Method and apparatus for efficient optical coupling between optical fibers and photonic integrated chips

Abstract

Methods and structures for edge coupling between waveguides and a fiber array for photonic integrated circuit (PIC) chips with warpage. Some methods are used to measure the displacement of the waveguide end faces due to the warpage of the PIC chip. Some methods and structures are provided for using the measured waveguide displacement to fabricate the fiber array to improve the optical coupling efficiency between individual waveguides and fibers.

Description

[0001] Incorporate any priority claim by reference. This application claims the benefit of U.S. Provisional Patent Application No. 63 / 620697, filed January 12, 2024, entitled “Methods and Devices for Efficient Optical Coupling Between Optical Fiber Arrays and Photonic Integrated Chips,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure generally relates to optical coupling between optical fibers and waveguides, and more specifically, to coupling between optical fibers and waveguides fabricated on photonic integrated chips. Background Technology

[0003] The advent of monolithic fabrication technology for manufacturing on-chip photonic devices and components has enabled the fabrication of photonic integrated circuits (PICs), which include multiple photonic devices with optical interconnects on a chip or substrate. PICs used in optical systems can communicate optically with another optical system, optical subsystem, or optical device. Optical connections between a PIC and another optical system or device can be established using edge coupling between multiple waveguides and multiple optical fibers on the PIC. Attached Figure Description

[0004] In the following description of various embodiments, reference is made to the accompanying drawings, which form a part of this disclosure, and various embodiments of the device are illustrated by way of illustration in the drawings. It should be understood that other embodiments may be utilized and structural changes may be made. It should be understood that the drawings are not drawn to scale and certain dimensions may be exaggerated for clarity and / or emphasis.

[0005] Figure 1A It is a schematic diagram showing the side view (top panel) and top view (bottom panel) of the edge portion of the PIC die stacked on the EIC to form a photonic integrated circuit (PIC) bonded to an electronic integrated circuit (EIC), which depicts multiple edge coupler waveguides and corresponding edge coupler waveguide end faces.

[0006] Figure 1B This demonstrates alignment with fiber arrays for fiber-to-chip optical coupling. Figure 1A The diagram shows a side view (top panel) and a top view (bottom panel) of the edge portion of the PIC stacked on the EIC.

[0007] Figure 2A This is a schematic diagram showing a warped PIC with a convex top surface stacked on an EIC (top panel) and a warped PIC aligned with a fiber array on an EIC (bottom panel). The fiber end faces are aligned with the edge waveguide coupler end faces of the PIC chips for fiber-to-chip optical coupling.

[0008] Figure 2B This is a schematic diagram showing a warped PIC with a concave top surface stacked on an EIC (top panel) and a warped PIC aligned with an optical fiber array on an EIC (bottom panel). The fiber end faces are aligned with the edge waveguide coupler end faces of the PIC chips for fiber-to-chip optical coupling.

[0009] Figure 2C This is a schematic diagram showing a warped PIC with alternating convex and concave top surface areas stacked on an EIC (top panel) and a warped PIC aligned with an fiber array on an EIC (bottom panel). The fiber end faces are aligned with the edge waveguide coupler end faces of the PIC chip for fiber-to-chip optical coupling.

[0010] Figure 3 This is a schematic diagram showing a side view of a warped PIC on the EIC, depicting... Figure 2C The warped PIC shown in the figure is an instance area on the EIC, which can be used to characterize the warping used to adjust the position of the corresponding fiber.

[0011] Figure 4A This is a top-view schematic diagram showing the edge portion of the PIC stacked on the EIC with the fiber array aligned, where the end face of each fiber contains a microlens for efficient fiber-to-waveguide optical coupling.

[0012] Figure 4B This is a top-view schematic diagram showing the edge portion of the PIC stacked on the EIC with the fiber array aligned, where microlenses are placed on the waveguide end face of each edge coupler for efficient fiber-to-waveguide optical coupling.

[0013] Figure 5A This is a schematic side view of a fiber optic array structure including a fiber optic mount with a V-groove array having V-grooves of substantially the same depth and opening width.

[0014] Figure 5B This is a schematic side view of a custom fiber array structure including a fiber mount with a v-groove array, the v-groove array having custom depth and opening width for efficient optical coupling to a warped PIC.

[0015] Figure 5CThis is a schematic diagram showing a close-up side view of an optical fiber positioned within a V-groove of an optical fiber mount, depicting the width (w) of the V-groove opening, the depth (d) of the V-groove, the vertical offset (h) of the optical fiber (relative to the top surface of the optical fiber mount), the core region of the optical fiber, and the center of the core region.

[0016] Figure 6 This is a schematic side view of a custom fiber array structure aligned with a warped PIC, where individual V-grooves are custom-made to align the fiber with the corresponding edge coupler waveguide end face of the PIC. Detailed Implementation

[0017] The advent of monolithic fabrication technology for manufacturing on-chip photonic devices and components has enabled the fabrication of photonic integrated circuits (PICs), which include multiple photonic devices with optical interconnects on a chip or substrate. In some cases, an entire optical system or a portion thereof can be fabricated on one or more chips.

[0018] In some cases, a PIC may be mounted or bonded to an electronic integrated circuit (EIC), for example, to provide an electrical connection between the electronic circuitry of the EIC and one or more optical devices or components of the PIC (e.g., detectors, lasers, modulators, heaters, attenuators, or other electronic or optoelectronic devices). In some embodiments, the PIC may be bonded to the EIC via an array or matrix of solder bumps configured to electrically connect one or more contact pads of the EIC to one or more contact pads of the PIC. In some cases, the EIC may include a complementary metal-oxide-semiconductor (CMOS) die. In some instances, the CMOS die may include one or more CMOS transistors that can form electronic circuitry.

[0019] While the optical components of a PIC can be optically interconnected via monolithically fabricated waveguides, in some cases, the PIC may receive and / or transmit optical signals to and from an optical system or device (e.g., a light source, another PIC, fiber-coupled optics, and the like). Fiber-optic waveguides (also known as optical fibers) are commonly used to establish optical connections (e.g., low-loss optical connections) between the PIC and another optical device, optical system, or optical subsystem. Therefore, efficient optical coupling between the fiber and the PIC can play a significant role in the performance (e.g., power efficiency, signal-to-noise ratio, and the like) of the PIC's optical system, including optical connections to another optical device or optical subsystem.

[0020] In some embodiments, fiber coupling to the PIC may include edge coupling one or more optical fibers (e.g., a periodic or aperiodic arrangement of optical fibers comprising an array) to the PIC via an end face (referred to herein as an edge coupling end face). In some cases, the PIC may include an optical waveguide (referred herein as an edge coupler waveguide) configured to optically connect one or more optical devices and / or components of the PIC to one or more optical fibers (e.g., a periodic or aperiodic arrangement of optical fibers comprising an array) via the edge coupling end face of the PIC. In some instances, the edge coupler waveguide may extend from an optical device or waveguide formed on the PIC to an edge region of the PIC. In some such instances, the edge coupler waveguide may terminate at or near the edge coupling end face of the PIC. In some embodiments, the edge coupling end face may be formed by splitting (or splitting and polishing) the PIC chip near the output end of the edge coupler waveguide. In some cases, the edge coupling end face may include one or more edge coupler waveguide end faces formed during the splitting process. In some instances, the edge coupler waveguide end faces can be formed before the PIC is split (e.g., by etching). The edge coupler end faces and / or corresponding edge coupler waveguide end faces can serve as one or both input and output optical ports of the PIC. In some cases, the edge coupler end faces and / or corresponding edge coupler waveguide end faces can be coated with an anti-reflection (AR) layer configured to reduce optical reflections from the interfaces between the edge coupler waveguide end faces and from the air gap between the edge coupler end faces and the fiber array. In some cases, the AR layer may comprise multiple sublayers whose refractive index and thickness are configured to reduce optical reflections at the edge coupler end faces and / or corresponding edge coupler waveguide end faces within a specified wavelength range.

[0021] In some cases, the edge coupling endface may include a surface region substantially perpendicular to the main surface of the PIC (e.g., the surface on which photonic circuitry is formed or a surface parallel to the surface on which photonic circuitry is formed). In some cases, the edge coupling endface may extend along a first direction parallel to the main surface of the PIC (e.g., a flat or planar main surface) or a plane corresponding to the main surface of the PIC chip. In some embodiments, multiple edge coupler waveguide endfaces may be arranged along the edge coupling endface such that the vertical distance between the edge coupler waveguide endfaces and the main surface of the PIC remains substantially constant along the edge coupling endface. The vertical distance may be a distance along a second direction (e.g., a vertical direction) perpendicular to the main surface of the PIC chip or a plane corresponding to the main surface of the PIC chip. This arrangement facilitates optical alignment and coupling between the multiple edge coupler waveguide endfaces and multiple optical fibers arranged such that the centers of all fiber cores are in a common plane (referred to herein as the fiber array plane). For example, when the distance between consecutive edge coupler waveguide end faces matches the distance between corresponding fiber cores, all fiber cores can be simultaneously aligned with their respective edge coupler waveguide end faces by aligning one fiber core with the edge coupler waveguide end face and keeping the fiber array plane substantially parallel to the main surface of the PIC chip. In some instances, multiple edge coupler waveguide end faces may comprise a periodic arrangement or a periodic array having a pitch (e.g., waveguide end face to waveguide end face distance) equal to the pitch of a periodic fiber arrangement (e.g., a periodic fiber array) with the same pitch (e.g., fiber-to-fiber distance). In some other instances, multiple edge coupler waveguide end faces may be non-periodic (e.g., they may comprise an aperiodic array), and the lateral position of the edge coupler waveguide end faces may match the lateral position of an aperiodic or aperiodic arrangement of fibers (e.g., an aperiodic fiber array).

[0022] In some cases, during or after manufacturing, a PIC (or the wafer on which the PIC is fabricated) may deform or warp, for example, due to process stress, or mismatch between the physical properties of different layers, and the like. In some cases, warping may be caused by different stress levels in different materials, different thermal expansion of different materials, or non-ideals in the PIC manufacturing process. In some cases, warping of the EIC may cause warping of the PIC when the PIC is bonded to a warped EIC (e.g., a CMOS die). In other cases, non-ideals in the bonding process of the PIC onto the EIC may cause warping of both the PIC and the EIC. Therefore, in some cases, a flat PIC may become warped after bonding to an EIC or other substrate (e.g., a carrier substrate).

[0023] This warping can cause the end faces of the edge coupler waveguide to shift relative to each other in a vertical direction perpendicular to a plane (e.g., the non-warped surface) corresponding to the main surface of the PIC. This shift can reduce optical coupling between some of the edge coupler waveguides and corresponding fibers of a fiber array having a flat fiber array plane. In some cases, when the PIC warps, the plane corresponding to its main surface can be a plane perpendicular to at least two cleaved end faces of the PIC extending in two different directions, and the vertical direction can be a direction perpendicular to said plane.

[0024] This disclosure relates to edge coupling between the waveguide of a photonic integrated circuit (PIC) chip and an optical fiber array when the PIC has warpage. Some methods involve measuring the displacement of the end face of the edge coupler waveguide due to the warpage of the PIC chip (e.g., with respect to a nominal plane corresponding to the main surface of the PIC). Some methods and structures involve custom optical fiber array structures having fiber cores positioned based on the measured displacement of the edge coupler waveguide end face to improve the optical coupling efficiency between individual edge coupler waveguide end faces and optical fibers. Some embodiments may use microlens arrays between the integrated circuit (PIC) chip and the optical fiber array to improve optical coupling. In various embodiments, the microlens array may be disposed on the core region of an individual optical fiber end face or on an individual edge coupler waveguide end face.

[0025] In some embodiments, the PIC chip may include a substrate and a waveguide layer disposed on the substrate. In some embodiments, the edge coupler waveguide may be fabricated on or within the waveguide layer. In some instances, the substrate may include silicon (e.g., a silicon wafer). In some instances, the waveguide layer may include silicon dioxide (SiO2). In some instances, the edge coupler waveguide may include silicon nitride (SiN). In some embodiments, the PIC chip may include a waveguide layer comprising a SiN edge coupler waveguide embedded in a silicon dioxide layer (also called a cladding layer) disposed on a silicon substrate. In some embodiments, the PIC chip may include a waveguide layer comprising a silicon edge coupler waveguide embedded in a silicon dioxide layer (also called a cladding layer) disposed on a silicon substrate. In some other embodiments, the edge coupler waveguide, substrate, and / or cladding layer may include other materials. In some instances, the edge coupler waveguide may include a first material, and the cladding may include a second material having a refractive index lower than that of the first material.

[0026] Figure 1AThis is a schematic diagram showing a side view (top panel) and a top view (bottom panel) of an edge portion (or area) of a photonic integrated circuit (PIC) die 101 (or PIC 101) stacked on or above (e.g., bonded to) an electronic integrated circuit (EIC) die 102 (or EIC 102), depicting multiple edge coupler waveguides and corresponding edge coupler waveguide end faces. In some embodiments, the PIC 101 may be bonded to the EIC 102 via a bonding interface 104 to form a composite structure referred to herein as PIC stacked on EIC 100. In some cases, the bonding interface 104 may include an array or matrix of solder bumps. In some cases, the EIC 102 may include a CMOS die containing complementary metal-oxide-semiconductor (CMOS) transistors that communicate electrically with the PIC 101 (e.g., for controlling, monitoring, or otherwise exchanging electrical signals with the photonic elements of the PIC 101).

[0027] PIC 101 may include a waveguide layer 101a, within which one or more edge coupler waveguides are embedded. Waveguide layer 101a may be fabricated on a substrate 101b. In some instances, waveguide layer 101a may include silicon dioxide, and substrate 101b may include silicon. In some embodiments, edge coupler waveguide 108 and corresponding edge coupler waveguide end face 107 may have a thickness (e.g., along the z-axis) of 200 nm to 350 nm, 350 nm to 400 nm, or other thicknesses, and a width (e.g., along the x-axis) of 100 nm to 300 nm, or other widths. In some embodiments, the edge coupler waveguide end face may be formed as a periodic end face array having a pitch of 100 to 127 micrometers, 127 to 250 micrometers, or larger or smaller values. In some cases, the corresponding edge coupler waveguide array may be a periodic waveguide array having the same or different pitches compared to the periodic end face array. For example, at least a portion of the periodic waveguide array may have a pitch different from (e.g., smaller) than that of the periodic endface array. In some embodiments, the lateral position of at least a portion of the edge coupler waveguide endface may not be periodic.

[0028] In some embodiments, PIC 101 may include an edge-coupled end face 106 extending in a first direction (e.g., along the x-axis) parallel to the top main surface 105 of PIC 101, and a plurality of edge coupler waveguide end faces may be arranged along the edge-coupled end face 106 such that the vertical distance (e.g., along the z-axis) between the edge coupler waveguide end faces (shown as small squares) and the top main surface 105 of PIC 101 remains substantially constant along the first direction (e.g., the x-axis). The vertical distance may be a distance along a second direction (e.g., parallel to the z-axis). In some cases, the second direction may be substantially orthogonal to the first direction. Thus, in the illustrated example, the PIC die 101 and the EIC (CMOS) die 101 are flat, and the edge coupler waveguide end faces lie on a flat surface parallel to the xy plane and perpendicular to the z-axis. Since PIC 101 is not warped, in this case, the top main surface 105 of PIC 101 can be a plane that defines the vertical direction and measures or determines the vertical position of the edge coupler waveguide end face.

[0029] Figure 1B This demonstrates alignment with fiber array 110 for fiber-to-chip optical coupling. Figure 1A The diagram shows a side view (top panel) and a top view (bottom panel) of the edge portion of the PIC stacked on the EIC 100. Individual fibers 112 of the fiber array 110 may include a core region 114 (also called a fiber core) surrounded by a cladding, through which light generally resides and is guided. In some instances, the fiber array 110 may include multiple fibers positioned such that the center of the corresponding fiber core lies generally in a flat plane (e.g., parallel to the xy plane) parallel to the top main surface of the PIC 101 or the top surface of the fiber mount on which the fiber array is formed. Because the edge coupler waveguide end faces are located in a flat plane (parallel to the xy plane), each fiber core 114 can be aligned with the corresponding edge coupler waveguide end face 107 to provide efficient fiber-to-waveguide coupling when the fibers and edge coupler waveguide end faces are uniformly (e.g., periodically) spaced at the same pitch in the lateral direction (e.g., along the x-axis). Figure 1A and 1B In the examples shown, the edge coupler waveguide end face of the PIC 101 is periodically positioned in the lateral direction. However, the embodiments are not so limited, and in some cases, the lateral position of the PIC's edge coupler waveguide end face may not be periodic in the lateral direction. In these embodiments, the lateral position of the fibers of the fiber array optically coupled to the edge coupler waveguide end face may match the lateral position of the edge coupler waveguide end face, and thereby may not be periodic in the lateral direction.

[0030] As mentioned above, in practice, PIC and / or CMOS dies may exhibit warping, for example, warping caused by manufacturing-induced stress. Warping can occur in a single direction, such as... Figure 2A and 2B The displayed or included pattern (e.g., random pattern), such as Figure 2C As illustrated herein, regardless of the warp direction or profile, when the PIC 101 has warp, the edge coupler waveguide end faces are no longer located on a flat plane. Therefore, efficient coupling between all the fibers of the fiber array and all the edge coupler waveguide end faces may be impossible when the fiber cores of the fiber array are in a flat plane. In some of the embodiments disclosed herein, efficient optical coupling between the fibers of the fiber array and the warped edge coupler waveguide end faces of the PIC can be achieved by arranging the fibers such that the corresponding fiber cores form a warp-matched pattern with the edge coupler waveguide end faces, thus achieving optical alignment between all or most of the edge coupler waveguide end faces and the corresponding fibers using a non-flat pattern (e.g., a warped pattern). Some of the methods disclosed herein may include determining the relative position of the fibers of the fiber array along a vertical direction (e.g., along the z-axis) of a plane perpendicular to the plane of the main surface of the fiber array (e.g., the main surface of the PIC) and the main surface of the fiber mount on which the fiber array is formed (e.g., the planar main surface) of the PIC 101 is relative to the waveguide end face of the PIC 101, for example, with respect to a plane corresponding to the main surface of the PIC (e.g., the main surface of the PIC) (e.g., the main surface of the PIC) (e.g., the main surface of the PIC) and the plane on which the fiber array is formed.

[0031] Figure 2A This is a schematic side view illustrating a non-limiting example of a warped PIC 201 with a convex top main surface 209a stacked on an EIC 200 (top panel) and a warped PIC stacked on an EIC 200 (bottom panel) aligned with a custom fiber array 210. The edge coupler waveguide end face of the warped PIC 201 is aligned with the fiber core of the custom fiber array 210 to provide fiber-to-chip optical coupling.

[0032] Figure 2B This is a schematic side view illustrating another non-limiting example of a warped PIC 201 with a concave top surface 209b stacked on an EIC 202 (top panel) and a warped PIC 202 aligned with a custom fiber array 212 on an EIC 202 (bottom panel). The edge coupler waveguide end face of the warped PIC 201 is aligned with the fiber core of the custom fiber array 212 to provide fiber-to-chip optical coupling.

[0033] Figure 2CThis is a schematic side view illustrating yet another non-limiting example of a warped PIC 201 with a warped top surface 209c having alternating convex and concave regions, stacked 204 of warped PICs on an EIC (top panel), and another warped PIC stacked 204 of warped PICs aligned with a custom fiber array 214 (bottom panel). The edge coupler waveguide end face of the warped PIC 204 is aligned with the fiber core of the custom fiber array 214 to provide fiber-to-chip optical coupling (bottom panel).

[0034] As in Figures 2A to 2C As shown, in various embodiments where the PIC is warped and its edge coupler waveguide end faces are vertically displaced (e.g., they are not positioned in a flat plane), a custom fiber array can be formed such that the relative vertical displacement of the corresponding fiber core with respect to a plane 213 corresponding to the main surface (e.g., the top main surface) of the warped PIC matches the relative vertical displacement of the edge coupler waveguide end faces. In some embodiments, the custom fiber array can be fabricated by first measuring the relative vertical displacement of the edge coupler waveguide end faces in the warped PIC (e.g., with respect to plane 213 corresponding to the top main surfaces 209a to c), and the measured relative vertical displacement can be used to design and fabricate a custom fiber mount configured to vertically align the individual fibers of the custom fiber array to match the vertical alignment of the corresponding edge coupler waveguide end faces. In some embodiments, a custom fiber array can be manufactured by first measuring the change in the vertical position (along the z-axis) of the edge coupler waveguide end face about plane 213 in the lateral direction (e.g., along the x-axis) and using the measured change in vertical position to design and manufacture a custom fiber mount, which is configured to vertically align the individual fibers of the custom fiber array to match the vertical alignment of the corresponding edge coupler waveguide end face.

[0035] In some embodiments, a method of designing and forming an optical fiber array for optically coupling to a warped PIC (e.g., PICs stacked on an EIC in 200, 202, 204) coupler waveguide may include characterizing the warping of the warped PIC or the warping profile of the corresponding edge coupler waveguide end face (z-displacement profile along the x-axis, also referring to the height profile).

[0036] In some embodiments, the warped PIC may include a plurality of edge coupler waveguide end faces whose relative vertical position varies in the lateral direction by more than 2%, 4%, 6%, 8%, or 10% of the average vertical position of the plurality of edge coupler waveguide end faces, wherein the vertical position is measured with respect to a plane corresponding to the main surface of the warped PIC (e.g., plane 213 corresponding to the top main surfaces 209a to c), and the vertical direction (e.g., the z-direction) is perpendicular to said plane. In some embodiments, the warped profile may include a variation in vertical position in the lateral direction (e.g., along the x-axis).

[0037] In various embodiments, different portions, regions, end faces, or surfaces of the warped PIC can be measured to determine the warping profile. For example, the surface profile of PIC 204 (e.g., the profile of the warped top main surface 209c) can be measured (e.g., using an optical profilometer or a stylus-based profilometer). The surface profile can be used to determine the warping profile of the edge coupler waveguide end face (e.g., the variation in position of the edge coupler waveguide end face along the z-axis). In some embodiments, the warping profile of the edge coupler waveguide end face can be determined by measuring the profile of the interface between waveguide layer 101a and substrate 101b (e.g., using imaging). In some embodiments, the warping profile of the edge coupler waveguide end face can be determined by directly imaging the edge coupler waveguide end face.

[0038] In some embodiments, the warpage profile may include or be derived from the measured height profile of the PIC. In some embodiments, the height profile may include the lateral variation in distance between the top primary surface of the PIC and a flat plane associated with the top primary surface. In some such embodiments, the height profile may be measured by measuring the surface profile of the top primary surface of the PIC (e.g., using a profilometer). In some embodiments, the height profile may include the lateral vertical variation profile of an interface (e.g., between a waveguide layer and a PIC substrate) or an edge coupler waveguide end face. In some such embodiments, the height profile may be measured by obtaining an image of the end face of the PIC (e.g., the edge-coupled end face of the PIC).

[0039] Figure 3 It is a description Figure 2C The schematic diagram shown illustrates an example region of a warped PIC stacked 204 on an EIC, which can be measured using three different methods described below to determine the warped profile of the corresponding edge coupler waveguide end face. In various embodiments, the geometry of one or more of these regions may be proportional to, or used to estimate or calculate, the warped profile of the edge coupler waveguide end face. In some instances, the warped profile of the edge coupler waveguide end face may include the variation in the vertical distance of the edge coupler waveguide end face with respect to a flat plane.

[0040] Method 1: In some embodiments, the chip facets of the PIC 204 can be imaged using a microscope. For example, the edge-coupled waveguide facets of the PIC 204 can be imaged, and individual edge-coupled waveguide facets can be identified in the microscopic image. In some instances, digital image processing methods can be used to identify the edge-coupled waveguide facets. In some cases, once the edge-coupled waveguide facets are identified, the relative position (relative vertical variation or displacement) of the identified waveguide facets can be measured from the image, for example, to generate a warped profile 216. In some instances, the warped profile of the edge-coupled waveguide facets may include the z-coordinates of different waveguide edge-coupled waveguide facets (e.g., the center of the waveguide facet) distributed along the x-axis.

[0041] Method 2: In some embodiments, the warpage of the plane defined by the edge-coupled waveguide (silicon nitride (SiN) waveguide) can be considered to be substantially or substantially the same as the warpage of the top surface of the warped PIC die 201. In some such embodiments, the profile of the warped top surface of the PIC 201 (or, for example, the top surface 218 of the waveguide layer 201a of the SiO2 layer) can be measured using a surface profilometer. Subsequently, the vertical offset of each edge-coupled waveguide end face can be calculated or extracted from the measured warpage at the corresponding lateral location (e.g., along the x-axis) of the top surface of the waveguide layer.

[0042] Method 3: In some embodiments, the warpage profile of the plane defined by the edge-coupled waveguide (SiN waveguide) can be considered to be substantially or substantially the same as the warpage profile of the interface 220 (Si-SiO2 interface) between the waveguide layer 201a and the substrate 201b of the warped PIC 201. In some cases, the warpage profile of the interface 220 between the waveguide layer 201a and the substrate 201b can be measured using a profilometer and / or imaging system. In some cases, the vertical offset (along the z-axis) of the individual edge coupler waveguide end face can be calculated or extracted from the measured warpage at the corresponding lateral position (along the x-axis) of the Si-SiO2 interface. In some embodiments, the warpage profile of the PIC can be measured by measuring the vertical variation profile of the interface 220 between the waveguide layer 201a and the substrate 201b.

[0043] In some embodiments, a warped PIC may include warping or a warped profile that can be measured, characterized, or quantified using one of the methods described above or other methods. In some embodiments, a warped PIC may include a warped interface, a warped surface, or a nominal warped path or line defined by the edge coupler waveguide end face. In some instances, the vertical position of a lateral separation point (e.g., along the x-axis) on a warped interface, warped surface, or warped path may vary by more than 2%, 4%, 6%, 8%, 10%, or a percentage within a range defined by any of these values, relative to the average vertical position of the lateral separation point. In some cases, the vertical position may be measured with respect to a plane corresponding to the main surface of the warped PIC (e.g., plane 213 corresponding to the top main surfaces 209a to c), wherein the vertical direction (e.g., the z-direction) may be perpendicular to said plane.

[0044] Once the warp profile of the warped PIC is measured or determined (e.g., using the methods described above or other methods), the measured / determined warp profile can be used to determine the position (e.g., vertical position) of individual fibers in the fiber array. In some embodiments, after determining the position of individual fibers, a custom fiber array comparison fiber mount with a custom vertical position can be manufactured by fabricating a custom fiber mount and mounting the individual fibers on the custom fiber mount (e.g., a V-groove array), the custom fiber mount being configured to provide custom and custom relative vertical displacement for the different fibers of the custom fiber array. This custom and / or custom fiber positioning (based on the measured edge coupler waveguide end face position or the measured warp profile of the PIC) can facilitate and improve the optical coupling efficiency between individual edge coupler waveguides and corresponding fibers.

[0045] In some embodiments, one or more microlenses may be disposed on corresponding one or more end faces of an optical fiber array (e.g., optical fiber array 110 or a custom optical fiber array 210, 212 or 214), or disposed on a PIC chip (e.g., Figure 2A , 2B On one or more of the corresponding edge coupler waveguide end faces of the flat PIC 101 or warped PIC 201 in 2C, to improve the optical coupling efficiency between individual optical fibers and the corresponding edge coupler waveguide. Figure 4A This is a schematic top view of the edge portion (or area) of the PIC stacked on the EIC, which is aligned with the fiber array, where microlenses are placed or formed on the end faces of individual fibers to improve fiber-to-waveguide optical coupling. Figure 4B This is a top-view schematic diagram showing the edge portion (or area) of a PIC stacked on an EIC aligned with an optical fiber array, wherein microlenses are formed or placed on the end face of individual edge couplers waveguides for efficient fiber-to-waveguide optical coupling.

[0046] In some instances, refer to Figure 4A Microlens 402 can be disposed on the end face of optical fiber 112 and on the core region 114 of optical fiber 112 to match the optical mode profile (e.g., mode size) of optical fiber 112 with the optical mode profile (e.g., mode size) of the corresponding edge coupler waveguide 108. In some examples, refer to Figure 4B The microlens 403 formed or disposed on the edge coupling end face 106 can be configured to match the optical mode profile (e.g., mode size) of the edge coupler waveguide 108 with the optical mode profile (e.g., mode size) of the corresponding optical fiber 112.

[0047] In some implementations, microlenses can be attached, 3D printed, or fabricated (e.g., using UV curing) on ​​the PIC chip end face or fiber array end face. In some cases, the end region of the fiber near the edge coupling end face 106 can be shaped (e.g., tapered) to form a lens. For example, the fiber can be cleaved by wet etching or heat treatment and then tapered. In some other embodiments, the fiber of the fiber array may include numerical aperture (e.g., high numerical aperture) configured such that the size (e.g., the beam waist) of the bundle emitted through the fiber matches the pattern size of the corresponding edge coupler waveguide.

[0048] Some embodiments disclosed herein can provide structures for fabricating fiber arrays having a vertical displacement profile that matches the vertical displacement profile of the edge coupler waveguide end face of a PIC to which the fiber array can be coupled. In some embodiments, these structures may include fiber mounting substrates configured to position and stabilize (e.g., mechanically stabilize) the fibers of the fiber array according to a measured warp profile of the corresponding PIC (e.g., the warp profile of the edge coupler waveguide end face of the PIC).

[0049] Figure 5AThis is a schematic side view of a fiber array structure 500 fabricated on a fiber mount 506 (also referred to as a fiber mount) having a V-groove pattern or array. In some instances, the fiber mount 506 may include a patterned fiber substrate comprising a plurality of grooves, such as V-grooves (referred to herein as V-grooves), or grooves having other shapes (e.g., cross-sectional shapes), such as rectangular, circular, elliptical, and the like. In some embodiments, the fiber substrate or fiber mount may include any mounting structure configured to position and stabilize the fiber. In some embodiments, the fiber mount may include a plurality of V-grooves (e.g., a periodic or non-periodic arrangement of V-grooves or an array of grooves), wherein individual V-grooves 502 include an opening width and an opening depth (e.g., an etch depth). In some cases, the vertical position of an individual fiber 112 and therefore its core region 114 (e.g., with respect to a flat top or bottom surface of the fiber mount 506) may depend on the opening width of the corresponding V-groove 502. In the illustrated example, the fiber optic mount 506 includes an array of v-grooves having substantially equal depths (D) and equal opening widths. In some cases, the v-grooves of the fiber optic array structure 500 can position the fiber such that the center of its core region lies in a flat plane (e.g., parallel to the flat top or bottom surface of the fiber optic mount 506). In some examples, the fiber optic mount 506 may include v-grooves formed in a block of silicon or glass; however, embodiments are not limited thereto, and v-grooves may be formed on a substrate composed of other materials (e.g., other semiconductors, other crystalline materials, metals, ceramics, polymers, and the like). In the illustrated example, the v-grooves are uniformly (e.g., periodically) distributed along the x-axis. In some embodiments, the fiber optic array v500 may be optically coupled to a flat PIC having an edge-coupled waveguide end face positioned along a straight line parallel to the main surface of the PIC (e.g., the fiber optic array structure 500 may include an edge-coupled waveguide end face positioned along a straight line parallel to the main surface of the PIC 101). Figure 1B (Fiber optic array 110 in the middle).

[0050] In some cases, when the fiber array structure 500 is aligned with a warped PIC (e.g., warped PIC 201), some fibers may not be optically coupled to the corresponding edge coupler waveguide with sufficient efficiency. In some embodiments disclosed herein, the width and depth of one or both openings of the individual v-grooves of the custom fiber mounting structure can be tailored based on the determined z-displacement of the fibers placed in the v-grooves. In some cases, the z-displacement of the fibers can be determined at least in part based on the measured warp profile of the PIC.

[0051] Figure 5BThis is a schematic side view of a custom fiber array structure 501 fabricated on a custom fiber mount 508, which is configured to vertically position individual fibers of the fiber array in a non-planar pattern, such that the core region of the individual fiber can be aligned with the corresponding edge coupler waveguide of a warped PIC (e.g., PIC 201). In some cases, fibers at different lateral positions (e.g., along the x-axis) and / or at their core regions can be vertically aligned according to a measured warp profile of the corresponding warped PIC to match the position of the edge coupler waveguide end face of the warped PIC to which the custom fiber array structure 501 will be coupled. In some embodiments, the v-groove of the custom fiber array structure 501 may have an opening depth and opening width tailored to the measured warp profile of the PIC. Figure 5B As shown, the relative vertical position of the optical fiber can be customized by customizing one or both of the opening width and opening depth (e.g., etching depth) of individual V-grooves. For example, a wider V-groove opening positions the optical fiber at a lower vertical position, while a narrower V-groove opening positions the optical fiber at a higher vertical position (e.g., with respect to the flat top or bottom surface of the customized fiber mount 508). In some instances, such as when the V-groove is formed by wet etching, increasing the opening width can increase the opening depth. In other words, in some cases, the width and depth of the V-groove can be changed proportionally during the manufacturing process. Figure 5B The dashed lines in the diagram serve as visual reference lines, indicating variations in the depth of different V-grooves caused by the custom opening width. In some instances, the difference between the widths of the two openings formed on the custom fiber optic mount 508 can be greater than 2%, greater than 4%, greater than 6%, or greater than 8%.

[0052] In some cases, aligning and stabilizing multiple fibers on a custom fiber mount 508 allows for a greater ratio of fibers to be efficiently coupled to the corresponding waveguide end face of a warped PIC (e.g., with optical coupling efficiency greater than a threshold) compared to the ratio of highly coupled fibers mounted on a fiber mount 506 with a flat vertical profile.

[0053] Figure 5C This is a schematic diagram showing a close-up side view of an optical fiber positioned within a V-groove, depicting the width (w) of the V-groove opening, the depth (d) of the V-groove, the vertical offset (h) of the optical fiber, the core region 114 of the optical fiber, and the center 115 of the core region. As described above, the vertical offset (h) of the optical fiber 112 can be adjusted by adjusting the width (w).

[0054] Figure 6This is a schematic side view illustrating a custom fiber array structure aligned with a warped PIC, wherein individual V-grooves are custom-made to align the fiber core with the corresponding edge coupler waveguide end face formed within the warped waveguide layer 510 of the warped PIC. The warped waveguide layer 510 of the PIC is depicted in dashed lines (other parts of the PIC are not shown). In some embodiments, the opening width (w) and / or opening depth (h) of the individual V-grooves may be customized to align with a vertical offset (h) at the center of the fiber core (e.g., with respect to the top surface of the fiber mount 508), such that the fiber core is at least vertically aligned with the corresponding edge coupler waveguide end face. In some cases, the vertical alignment between the core region 114 of the fiber 122 and the end face 107 of the edge coupler waveguide may include the vertical distance between the top main surface of the fiber mount 508 and the center of the core region 114, and the vertical distance between the top main surface of the fiber mount 508 and the center of the end face 107 of the edge coupler waveguide, which are generally equal to or have a difference of 1%, 5%, 10%, 20%, 30%, 40%, or 50% less than the thickness of the corresponding edge coupler waveguide.

[0055] In some embodiments, a custom fiber optic mount may include alignment and / or stabilization structures, distinct from V-grooves, for positioning and stabilizing the fiber relative to each other and with respect to the edge coupler waveguide endface. In these embodiments, the relative vertical position of the fiber can be customized by engineering different geometric parameters of such alignment and / or stabilization structures. In various embodiments, the alignment and / or stabilization structures (referred to herein as mount structures) may include grooves or microstructures formed on a primary surface (e.g., the top primary surface) of a substrate (referred to herein as an fiber substrate). In some cases, the grooves or microstructures may have different cross-sectional shapes and may be grown, joined, disposed, or otherwise formed on the fiber substrate.

[0056] In some embodiments, the mounting structure of a custom fiber optic mount can be configured such that when multiple fibers are mounted on the custom fiber optic mount, the vertical position of the fiber endfaces substantially tracks the vertical position of the waveguide endface of the warped PIC. In some such embodiments, the mounting structure can be individually customized to adjust the vertical position of individual fibers in the lateral direction to match the height profile of the PIC's coupler waveguide endface. For example, in some embodiments, the fiber optic mount may include an array of rectangular grooves, in which case the vertical position of individual fibers can be adjusted by adjusting the depth of the rectangular grooves independently of the width of the grooves. In some embodiments, the fiber optic mount can be manufactured by forming an array of mounting structures on a substrate, wherein the mounting structures include geometric features determined at least in part based on the measured warp of the PIC. In some instances, the difference between the geometric features (e.g., dimensions, such as width, depth, height, slope, and the like) of a first mounting structure of the fiber optic mount and the corresponding features of a second mounting structure of the fiber optic mount may be greater than 2%, greater than 4%, greater than 6%, or greater than 8%.

[0057] In some embodiments, a custom fiber optic mount may include a periodic or aperiodic arrangement of mounting structures (e.g., an array of mounting structures). Therefore, multiple optical fibers mounted on a custom fiber optic mount can form a periodic or aperiodic arrangement of optical fibers (e.g., an optical fiber array).

[0058] Although Figures 2A to 2C In the examples shown in 3, 4A to 4B, 5A to 5B, and 6, the edge coupler waveguide end face of the warped PIC is periodically positioned along the lateral direction (e.g., along the x-axis). However, the embodiments are not limited, and in some cases, the position of the edge coupler waveguide end face of the warped PIC may not be periodic along the lateral direction. In these embodiments, the lateral position of the fibers of the fiber array optically coupled to the edge coupler waveguide end face may match the lateral position of the edge coupler waveguide end face, and therefore may not be periodic along the lateral direction. In some embodiments, the above description regarding... Figures 2A to 2C The alignment techniques, fiber arrays, and fiber mounting structures described in 3, 4A to 4B, 5A to 5B, and 6 can be used to improve and facilitate optical coupling between a PIC having at least some edge coupler waveguide end faces that are not periodically positioned in the lateral direction and an fiber array having fibers (including at least some fibers positioned in non-periodic lateral positions) having lateral positions that match the lateral positions of the edge coupler waveguide end faces.

[0059] Additional Examples

[0060] Various additional exemplary embodiments of this disclosure can be described through the following examples:

[0061] Example 1

[0062] Example 1. A photonic system comprising:

[0063] A photonic integrated circuit (PIC) includes a plurality of optical waveguides formed on a PIC substrate, different of the optical waveguides having waveguide end faces terminating at different vertical distances relative to a plane corresponding to a main surface of the PIC substrate to an edge surface of the PIC; and

[0064] Multiple optical fibers are disposed on an optical fiber substrate, the optical fibers terminating at fiber end faces corresponding to the waveguide end faces, wherein different fiber end faces terminate at different vertical distances relative to a plane corresponding to the main surface of the optical fiber surface.

[0065] The different vertical distances of the fiber end face generally follow the different vertical distances of the corresponding waveguide end face.

[0066] Example 2. The photonic system according to Example 1, wherein the waveguide end face is arranged periodically in a transverse direction parallel to the plane corresponding to the main surface of the PIC substrate.

[0067] Example 3. The photonic system according to Example 1 or Example 2, wherein the fiber end faces are arranged periodically in a transverse direction parallel to the plane corresponding to the main surface of the fiber substrate.

[0068] Example 4. The photonic system according to Example 1, wherein at least some of the waveguide end faces and the corresponding fiber end faces are not periodically positioned.

[0069] Example 5. A photonic system according to any of the examples above, wherein the fiber substrate patterns the main surface such that the different vertical distances of the fiber end face substantially track the different vertical distances of the waveguide end face.

[0070] Example 6. A photonic system according to any of the examples above, wherein the different vertical distances of the waveguide end face are caused by warping of the PIC during manufacturing.

[0071] Example 7. A photonic system according to any of the examples above, wherein the different vertical distances of the fiber endfaces are caused by the different opening widths of the grooves formed on the main surface of the fiber substrate.

[0072] Example 8. A photonic system according to any of the examples above, wherein the different vertical distances of the fiber endfaces are caused by different depths of grooves formed on the main surface of the fiber substrate.

[0073] Example 9. A photonic system according to any of Examples 7 and 8 above, wherein the groove is positioned at a periodic lateral position.

[0074] Example 10. A photonic system according to any of the examples above, wherein the PIC includes a waveguide layer disposed on the PIC substrate.

[0075] Example 11. The photonic system according to Example 10, wherein the waveguide layer comprises silicon dioxide and the PIC substrate comprises silicon.

[0076] Example 12. The photonic system according to Example 10, wherein the optical waveguide includes a silicon nitride waveguide embedded within a waveguide layer.

[0077] Example 13. A photonic system according to any of the examples above, wherein the fiber substrate includes a fiber mounting base.

[0078] Example 14. The photonic system according to Example 13, wherein the fiber optic mount includes a mounting structure configured to position and stabilize the fiber optic cable.

[0079] Example 15. The photonic system according to Example 14, wherein the mounting structure includes a plurality of grooves with different depths.

[0080] Example 16. The photonic system according to Example 15, wherein the plurality of grooves includes a plurality of V-shaped grooves.

[0081] Example 17. The photonic system according to Example 16, wherein the plurality of V-grooves are configured to establish relative vertical displacement between the fiber end faces.

[0082] Example 18. The photonic system according to any of the above examples further includes a plurality of microlenses disposed between a plurality of waveguide end faces and the corresponding fiber end faces.

[0083] Example 19. The photonic system according to Example 18, wherein the plurality of microlenses are disposed on the end face of the waveguide.

[0084] Example 20. The photonic system according to Example 18, wherein the plurality of microlenses are disposed on the end face of the optical fiber.

[0085] Example Implementation II

[0086] Example 1. An optical fiber arrangement comprising:

[0087] Multiple optical fibers are disposed on an optical fiber substrate having multiple grooves extending in the longitudinal direction of the optical fibers, wherein the grooves have different depths, such that the optical fibers terminate at optical fiber end faces at different vertical distances relative to a plane corresponding to the main surface of the optical fiber substrate.

[0088] Example 2. The optical fiber arrangement according to Example 1, wherein the groove includes a V-shaped groove.

[0089] Example 3. According to the fiber arrangement described in Example 2, at least some of the V-shaped grooves have different opening widths.

[0090] Example 4. The optical fiber arrangement according to Example 2 further includes a plurality of microlenses disposed on at least some of the end faces of the optical fiber.

[0091] Example 5. An optical fiber arrangement according to Example 1, wherein the optical fiber is arranged to optically couple to a plurality of optical waveguides of a photonic integrated circuit (PIC), wherein different optical waveguides have waveguide end faces terminating at different vertical distances relative to a plane corresponding to the main surface of the PIC substrate to an edge surface of the PIC.

[0092] Example 6. The fiber arrangement according to Example 5, wherein the different vertical distances of the waveguide end face are caused by the measurable warpage of the PIC.

[0093] Example 7. The optical fiber arrangement according to Example 6 further includes a plurality of microlenses disposed on at least some of the waveguide end face.

[0094] Example 8. The optical fiber arrangement according to Example 5, wherein the optical fiber and the PIC form a photonic system according to any of the examples in Examples I, IV and V.

[0095] Example 3

[0096] Example 1. A method for manufacturing an optical fiber array for optical coupling to a photonic integrated circuit (PIC), the method comprising:

[0097] A PIC is provided, comprising an array of optical waveguides formed on a PIC substrate, wherein the optical waveguides terminate at the edge of the PIC with waveguide end faces at different vertical positions in a lateral position along a lateral direction along the main surface of the PIC substrate and in a vertical position orthogonal to the main surface of the PIC substrate.

[0098] Measure the height profile of the PIC along the lateral direction;

[0099] The different vertical positions of the waveguide end face are determined at least in part based on the measured height profile; and

[0100] An optical fiber array is fabricated on an optical fiber substrate such that the fiber end faces are arranged along different lateral positions corresponding to the lateral positions of the waveguide end faces in the lateral direction and in the vertical direction.

[0101] The vertical position of the fiber end face generally tracks the vertical position of the waveguide end face.

[0102] Example 2. According to the method of Example 1, wherein the fiber substrate is patterned such that the vertical position of the fiber end face substantially tracks the vertical position of the waveguide end face.

[0103] Example 3. According to the method of Example 1, the height profile of the PIC includes the variation of the vertical distance between the top main surface of the PIC and the flat plane along the lateral direction.

[0104] Example 4. The method according to Example 1, wherein measuring the height profile of the PIC includes using a profilometer to measure the surface profile of the top main surface of the PIC.

[0105] Example 5. According to the method of Example 1, wherein measuring the height profile of the PIC includes measuring the vertical variation profile of the interface between the waveguide layer and the PIC substrate along the lateral direction.

[0106] Example 6. According to the method of Example 1, wherein measuring the height profile of the PIC includes obtaining an image of the waveguide end face and using the image to measure the vertical variation profile of the waveguide end face.

[0107] Example 7. The method according to Example 1, wherein positioning multiple optical fibers based on the determined vertical position between the optical fibers includes manufacturing an optical fiber mount having multiple v-grooves, and placing multiple optical fibers in the multiple v-grooves, wherein one or both openings of at least two v-grooves have different widths and depths.

[0108] Example 8. A method for manufacturing an optical fiber array, the method comprising:

[0109] Provide substrate;

[0110] A plurality of v-grooves are formed on the substrate, the plurality of grooves being arranged at lateral positions along the lateral direction of the main surface of the substrate; and

[0111] Multiple optical fibers are disposed on the substrate by placing individual optical fibers in the individual grooves;

[0112] The optical fiber terminates with an optical fiber end face arranged along the lateral position, and the groove is configured such that the optical fiber end face has different vertical positions in a vertical direction orthogonal to the main surface corresponding to the substrate.

[0113] Example 9. According to the method of Example 8, wherein the different vertical positions of the fiber endface substantially track different vertical positions of the waveguide endface of a photonic integrated circuit (PIC), the PIC including an array of optical waveguides formed on a PIC substrate, the optical waveguides terminating at the edge of the PCI with the waveguide endface, wherein the position of the waveguide endface along the lateral direction corresponds to the lateral position of the fiber endface.

[0114] Example 10. According to the method of Example 8, wherein the plurality of grooves includes a plurality of V-shaped grooves configured such that the fiber end face has different vertical positions.

[0115] Example 11. According to the method of Example 10, the opening widths of the plurality of V-shaped grooves are configured such that the fiber end faces have different vertical positions.

[0116] Example 12. According to the method of Example 10, wherein the opening width of the V-groove is configured such that the different vertical positions of the fiber end face substantially track the different vertical positions of the waveguide end face of a photonic integrated circuit (PIC), the PIC including an array of optical waveguides formed on a PIC substrate, the optical waveguides terminating at the edge of the PCI with the waveguide end face, wherein the position of the waveguide end face along the lateral direction corresponds to the lateral position of the fiber end face.

[0117] Example 13. A method for coupling an optical fiber to a photonic integrated circuit (PIC), the method comprising:

[0118] A PIC is provided comprising an array of optical waveguides formed on a PIC substrate, the optical waveguides terminating at an edge of the PIC with waveguide end faces at different vertical positions at lateral positions along a lateral direction along a main surface of the PIC substrate and at vertical positions orthogonal to a vertical direction corresponding to the main surface of the PIC substrate; and

[0119] An array of optical fibers is provided, disposed on an optical fiber substrate, wherein the optical fibers terminate at fiber end faces arranged at lateral positions along the lateral direction and at different vertical positions in the vertical direction.

[0120] The fiber substrate is patterned with a main surface of varying heights such that the vertical position of the fiber end face substantially tracks the vertical position of the waveguide end face.

[0121] Example 4

[0122] Example 1. An optical fiber coupled photonic system, comprising:

[0123] An integrated circuit (PIC) chip includes an optical waveguide array comprising a plurality of waveguide end faces arranged at different positions along a first direction parallel to a plane corresponding to a main surface of the PIC chip, at least some of the waveguide end faces also having different positions along a second direction orthogonal to the plane corresponding to the main surface of the PIC chip, the plurality of waveguide end faces including a first and a second waveguide end face having different positions along the first direction, wherein the first waveguide end face has a first vertical distance from the second waveguide end face along the second direction; and

[0124] An optical fiber array comprising a plurality of optical fiber end faces arranged at different positions along a first direction, at least some of the optical fiber end faces also having different positions along a second direction, the plurality of optical fiber end faces including a first and a second optical fiber end face having different positions along the first direction, wherein the center of the core region of the first optical fiber end face has a second vertical distance along the second direction from the center of the core region of the second first optical fiber end face.

[0125] The first vertical distance is approximately equal to the second vertical distance.

[0126] Example 2. According to the fiber-coupled photonic system of Example 1, wherein the plurality of waveguide end faces include a third waveguide end face having different positions along the first direction with respect to the first and second waveguide end faces, wherein the third waveguide end face has a third vertical distance from the first waveguide end face along the second direction; wherein the third vertical distance is different from the first and second vertical distances, wherein the plurality of fiber end faces includes the third fiber end face, wherein the center of the core region of the third fiber end face has different positions along the first direction with respect to the first and second fiber end faces, wherein the third fiber end face has a fourth vertical distance from the first fiber end face along the second direction; and wherein the third distance is substantially equal to the fourth distance.

[0127] Example 3. The fiber-coupled photonic system according to Example 1, wherein the PIC includes a waveguide layer disposed on a substrate.

[0128] Example 4. The fiber-coupled photonic system according to Example 3, wherein the waveguide layer comprises silicon dioxide and the substrate comprises silicon.

[0129] Example 5. The fiber-coupled photonic system according to Example 4, wherein the optical waveguide includes a silicon nitride waveguide embedded in the waveguide layer.

[0130] Example 6. The fiber-coupled photonic system according to Example 1, wherein the PIC has warpage, and the first vertical distance is associated with the warpage.

[0131] Example 7. The fiber-coupled photonic system according to Example 6, wherein the plurality of optical fibers are mounted on an optical fiber mount, the optical fiber mount including a plurality of mounting structures configured to position and stabilize the optical fibers.

[0132] Example 8. The fiber-coupled photonic system according to Example 7, wherein the plurality of mounting structures are configured to establish relative vertical displacement between the fiber end faces according to the warping profile of the PIC.

[0133] Example 9. The fiber-coupled photonic system according to Example 7, wherein the first and second mounting structures are configured to position the first and second fiber end faces such that the first vertical distance is substantially equal to the second vertical distance.

[0134] Example 10. A fiber-coupled photonic system according to any one of Examples 7 to 9, wherein the mounting structure includes a groove formed on a fiber substrate.

[0135] Example 11. The fiber-coupled photonic system according to Example 10, wherein the groove includes a V-shaped groove.

[0136] Example 12. The fiber-coupled photonic system according to Example 1 further includes a plurality of microlenses disposed between a plurality of waveguide end faces and corresponding fiber end faces.

[0137] Example 13. The fiber-coupled photonic system according to Example 12, wherein microlenses are disposed on the end faces of the plurality of waveguides.

[0138] Example 14. The fiber-coupled photonic system according to Example 12, wherein microlenses are disposed on the end faces of the plurality of optical fibers.

[0139] Example 15. A method for manufacturing an optical fiber array for optical coupling to a photonic integrated circuit (PIC), the PIC including a plurality of waveguide end faces arranged at different locations along a first direction, the method comprising:

[0140] Measure the warpage profile of the PIC;

[0141] The vertical position between the waveguide end faces along a second direction orthogonal to the first direction is determined at least in part based on the measured warping profile;

[0142] The vertical position of the fiber end faces of the fiber array waveguide along the second direction is determined at least in part based on the determined vertical position between the waveguide end faces; and

[0143] Multiple optical fibers are positioned to form the optical fiber array based on the determined vertical position between the fiber end faces.

[0144] Example 16. According to the method of Example 15, wherein the warped profile of the PIC includes the variation of the distance between the top main surface of the PIC and the flat plane along the first direction.

[0145] Example 17. The method according to Example 15, wherein measuring the warpage profile of the PIC includes using a profilometer to measure the surface profile of the top main surface of the PIC.

[0146] Example 18. The method according to Example 15, wherein measuring the warpage profile of the PIC includes measuring the vertical variation profile of the interface between the waveguide layer and the substrate layer of the PIC along the second direction.

[0147] Example 19. The method according to Example 15, wherein measuring the warp profile of the PIC includes obtaining an image of the waveguide end face and using the image to measure the vertical variation profile of the waveguide end face.

[0148] Example 20. The method according to Example 15, wherein positioning multiple optical fibers based on the determined vertical position between the fiber end faces includes manufacturing an optical fiber mount having multiple grooves, and placing the multiple optical fibers in the multiple grooves, wherein one or both openings of at least two grooves have different widths and depths.

[0149] Example 21. A method of manufacturing an optical fiber mount configured to form an optical fiber array for coupling to a warped PIC, the method comprising:

[0150] Provide substrate; and

[0151] An array of grooves is formed on the substrate, the grooves having dimensions determined at least in part based on the measured warp of the PIC;

[0152] The difference between the first dimension and the second dimension is greater than 2%.

[0153] Example 22. The method according to Example 21, wherein the groove includes a V-shaped groove, and the dimension includes the opening width of the individual V-shaped groove.

[0154] Example 23. The method according to Example 21, wherein the groove comprises a rectangular groove, and the dimension comprises the depth of the individual rectangular groove.

[0155] Example 24. A method of manufacturing an optical fiber mount configured to form an array of optical fibers for coupling to a warped PIC, the method comprising:

[0156] Provide substrate; and

[0157] An array of mounting structures is formed on the substrate, the mounting structures having geometric features determined at least in part based on the measured warp of the PIC;

[0158] The difference between the first geometric feature and the second geometric feature is greater than 2%.

[0159] Example v

[0160] Example 1. A photonic system comprising:

[0161] A photonic integrated circuit (PIC) includes a plurality of optical waveguides formed on a PIC substrate, wherein the PIC substrate has a measurable warp such that different optical waveguides have waveguide end faces terminating at different vertical distances relative to a plane corresponding to a plane corresponding to a main surface of the PIC substrate; and

[0162] Multiple optical fibers are disposed on an optical fiber substrate, the optical fibers terminating at optical fiber end faces corresponding to the waveguide end faces, wherein the optical fiber end faces terminate at different vertical distances relative to a plane corresponding to the main surface of the optical fiber end face to substantially track the vertical distance of the corresponding waveguide end face.

[0163] Example 2. The photonic system according to Example 1, wherein the waveguide end face is arranged periodically in a transverse direction parallel to the plane corresponding to the main surface of the PIC substrate.

[0164] Example 3. The photonic system according to Example 1 or Example 2, wherein the fiber end faces are arranged periodically in a transverse direction parallel to the plane corresponding to the main surface of the fiber substrate.

[0165] Example 4. The photonic system according to Example 1, wherein at least some of the waveguide end faces and the corresponding fiber end faces are not periodically positioned.

[0166] Example 5. A photonic system according to any of the examples above, wherein the fiber substrate patterns the main surface such that the different vertical distances of the fiber end face substantially track the different vertical distances of the waveguide end face.

[0167] Example 6. A photonic system according to any of the examples above, wherein the different vertical distances of the waveguide end face are caused by warping of the PIC during manufacturing.

[0168] Example 7. A photonic system according to any of the examples above, wherein the different vertical distances of the fiber endfaces are caused by the different opening widths of the grooves formed on the main surface of the fiber substrate.

[0169] Example 8. A photonic system according to any of the examples above, wherein the different vertical distances of the fiber endfaces are caused by different depths of grooves formed on the main surface of the fiber substrate.

[0170] Example 9. The photonic system according to any one of Examples 7 and 8 above, wherein the groove is positioned at a periodic lateral position.

[0171] Example 10. A photonic system according to any of the examples above, wherein the PIC includes a waveguide layer disposed on the PIC substrate.

[0172] Example 11. The photonic system according to Example 10, wherein the waveguide layer comprises silicon dioxide and the PIC substrate comprises silicon.

[0173] Example 12. The photonic system according to Example 10, wherein the optical waveguide includes a silicon nitride waveguide embedded within a waveguide layer.

[0174] Example 13. A photonic system according to any of the examples above, wherein the fiber substrate includes a fiber mounting base.

[0175] Example 14. The photonic system according to Example 13, wherein the fiber optic mount includes a mounting structure configured to position and stabilize the fiber optic cable.

[0176] Example 15. The photonic system according to Example 14, wherein the mounting structure includes a plurality of grooves with different depths.

[0177] Example 16. The photonic system according to Example 15, wherein the plurality of grooves includes a plurality of V-shaped grooves.

[0178] Example 17. The photonic system according to Example 16, wherein the plurality of V-grooves are configured to establish relative vertical displacement between the fiber end faces.

[0179] Example 18. The photonic system according to any of the above examples further includes a plurality of microlenses disposed between a plurality of waveguide end faces and the corresponding fiber end faces.

[0180] Example 19. The photonic system according to Example 18, wherein the plurality of microlenses are disposed on the end face of the waveguide.

[0181] Example 20. The photonic system according to Example 18, wherein the plurality of microlenses are disposed on the end face of the optical fiber.

[0182] Additional considerations

[0183] As for additional details relating to the invention, materials and manufacturing techniques can be employed at the level of a person skilled in the art. This also applies to the method-based aspects of the invention, in terms of additional actions typically taken or logically employed. Furthermore, it is conceivable that any optional features of the described variants of the invention may be presented and claimed independently or in combination with any one or more of the features described herein. Similarly, references to singular items include the possibility of the same item existing in plural forms. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural indicators unless the context clearly indicates otherwise. It should be further noted that claims may be drafted to exclude any optional elements. Thus, this statement is intended to serve as a prior basis for using this proprietary terminology, such as “alone,” “only,” and the like, or for using the “negative” limitation, in conjunction with the elements of the stated claims. Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The breadth of this disclosure is not limited by the subject matter description but only by the explicit meaning of the terminology used in the claims.

[0184] In the embodiments described above, apparatus, systems, and methods for sensing electrical overstress events are described in conjunction with specific embodiments. However, it will be understood that the principles and advantages of the embodiments can be used in any other systems, apparatus, or methods that require sensing and / or preventing electrical overstress events.

[0185] The principles and advantages described herein can be implemented in a variety of devices. Examples of such devices include, but are not limited to, consumer electronics, components of consumer electronics, and electronic test equipment. Examples of components of consumer electronics may include clock control circuits, analog-to-digital converters, amplifiers, rectifiers, programmable filters, attenuators, and frequency converters. Examples of electronic devices may also include memory chips, memory modules, circuitry for optical networks or other communication networks, and disk drive circuitry. Consumer electronics may include, but are not limited to, wireless devices, mobile phones (e.g., smartphones), cellular base stations, telephones, televisions, computer monitors, computers, handheld computers, tablet computers, laptop computers, personal digital assistants (PDAs), microwave ovens, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, digital video recorders (DVRs), VCRs, MP3 players, radios, camcorders, cameras, digital cameras, portable memory chips, washing machines, dryers, washer / dryer systems, copiers, fax machines, scanners, watches, smartwatches, clocks, and wearable health monitoring devices. Furthermore, devices may include unfinished products.

[0186] Unless the context explicitly requires otherwise, throughout the description and claims, the terms “comprise,” “comprising,” “include,” “including,” and the like shall be interpreted in an inclusive sense, not an exclusive or exhaustive sense; that is, in the sense of “comprising, but not limited to,” the use of singular or plural terms shall also include the plural or singular, respectively. The terms “coupled” or “connected,” as commonly used herein, refer to two or more sub-elements that can be directly connected or connected via one or more intermediate elements. Furthermore, the terms “this,” “above,” “below,” and terms with similar meanings, when used in this application, shall refer to the application as a whole, not to any particular part of the application. Where the context permits, the use of singular or plural terms in specific embodiments may also include the plural or singular, respectively. The term “or,” referring to a list of two or more items, is intended to cover all the following interpretations of the term: any item in the list, all items in the list, and any combination of items in the list. All numerical values ​​provided herein are intended to include similar values ​​within measurement error.

[0187] Furthermore, unless otherwise specifically stated or otherwise understood in the context in which they are used, the conditional language used herein, such as “can,” “could,” “might,” “may,” “eg,” “for example,” “such as,” and the like, is generally intended to convey that certain embodiments include certain features, elements, and / or states that are not included in other embodiments.

[0188] The teachings of this invention provided herein can be applied to other systems, not necessarily those described above. Elements and actions of the various embodiments described above can be combined to provide other embodiments. The actions of the methods discussed herein can be performed in any order as needed. Furthermore, the actions of the methods discussed herein can be performed sequentially or in parallel as needed.

[0189] While certain embodiments of the invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this disclosure. In fact, the novel methods and systems described herein can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made to the methods and systems described herein without departing from the spirit of this disclosure. The appended claims and their equivalents are intended to cover forms or modifications falling within the spirit and scope of the disclosure. Therefore, the scope of the invention is defined by reference to the claims.

Claims

1. A photonic system comprising: A photonic integrated circuit (PIC) includes a plurality of optical waveguides formed on a PIC substrate, different of the optical waveguides having waveguide end faces terminating at different vertical distances relative to a plane corresponding to a main surface of the PIC substrate at an edge surface of the PIC. and Multiple optical fibers are disposed on an optical fiber substrate, the optical fibers terminating at fiber end faces corresponding to the waveguide end faces, wherein different fiber end faces terminate at different vertical distances relative to a plane corresponding to the main surface of the optical fiber surface. The different vertical distances of the fiber end face generally follow the different vertical distances of the corresponding waveguide end face.

2. The photonic system of claim 1, wherein the waveguide end face is arranged periodically in a transverse direction parallel to the plane corresponding to the main surface of the PIC substrate.

3. The photonic system according to claim 2, wherein the fiber end faces are arranged periodically in a transverse direction parallel to the plane corresponding to the main surface of the fiber substrate.

4. The photonic system according to claim 1, wherein at least some of the waveguide end faces and the corresponding fiber end faces are not periodically positioned.

5. The photonic system of claim 1, wherein the fiber substrate patterns the main surface such that the different vertical distances of the fiber end face substantially track the different vertical distances of the waveguide end face.

6. The photonic system of claim 1, wherein the different vertical distances of the waveguide end face are caused by warping of the PIC during manufacturing.

7. The photonic system of claim 1, wherein the different vertical distances of the fiber endfaces are caused by the different opening widths of the grooves formed on the main surface of the fiber substrate.

8. The photonic system of claim 1, wherein the different vertical distances of the fiber endfaces are caused by different depths of grooves formed on the main surface of the fiber substrate.

9. The photonic system of claim 7, wherein the groove is positioned at a periodic lateral position.

10. The photonic system of claim 1, wherein the PIC includes a waveguide layer disposed on the PIC substrate.

11. The photonic system of claim 10, wherein the waveguide layer comprises silicon dioxide and the PIC substrate comprises silicon.

12. The photonic system of claim 10, wherein the optical waveguide comprises a silicon nitride waveguide embedded within the waveguide layer.

13. The photonic system of claim 1, wherein the optical fiber substrate includes an optical fiber mounting base.

14. The photonic system of claim 13, wherein the fiber optic mount includes a mounting structure configured to position and stabilize the fiber optic cable.

15. The photonic system of claim 14, wherein the mounting structure comprises a plurality of grooves having different depths.

16. The photonic system of claim 15, wherein the plurality of grooves comprises a plurality of V-shaped grooves.

17. The photonic system of claim 16, wherein the plurality of V-grooves are configured to establish relative vertical displacement between the fiber end faces.

18. The photonic system of claim 1, further comprising a plurality of microlenses disposed between the waveguide end face and the corresponding fiber end face.

19. The photonic system of claim 18, wherein the plurality of microlenses are disposed on the end face of the waveguide.

20. The photonic system of claim 18, wherein the plurality of microlenses are disposed on the end face of the optical fiber.

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