflector [310C]. The first Faraday rotator [500A] is inserted between the second lens [320B] and the first coupler [110A], and the second Faraday rotator [500B] is inserted between the third lens [320C] and the second coupler [110B]. The light emitted by the photonic integrated circuit [100] propagates through the first coupler [110A] to the first Faraday rotator [500A], from the first Faraday rotator [550A] to the second lens [320B], from the second lens [320B] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the third polarization-selective reflector [310C], from the third polarization-selective reflector [310C] to the fourth lens [320D], from the fourth lens [320D] to the third optical element [200B], or in the reverse order. The light emitted by the photonic integrated circuit [100] propagates through the second coupler [110B] to the second Faraday rotator [500B], from the second Faraday rotator [500B] to the third lens [320C], from the third lens [320C] to the second polarization-selective reflector [310B], from the second polarization-selective reflector [310B] to the third polarization-selective reflector [310C], from the third polarization-selective reflector [310C] to the fourth lens [320D], and from the fourth lens [320D] to the third optical element [200B], or in the reverse order.

2. The optical inserter [300] according to claim 1, wherein the photonic integrated circuit [100] includes a polarization-selective or connected second coupler [110B] to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], and according to its polarization, from the first polarization-selective reflector [310A] to the second lens [320B] or to the third lens [320C], from the second lens [320B] to the first coupler [110A] or from the third lens [320C] to the second coupler [110B], or in the reverse order.

3. The optical inserter [300] according to claim 1, Its features Light is coupled from the second optical element [200A] to the first coupler [110A], and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A]. Light is coupled from the first coupler [110A] to the second optical element [200A], and the photonic integrated circuit [100] is isolated from reflections that occur at or after the second optical element [200A].

4. The optical inserter [300] according to claim 1, wherein the photonic integrated circuit [100] includes a polarization-selective second coupler [110B] connected to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], and according to its polarization, from the first polarization-selective reflector [310A] to the second lens [320B] or to the third lens [320C], from the second lens [320B] to the first Faraday rotator [500A], from the first Faraday rotator [500A] to the first coupler [110A], or from the third lens [320C] to the second Faraday rotator [500B], from the second Faraday rotator [500B] to the second coupler [110B], or in the reverse order. Light is coupled from the second optical element [200A] to the first coupler [110A] for one polarization and from the second optical element [200A] to the second coupler [110B] for another polarization, and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A] and the second coupler [110B]. Light is coupled from the first coupler [110A] to the second optical element [200A] with one polarization and from the second coupler [110B] to the second optical element [200A] with another polarization, and the photonic integrated circuit [100] is isolated from reflections that occur at or after the second optical element [200A].

5. The optical inserter [300] according to claim 1, wherein the photonic integrated circuit [100] includes a polarization-selective second coupler [110B] connected to a polarization-selective subsystem and a photonic subcircuit [140] having a first optical port [141A] and a second optical port [141B]. Its features The first optical port [141A] is connected to the first coupler [110A] and the second optical port [141B] is connected to the second coupler [110B]. At least some of the light that enters the photonic sub-circuit [140] through the first optical port [141A] leaves the photonic sub-circuit [140] through the second optical port [141B], and vice versa; The light emitted by the second optical element [200A] is coupled to the photonic integrated circuit [100] through one of the first coupler [110A] or the second coupler [110B] according to its polarization; The light emitted by the photonic integrated circuit is coupled to the third optical element [200B] through the first coupler [110A] or the second coupler [110B].

6. The optical inserter [300] according to claim 1, Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], and according to its polarization, from the first polarization-selective reflector [310A] to the second lens [320B] or to the second polarization-selective reflector [310B], from the second lens [320B] to the first Faraday rotator [500A], from the first Faraday rotator [500A] to the first coupler [110A], from the second polarization-selective reflector [310B] to the third lens [320C], from the third lens [320C] to the second Faraday rotator [500B], from the second Faraday rotator [500B] to the second coupler [110B], or in the reverse order.

7. The optical inserter [300] according to any one of claims 1 to 6, wherein the first coupler [110A] and the second coupler [110B] are surface emitter / receiver couplers orthogonally oriented to each other.

8. The optical inserter [300] according to any one of claims 1 to 6, wherein the first coupler [110A] and the second coupler [110B] are surface emitter / receiver couplers oriented parallel or antiparallel to each other.

9. The optical inserter [300] according to any one of claims 1 to 6, wherein the photonic integrated circuit [100] further comprises a first polarization-selective element [130A] and a second polarization-selective element [130B], the first coupler [110A] and the second coupler [110B] being edge couplers and respectively connected to the first polarization-selective element [130A] and the second polarization-selective element [130B]. Its features The first polarization selective element [130A] and the second polarization selective element [130B] are adapted to transmit different polarizations.

10. An optical inserter [300] comprising a first lens [320A], a second lens [320B], and a first polarization-selective reflector [310A], the optical inserter [300] coupling light from a second optical element [200A] to or from a photonic integrated circuit (PIC) [100] to the second optical element [200A], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the second lens [320B], from the second lens [320B] to the first coupler [110A], or in the reverse order. Light is coupled from the second optical element [200A] to the first coupler [110A] for one polarization, and to the second coupler [110B] of the photonic integrated circuit [100] for another polarization, or Light is coupled from the first coupler [110A] to the second optical element [200A] with one polarization, and from the second coupler [110B] of the photonic integrated circuit [100] to the second optical element [200A] with another polarization, or Light is coupled from the second optical element [200A] to the first coupler [110A], and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A]. Light is coupled from the first coupler [110A] to the second optical element [200A], and the photonic integrated circuit [100] is isolated from reflections occurring at or after the second optical element [200A]. The optical inserter [300] includes at least a first Faraday rotator [500A], and the optical inserter includes a third lens [320C] and a fourth lens [320D], as well as a second polarization-selective reflector [310B] and a third polarization-selective reflector [310C]. The first Faraday rotator [500A] is inserted between the second lens [320B] and the first coupler [110A], and the second Faraday rotator [500B] is inserted between the third lens [320C] and the second coupler [110B]. Its features The first polarization-selective reflector [310A] and the first Faraday rotator [500A] together form a circulator; The second polarization-selective reflector [310B] together with the second Faraday rotator [500B] forms a circulator; The first polarization-selective reflector [310A] splits the incident light from the second optical element [200A] according to its polarization before the incident light is coupled to the photonic integrated circuit [100], and the third polarization-selective reflector [310C] combines the different polarized light returning from the photonic integrated circuit [100] before the returning light is coupled to the third optical element [200B]. The third polarization-selective reflector [310C] splits the incident light from the second optical element [200A] according to its polarization before the incident light is coupled to the photonic integrated circuit [100], and the first polarization-selective reflector [310A] combines the different polarized light returning from the photonic integrated circuit [100] before the returning light is coupled to the third optical element [200B].

11. The optical inserter [300] of claim 10, wherein the photonic integrated circuit [100] includes a polarization-selective or connected second coupler [110B] to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], and according to its polarization, from the first polarization-selective reflector [310A] to the second lens [320B] or to the third lens [320C], from the second lens [320B] to the first coupler [110A] or from the third lens [320C] to the second coupler [110B], or in the reverse order.

12. The optical inserter [300] according to claim 10, Its features Light is coupled from the second optical element [200A] to the first coupler [110A], and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A]. Light is coupled from the first coupler [110A] to the second optical element [200A], and the photonic integrated circuit [100] is isolated from reflections that occur at or after the second optical element [200A].

13. The optical inserter [300] of claim 10, wherein the photonic integrated circuit [100] includes a polarization-selective or connected second coupler [110B] to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], and according to its polarization, from the first polarization-selective reflector [310A] to the second lens [320B] or to the third lens [320C], from the second lens [320B] to the first Faraday rotator [500A], from the first Faraday rotator [500A] to the first coupler [110A], or from the third lens [320C] to the second Faraday rotator [500B], from the second Faraday rotator [500B] to the second coupler [110B], or in the reverse order. Light is coupled from the second optical element [200A] to the first coupler [110A] for one polarization and from the second optical element [200A] to the second coupler [110B] for another polarization, and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A] and the second coupler [110B]. Light is coupled from the first coupler [110A] to the second optical element [200A] with one polarization and from the second coupler [110B] to the second optical element [200A] with another polarization, and the photonic integrated circuit [100] is isolated from reflections that occur at or after the second optical element [200A].

14. The optical inserter [300] of claim 10, wherein the photonic integrated circuit [100] comprises a polarization-selective second coupler [110B] connected to a polarization-selective subsystem and a photonic subcircuit [140] having a first optical port [141A] and a second optical port [141B]. Its features The first optical port [141A] is connected to the first coupler [110A] and the second optical port [141B] is connected to the second coupler [110B]. At least some of the light that enters the photonic sub-circuit [140] through the first optical port [141A] leaves the photonic sub-circuit [140] through the second optical port [141B], and vice versa; The light emitted by the second optical element [200A] is coupled to the photonic integrated circuit [100] through one of the first coupler [110A] or the second coupler [110B] according to its polarization; The light emitted by the photonic integrated circuit is coupled to the third optical element [200B] through the first coupler [110A] or the second coupler [110B].

15. The optical inserter [300] according to any one of claims 10 to 14, wherein the first coupler [110A] and the second coupler [110B] are surface emitter / receiver couplers orthogonally oriented to each other.

16. The optical inserter [300] according to any one of claims 10 to 14, wherein the first coupler [110A] and the second coupler [110B] are surface emitter / receiver couplers oriented parallel or antiparallel to each other.

17. The optical inserter [300] according to any one of claims 10 to 14, wherein the photonic integrated circuit [100] further comprises a first polarization-selective element [130A] and a second polarization-selective element [130B], the first coupler [110A] and the second coupler [110B] being edge couplers and respectively connected to the first polarization-selective element [130A] and the second polarization-selective element [130B]. Its features The first polarization selective element [130A] and the second polarization selective element [130B] are adapted to transmit different polarizations.

18. An optical inserter [300] comprising a first lens [320A] and a second lens [320B] and a first polarization-selective reflector [310A], the optical inserter [300] coupling light from a second optical element [200A] to or from a photonic integrated circuit (PIC) [100] to the second optical element [200A], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the second lens [320B], from the second lens [320B] to the first coupler [110A], or in the reverse order. Light is coupled from the second optical element [200A] to the first coupler [110A] for one polarization, and to the second coupler [110B] of the photonic integrated circuit [100] for another polarization, or Light is coupled from the first coupler [110A] to the second optical element [200A] with one polarization, and from the second coupler [110B] of the photonic integrated circuit [100] to the second optical element [200A] with another polarization, or Light is coupled from the second optical element [200A] to the first coupler [110A], and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A]. Light is coupled from the first coupler [110A] to the second optical element [200A], and the photonic integrated circuit [100] is isolated from reflections occurring at or after the second optical element [200A]. The free beam [400] propagates inside the optical inserter [300]; The free beam [400] is not limited by guidance in the waveguide; The free beam [400] therein is collimated or nearly collimated; The k-vector distribution of the free beam [400] is much narrower than that of the beam emitted / received by the second optical element [200A] and the first coupler [110A]. The free beam [400] reaches the first polarization selective reflector [310A].

19. An optical inserter [300] comprising a first lens [320A], a second lens [320B], and a first polarization-selective reflector [310A], the optical inserter [300] coupling light from a second optical element [200A] to or from a photonic integrated circuit (PIC) [100] to the second optical element [200A], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the second lens [320B], from the second lens [320B] to the first coupler [110A], or in the reverse order. Light is coupled from the second optical element [200A] to the first coupler [110A] for one polarization, and to the second coupler [110B] of the photonic integrated circuit [100] for another polarization, or Light is coupled from the first coupler [110A] to the second optical element [200A] with one polarization, and from the second coupler [110B] of the photonic integrated circuit [100] to the second optical element [200A] with another polarization, or Light is coupled from the second optical element [200A] to the first coupler [110A], and the second optical element [200A] is isolated from reflections occurring at or after the first coupler [110A]. Light is coupled from the first coupler [110A] to the second optical element [200A], and the photonic integrated circuit [100] is isolated from reflections occurring at or after the second optical element [200A]. The free beam [400] propagates inside the optical inserter [300]; The free beam [400] is not limited by guidance in the waveguide; A portion of the optical inserter is molded by pressing a top mold [1201A] and a bottom mold [1201B] together during a molding process, and the free beam [400] propagates along a propagation direction from the element of the optical inserter formed by the top mold [1201A] to the element of the optical inserter formed by the bottom mold [1201B]. Its features The propagation direction is parallel to the first direction [1202A] and the second direction [1202B] that press the top mold and the bottom mold together, or within + / -20° of the first direction [1202A] and the second direction [1202B].

20. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; The first component block [1100A] and the second component block [1100B] are component blocks of the first type [600], wherein the first optical axis [1107A] of the first lens [320A] and the second optical axis [1107B] of the second lens [320B] intersect the first optical facet [1103A] and the second optical facet [1103B], respectively, wherein the first component block [1100A] and the second component block [1100B] may have been separated or attached to each other before the optical inserter is assembled.

21. The method of claim 20, wherein one of the first optical facet [1103A] and the second optical facet [1103B] is surface-treated, wherein the first optical facet [1103A] and the second optical facet [1103B] are combined to form the inner surface of the optical inserter [300]. Its features Light is transmitted through or reflected at the inner surface according to its polarization, forming a first polarization-selective reflector, a second polarization-selective reflector, or a third polarization-selective reflector.

22. The method of claim 20, wherein light does not reach the first component block [1100A] or the second component block [1100B] under normal operation, and wherein the functionally unnecessary lens [602B] is therefore unnecessary for realizing the function of the optical inserter [300].

23. The method according to any one of claims 20 to 22, wherein at least the first component block [1100A] or the second component block [1100B] includes a facet [1101A], the facet [1101A] forming a mechanical contact for attachment of the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B]. Its features The first component block [1100A] or the second component block [1100B] is attached to the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B] at the facet [1101A] to seal the cavity between the first component block [1100A] or the second component block [1100B] and the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B], such that the first lens [320A] or the second lens [320B] is located within the cavity.

24. The method of claim 23, wherein the cavity is formed between the second component block [1100B] and the photonic integrated circuit [100], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features The first coupler [110A] is inside the cavity.

25. The method according to any one of claims 20 to 22, wherein the first component block [1100A] and the second component block [1100B] are formed by glass molding of a preform [1000].

26. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; The first component block [1100A] is a first type of component block [600], and the second component block [1100B] is a second type of component block [700]. The first type of component block [600] and the second type of component block [700] respectively include a first lens [320A] and a second lens [320B], as well as a first optical surface [1103A] and a second optical surface [1103B]. The first optical axis [1107A] of the first lens [320A] intersects with the first optical surface [1103A], and the second optical axis [1107B] of the second lens [320B] intersects with the second optical surface [1103B]. Its features The first optical facet [1103A] of the first type of component block [600] is oriented at -45° relative to the first optical axis [1107A] of the first lens [320A], or within a range of + / -20° of that angle; The second optical facet [1103B] of the second type of component block [700] is oriented at +45° relative to the second optical axis [1107B] of the second lens [320B], or within + / -20° of that angle; or vice versa.

27. The method of claim 26, wherein one of the first optical facet [1103A] and the second optical facet [1103B] is surface-treated, wherein the first optical facet [1103A] and the second optical facet [1103B] are combined to form the inner surface of the optical inserter [300]. Its features Light is transmitted through or reflected at the inner surface according to its polarization, forming a first polarization-selective reflector, a second polarization-selective reflector, or a third polarization-selective reflector.

28. The method of claim 26 or 27, wherein at least the first component block [1100A] or the second component block [1100B] includes a facet [1101A], the facet [1101A] forming a mechanical contact for attachment of the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B]. Its features The first component block [1100A] or the second component block [1100B] is attached to the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B] at the facet [1101A] to seal the cavity between the first component block [1100A] or the second component block [1100B] and the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B], such that the first lens [320A] or the second lens [320B] is located within the cavity.

29. The method of claim 28, wherein the cavity is formed between the second component block [1100B] and the photonic integrated circuit [100], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features The first coupler [110A] is inside the cavity.

30. The method according to claim 26 or 27, wherein the first component block [1100A] and the second component block [1100B] are formed by glass molding of a preform [1000].

31. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; At least the first component block [1100A] or the second component block [1100B] includes a facet [1101A], which forms a mechanical contact for attachment of the photonic integrated circuit [100], the second optical element [200A], or the third optical element [200B]. Its features The first component block [1100A] or the second component block [1100B] is attached to the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B] at the facet [1101A] to seal the cavity between the first component block [1100A] or the second component block [1100B] and the photonic integrated circuit [100] or the second optical element [200A] or the third optical element [200B], such that the first lens [320A] or the second lens [320B] is located within the cavity.

32. The method of claim 31, wherein one of the first optical facet [1103A] and the second optical facet [1103B] is surface-treated, wherein the first optical facet [1103A] and the second optical facet [1103B] are combined to form the inner surface of the optical inserter [300]. Its features Light is transmitted through or reflected at the inner surface according to its polarization, forming a first polarization-selective reflector, a second polarization-selective reflector, or a third polarization-selective reflector.

33. The method of claim 31 or 32, wherein the cavity is formed between the second component block [1100B] and the photonic integrated circuit [100], the photonic integrated circuit including a polarization-selective first coupler [110A] or connected to a polarization-selective subsystem. Its features The first coupler [110A] is inside the cavity.

34. The method according to claim 31 or 32, wherein the first component block [1100A] and the second component block [1100B] are formed by glass molding of a preform [1000].

35. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; The first component block [1100A] and the second component block [1100B] are formed by glass molding of a preform [1000], which is a glass wafer with two polished surfaces. Multiple component blocks are molded in parallel on the glass wafer using a top mold [1201A] and a bottom mold [1201B]. The glass wafer is then surface-treated after molding to allow surface treatment of more than one component block.

36. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; The assembly of the optical inserter includes attaching a component block [1100] or an array of component blocks [1001] to a molded glass wafer.

37. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; The assembly of the optical inserter includes attaching the first component block [1100A] and the second component block [1100B] to a silicon wafer on which photonic integrated circuits have been fabricated.

38. A method of manufacturing any one of the optical inserters [300] described in claims 1 to 19, wherein the optical inserter [300] is formed by assembling at least a first component block [1100A] and a second component block [1100B], the first component block [1100A] and the second component block [1100B] respectively including a first lens [320A] having a first optical axis [1107A] and a second lens [320B] having a second optical axis [1107B], and a first optical facet [1103A] and a second optical facet [1103B]. Its features The first optical axis [1107A] and the second optical axis [1107B] oriented from the surface of the first lens [320A] and the second lens [320B] toward the interior of the first component block [1100A] and the second component block [1100B] are at an angle of +90°, -90° or 180°, or within + / -20° of these angles; The alignment of the first type of component block [600], the second type of component block [700] or the optical inserter [300] with the photonic integrated circuit [100] is verified by imaging the alignment reference of the photonic integrated circuit [100] with the optical elements of the first type of component block [600], the second type of component block [700] or the optical inserter [300].

39. An optical inserter [300] comprising a first lens [320A], a second lens [320B], and a first polarization-selective reflector [310A], the optical inserter [300] coupling light from a second optical element [200A] to a photonic integrated circuit (PIC) [100] and from the photonic integrated circuit [100] to a third optical element [200B], the photonic integrated circuit comprising a first dual-polarization coupler [170A], a second dual-polarization coupler [170B], and a photonic sub-circuit [140] having a first optical port [141A] and a second optical port [141B]. Its features The first optical port [141A] is connected to the first dual polarization coupler [170A], and the second optical port [141B] is connected to the second dual polarization coupler [170B]. At least some of the light entering the photonic sub-circuit [140] through the first optical port [141A] leaves the photonic sub-circuit [140] through the second optical port [141B], and vice versa; Light is coupled from the second optical element [200A] to a first dual-polarization coupler [170A] for one polarization and to a second dual-polarization coupler [170B] for the other polarization. Light is coupled from the first dual polarization coupler [170A] and the second dual polarization coupler [170B] to the third optical element [200B]; Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the second lens [320B], from the second lens [320B] to the first dual polarization coupler [170A], or in the reverse order.

40. The optical inserter [300] according to claim 39, wherein the optical inserter comprises a third lens [320C] and a fourth lens [320D], and a second polarization-selective reflector [310B] and a third polarization-selective reflector [310C].

41. The optical inserter [300] according to claim 40, Its features Light propagates from the second optical element [200A] to the first lens [320A], from the first lens [320A] to the first polarization-selective reflector [310A], and according to its polarization, from the first polarization-selective reflector [310A] to the second lens [320B] or to the second polarization-selective reflector [310B], from the second lens [320B] to the first dual polarization coupler [170A], from the second polarization-selective reflector [310B] to the third lens [320C], from the third lens [320C] to the second dual polarization coupler [170B], or in the reverse order.

42. The optical inserter [300] according to claim 41, Its features Light propagates from the photonic integrated circuit [100] through the first dual polarization coupler [170A] to the second lens [320B], from the second lens [320B] to the first polarization-selective reflector [310A], from the first polarization-selective reflector [310A] to the third polarization-selective reflector [310C], from the third polarization-selective reflector [310C] to the fourth lens [320D], and from the fourth lens [320D] to the third optical element [200B], or in the reverse order. Light propagates from the photonic integrated circuit [100] through the second dual polarization coupler [170B] to the third lens [320C], from the third lens [320C] to the second polarization-selective reflector [310B], from the second polarization-selective reflector [310B] to the third polarization-selective reflector [310C], from the third polarization-selective reflector [310C] to the fourth lens [320D], and from the fourth lens [320D] to the third optical element [200B], or in the reverse order.

43. The optical inserter [300] according to claim 40, Its features The first polarization-selective reflector [310A] verifies the equivalent function of the circulator; The second polarization-selective reflector [310B] verifies the equivalent function of the circulator; The first polarization-selective reflector [310A] splits the incident light from the second optical element [200A] according to its polarization before the incident light is coupled to the photonic integrated circuit [100], and the third polarization-selective reflector [310C] combines the different polarized light returning from the photonic integrated circuit [100] before the returning light is coupled to the third optical element [200B]. The third polarization-selective reflector [310C] splits the incident light from the second optical element [200A] according to its polarization before the incident light is coupled to the photonic integrated circuit [100], and the first polarization-selective reflector [310A] combines the different polarized light returning from the photonic integrated circuit [100] before the returning light is coupled to the third optical element [200B].

44. The optical inserter [300] according to any one of claims 39 to 43, wherein the first dual polarization coupler [170A] and the second dual polarization coupler [170B] are surface emitter / receiver couplers orthogonally oriented to each other.

45. The optical inserter [300] according to any one of claims 39 to 43, wherein the first dual polarization coupler [170A] and the second dual polarization coupler [170B] are surface emitter / receiver couplers oriented parallel or antiparallel to each other.

46. ​​The optical inserter [300] according to any one of claims 39 to 43, wherein the first dual polarization coupler [170A] and the second dual polarization coupler [170B] are edge couplers.

47. The optical inserter [300] according to any one of claims 39 to 43, wherein a free beam [400] propagates within the optical inserter [300]. Its features The free beam [400] is not restricted by the guidance in the waveguide.

48. The optical inserter [300] according to claim 47, wherein the free beam [400] is collimated or nearly collimated. Its features The k-vector distribution of the free beam [400] is much narrower than that of the beam emitted / received by the second optical element [200A] and the first dual polarization coupler [170A]. The free beam [400] reaches the first polarization selective reflector [310A].

49. The optical inserter [300] of claim 47, wherein a portion of the optical inserter is molded by pressing a top mold [1201A] and a bottom mold [1201B] together during a molding process, and wherein the free beam [400] propagates in a propagation direction from an element of the inserter formed by the top mold [1201A] to an element of the optical inserter formed by the bottom mold [1201B]. Its features The propagation direction is parallel to the first direction [1202A] and the second direction [1202B] that press the top mold and the bottom mold together, or within + / -20° of the first direction [1202A] and the second direction [1202B].

50. The optical inserter [300] according to any one of claims 39 to 43, wherein the first dual polarization coupler [170A] and the second dual polarization coupler [170B] include subwavelength structures to manage birefringence within the first dual polarization coupler [170A] and the second dual polarization coupler [170B].

51. The optical inserter [300] according to any one of claims 39 to 43, Its features The first dual polarization coupler [170A] receives and emits light at different angles, or light arrives at / originates from different positions of the first dual polarization coupler [170A], and The second dual polarization coupler [170B] receives and emits light at different angles, or the light arrives at / from different positions of the second dual polarization coupler [170B].

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