Detachable connection and detachable mechanical coupling of optical connectors using pedestals with integrated optical coupling features

Abstract

A detachable connection of an optical connector using a base having features for integrating optical coupling and detachable coupling. The base provides a removable passively aligned connection to the optical connector. The base is permanently attached and aligned to the PIC chip. The base includes an optical element that redirects and reshapes incident light to follow a desired beam shape and path between the optical connector and the optoelectronic device. The susceptor may include a combination of different optical elements having optical characteristics that produce a desired beam quality and direction. The base also includes a passive alignment feature that matches a passive alignment feature on a facing side of the optical connector. The base has a unitary unitary body provided with an optical element and a passive alignment feature.

Description

[0001] Priority claim

[0002] This application claims priority to (a) U.S. Provisional Patent Application No. 63 / 388,238, filed on July 11, 2022; (b) U.S. Provisional Patent Application No. 63 / 406,627, filed on September 14, 2022; (c) U.S. Provisional Patent Application No. 63 / 417,988, filed on October 20, 2022; and (d) U.S. Provisional Patent Application No. 63 / 512,011, filed on July 5, 2023. These applications are fully incorporated herein by reference as if fully set forth herein. All publications mentioned below are fully incorporated herein by reference as if fully set forth herein. Technical Field

[0003] The present invention relates to coupling light into and out of optoelectronic components, such as photonic integrated circuits (PICs), and more particularly to optical connections of optical fibers to PICs. Background Art

[0004] Photonic integrated circuits (PICs) or integrated optical circuits are part of an emerging technology that uses light as the basis of operation rather than electrical current. PIC devices integrate multiple (at least two) photonic functions and are therefore similar to electronic integrated circuits. The main difference between the two is that photonic integrated circuits provide functionality for information signals imposed on light wavelengths, which are typically in the visible spectrum or near infrared 850nm-1650nm.

[0005] PICs are used for various applications in the fields of telecommunications, instrumentation, and signal processing. PIC devices (in the form of photonic chip packages) typically use optical waveguides to implement and / or interconnect various on-chip elements such as waveguides, optical switches, couplers, routers, splitters, multiplexers / demultiplexers, modulators, amplifiers, wavelength converters, optical-to-electrical (O / E) and optical-to-optical (E / O) signal converters (e.g., photodiodes, lasers), etc. The waveguides in PIC devices are typically on-chip solid optical conductors that guide light due to the refractive index difference between the waveguide core and the cladding.

[0006] One of the most expensive components within a photonic network is the fiber optic connector. In order to operate correctly, PICs typically require efficient coupling of light between an external optical fiber and one or more on-chip waveguides. PIC devices typically need to have optical connections to other PIC devices, typically in the form of an organized network of optical signal communications. The connection distance can range from a few millimeters in the case of chip-to-chip communication to thousands of meters in the case of long-distance applications. Optical fibers can provide an efficient connection method because light can flow over long distances within the optical fiber at very high data rates (>25Gbps) due to low-loss optical fibers. In order to operate correctly, PIC devices require efficient coupling of light between an external optical fiber and one or more on-chip waveguides. The advantage of using light as the basis for the operation of circuits in PIC devices is that its energy cost for high-speed signal transmission is significantly lower than that of electronic chips. Therefore, efficient coupling between PIC devices and other optical devices (such as optical fibers) that maintain this advantage is an important aspect of PICs.

[0007] One method of coupling an optical fiber to a PIC device (or PIC chip package) is to attach an optical fiber array to the edge of the PIC chip. To date, an active alignment method has been used to align the optical fiber array to an element on the PIC, in which the position and orientation of the optical fiber are mechanically adjusted until the amount of light transmitted between the optical fiber and the PIC is maximized. This is a time-consuming process, which is usually completed after the PIC is cut from a wafer and installed in a package. This postpones the optical fiber connection until the end of the production process. Once the connection is made, it is permanent and will be non-detachable, non-separable or non-removable in the absence of the possibility of destroying the integrity of the connection for any hope of reinstalling the optical fiber array to the PIC. In other words, the optical fiber array is irremovably attached to the PIC, and the optical fiber array connection and separation will be destructive and irreversible (i.e., non-reconnectable).

[0008] Current state of the art attempts to achieve tight alignment tolerances are to use polymer connector components, but polymers have several fundamental disadvantages. First, they are elastically compliant, making them susceptible to deformation under externally applied loads. Second, they are dimensionally unstable and may change size and shape, particularly when subjected to elevated temperatures, such as those found in computing and networking hardware. Third, the coefficient of thermal expansion (CTE) of polymers is much greater than the CTE of materials commonly used in PIC devices. Therefore, temperature cycling results in misalignment between the optical fiber and the optical elements on the PIC device. In some cases, polymers cannot withstand the processing temperatures used when soldering PIC devices to printed circuit boards.

[0009] Furthermore, it would be advantageous if the fiber connections could be created before the discrete PIC devices are cut from the wafer; this is often referred to as wafer-level attach. Manufacturers of integrated circuits and PICs typically have expensive capital equipment capable of sub-micron alignment (e.g., wafer probers and handlers for testing integrated circuits), while companies that package the chips typically have less capable machines (typically alignment tolerances of a few microns, which is insufficient for single-mode devices) and typically use manual operations. However, it is impractical to permanently attach the optical fiber to the PICs prior to cutting because the fiber will become tangled, obstructing the fiber during the cutting operation and packaging process, and is virtually impossible to manage when the PICs are picked and placed onto printed circuit boards and then soldered to the PCBs at high temperatures.

[0010] Another design challenge is to improve the optical and mechanical compatibility of the optical connector with the PIC device without the need for elaborate or complex connector assemblies to achieve a robust optical connection. Typically, the PIC device is packaged in a structure, and if structural changes are made to the package to accommodate the mechanical coupling of the optical connector, the structural integrity may be compromised. In addition, cutting the PIC device from a wafer does not provide a good reference for the optical and physical alignment of the optical connector with the PIC device. Without modifying the PIC device, a delicate base is typically provided around the PIC device to facilitate mechanical and optical coupling through the optical connector. This will increase the volume of the entire structure. In addition, the PIC device has different optical input / output configurations, which will require the optical connector to be designed to be compatible with the optical input / output configuration of the PIC device.

[0011] U.S. Patent Publication No. 2016 / 0161686A1 (commonly assigned to the assignee of the present application and fully incorporated herein by reference) discloses a detachable optical connector for an optoelectronic device. The disclosed detachable optical connector includes an implementation of elastic averaging coupling to provide an improved method of optically coupling input / output optical fibers to PICs, which improves tolerance, manufacturability, ease of use, functionality, and reliability at a reduced cost. As known in the prior art, elastic averaging represents a subset of surface coupling types in which improved accuracy is derived from the average of errors over a large number of contact surfaces. In contrast to kinematic designs, elastic averaging is based on significantly overconstraining a solid body with a large number of relatively compliant components. When the system is preloaded, the elastic properties of the material allow the size and position errors of each individual contact structure to be averaged over the sum of the contact structures of the entire solid body. Although the repeatability and accuracy obtained by elastic averaging may not be as high as that of a deterministic system, the elastic averaging design allows for higher stiffness and lower local stresses when compared to kinematic coupling. In a well-designed and preloaded elastic averaging coupling, repeatability is approximately inversely proportional to the square root of the number of contact points.

[0012] Most PIC devices require single-mode optical connections, which require tight alignment tolerances between the optical fiber and the PIC, typically less than 1 micron. Efficient optical coupling to and from an on-chip single-mode waveguide to an external optical fiber is challenging due to the size mismatch between the single-mode waveguide and the light-guiding core within the optical fiber. For example, the size of a typical silica optical fiber is about forty times larger than a typical waveguide on a PIC. Due to this size mismatch, if the single-mode waveguide and the optical fiber are directly coupled, the corresponding modes of the waveguide and the optical fiber may not couple efficiently, resulting in unacceptable insertion loss (e.g., >20 dB).

[0013] U.S. Patent No. 11,022,755 (commonly assigned to the assignee of the present application and fully incorporated herein by reference) discloses a removable edge coupler with a microlens optical bench for a PIC, which provides a mechanism to bring the mode sizes of optical fibers in a fiber array and on-chip optical elements close to each other to achieve efficient optical coupling input / output of the optical fiber to the PIC device.

[0014] What is needed is an improved removable optical and mechanical coupling for connecting an optical connector to a PIC device that improves flexibility, tolerance, manufacturability, ease of use, functionality, and reliability at reduced cost. Summary of the invention

[0015] The present invention overcomes the shortcomings of the prior art by providing a base in the form of an adapter to provide a detachable / separable and reconnectable passive alignment coupling / connection bridge for achieving high alignment accuracy. An optical connector (e.g., an optical bench supporting an optical fiber or a portion of an optical bench supporting an optical fiber) is configured and constructed to be non-destructively and removably attached to reconnect to a base aligned therewith. The base may be an integral part of an optoelectronic device (e.g., a portion of a photonic integrated circuit (PIC) chip), or a separate component attached to or associated with an optoelectronic device and / or optically aligned relative to the optoelectronic device.

[0016] The present invention will be explained in conjunction with the illustrated embodiments. The base can be aligned with an electro-optical element (e.g., a grating coupler, a waveguide, etc.) in an optoelectronic device. The base is permanently positioned relative to the optoelectronic device to provide an alignment reference for an external optical connector. The optical connector can be removably attached to the base via a "separable" or "detachable" or "removable" action, which accurately optically aligns the optical components / elements in the optical connector to the optoelectronic device along the desired optical path. In order to maintain the optical alignment of each connection and disconnection and reconnection, the connector needs to be accurately and accurately aligned with the base. According to the present invention, the connector and the base are aligned to each other using passive mechanical alignment (e.g., motion alignment, quasi-motion alignment, and elastic average alignment), which is composed of geometric features on two bodies. The present invention will be discussed in more detail with reference to the mechanical alignment based on elastic average alignment. With the above as an introduction, the present invention can be summarized as follows.

[0017] In one aspect of the invention, the base includes one or more optical elements, which may include diffractive optical elements, lenses, prisms, reflective surfaces that can reflect light by total internal reflection (TIR) ​​of an opaque free surface exposed to the outside (e.g., air or a refractive index matching material), and reflect incident light directed from the outside to the free surface (i.e., the incident light does not pass through the body of the base), or any other optical features and elements that effectively redirect (i.e., reflect, fold, turn, reroute, reshape (e.g., focus, collimate, diverge, converge or separate)) incident light from the optical connector and / or the optoelectronic device. The (one or more) optical elements of the base redirect and / or reshape the incident light to follow the desired beam path between the optical connector and the optoelectronic device (i.e., match the optical axes of the optical connector and the optoelectronic device). The base may include a combination of different optical elements having optical properties that produce a desired beam quality and direction. In addition, the base includes passive alignment features, such as kinematic alignment features, quasi-kinematic alignment features, and elastic average alignment features, which match / complement the passive alignment features on the facing side of the optical connector. In one embodiment, the base comprises a single unitary body provided with the optical element and the passive alignment features. In another embodiment, the base may comprise separate bodies which are separately provided with the passive alignment features and the optical element.

[0018] In one embodiment, the base is a longitudinal glass substrate or plate having passive alignment features integrally formed on the top surface of the base body (i.e., the surface facing the optical connector to be attached to the base). In another embodiment, the base further includes passive alignment features integrally formed on the bottom surface of the base body facing the optoelectronic device. The passive alignment features are grouped into two groups, each group being close to opposite ends on the surface of the longitudinal plate. Between the passive alignment features, an array of optical elements (e.g., microlenses) is integrally formed on the base (i.e., not a separate lens disposed on the surface). The passive alignment features and the array of optical elements can be integrally defined on the base body, wherein the geometry and relative position are defined in the final forming step so as to accurately define the alignment relationship of the passive alignment features relative to the array of optical elements. For example, in the case where the base body is made of glass, the passive alignment features and the array of optical elements can be molded to define the final geometry and position of the array of optical elements and the passive alignment features.

[0019] In the case where the base does not have a passive alignment feature at its bottom surface, the base can be optically aligned with a support surface and fixedly attached to a support surface (e.g., a top surface of a PIC device, or a grating coupler and / or waveguide on a support on a base on a circuit board that optically communicates with the PIC device). The base can be visually aligned to the support surface using a visual reference defined on the support surface, or additionally or alternatively optically aligned by determining an optical signal from a loopback optical channel on the support surface that corresponds to a desired position of the base relative to the support surface. Once the base is optically aligned with the support surface, the base is fixedly attached to the support surface (e.g., by epoxy or solder). Thus, the base provides a detachable connection for an optical connector, wherein the optical connector has a matching passive alignment feature on its mounting-facing surface. In the case where the base additionally has a passive alignment feature on its bottom surface and the support surface has a matching passive alignment feature, the base can be passively aligned and fixedly attached to the support surface.

[0020] In another embodiment, the optical connector can be coupled to the base first. The optical connector is actively aligned to the optoelectronic device by positioning the base relative to the optoelectronic device (e.g., a PIC chip or an optical I / O chip) to obtain the best optical signal between the optoelectronic device and the optical connector (e.g., an optical fiber supported by the optical connector). The position of the base is fixed at an alignment position relative to the optoelectronic device (e.g., using solder to fix the position of the base on a support of the optoelectronic device, such as an interposer, a printed circuit board, a base, etc.). The optical connector is then removed from the base, and the base can be permanently attached to the support (e.g., reflow solder) without changing its position on the support. Thereafter, the optical connector can be repeatedly connected and disconnected and reconnected to the base non-destructively without losing the original optical alignment obtained by the active alignment between the optical connector and the optoelectronic device. For each connection, disconnection, and reconnection, the optical alignment according to the original active alignment is maintained to accurately and accurately align the optical connector to the base.

[0021] In one embodiment, the base comprises a single unitary body provided with the optical element and the passive alignment features. In another embodiment, the base may comprise separate bodies which are separately provided with the passive alignment features and the optical element.

[0022] In another embodiment, the base can be in the form of a silicon insert having an optically transparent body. The silicon insert can be integrally defined (e.g., by etching) with passive alignment features and an array of optical elements to facilitate direct connection to the top of a PIC device or grating coupler on a supporting surface. If a window is provided on a cooling plate above the PIC device, then this window can be used to design the optical connector body to provide a rough alignment to guide the connection body to achieve a detachable connection based on the passive alignment features.

[0023] In another aspect of the invention, a base can be configured for removable edge coupling of an optical connector to a waveguide terminating at an edge of an optoelectronic device. The base can be configured with different optical elements to define a desired beam path with a desired beam shape to maximize the optical coupling of the optical signal into / out of the optoelectronic device and into / out of the optical connector. For example, the beam can initially expand between the optical connector and the optoelectronic device and ultimately focus onto the optoelectronic device and the waveguide on the optical connector. Lower tolerances are required for the transmission of the expanded beam, where high tolerances are maintained at the point where the beam is focused at the target device.

[0024] In another embodiment, the base is in the form of an insert for guiding light to / from the exit end of a waveguide array at the top or bottom surface of an optoelectronic device (e.g., SiPIC). The insert includes an optical element array for guiding light from an optical connector and pins on both sides of the optical element array, the pins extending outwardly on the surface of the optoelectronic device. The pins are integrally formed with passive alignment features for passive alignment with passive alignment features defined on the surface of the optoelectronic device, thereby optically aligning the optical element array to the waveguide array.

[0025] In another embodiment, the base in each of the above embodiments may be an integral component of the optoelectronic device or a support member of the optoelectronic device.

[0026] With the above being an introduction, the present invention may be further discussed below to support the features recited in the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] For a more complete understanding of the nature and advantages of the present invention and the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings.In the following drawings, like reference numerals represent the same or similar parts throughout the drawings.

[0028] Figure 1A An adapter / base having a passive alignment feature according to one embodiment of the present invention is shown; Figure 1B An adapter / base having passive alignment features according to another embodiment of the present invention is shown.

[0029] Figure 2A and 2B The process of molding a glass adapter / base according to one embodiment of the present invention is schematically illustrated.

[0030] FIG. 3A to FIG. 3E Illustrated is the alignment of a glass base with a PIC device according to one embodiment of the present invention.

[0031] Figures 4A to 4C A detachable connection of an optical connector to a glass base is shown according to one embodiment of the present invention.

[0032] Figure 5 Passive alignment of a glass base and a PIC device according to another embodiment of the present invention is illustrated.

[0033] Figure 6 A glass base including one or more separate pieces according to another embodiment of the present invention is shown.

[0034] Figures 7A to 7FAn implementation of a silicon lens insert in an optical connector for a glass base according to another embodiment of the present invention is shown; Figure 7G An embodiment of a silicon lens insert for direct coupling into an optical connector of a PIC device is illustrated.

[0035] Fig. 8A and 8B An alternative application of an optical connector in a co-packaged optical device is shown.

[0036] Fig.9A and Fig.9D The implementation of a base as an edge coupler to a PIC chip according to one embodiment of the present invention is shown.

[0037] Fig. 10A and 10B shows a perspective view of a base according to one embodiment of the present invention; Fig. 10C and Fig. 10D Different optical elements (eg, lenses, reflective surfaces) are shown deployed on the base.

[0038] FIG. 11A to FIG. 11F Various mounts are shown that employ different optical elements for optical coupling to a PIC device according to alternative embodiments of the present invention.

[0039] FIG. 12A to FIG. 12F The implementation of a submount according to another embodiment of the invention as an edge coupler to a PIC chip having a waveguide at its top surface is illustrated.

[0040] FIG. 13A to FIG. 13D An implementation in which a base as an edge coupler to a PIC chip has a waveguide at its bottom surface according to another embodiment of the present invention is illustrated. DETAILED DESCRIPTION

[0041] The present invention is described below with reference to various embodiments with reference to the accompanying drawings. Although the present invention has been described according to the best mode for carrying out the purposes of the present invention, those skilled in the art will appreciate that variations can be implemented in light of these teachings without departing from the spirit or scope of the present invention.

[0042] The present invention overcomes the shortcomings of the prior art by providing a base in the form of an adapter to provide a detachable / separable and reconnectable passive alignment coupling / connection bridge for achieving high alignment accuracy. An optical connector (e.g., an optical bench supporting optical fibers or a portion of an optical bench supporting optical fibers) is configured and constructed to be non-destructively and removably attached for reconnection to a base aligned therewith.

[0043] The base can be an integral part of the optoelectronic device (e.g., part of a photonic integrated circuit (PIC) chip), or a separate component attached to or associated with the optoelectronic device and / or optically aligned relative to the optoelectronic device. The passive alignment coupling concept of the present invention is discussed below by referring to the example of a PIC device as an optoelectronic device and an optical connector including an optical bench, and optically coupling the input / output end of an optical component (e.g., an optical fiber) supported in the optical bench to the optoelectronic device. The present invention can be applied to provide removable / reconnectable template structures and components for use in other fields.

[0044] Figure 1A A base 100 used as an adapter or insert or inserter according to a simple embodiment of the present invention is shown having passive alignment features defined on a top surface thereof to illustrate the inventive concept.

[0045] In one aspect of the invention, the base 100 includes one or more optical elements. In the illustrated embodiment, the optical element is in the form of a microlens array L. In other embodiments discussed below (see, e.g., 9A to 9D and FIG. 11A to FIG. 11F ), additional and / or different optical elements are formed in the base to reshape and reflect incident light by total internal reflection (TIR) ​​of an opaque free surface exposed to the outside (e.g., air or a refractive index matching material), and reflect incident light directed to the free surface from the outside (i.e., the incident light is not guided through the body of the base). The optical elements of the base 100 redirect and / or reshape the incident light to follow the desired beam path between the optical connector and the PIC chip P (i.e., match the optical axis of the optical connector 10 with the optical axis of the PIC chip P).

[0046] In addition, the base 100 includes passive alignment features E2, such as kinematic alignment features, quasi-kinematic alignment features, and elastic averaging alignment features, which match / complement the passive alignment features E1 on the facing side of the optical connector 10. In the illustrated embodiment, the passive alignment features are based on surface features for elastic averaging connection. U.S. Patent Publication No. 2016 / 0161686A1 and U.S. Patent No. 11,500,166B2 disclose elastic averaging features suitable for connecting an optical connector to a support base.

[0047] In the illustrated embodiment, the base 100 comprises a unitary unitary body B2 that is provided with the microlens array L and the passive alignment features E2.

[0048] In the illustrated embodiment, the base body B2 is a longitudinal glass substrate or plate having passive alignment features E2 integrally formed on the top surface of the base body B2 (i.e., the surface facing the optical connector 10 when attached to the base). The passive alignment features E2 are grouped into two groups, each group being close to opposite ends on the surface of the longitudinal plate. Between the passive alignment features, the microlens array L is integrally formed on the base 10 (i.e., not as a separate lens element disposed on the surface). The array of passive alignment features E2 and the microlens array L can be integrally defined on the base body B2, and their geometry and relative positions are defined in the final forming step so as to accurately define the alignment relationship of the passive alignment features E2 relative to the microlens array L. For example, in the illustrated embodiment of the base body B2 made of glass, the passive alignment features E2 and the microlens array L can be molded to define the final geometry and position of the microlens array L and the passive alignment features E2. The alignment features E2 and the microlens array L produced on the same substrate with a single tool / mask minimize the positional error between the two features.

[0049] Glass is a good material for the base 100 and has a coefficient of thermal expansion (CTE) that matches the silicon of the PIC chip P (CTE ≈ 3×10 -6 K -1 ). Glass molding allows for optimized optical and mechanical design and can operate at temperatures of ~100°C. The glass can withstand reflow soldering at 280°C.

[0050] Figure 2A and Figure 2B The glass molding process discussed in the publication of Zhou et al. [“A Review of Micro / Nanostructure Mold Fabrication Technology for Precision Glass Molding”, International Journal of Extreme Manufacturing, 3(2021).042002] is schematically shown, which can be applied to mold the base 100 according to one embodiment of the present invention. Figure 2A It is a schematic diagram of the PFLF7-60A molding machine. Figure 2B is a diagram depicting the various stages of a glass molding process using such a molding machine, which relates to molding temperature and forming pressure at various stages of the molding process.

[0051] Figure 3A and Figure 3B The optical alignment of a glass base with a PIC device according to one embodiment of the present invention is illustrated. In the illustrated embodiment, the base 100 can be optically aligned with and fixedly attached to a support surface (e.g., the top surface of a PIC chip P, or a grating coupler and / or waveguide on a support on a submount on a circuit board in optical communication with the PIC chip P). Figure 3A In the embodiment of the present invention, the base 100 can be visually aligned to the support surface using visual references defined on the support surface. Figure 3B Once the base 100 is optically aligned to the support surface, the base 100 is fixedly bonded to the support surface (e.g., by epoxy or solder). The entire package can undergo solder reflow and other packaging processes. The bottom surface of the base body B2 can be plated to allow solder reflow attachment to the PIC chip P.

[0052] Figure 3C and 3E An alternative or additional optical alignment process for the base 100 is depicted by determining an optical signal from a loopback optical channel on the support surface that corresponds to a desired position of the base relative to the support surface. Figure 3C , a holder GR having mechanical passive alignment features similar to the passive alignment features E1 on the optical connector 10 is used to pick up the base 100 and place the base 100 on the PIC chip P. The base 10 is first aligned with the PIC chip P using the visual reference VF set on the PIC chip during packaging. This can achieve an alignment accuracy of several microns. This enables the "first light" to be used for further more accurate optical alignment. Next, the alignment of the holder GR is performed more accurately using optical alignment. The holder GR can integrate a laser light source LS and a photodiode PD. Light is injected into the 'loopback' LB on the PIC chip P (inlet port IP, waveguide WG, outlet port OP). During this optical alignment process, the functional waveguides of channels Ch1 to ChN of the PIC chip P are not used. The optical alignment process can refer to the optical passive alignment of the optical connector assembly with the optoelectronic device in the process disclosed in U.S. Patent No. 9,897,769B2, which is commonly assigned to the assignee of the present application.

[0053] Figures 4A to 4C FIG. 1 shows a detachable connection of an optical connector according to an embodiment of the present invention to a glass base 100 that has been bonded to a supported surface. Figure 4A As shown, the optical connector 10 includes an array of micromirrors M, which corresponds to the array of microlenses L on the base 100. The optical connector 10 also accurately supports the outlet end of the optical fiber OF relative to the micromirror array M and therefore also relative to the passive alignment feature E1. In the illustrated embodiment, the optical connector 10 includes a body B1 that supports the optical fiber array OF that transmits the optical signal. The base 100 therefore includes a body B2 that provides an alignment reference with an external optoelectronic device (e.g., a PIC chip P, or an I / O PIC chip of an ASIC chip (e.g., a CPU, GPU, switch ASIC)) that communicates optical signals with the optical fiber OF in the optical connector 10.

[0054] More specifically, the body B1 of the connector 10 defines a base that supports an optical fiber array OF having a planar surface defined by a two-dimensional planar array of alignment features E1, which are integrally defined on the surface of the base of the body B1. In this embodiment, the connector 10 incorporates a micro-optical bench OB for supporting and aligning the optical fiber array FA. The optical fiber array has a plurality of optical fibers OF protected by a protective buffer and matrix / jacket layer P. The base of the body B1 of the connector 10 defines a structural feature that includes an alignment structure including an open groove G for holding an exposed portion of the optical fiber OF (with an exposed cladding, without a protective buffer layer and matrix / jacket layer J), and a structured reflective surface (e.g., eight mirrors M). The size of the open groove G is designed to receive an end segment of the optical fiber OF and the open groove G is positioned to accurately position the end segment of the optical fiber OF along the optical path relative to the first array of mirrors M. The end face (input / output end) of each of the optical fibers OF is maintained at a predetermined distance relative to the corresponding mirror M. In the illustrated embodiment, a transparent glass, quartz or sapphire cover plate covers the exposed surfaces on the optical bench OB to protect the mirror M. In one embodiment, the connector 10 may be filled with an index-matched epoxy between the mirror M and the cover plate.

[0055] The base 100 provides a detachable connection for the optical connector 10 on a supporting surface associated with the PIC chip P, wherein the optical connector 10 has a matching passive alignment feature E1 on its facing mounting surface. Figure 4B Attachment of the optical connector 10 having the matching passive alignment feature E1 to the passive alignment feature E2 on the base 100 is depicted. Figure 4C It is depicted that after attaching the matching passive alignment feature E2 of the optical connector 10 to the passive alignment feature E2 on the base 100, the optical path to and from the micromirror array M will pass through the corresponding microlens array L. The passive alignment features E1 and E2 provide precise optical alignment, repeatability, and separability for the optical path.

[0056] Figure 1B A base F' having an additional passive alignment feature E2' for passive alignment with a PIC chip P according to another embodiment of the present invention is illustrated. In this illustrated embodiment, the base 100' further includes a passive alignment feature E2', which is integrally formed on the bottom surface of the base body B2' that will face the PIC chip P. The additional alignment feature E2' on the bottom of the base body B2' allows the base body B2' to be passively aligned to the surface of the PIC chip P if a receiving portion and a complementary feature are present on the surface of the PIC chip P. The passive alignment feature E2' may be similar to the feature E2 on the top surface of the body base B2'.

[0057] Figure 5 Passive alignment of a glass base 100" to a PIC chip P according to another embodiment of the present invention is shown. In this embodiment, the base 100" further has a passive alignment feature E2" at its bottom surface, and the supporting surface of the PIC chip P has a matching passive alignment feature E". They can be used to passively align the base 100" to the PIC chip P. Specifically, in this embodiment, the precision alignment feature E2" includes three hemispheres on the bottom of the base body B2", which have good position tolerances related to the microlens array L. Complementary precision alignment features including three V-grooves are provided on the top surface of the PIC chip P to align with the grating coupler in the PIC chip P. A reference mark VF" can be provided on the top surface of the glass body B2", which is used to visually align the base 100" to a complementary reference mark on the PIC chip P (if provided; not shown) to provide a first light. The base 100" can be passively aligned and fixedly attached to the supporting surface of the PIC chip P.

[0058] In another embodiment, the base 100 may include a single body that is separately provided with the passive alignment features and the optical elements. Figure 6 A glass base 101 according to another embodiment of the present invention is shown, which includes one or more separate, unconnected components. In this embodiment, since the alignment base 101A and the microlens array insert L1 are separate components, the alignment base 101A can be on the top surface of the PIC chip P or on the outside of the PIC chip P. This configuration is less expensive because it minimizes the area of ​​the functional elements, thereby reducing the cost of glass molding. However, there will be more parts per molding operation.

[0059] According to the embodiments discussed above, the base 100 (and its variations) can be aligned with optoelectronic components (e.g., grating couplers, waveguides, etc.) inside or outside the optoelectronic device (see also in conjunction with FIG. 4, Figure 5, further description of FIG. 9 and FIG. 11). The base 100 is permanently positioned relative to the optoelectronic device (e.g., PIC chip P) to provide an alignment reference to the external optical connector 10. The optical connector 10 can be removably / detachably attached to the base F via a "detachable" or "detachable" or "removable" action, which accurately optically aligns the optical connector 10 to the optoelectronic device along the desired optical path. In order to maintain the optical alignment for each connection and disconnection and reconnection, the connector needs to be precisely and accurately aligned with the base. According to the present invention, the optical connector and the base are aligned with each other using passive mechanical alignment (e.g., kinematic alignment, quasi-kinematic alignment, and elastic average alignment), which is composed of geometric features on two bodies. In a specific embodiment, the present invention more specifically adopts a mechanical alignment based on elastic average alignment.

[0060] In one embodiment, each reflector M is an exposed free surface of the base of the body B1 (i.e., a surface exposed to air, or a surface that is not inside the body of the base of the optical bench) having an exposed reflective free side facing away from the body B1. The exposed reflective free side includes a structured reflective surface profile at which light is directed to or from the optical fiber OF, or to or from the base 100 (including alternative embodiments disclosed herein). Each reflector M bends, reflects and / or reshapes incident light. Depending on the geometric size and shape (e.g., curvature) of the structured reflective surface profile, the reflector M can collimate, expand or focus the incident light beam. For example, the structured reflective surface profile can include one of the following geometric shapes / profiles: (a) ellipsoidal, (b) off-axis parabolic, or (c) other free-form optical surfaces. For example, to provide optical power (optical power), the reflector surface can have any of the following surface geometric curvature functions, either individually or in combination: ellipsoidal or hyperbolic conical focus, annular aspheric surfaces with various numbers of even or odd aspheric terms, XY aspheric curves with various numbers of even or odd aspheric terms, Zernike polynomials of various orders, and various simpler surface families contained by these functions. The surface can also be a free-form surface that does not have symmetry along any plane or vector. The reflector M can be defined on the body B1 by stamping a ductile metal material. Various ductile metals that can be stamped with tool steel or tungsten carbide tools can form the body of the reflector, including any 300 or 400 series stainless steel, any Kovar composition, any precipitation or solution hardening metal, and any alloy of Ag, Al, Au, Cu. At long wavelengths above 1310nm, aluminum has high reflectivity (>98%) and is economically formed by stamping. The reflective surface of the metal portion comprising the reflector may be any of the metals mentioned above, or any highly reflective metal coating applied by sputtering, evaporation or electroplating processes.

[0061] Figures 7A to 7F An embodiment of the invention is shown which also provides for expanded beam optical coupling. Fig. 7A The connection of an optical fiber OF to a photonic integrated circuit (PIC) P1 is shown via an optical connector OC. Fig. 7E The PIC shown in has a 2D array of optical I / O ports where light leaves or enters the PIC. Fig.7D The base GF shown includes passive alignment features and a 2D lens array. The base GF can be made of silicon or glass. Figure 7B and 7C As shown, the silicon lens insert SI is also connected to the end face of the optical connector OC. This connection is according to another embodiment of the present invention. Passive alignment features on both the silicon lens insert SI and the base GF ensure that the lens arrays on SI and GF are aligned to obtain high coupling connection efficiency. The lens arrays in the base GF and the silicon insert SI provide an extended beam interface. The silicon insert SI can be integrally defined (e.g., by etching) with passive alignment features and an array of optical elements to facilitate direct connection to the top of a grating coupler or PIC device on a supporting surface.

[0062] exist Figure 7B In FIG. 1 , the positive side of the silicon front interposer SI has 2×22 channels of microlenses ML, which are aligned in position to the alignment features AF (protrusions) on the silicon interposer SI, as shown in FIG. Figure 7B As shown. Figure 7C In FIG. 1 , the silicon insert SI has 2×22 channels of an array of blind holes H (eg, 125.5 μm diameter) from the back side, which are connected to Figure 7B These blind holes receive the tips of the optical fibers to passively align the silicon insert SI to the optical fiber array in the optical connector OC, where Figure 7C The side shown in faces the end of the optical fiber in the optical connector OC. For the glass base GF, Fig.7D shows a 2x22 array of microlenses LA and Figure 7F The female alignment features AC on the top of the PIC chip P1 are shown to match the parallel array of alignment features AG. Fig. 7E Shown with Figure 7B The alignment features AF on the positive side of the silicon interposer SI are shown to be complementary to the alignment features AG'. The PIC chip P1 is shown in Figure 7F In. Figure 7F Shown in FIG. 1 is a 2×22 microlens array on top of a PIC chip P1.

[0063] Figure 7G Demonstrates the use of Fig.7D and Fig. 7EIn the case of the glass microlens array shown, the implementation is directly coupled to the silicon lens insert SI in the optical connector OC of the PIC chip P1. Figure 7G In embodiments of the present invention, the output of the microlens array ML on the silicon interposer is expanded within the PIC, which establishes a path for even higher fiber counts (eg, 3 or 4 rows).

[0064] Fig. 8A and 8B An alternative application of an optical connector in a co-packaged optical device is shown. If a window W is provided on the heat dissipating cooling plate CP above the PIC device, then this window can be used to design the optical connector body to provide a rough alignment to guide the connector body to achieve an accurate detachable connection based on the passive alignment features.

[0065] In another aspect of the invention, a base can be configured for a removable edge-coupled connection of an optical connector to a waveguide terminating at an edge of an optoelectronic device. The base can be configured with different optical elements to define a desired beam path with a desired beam shape to maximize the optical coupling of the optical signal into / out of the optoelectronic device and into / out of the optical connector. For example, the beam can initially expand between the optical connector and the optoelectronic device and ultimately focus onto the optoelectronic device and the waveguide on the optical connector. Lower tolerances are required for the transmission of the expanded beam, where high tolerances are maintained at the point where the beam is focused at the target device.

[0066] Fig.9A and Fig.9D The implementation of a base F1 as an edge coupler to a PIC chip C according to another embodiment of the present invention is shown. In this embodiment, the optical connector OP has an alignment cover CV1 formed with a passive alignment feature PA1 facing the base F1. The cover CV1 is provided with a through opening for light to pass along an optical path LP1. In this embodiment and Figures 12A-12F In the embodiment of , the base F1 is used as a glass bridge to guide and reshape the optical path LP1. As in the previous embodiment, the top surface of the base F1 is formed with a passive alignment feature PA2. The base F1 can be supported on top of a support structure SS and a PIC chip C, wherein the support structure SS is separated from the edge of the PIC chip C by a space SP, thereby forming a glass bridging structure. In particular, the base F1 includes an array of protrusions or a single connected protrusion PT1 on the lower side facing the PIC chip C, which provides an array of reflection surfaces corresponding to the channels in the PIC chip to be coupled, the number of reflector arrays M1, and the number of optical fibers OF through total internal reflection (TIR). Fig. 9CAs more clearly shown in the enlarged view of FIG. 1 , protrusion PT1 is received in space SP so that protrusion PT1 is below the top surface of PIC chip C to allow light to be directed to a waveguide or other optical element or component at the top of PIC chip C. A glass waveguide array may be provided at the bottom of base F1 to direct light to and from the mirror at protrusion PT1. As in the earlier embodiments, the removable coupling between the optical connector OP and the PIC chip is achieved by passive alignment of features PA1 and PA1 between cover plate CV1 and base F1, as shown in FIG. Fig.9D Return to reference Fig.9A , the optical path LP1 is an expanded collimated beam between the reflectors M1 and M2, which is focused at the ends of the optical fiber OF and the waveguide FWG. Both mirrors M1 and M2 are aspherical mirrors.

[0067] Fig. 10A and 10B shows a perspective view of a base F1 according to one embodiment of the present invention; Fig. 10C and Fig. 10D Different optical elements (e.g., lenses, reflective surfaces) and / or different reflective geometries deployed on the base are shown. Fig. 10C In the example, the reflective surface at protrusion PT1 is an aspherical mirror, which bends and collimates the incident light (or vice versa, depending on the direction the light is traveling). Between M1 and M2, this is similar to Fig. 9C The embodiment shown in Fig. 10D In FIG. 1 , the reflector M2′ is a flat surface in the protrusion PT1′ of the base F1′, which does not collimate the incident light. Instead, an aspheric lens AL is disposed on the top surface of the base F1′, corresponding to the position of the through opening TO in the cover plate CV1, which is used to collimate the light beam between the reflectors M2′ and M1. Various optical elements (e.g., lenses) and / or reflection geometries may be used to obtain the desired beam shape and direction. In FIG. FIG. 11A to FIG. 11F 9, which shows various mounts that employ different optical elements to optically couple to PIC devices according to alternative embodiments of the present invention. Some of the components that are similar to those in the embodiment of FIG. 9 will not be discussed below. The differences are highlighted below.

[0068] exist Fig.11A In an embodiment of the present invention, a recess is defined at the top of the base F2, which receives an optical isolator that prevents optical power from reflecting back along the optical interconnect and entering the laser source, where it would damage the laser. The optical isolator acts as a one-way valve, allowing light to propagate in only a single direction.

[0069] Fig. 11B The embodiment corresponds to Fig. 10DAn embodiment in which an aspherical lens is applied to collimate the light because the surface of the reflector M2' is a flat reflective surface in the base F1'.

[0070] exist Fig. 11C In the embodiment of FIG. 9 , the reflector M2 in the base F3 is similar to the aspheric mirror M2 in the embodiment of FIG. 9 , but the reflector M1′ in the optical connector OP3 is a plane mirror. Therefore, a refocusing lens RL is applied to the top of the base F3 at a position corresponding to the through opening TO in the cover plate CV1 to focus the light through the base F3 (or collimate the light entering the base F3, depending on the direction of light travel).

[0071] exist Fig.11D In the embodiment of FIG. 9 and FIG. 10D , the base F1 is similar to the base F1 in FIG. 9 and FIG. 10D . However, in this embodiment, an aspherical lens is provided on the lower side of the cover plate CV4 (corresponding to the position of the through hole TO in the previous embodiment) to focus / collimate the light along the optical path between the reflectors M1 'and M2, where the reflector M1 'is a plane mirror and M2 is an aspherical mirror, as in the previous embodiment. In this embodiment, the cover plate CV4 does not include a through opening TO for the light beam to pass through.

[0072] exist Fig.11E In the embodiment of the present invention, the base F5 has a through opening FTO, which defines an exposed aspheric mirror surface M5. The mirror M1 in the optical connector OP is an aspheric mirror. The mirror M5 can be metal-coated to improve reflectivity.

[0073] exist Fig.11F In the embodiment of the present invention, the top surface of the PIC chip C' is provided with a cavity CAV to receive the protruding portion PT6 of the base F6. In this embodiment, the reflective surface in the protruding portion PT6 is a flat reflective surface M2', so the aspherical lens is provided on the top of the base F6, at a position corresponding to the through opening TO in the cover CV1, as shown in FIG. Fig. 11B As is the case with the embodiment of .

[0074] In all of the above embodiments of the base having a protruding portion on the bottom surface, it should be noted that the protrusion is longitudinal in structure, e.g. Fig. 10A and 10B As shown. Fig.11F In the embodiment of FIG. 4 , the cavity CAV is a longitudinal groove at the top surface of the PIC chip C′ so as to accommodate a longitudinal protrusion at the bottom of the base F6 .

[0075] In another embodiment, the base FF takes the form of an insert for guiding light to / from the exit end of the waveguide array at the top or bottom surface of the optoelectronic device (eg, PIC chip C). FIG. 12A to FIG. 12FThe diagram illustrates an implementation of a base according to another embodiment of the present invention as an edge coupler to a PIC chip having a waveguide at its top surface. In this embodiment, the base FF includes an exposed micromirror array MM defined on the body FB', which corresponds to the number of outlet ends of the waveguide CWG on the top surface of the PIC chip CC, for guiding light from an optical connector (not shown). The base FF includes pins PP on both sides of the array of micromirrors MM, which extend outward from the body FB on the surface of the PIC chip CC. The pins PP are integrally formed with the passive alignment feature PAF1 so as to passively align with the passive alignment feature PAF2 defined (e.g., etched) on the surface of the PIC chip CC, thereby optically aligning the micromirror array MM to the waveguide array CWG. In the illustrated embodiment, the passive alignment feature PAF1 is a hemispherical protrusion that matches the square opening and conical bottom of the passive alignment feature PAF2 on the PIC chip CC.

[0076] FIG. 13A to FIG. 13D An implementation of a base FF' as an edge coupler to a PIC chip CC' having a waveguide CWG' at its bottom surface according to another embodiment of the present invention is shown. The base FF' is similarly constructed with a pin PP' extending from a body FB' having a similar passive alignment feature PAF1' that matches the similar passive alignment feature PAF2' in the previous embodiment of FIG. 12 . However, assuming that the waveguide CWG' is located on the bottom surface of the micromirror MM', the micromirror MM' is oriented in the same direction away from the passive alignment feature PAF1' on the upper side of the pin PP', in contrast to the previous embodiment of FIG. 12 , in which the micromirror MM was oriented opposite to the extension direction of the hemispherical passive alignment feature PAF1.

[0077] Instead of using glass for the submount described in the above embodiments, a silicon material may be used instead, with similar benefits, since silicon material is optically transparent to infrared light and can be manufactured with dimensional tolerances better than 100 nanometers.

[0078] Notice, Fig.12E and Fig. 13C All are side views or cross-sectional views, and no waveguide CWG / CWG' or micromirror MM / MM' is used alone.

[0079] According to the present invention, the optical connector and the base define a detachable coupling with an optical element formed on the base to provide light reshaping and / or redirection. In addition, a detachable elastic mean coupling between the optical connector and the base is defined without using any complementary alignment pins and alignment holes.

[0080] ***

[0081] Although the present invention has been specifically shown and described with reference to preferred embodiments, it will be appreciated by those skilled in the art that various changes may be made in form and detail without departing from the spirit, scope and teachings of the present invention. Therefore, the disclosed invention is considered to be illustrative only and limited only to the scope specified in the appended claims.

Claims

1. A detachable connection for an optical connector and an optical connection point, comprising: A base disposed along an optical path between an optical connector and an optical connection point, supporting the optical connector in optical alignment with the optical connection point, and facilitating removable connection of the optical connector to the base, wherein the base includes at least one optical element and a passive alignment feature, the at least one optical element being used to reshape and / or redirect incident light between the optical connector and the optical connection point, the passive alignment feature being on a surface of the base to provide a removable connection with a matching passive alignment feature of the optical connector, wherein a position of the optical element is defined relative to the passive alignment feature so as to define optical alignment with reference to the passive alignment feature, and wherein the base is attached to the optical connection point.

2. The detachable connection of claim 1, wherein the base is fixedly attached relative to the optical connection point to provide an optical alignment reference for the optical connector.

3. A detachable connection according to any one of the preceding claims, wherein: The optical element of the base includes at least one of a lens and a reflective surface to reshape and / or redirect light between the optical connector and the optical connection point.

4. A detachable connection according to any one of the preceding claims, wherein: The optical connection point includes an optoelectronic device.

5. A detachable connection according to any one of the preceding claims, wherein: The optoelectronic device includes a photonic integrated circuit (PIC) chip.

6. A detachable connection according to any of the preceding claims, wherein the detachable connection according to any of the preceding claims, wherein the passive alignment feature is constructed and configured to provide mechanical alignment based on one of kinematic alignment, quasi-kinematic alignment and elastic average alignment.

7. A detachable connection according to any one of the preceding claims, wherein: The base may include a combination of different optical elements having optical properties that produce a desired beam quality and direction.

8. A detachable connection according to any one of the preceding claims, wherein: The base includes an integral unitary body that is provided with the optical element and the passive alignment feature.

9. A detachable connection according to any one of the preceding claims, wherein: The base includes a separate body that is separately provided with passive alignment features and optical elements.

10. A detachable connection according to any one of the preceding claims, wherein the base is a longitudinal glass substrate having passive alignment features integrally formed on a top surface of the base body (ie the surface facing the optical connector to be attached to the base).

11. A detachable connection according to any one of the preceding claims, wherein: The base also includes a passive alignment feature integrally formed on a bottom surface of the base body to which the optical connection point will be attached.

12. A detachable connection according to any one of the preceding claims, wherein: The passive alignment features are grouped into two groups, each group near opposite ends on the surface of the longitudinal plate, and wherein, between the passive alignment features, an array of optical elements (e.g., microlenses) is integrally formed on the base (i.e., no individual lenses are disposed on the surface).

13. A detachable connection according to any one of the preceding claims, wherein: The passive alignment features and the optical element array may be integrally defined on the base body, wherein the geometry and relative positions are defined in a final forming step to precisely define the alignment relationship of the passive alignment features relative to the optical element array.

14. A detachable connection according to any one of the preceding claims, wherein: The base may be in the form of a silicon interposer having an optically transparent body integrally defined (eg, by etching) with passive alignment features and an array of optical elements to facilitate direct connection to the optical connection points.

15. A detachable connection according to any one of the preceding claims, wherein: The base is configured for removably edge-coupling the optical connector to a waveguide terminating at an edge of an optoelectronic device, wherein the base includes at least one reflective surface.

16. A detachable connection according to any one of the preceding claims, wherein: The base includes a reflective surface on a protrusion extending from a bottom of the base; wherein the optical connector has an alignment cover formed with passive alignment features that face the passive alignment features on the top surface of the base, wherein the base acts as a glass bridge to guide and reshape the light between the optical connector and an edge of the optical connection point.

17. A detachable connection according to any one of the preceding claims, wherein: The base is in the form of an insert for guiding light to / from an exit end of a waveguide array at a top surface or a bottom surface of an optoelectronic device (i.e., a SiPIC), wherein the insert comprises an optical element array for guiding light from the optical connector and pins on both sides of the optical element array, the pins extending outwardly on a surface of the optoelectronic device, and wherein the pins are integrally formed with passive alignment features for passively aligning with the passive alignment features defined on the surface of the optoelectronic device, thereby optically aligning the optical element array to the waveguide array.

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