Elastic Average Bond

Abstract

A passive optical alignment coupling is provided between an optical connector having a first two-dimensional planar array of alignment features and a base having a second two-dimensional planar array of alignment features. One of the arrays is a network of orthogonal longitudinal grooves defining an array of discrete projections, each of which is generally square pyramidal in shape with a truncated apex separated from the other by orthogonal longitudinal grooves, and the other array is longitudinal cylindrical projections. The cylindrical projections are received within the grooves, with the marked surfaces of the cylindrical projections contacting the groove surfaces and the apexes of the discrete projections contacting the surfaces surrounded by the cylindrical projections. The optical connector is removably mounted to the base to define a detachable coupling, with the first array of alignment features defining an elastic average coupling with the second array of alignment features.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 969,536, filed February 3, 2020, which is incorporated by reference in its entirety as if fully set forth herein. All publications mentioned below are incorporated by reference in their entirety as if fully set forth herein. [Technical field]

[0002] The present invention relates to techniques for coupling light to the inputs and outputs of optoelectronic components (eg, photonic integrated circuits (PICs)), and more particularly to optical fiber optical connections to PICs. [Background technology]

[0003] Photonic Integrated Circuits (PIC) or Optical Integrated Circuits are part of an emerging technology that uses light rather than electrical current as the basis of operation. PIC devices integrate multiple (at least two) photonic functions and are therefore similar to electronic integrated circuits. The main difference between the two above is that photonic integrated circuits provide functionality for information signals that are given optical wavelengths, usually in the visible spectrum or near infrared, between 850nm and 1650nm.

[0004] PICs are used in a variety of 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 electrical-to-optical (E / O) signal converters (e.g., photodiodes, lasers), etc. The waveguides in PIC devices are typically on-chip solid light conductors that guide light by the refractive index contrast between the waveguide core and the cladding.

[0005] One of the most expensive components in a photonic network is the fiber optic connector. For proper operation, a PIC typically needs to efficiently couple light between an external optical fiber and one or more on-chip waveguides. PIC devices are often required to have optical connections to other PIC devices in the form of organized networks of optical communication. The connection distances can range from a few millimeters for chip-to-chip connections up to several kilometers for long-distance applications. Optical fibers can provide an effective connection method because low-loss optical fibers allow light to pass through optical fibers at very high data rates (>25 Gbps) over long distances. For proper operation, a PIC device needs to efficiently couple light between an external optical fiber and one or more on-chip waveguides. An advantage of using light as the basis for circuit operation in a PIC device is that the energy cost for high-speed signal transmission is substantially lower than that of an electronic chip. Thus, an effective coupling between a PIC device and other optical devices, such as optical fibers, that maintains this advantage is an important aspect of the PIC.

[0006] One approach to coupling optical fibers to a PIC device (or PIC chip package) is to attach an optical fiber array to the edge of the PIC chip. Traditionally, the optical fiber array is aligned with the elements on the PIC using an active alignment approach, in which the position and orientation of the optical fibers are mechanically adjusted until the amount of light transmitted between the fibers and the PIC is maximized. This is a time-consuming process that is usually performed after the PICs are diced from the wafer and mounted in the package. This postpones the optical fiber connection to the end of the manufacturing process. The connection, once made, is permanent and cannot be removed, separated or detached without possibly destroying the integrity of the connection, should there be any desire to reattach the optical fiber array to the PIC. In other words, the optical fiber array cannot be removably attached to the PIC device, and the fiber array connection and disconnection are destructive and not reversible (i.e., not reconnectable).

[0007] Although the current state of the art attempts to achieve tight alignment tolerances using polymer connector elements, polymers have several fundamental disadvantages. First, polymers are stretchable and easily deform under external applied loads. Second, polymers are not dimensionally stable and can change size and shape when exposed to high temperatures, especially those found in computing and networking hardware. Third, the coefficient of thermal expansion (CTE) of polymers is much greater than the CTE of materials typically used in PIC devices. Thus, temperature cycling creates misalignment between the optical fiber and the optical elements on the PIC device. In some cases, polymers cannot withstand the processing temperatures used during soldering of PIC devices onto printed circuit boards.

[0008] Furthermore, it would be advantageous to make the fiber optic connections before dicing the individual PICs from the wafer; this is often referred to as wafer-level attachment. While manufacturers of integrated circuits and PICs often have expensive capital equipment capable of sub-micron alignment (e.g., wafer probers and handlers for testing integrated circuits), companies that package the chips usually have less capable machines (typically with alignment tolerances of a few microns that are not suitable for single-mode devices) and often use manual operations. However, permanently attaching the optical fibers to the PICs before dicing is impractical because the optical fibers would tangle and get in the way during dicing operations and packaging procedures, and it would be virtually impossible to manage the optical fibers as the PICs are picked and placed on the printed circuit board and then soldered to the PCB at high temperatures.

[0009] US Patent Publication No. 2009 / 0139996 (commonly assigned to the assignee of the present application and fully incorporated herein by reference) discloses a detachable optical connector for optoelectronic devices. The disclosed detachable optical connector includes the implementation of elastic averaging coupling and provides an improved approach for optically coupling an optical fiber input / output to a PIC, thereby improving tolerances, manufacturability, ease of use, functionality and reliability at a low cost. As known in the prior art, elastic averaging represents a subset of surface coupling types, where improved accuracy is derived from averaging errors over multiple contact surfaces. In contrast to kinematic designs, elastic averaging is based on significantly over-constraining a solid with multiple relatively flexible members. When a preload is applied to the system, the elastic properties of the material average out the errors in size and position of each contact feature relative to the sum of the contact features over the entire solid. Although the repeatability and accuracy obtained with elastic averaging may not be as high as a deterministic system, elastic averaging designs allow for higher stiffness and lower local stresses when compared to kinematic couplings. In a well designed and preloaded elastic mean bond, repeatability is approximately inversely proportional to the square root of the number of contact points.

[0010] Most PIC devices require single-mode optical connections that require tight alignment tolerances between the optical fiber and the PIC, typically less than 1 micrometer. Effective optical coupling to and from on-chip single-mode waveguides to external optical fibers is difficult due to the size mismatch between the single-mode waveguide and the optical guiding core in the optical fiber. For example, the dimensions of a typical silica optical fiber are about 40 times larger than a typical waveguide on a PIC. This size mismatch means that when a single-mode waveguide is directly coupled to an optical fiber, the respective modes of the waveguide and the optical fiber do not effectively couple, resulting in unacceptable insertion losses (e.g., >20 dB).

[0011] US Patent No. 5,399,663 (commonly assigned to the assignee of the present application and fully incorporated herein by reference) discloses a detachable edge coupler with a micromirror optical bench for a PIC, which brings the mode sizes of the optical fibers and on-chip optical elements in a fiber array closer together and provides a mechanism for efficient optical coupling of the optical fiber input / output to the PIC device. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] US Patent Application Publication No. 2016 / 0161686 [Patent Document 2] US Patent Application Publication No. 2020 / 0124798 Summary of the Invention [Problem to be solved by the invention]

[0013] What is needed is an improved removable optical coupling between connectors based on improved elastic averaging techniques that further improves tolerances, manufacturability, ease of use, functionality and reliability at low cost. [Means for solving the problem]

[0014] The present invention overcomes the shortcomings of the prior art by providing a removable / separable and reconnectable passive alignment coupling / connection that achieves high alignment accuracy. An optical connector (e.g., supporting or being part of an optical bench that supports an optical fiber) is configured and structured to be non-destructively and removably attachable for reconnection in alignment with a base. The base may be an integral part of the optoelectronic device (e.g., part of a photonic integrated circuit (PIC) chip) or may be a separate component attached to the optoelectronic device.

[0015] The present invention will be described in relation to the illustrated embodiment. The base can be aligned to an electro-optical element (e.g., grating coupler, waveguide, etc.) in an optoelectronic device. The base is permanently aligned 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 that precisely optically aligns the optical component / optical element in the optical bench to the optoelectronic device along the desired optical path. In order to maintain optical alignment for each connection and disconnection and reconnection, the connector needs to be precisely and accurately aligned to the base. According to the present invention, the connector and the base are aligned to each other using a passive mechanical alignment, specifically an elastic mean alignment, that is constructed from geometric features on the two bodies. With the above as an introduction, the present invention can be summarized as follows.

[0016] The present invention is directed to a passive optical alignment coupling for an optical connector and a base (e.g., associated with a PIC chip). The optical connector comprises a first body that transmits an optical signal. The first body defines a first base (which may support an optical fiber array), the first base having a first plane defined by a first two-dimensional planar array of alignment features integrally defined on a first surface of the first base; the base (which may be coupled to a photonic integrated circuit PIC) comprises a second body that provides an alignment reference for an external optoelectronic device that communicates optical signals with the optical connector. The second body defines a second base, the second base having a second plane defined by a second two-dimensional planar array of alignment features integrally defined on a second surface of the second base. One of the first array of alignment features and the second array of alignment features comprises a first network of orthogonal longitudinal open grooves, and the other of the first array of alignment features and the second array of alignment features comprises a second network of longitudinal cylindrical projections (each of which may be a continuous cylindrical projection or may be a broken chain of cylindrical projections), each having a longitudinal axis parallel to a corresponding one of the first surface of the first base or the second surface of the second base. (Alternatively, the alignment features on the optical connector and the base may be interchanged.) The second network of cylindrical projections is received within the matching complementary first network of open grooves, with the projection surfaces of the cylindrical projections in contact with the groove surfaces of the longitudinal flutes. The optical connector is removably mounted to the base to define a detachable coupling, and the first array of alignment features defines an elastic average coupling with the second array of alignment features, thereby aligning the optical connector to the base.

[0017] In one embodiment, the first network of orthogonal grooves of the first alignment feature defines an array of discrete protrusions separated and isolated from one another by orthogonal grooves on the first surface of the first base (or on the second surface of the second base), each of which is generally pyramidal in shape with a truncated apex (e.g., flat or slightly convex curved apex). The array of discrete protrusions may each comprise a raised structure that is symmetrical about a first plane that is orthogonal to the corresponding one of the first surface of the first base and the second surface of the second base, and further symmetrical about a second plane that is orthogonal to the first plane and orthogonal to the corresponding one of the first surface and the second surface (i.e., the raised structure is symmetrical along two orthogonal planes, respectively, about a central axis that is orthogonal to the first surface of the first base (or on the second surface of the second base of the pedestal) of the optical connector.

[0018] In one embodiment, the second network of cylindrical projections comprises a network of intersecting longitudinal cylindrical projections (forming a cross-grid structure on the surface of the corresponding base), each of which, in one embodiment, may be of a substantially semicircular profile in cross section. Other convex cross sections (e.g., elliptical, parabolic, or gothic arch profiles) may also be employed.

[0019] In one embodiment, the protrusion surfaces of the longitudinal cylindrical protrusions make line contact with the groove surface to define an array of line contacts when the optical connector is coupled to the base. In this embodiment, the longitudinal grooves are V-shaped grooves and each discrete protrusion comprises a substantially flat surface corresponding to the groove surface and defines a line contact with the protrusion surface when the optical connector is coupled to the base. In another embodiment, the protrusion surfaces of the longitudinal cylindrical protrusions make point contact with the groove surface to define an array of point contacts when the optical connector is coupled to the base. In this embodiment, each discrete protrusion comprises a convex curved surface corresponding to the groove surface and defines a point contact with the protrusion surface when the optical connector is coupled to the base.

[0020] In one embodiment, the array of discrete protrusions is a rectangular array of (M+1)×(N+1) discrete protrusions corresponding to the first network of intersecting grooves including M×N orthogonal longitudinal grooves. The second network of cylindrical protrusions includes M×N orthogonal longitudinal cylindrical protrusions and matches the first network of M×N intersecting longitudinal grooves. For a coupling interface between the first surface of the optical connector and the second surface of the base having a planar area of ​​about 3 mm×3 mm, M is preferably in the range of 3 to 10 and N is in the range of 3 to 10 to achieve a coupling accuracy of less than 1 micrometer between the optical connector and the base.

[0021] In one embodiment, the discrete protrusions defined by the longitudinal grooves contact a corresponding one of the first surface and the second surface when the optical connector is coupled to the base. Moreover, in one embodiment, to ensure that the optical connector is seated on the base at a predetermined unique position, the array of discrete protrusions further comprises a plurality of guide key protrusions having raised structures located along the perimeter / edge of the first surface (or the second surface), which have a different surface profile on the surface facing away from the perimeter / edge (i.e., the surface that does not contact the cylindrical protrusion when the optical connector is coupled to the base) compared to the surface profile of the symmetrical discrete protrusions located inside the perimeter / edge (i.e., the discrete protrusions contact a corresponding one of the first surface and the second surface). For example, some of the discrete protrusions at the periphery of a 10×5 array of discrete protrusions (i.e., M=9 and N=4), e.g., corners (1,1), (10,1), (1,5) and (10,5), may each include a surface profile that is different from the surface profile of the discrete protrusions at interior locations away from the periphery of the array (e.g., at (2,2) through (9,2), etc.). The shape of the corner protrusions would not fit into the interior space enclosed by the cylindrical protrusions on the four pieces of the opposing surface. The corner protrusions would only fit into the space at the corners on the opposing surface because they are not enclosed by the cylindrical protrusions. Thus, guide keys are provided at the coupling interface to initially guide the mating of the first array of alignment features and the second array of alignment features, and uniquely seat the relative positions of the complementary alignment features to couple the optical connector to the base at the predetermined intended relative positions.

[0022] In one embodiment, the first base comprises a first malleable metal material and a first array of alignment features for the optical connector are integrally defined on the first base by stamping the malleable metal material, and the second base comprises a second malleable material and a second array of alignment features are integrally defined on the base by stamping the second malleable metal material.

[0023] In one embodiment, the optical connector further comprises a first micromirror optical bench comprising: a first base; a first array of mirrors defined on the first base, each mirror including a structured reflective surface profile that redirects light between a first optical path along a first direction in a first plane substantially parallel to a first surface of the first base and a second optical path along a second direction outside the first plane; and an array of fiber grooves defined on the first base, each groove receiving a section of an optical fiber with its longitudinal axis along the first optical path and an end optically aligned with a corresponding mirror along the first optical path. In one embodiment, the base comprises a second micromirror optical bench comprising: a second base; and a second array of mirrors defined on the second base, each mirror in the second array of mirrors including a structured reflective surface profile that redirects light between a third optical path along a third direction in a second plane substantially parallel to a second surface of the second base and a fourth optical path along a fourth direction outside the second plane. In one embodiment, the first array of mirrors and the first array of alignment features are simultaneously defined on the first base by stamping a first body of a metal blank, and the second array of mirrors and the second array of alignment features are simultaneously defined on the second base by stamping a second body of a metal blank. Precision stamping to integrally / simultaneously form passive alignment features and / or micro-optical benches (MOBs) on the base and optical connectors allows parts to be produced economically in high or low volume while improving tolerances, manufacturability, ease of use, functionality, and reliability. The base and / or optical bench parts are made of stampable materials such as ductile metals such as Kovar, Invar, stainless steel, aluminum, etc. Preferably, both the optical bench and base have similar coefficients of thermal expansion (CTE) to avoid misalignment and stress / strain during temperature cycling.

[0024] In one embodiment, a first base of the optical connector has a first reference surface on a first side of the first base and a second base of the platform has a second reference surface on a second side of the second base, the first and second reference surfaces being generally aligned by a compliant clip that biases the first base relative to the second base with the first array of alignment features facing the second array of alignment features.

[0025] According to the present invention, the optical connector and the base define a free space coupling without any refractive optical element disposed between the optical connector and the base to provide light reshaping. Furthermore, a removable elastic mean coupling between the optical connector and the base is defined without the use of any complementary alignment pins and alignment holes.

[0026] The elastic average coupling of the present invention can be deployed in a photonic device. In one embodiment, the photonic device comprises: a support; an optoelectronic device mounted on the top surface of the support; and a passive optical alignment including the elastic average coupling of the present invention. The base is positioned relative to the optoelectronic device, either on the optoelectronic device and / or on the support, to define an alignment position for the optoelectronic device to communicate optical signals with an optical connector detachably / removably coupled to the base. The optoelectronic device may comprise a photonic integrated circuit (PIC) chip, which comprises optical elements as an optical interface to the outside of the PIC chip. The base is optically aligned with the optical elements of the PIC chip.

[0027] In one embodiment, the base includes an edge coupler supported on a support in optical alignment with the PIC chip. Optical elements of the PIC chip direct light to an edge of the PIC chip. The edge coupler may include an array of mirrors optically aligned with the optical elements of the PIC chip, where light is transmitted along an optical path between mirrors in the array of mirrors and corresponding optical elements in the PIC chip.

[0028] The present invention is also directed to a method for providing a releasable connection between an optical connector and an optoelectronic device, the method comprising the steps of: providing a support; mounting an optoelectronic device on an upper surface of the support; and providing a passive optical alignment coupling as claimed in any of the claims, wherein a base is positioned relative to the optoelectronic device, either on the optoelectronic device and / or on the support, and the base defines an alignment position for the optoelectronic device to communicate optical signals with an optical connector releasably coupled to the base.

[0029] In one embodiment, the optical connector is first coupled to the base. 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 an optimal 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 relative to the optoelectronic device in the aligned position (e.g., by using solder to fasten the base to a support for the optoelectronic device, such as an interposer, a printed circuit board, a submount, etc.). The optical connector is then detached from the base, and the base can be permanently attached to the support without changing its position on the support (e.g., by reflowing the solder). The optical connector can then 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. The optical alignment according to the original active alignment is maintained with every connection and disconnection and reconnection, precisely and accurately aligning the optical connector to the base.

[0030] In one embodiment, the base may be an integral part of the optoelectronic device or a support for an optoelectronic device.

[0031] For a more complete understanding of the nature and advantages of the present invention, as well as the preferred modes of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings, in which like reference numerals refer to like or similar parts throughout the drawings. [Brief description of the drawings]

[0032] [Figure 1A] FIG. 1 illustrates passive alignment features of an optical connector and base according to one embodiment of the present invention. [Figure 1B] FIG. 1 illustrates passive alignment features of an optical connector and base according to one embodiment of the present invention. [Figure 1C] FIG. 1 illustrates passive alignment features of an optical connector and base according to one embodiment of the present invention. [Figure 2A] FIG. 1 illustrates a resilient mean coupling interface of an optical connector to a base, according to one embodiment of the present invention. [Figure 2B] FIG. 1 illustrates a resilient mean coupling interface of an optical connector to a base, according to one embodiment of the present invention. [Figure 2C] FIG. 1 illustrates a resilient mean coupling interface of an optical connector to a base, according to one embodiment of the present invention. [Figure 2D] FIG. 1 illustrates a resilient mean coupling interface of an optical connector to a base according to one embodiment of the present invention. [Figure 3A] FIG. 13 illustrates passive alignment features of the optical connector and base according to another embodiment of the present invention. [Figure 3B] FIG. 13 illustrates passive alignment features of the optical connector and base according to another embodiment of the present invention. [Figure 4A] FIG. 1 illustrates an elastic mean coupling interface of an optical connector to a base according to another embodiment of the present invention. [Figure 4B] FIG. 1 illustrates an elastic mean coupling interface of an optical connector to a base according to another embodiment of the present invention. [Figure 4C] FIG. 1 illustrates an elastic mean coupling interface of an optical connector to a base according to another embodiment of the present invention. [Figure 4D] FIG. 1 illustrates an elastic mean coupling interface of an optical connector to a base according to another embodiment of the present invention. [Diagram 5] FIG. 13 illustrates a guide key protrusion according to another embodiment of the present invention. [Figure 6A] FIG. 1 illustrates the positioning of the base as an edge coupler to the PIC chip, according to one embodiment of the present invention. [Figure 6B] FIG. 1 illustrates the positioning of the base as an edge coupler to the PIC chip, according to one embodiment of the present invention. [Figure 7A] FIG. 1 illustrates the connection of an optical connector to a base according to one embodiment of the present invention. [Figure 7B] FIG. 1 illustrates the connection of an optical connector to a base according to one embodiment of the present invention. [Figure 7C] FIG. 1 illustrates the connection of an optical connector to a base according to one embodiment of the present invention. [Figure 8A] 1 illustrates a process for fixing the position of the base for subsequent removable connection according to one embodiment of the present invention. [Figure 8B] 1 illustrates a process for fixing the position of the base for subsequent removable connection according to one embodiment of the present invention. [Figure 8C] 1 illustrates a process for fixing the position of the base for subsequent removable connection according to one embodiment of the present invention. [Figure 8D] 1 illustrates a process for fixing the position of the base for subsequent removable connection according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The present invention will now be described with reference to various embodiments and with reference to the drawings. While the present invention has been described in terms of the best mode for achieving the objects of the invention, those skilled in the art will recognize that variations can be made in light of these teachings without departing from the spirit and scope of the invention.

[0034] The present invention overcomes the shortcomings of the prior art by providing a removable / separable and reconnectable passive alignment coupling / connection that achieves high alignment accuracy. An optical connector (e.g., supporting or being part of an optical bench that supports an optical fiber) is configured and structured to be non-destructively and removably attachable for reconnection in alignment with a base. The base may be an integral part of the optoelectronic device (e.g., part of a photonic integrated circuit (PIC) chip) or may be a separate component attached to the optoelectronic device.

[0035] The elastic average coupling concept of the present invention is discussed below with reference to an embodiment of a PIC as an optoelectronic device and an optical connector comprising an optical bench and optically coupling an input / output end of an optical component (e.g., an optical fiber) supported in the optical bench to the optoelectronic device. The present invention is applicable to provide structures and components in a removable / reconnectable configuration for use in other fields.

[0036] 1A-1C show passive alignment features of an optical connector 10 and base 12 according to one embodiment of the present invention. The optical connector 10 comprises a first body B1 that supports an optical fiber array (schematically shown by dotted line FA) that transmits optical signals. The base 12 comprises a second body B2 that provides an alignment reference for an external optoelectronic device (e.g., PIC chip 100 of FIG. 7 or I / O PIC chip 101 for ASIC chip (e.g., CPU, GPU, Switch ASIC) 102 of FIG. 8) that communicates optical signals with the optical fibers OF within the optical connector 10.

[0037] The first body of the connector 10 defines a first base B1 supporting an optical fiber array FA, ​​the first base B1 having a first plane S1 defined by a first two-dimensional planar array F1 of alignment features integrally defined on a first surface S1 of the first base 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 FA has a plurality of optical fibers OF protected by a protective buffer and matrix / jacket layer P. The base B1 of the connector 10 defines a structured feature including alignment structures with an open groove G for holding bare portions of the optical fibers OF (with exposed cladding without the protective buffer and matrix / jacket layer J) and a structured reflective surface (e.g., eight mirrors M1) having a plane inclined at an angle with respect to the larger plane of the base B1. The open grooves G are sized and positioned to receive and precisely position the end sections of the optical fibers OF aligned with the first array of mirrors M along the first optical path L1. The end faces (input / output ends) of each optical fiber OF are maintained at a predetermined distance relative to the corresponding mirror M1. In the embodiment of FIG. 6A, a transparent glass, quartz, or sapphire plate cover SP1 covers the exposed surface on the optical bench OB to protect the mirror M1. In one embodiment, the connector 10 may be filled with index-matching epoxy between the mirror surface M1 and the plate cover SP1.

[0038] In one embodiment, each mirror M1 is an exposed free surface of the base B1 (i.e., a surface exposed to air or not inside the body of the base of the optical bench) with an exposed reflective free side facing away from the base B1. The exposed reflective free side includes a structured reflective surface profile that directs light into and out of the optical fiber OF and the base 12. Each mirror M1 bends, reflects, and / or reshapes the incident light. Depending on the configuration and shape (e.g., curvature) of the structured reflective surface profile, the mirror M may collimate, expand, or focus the incident light beam. For example, the structured reflective surface profile may include one of the following geometric shapes / profiles: (a) an ellipsoid, (b) an off-axis parabola, or (c) another free-form optical surface. For example, the mirror surface may have any of the following surface geometric curvature functions, individually or superimposed, to provide optical power: ellipsoidal or hyperbolic conic foci, toroidal aspheric surfaces with various numbers of even or odd aspheric terms, XY aspheric curves with various numbers of even or odd terms, Zernike polynomials of various orders, and various families of simpler surfaces contained in these functions. The surface may also be a free-form surface with no symmetry along any plane or vector. The mirror M may be defined on the base B by stamping a malleable metal material. A variety of malleable metals stampable with tool steel or tungsten carbide tools may constitute the body of the mirror, including any 300 or 400 series stainless steel, any composition of Kovar, any precipitated or solution hardened metal, and any alloy of Ag, Al, Au, Cu. At long wavelengths above 1310 nm, aluminum is highly reflective (>98%) and economically shaped by stamping. The reflective surface of the metallic portion that constitutes the mirror can be any of the metals listed above, or any coating of a highly reflective metal applied by sputtering, evaporation, or plating processes.

[0039] U.S. Patent No. 7,343,770, commonly assigned to the present application, discloses a novel precision stamping system for manufacturing close tolerance parts. Such novel stamping systems can be implemented to produce the connector 10 and base 12 structures disclosed therein, including the structures for the optical bench OB described above, as well as those discussed below. These stamping processes involve stamping malleable bulk metal materials (e.g., metal blanks or stocks) to form final surface features with tight (i.e., small) tolerances, including reflective surfaces with desired geometries that are precisely aligned with other defined surface features. U.S. Patent Application Publication No. 2016 / 0016218, commonly assigned to the present application, further discloses a composite structure including a base having a primary portion and a secondary portion of dissimilar metal materials. The base and secondary portion are formed by stamping. When the auxiliary part is stamped, it interlocks with the base and simultaneously forms the desired structural features (e.g., structural reflective surfaces, features for optical fiber alignment, etc.) on the auxiliary part. With this approach, less critical structural features can be molded on the bulk of the base with less effort to maintain a relatively large tolerance, while more critical structural features present on the auxiliary part are more precisely molded with additional considerations that define the dimensions, geometry, and / or finish with smaller tolerances. The auxiliary part may include further composite structures of two dissimilar metallic materials with different properties for stamping different structural features. This stamping approach is an improvement over the stamping approach of the earlier U.S. Pat. No. 7,343,770, where the bulk material used for stamping is a homogenous material (e.g., strips of metal such as Kovar or aluminum). The stamping process produces structural features from a single homogenous material. Thus, different features will share properties of the material, which may not be optimal for one or more features.For example, a material that has suitable properties for stamping alignment features may not have suitable properties for stamping reflective surface features that have optimal light reflection efficiency to reduce optical signal loss.

[0040] The overall functional structure of the optical bench OB is generally similar to the structure of some embodiments of optical benches disclosed in the assignee's earlier patent documents mentioned above (i.e., fiber alignment grooves aligned with structured reflective surfaces, and additional features that aid in proper optical alignment). The composite construction and stamping techniques disclosed above may be employed to produce the connector 10 including the mirror M1, groove G and first array of alignment features F1 in the optical bench OB, and further the base 12 including the mirror M2 and a second array of alignment features described below. The respective alignment features F1 and F2 are formed on the planes S1 and S2, respectively, which facilitate alignment and / or precise positioning of the connector 10 relative to the base 12, and thus relative to the PIC chip 100 / chip 102 or I / O chip 101, as described below.

[0041] The mirror M1 surfaces and fiber optic alignment structures in optical connectors can be integrally / simultaneously formed by precision stamping of stock material (e.g., metal blanks or strips), allowing connector parts to be economically manufactured in high or low volumes with improved tolerances, manufacturability, ease of use, functionality and reliability. By simultaneously forming the structural reflective surfaces, passive alignment features (discussed below), and fiber optic alignment structures in the same single final stamping operation, the dimensional relationships of all features requiring alignment on the same workpiece / part can be maintained in the final stamping step. Instead of a single hit punch punching operation to form all features on the optical bench, it may be envisaged that multiple hits are performed to progressively pre-form certain features on the optical bench, with the final hit simultaneously defining the final dimensions, geometry and / or finish of various structured features on the optical bench, including mirrors, optical fiber alignment structures / grooves, passive alignment features discussed below, etc., that are required to ensure (or play a key role in ensuring) proper alignment of the respective parts / structures along the designed optical path.

[0042] Essentially, with respect to the optical connector 10, the base B1 defines an optical bench OB for aligning the optical fiber OF with respect to the mirror M1. By including the fiber groove G in the same single structure that also defines the mirror M, alignment of the end section of the optical fiber OF with respect to the mirror M1 can be achieved more precisely with relatively small tolerances by a single final stamping that simultaneously defines the final structure in a single part, as compared to trying to achieve a similar alignment based on features defined on separate parts or structures or based on separate forming steps. By forming the mirror M1 and the optical fiber alignment groove G simultaneously in the same single final stamping operation, the dimensional relationships of all features / components that require alignment (or serve to achieve alignment) on the same workpiece / part can be maintained in the final stamping step. Furthermore, by the same token, the first array of alignment features F1 can also be formed simultaneously with the mirror M1 and groove G in the same single final stamping operation to maintain the dimensional relationships of all features (i.e., groove G, mirror M1 and alignment feature F1) and achieve the desired alignment with close tolerances.

[0043] In the embodiment shown in Figures 1A-1C, the first array F1 of alignment features of the connector 10 includes a first network of orthogonal longitudinal open grooves LG1 and LG2, each of which is a V-shaped groove with flat walls. In one embodiment, the first network of orthogonal longitudinal grooves LG1 and LG2 of the first alignment feature F1 defines an array of discrete projections P separated and isolated from one another by the orthogonal longitudinal grooves LG1 and LG2 on the first surface S1 of the first base B1, each of which is generally a square pyramid shape having four flat inclined sides GS and a truncated apex T (e.g., a flat or slightly convex curved apex). The apex T of the projections P generally conforms to the first surface S1. Each discrete protrusion P (except at the corners and / or edges, as further described below) is a raised structure that is symmetrical about a first plane perpendicular to the first surface S1 of the first base B1 and further symmetrical about a second plane perpendicular to the first plane and perpendicular to the first surface S1 (i.e., each raised structure is symmetrical along two orthogonal planes about a central axis A perpendicular to the first surface S1 of the first base B1). The features of the protrusions P are better shown in the enlarged view of FIG. 1C.

[0044] U.S. Patent Application Publication No. 2020 / 0124798 (commonly assigned to the assignee of the present application and fully incorporated herein by reference) discloses a removable edge coupler with a micromirror optical bench for a PIC, which provides a mechanism for bringing the mode sizes of the optical fiber and the on-chip optical elements in the fiber array closer together to achieve effective optical coupling input and output of the optical fiber to the PIC device. The base 12 herein has a similar structure to the edge coupler, and in fact can be configured similarly to the edge coupler previously disclosed herein, except for the passive alignment features on the base 12 compared to the passive alignment features disclosed herein.

[0045] 1A and 1B, the base 12 comprises a body having a base B2 (e.g., made of silicon, glass, Kovar, Invar, aluminum, stainless steel, or other malleable metal), on which a second array of mirrors M2 is defined. In the embodiment of FIG. 6B, a transparent glass, quartz, or sapphire plate cover SP2 covers the exposed surface on the base B2. In one embodiment, the base 12 may be filled with index-matching epoxy between the mirror surface M2 and the plate cover SP2. The structure of the mirror M2 on the base B2 of the base 12 is very similar to the corresponding structure of the mirror M1 on the base B1 of the connector 10. The optical geometry of each mirror M1 and M2 is selected to achieve a desired optical path. In the illustrated embodiment, the base 12 does not include an optical fiber compared to the connector 10. However, base B2 may further define a groove to receive a short section of optical fiber (not shown) as a waveguide to communicate optical signals to and from mirror B2, such as in the case of the edge coupler disclosed in U.S. Patent Application Publication No. 2020 / 0124798.

[0046] The base B2 of the base 12 has a second plane S2 defined by a second two-dimensional planar array of alignment features F2 integrally defined on the second surface S2 of the second base B2. The second array of alignment features F2 of the base 12 comprises a second network of longitudinal cylindrical projections (each of which may be a continuous cylindrical projection, or a broken chain or row of discrete cylindrical projections in a common axial direction of the discrete cylindrical projections), each having a longitudinal axis parallel to a corresponding one of the second surface S2 of the second base B2. In this illustrated embodiment, the second network of cylindrical projections includes a network of intersecting longitudinal cylindrical projections LP1 and LP2 (forming a cross-grid projection structure as shown in Figures 1A and 1B), each of which has a substantially semicircular cross section in cross section. Other convex cross sections (e.g., elliptical, parabolic, or gothic arch profiles) may be employed.

[0047] 2A-2D show an elastic mean coupling interface of an optical connector to a base according to an embodiment of the present invention. FIG. 2A shows a view of the coupling of the connector 10 on the base 12 from the end in the direction along the longitudinal axis of the optical fiber OF. FIG. 2A shows an enlarged view of the contact surface between the first and second arrays of alignment features. FIG. 2C and FIG. 2D (enlarged cross-sectional view) show a cross-sectional view along the line 2C-2C in FIG. 2A and FIG. 2C. A second network of orthogonal cylindrical projections LP1 and LP2 is received within a complementary mating first network of orthogonal open grooves LG1 and LG2. The projection faces of the cylindrical projections LP1 and LP2 contact the groove surfaces GS of the longitudinal grooves LG1 and LG2.

[0048] As seen in FIG. 2B, each of the longitudinal grooves LG1 is a V-shaped groove having a flat groove wall surface in its longitudinal direction, and each of the discrete projections P includes a substantially flat inclined surface corresponding to the V-shaped groove surface. The flat surface of the V-shaped groove LG1 and the convex curved surface of the cylindrical projection LP1 define a line contact LC between adjacent cylindrical projections LP2 (as shown in FIG. 2C and FIG. 2D) when the optical connector 10 is coupled to the base 12. Thus, the projection surfaces of the network of intersecting longitudinal cylindrical projections LP1 and LP2 are straight surfaces in their respective longitudinal directions, and when the optical connector 10 is coupled to the base 12, they are in line contact with the flat surfaces of the network of intersecting longitudinal grooves LG1 and LG2 to define an array of line contacts LC. The multiple line contacts correspond to elastic average coupling, and the optical connector 10 is removably mountable to the base to define a removable coupling, and the first array of alignment features F1 defines an elastic average coupling with the second array of alignment features F2, thereby aligning the optical connector to the base. It should be noted that to achieve the line contact LC, the cylindrical projections LP1 and LP2 may each be a broken chain of discrete / isolated cylindrical projections along an axial direction parallel to the base B2 of the base 12, as long as the cylindrical projection surface is within the region of the interface with the flat surface GS of each discrete projection P. In other words, the cylindrical projections LP1 and LP2 do not need to physically intersect to form a cross-grid structure as shown in FIG. 1A and FIG. 1B.

[0049] 3A and 3B illustrate passive alignment features of an optical connector and base according to another embodiment of the present invention. In this embodiment, the base 12 remains similar to the embodiment shown in FIG. 1. The connector 10 is generally similar to the previous embodiment, with modifications to the structure of the intersecting longitudinal grooves LG1' and LG2' and the discrete protrusions P'. Each of the protrusions P' is generally pyramidal in shape, with a groove surface GS' and a convex curved surface GS' corresponding to a flat or convex apex T. The intersecting longitudinal grooves LG1' and LG2' are no longer V-shaped grooves with flat walls as in the previous embodiment of FIG. 1. In this embodiment, the longitudinal grooves LG1' and LG2' are generally V-shaped grooves, each having a sidewall with a convex surface corresponding to the protrusion P'. In particular, the protrusion P' has a sloped surface GS' that is convex at least in the direction along the longitudinal groove. It should be noted that the sloped surface GS' may be curved in the height direction or the slope direction or a combination thereof.

[0050] Figures 4A-4D show an elastic mean coupling interface of the optical connector 10 to the base 12 according to the embodiment of Figures 3A and 3B. The view of Figure 4 corresponds to the view of Figure 2 discussed above and provides a comparison with the previous embodiment.

[0051] As seen in FIG. 4B, each of the longitudinal grooves LG1′ is a generally V-shaped groove, and each of the discrete projections P′ includes a convex inclined surface GS′ corresponding to the groove surface GS′. The convex surface GS′ of the groove LG1′ and the convex curved surface of the cylindrical projection LP1 define a point contact PC between adjacent cylindrical projections LP2 (as shown in FIGS. 4C and 4D) when the optical connector 10 is coupled to the base 12. Thus, the projection surfaces of the network of intersecting longitudinal cylindrical projections LP1 and LP2 are straight surfaces in their respective longitudinal directions, and when the optical connector 10 is coupled to the base 12, they are in point contact with the convex surface GS′ of the network of intersecting longitudinal grooves LG1′ and LG2′ to define an array of point contacts PC. The multiple point contacts PC correspond to an improved elastic average coupling, whereby the optical connector 10 is removably attachable to the base to define a removable coupling, and the first array of alignment features F1 defines an elastic average coupling with the second array of alignment features F2, whereby the optical connector is aligned to the base. Considering the point contacts PC, it is noted that the cylindrical projections LP1 and LP2 may each be a broken chain of discrete / isolated cylindrical projections along an axial direction parallel to the base B2 of the base, as long as the cylindrical projection surface is within the region of the interface with the convex surface GS' of each discrete projection PL. In other words, the cylindrical projections LP1 and LP2 do not need to physically intersect to form a cross-grid structure as shown in FIG. 1.

[0052] The array of discrete projections (P, P') is a rectangular array of (M+1) x (N+1) discrete projections corresponding to the first network of intersecting grooves including M x N orthogonal longitudinal grooves (LG1, LG2; LG1' and LG2'). The second network of cylindrical projections includes M x N orthogonal longitudinal cylindrical projections LP1 and LP2, matching the first network of M x N intersecting longitudinal grooves. In both embodiments shown in Figures 2 and 4, M = 10 and N = 4 for illustrative purposes only. For a coupling interface between the first surface S1 of the optical connector 10 and the second surface S2 of the base 12, which has a planar area of ​​about 3 mm x 4 mm, M is preferably in the range of 3 to 10 and N is in the range of 3 to 10 to achieve a coupling accuracy of less than 1 micrometer between the optical connector and the base.

[0053] 2B , the discrete projections P defined by the network of intersecting longitudinal grooves LG1 and LG2 on the connector 10 contact second surfaces S2 in the spaces between adjacent cylindrical projections LP1 of the base 12 when the optical connector 10 is coupled to the base 12. Similarly, in the embodiment of FIG. 4B , the discrete projections P' defined by intersecting longitudinal grooves LG1' and LG2' on the connector 10 contact second surfaces S2 in the spaces between adjacent cylindrical projections LP1 of the base 12 when the optical connector 10 is coupled to the base 12.

[0054] In one embodiment, referring to FIG. 1C, in order to ensure that the optical connector 10 is seated on the base 12 at a predetermined unique position, the array of discrete protrusions P further comprises a plurality of guide key protrusions GP having raised structures located along the periphery / edge of the first surface S1, which have a different surface profile at the surface facing away from the periphery / edge (i.e., the surface that does not contact the cylindrical protrusion when the optical connector is coupled to the base) compared to the surface profile of the symmetrical discrete protrusions located inside the periphery / edge (i.e., the discrete protrusions contacting the second surface S2 of the base 12). As shown in FIG. 1C, each of the protrusions GP along the periphery of the first surface S1 has a straight wall surface W facing away from the periphery. Considering the wall surface W, the shape of the protrusion GP will not fit into the internal space surrounded by the cylindrical protrusions LP1 and LP2 on the four sides of the opposing surface S2. However, since the straight wall surface W is not surrounded by the cylindrical protrusions at the edges, the protrusion GP will only fit into the space along the edges on the opposing surface S2.

[0055] FIG. 5 illustrates an embodiment of guide key protrusions that may be implemented on the convex protrusion surface GS' in the embodiment of FIG. 3. For example, for the illustrated 10×5 array of discrete protrusions P' (i.e., M=9 and N=4), the discrete protrusions GP' at corners (1,1), (10,1), (1,5) and (10,5) may each include a different surface profile on the surface facing away from the perimeter / edge than the surface profile of the discrete protrusions at interior locations away from the perimeter of the array (e.g., at (2,2) through (9,2), etc.), as shown. Given the shape of the corner protrusions GP', they would not fit into the interior space enclosed by the cylindrical protrusions LP1 and LP2 on the four sides of the opposing surface S2. The corner protrusions GP' would only fit into the space at the corners on the opposing surface S2 because they are not completely enclosed by the cylindrical protrusions LP1 and LP2 at the corners.

[0056] Thus, guide keys such as GP and GP' can be provided at the coupling interface to guide the first array of alignment features F1 and the second array of alignment features F2 and uniquely seat the relative positions of the complementary alignment features to couple the optical connector 10 to the base 12 in a predetermined intended relative position.

[0057] Alternatively, it will be understood that the longitudinal groove and longitudinal cylindrical protrusion alignment features disclosed in the above embodiments may be interchanged between the interface surfaces of the optical connector 10 and the base 12 without departing from the scope and spirit of the present invention.

[0058] In one embodiment, the first base B1 comprises a first malleable metal material and a first array of alignment features F1 of the optical connector 10 is integrally defined on the first base by stamping a malleable metal material, and the second base B2 comprises a second malleable material and a second array of alignment features F2 of the base is integrally defined on the base by stamping a second malleable metal material. In one embodiment, the first array of mirrors M1 and the first array of alignment features F1 are simultaneously defined on the first base by stamping a first body of metal blank, and the second array of mirrors M2 and the second array of alignment features F2 are simultaneously defined on the second base by stamping a second body of metal blank. Precision stamping to integrally / simultaneously form passive alignment features and / or micro-optical benches (MOBs) on the base and optical connectors allows parts to be produced economically in high or low volume while improving tolerances, manufacturability, ease of use, functionality, and reliability. The base and / or optical bench parts are made of stampable materials such as ductile metals such as Kovar, Invar, stainless steel, aluminum, etc. Preferably, both the optical bench and base have similar coefficients of thermal expansion (CTE) to avoid misalignment and stress / strain during temperature cycling.

[0059] 6A and 6B show the positioning of the base 12 as an edge coupler with respect to the PIC chip 100, according to one embodiment of the present invention. As shown, the base 12 is butted against the PIC chip 100 or placed with a gap between an edge of the base B2 of the base and an opposing edge of the PIC chip 100 (as shown in FIG. 7C), and the cover SP2 extends over the PIC chip 100. In this embodiment, the base 12 is supported on a support S in optical alignment with the PIC chip 100. The optical elements of the PIC chip 100 direct light to the edge of the PIC chip 100. The base 12 functions as an edge coupler. As explained above, the array of mirrors M2 of the base 12 is optically aligned with the optical elements of the PIC chip 100, and light is transmitted along an optical path L3 between the mirror M2 in the mirror array and the corresponding optical elements in the PIC chip 100.

[0060] In the embodiment shown in FIG. 6A, optical alignment of the mirror M2 in the base 12 and the optical elements in the PIC chip 100 is achieved by passive alignment of the mirror M2 to the edge of the PIC chip based on fiducials V provided on an extended section of the cover SP2 beyond the edge of the base B2 of the base 12 and fiducials (not shown) provided on the top surface near the edge of the PIC chip 100. The gaps may be filled with a material having an optical index similar to that of the optical fiber cores and waveguides on the PIC chip 100. The base 12 is passively aligned to the PIC chip 100 by optically aligning the fiducials V on the cover SP2 to fiducials (not shown) provided on the top surface of the PIC chip 100. In another embodiment, the base 12 may be an integral part of the PIC chip 100 or the support S for the PIC chip 100.

[0061] 7A-7C show the connection of the optical connector 10 to the base 12 according to an embodiment of the present invention. The PIC chip 100 is supported on a support S (which may be a submount, an interposer) which may be supported on a printer circuit board PCB in FIG. 7B. The first base B1 of the optical connector 10 has a first reference surface R1 on at least one side of the first base B1, and the second base B2 of the base 12 has at least a second reference surface R2 on a second side of the second base B2. The first reference surface R1 and the second reference surface R2 are generally aligned by a compliant clip C which biases the first base B1 against the second base B2, and the first array of alignment features F1 is seated against the second array of alignment features F2. In FIG. 7B, the optical fiber array FA may be a fiber optic jumper cable providing a flexible optical connection for optical signal communication with the PIC chip 100.

[0062] FIG. 7C is a cross-sectional view along line 7A-7A in FIG. 7A. Each of the mirrors M1 includes a structured reflective surface profile that redirects light between a first optical path L1 along a first direction in a first plane substantially parallel to the first surface S1 of the first base B1 of the connector 10, and a second optical path L2 along a second direction outside the first plane (e.g., 90 degrees). Each of the arrays of fiber grooves G defined on the first base B1 supports an end section of an optical fiber OF in optical alignment with a corresponding mirror M1 along the first optical path L1. Each of the second mirror arrays M2 defined on the second base B2 of the base includes a structured reflective surface profile that redirects light between a third optical path L3 along a third direction in a second plane substantially parallel to the second surface S2 of the second base B2, and a fourth optical path L4 along a fourth direction outside the second plane. Optical paths L3 and L4 coincide when connector 10 and base 12 are coupled in the illustrated configuration, completing an optical path between PIC chip 100 and optical fibers OF in fiber array FA.

[0063] The structured reflective surface profile of mirror M1 and / or mirror M2 may be configured to reshape the light beam from the PIC chip 100 to generate a mode field that more closely matches the mode field of the optical fiber OF in the connector 10. Additionally, mirror M2 in the base 12 may be configured with a reflective surface profile to expand or collimate the light beam from the optical element in the PIC chip 100 and output it to mirror M1 in the connector 10, and mirror M1 in the connector 10 may be configured with a reflective surface profile to focus the light beam from mirror M2 in the base 12 to the core of the tip / end face of the optical fiber OF held in groove G on base B1 of the optical bench in the connector 10. This expanded beam optical coupling configuration reduces the optical alignment tolerance requirements between mirror M2 and the optical fiber OF held in the connector 10.

[0064] 8A-8D show a process of fixing the position of the base 12 for a subsequent removable connection according to an embodiment of the present invention. In this embodiment, an additional I / O chip 101 is provided to interface with an ASIC (e.g., CPU, GPU, switch ASIC) chip 102. The optical path is similar to that shown in FIG. 7C, with the I / O chip 101 replacing the PIC chip 100. First, in FIG. 8A, the optical connector 10 is coupled to the base 12. The optical connector 10 is actively aligned with respect to the chip 101 by positioning the base 12 with respect to the chip 101 to obtain an optimal optical signal between the chip 101 / chip 102 and the optical fiber OF supported by the optical connector 10. The position of the base 12 is fixed with respect to the chip 101 in an optically aligned position (e.g., by using solder to fasten the position of the base 12 on the support S (interposer, printed circuit board, submount, etc.) for the chip 101). Then, in Fig. 8B, the optical connector 10 is removed from the base 12. In Fig. 8C, the base 12 can be permanently attached to the support S (e.g., by reflowing the solder) without changing its position on the support S. Thereafter, in Fig. 8D, the optical connector 10 can be repeatedly connected and disconnected and reconnected to the base 12 non-destructively and without losing the original optical alignment obtained by the active alignment between the optical connector 10 and the chip 101 / chip 102. The optical alignment according to the original active alignment is maintained with each connection and disconnection and reconnection, precisely and accurately aligning the optical connector 10 to the base 12.

[0065] According to the present invention, the optical connector and the base define a free space coupling without any refractive optical element disposed between the optical connector and the base to provide light reshaping. Furthermore, a removable elastic mean coupling between the optical connector and the base is defined without the use of any complementary alignment pins and alignment holes.

[0066] Although the present invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit, scope and teaching of the invention. Accordingly, the invention disclosed herein is to be considered merely as illustrative and limited in scope only as specified in the appended claims. Other embodiments 1. An optical connector comprising a first body for transmitting an optical signal; a second body that provides an alignment reference for an external optoelectronic device that communicates optical signals with the optical connector; A passive optical alignment coupling comprising: the first body defines a first base having a first plane defined by a first two-dimensional planar array of alignment features integrally defined on a first surface of the first base; the second body defines a second base having a second plane defined by a second two-dimensional planar array of alignment features integrally defined on a second surface of the second base; one of the first array of alignment features and the second array of alignment features comprises a first network of orthogonal longitudinal grooves, and the other of the first array of alignment features and the second array of alignment features comprises a second network of longitudinal cylindrical projections, each having a longitudinal axis parallel to a corresponding one of a first surface of the first base or a second surface of the second base; the second network of cylindrical projections is received within the first network of grooves with projection surfaces of the cylindrical projections in contact with groove surfaces of the grooves; and The optical connector is removably attached to the base to define a detachable coupling, and the first array of alignment features defines an elastic mean coupling with the second array of alignment features, thereby aligning the optical connector to the base. 1. A passive optical alignment coupling comprising: 2. A passive optical alignment coupling as described in embodiment 1, wherein the first network of orthogonal grooves of the first alignment feature defines an array of discrete protrusions separated and isolated from one another by orthogonal grooves on a corresponding one of the first surface of the first base or the second surface of the second base, each of the discrete protrusions being generally pyramidal in shape with a truncated apex. 3. The passive optical alignment coupling of embodiment 2, wherein the array of discrete protrusions comprises raised structures, each of which is symmetrical about a first plane perpendicular to a corresponding one of the first surface of the first base and the second surface of the second base, and further symmetrical about a second plane perpendicular to the first plane and perpendicular to the corresponding one of the first surface and the second surface. 4. The passive optical alignment coupling of embodiment 3, wherein the array of discrete protrusions further comprises a plurality of guide key protrusions having raised structures located along a perimeter / edge of a corresponding one of the first and second surfaces, the guide key protrusions having a different surface profile on a surface facing away from the perimeter / edge compared to a surface profile of the symmetrical discrete protrusions located inside the perimeter / edge, thereby initially guiding the relative positions of the first and second arrays of alignment features and uniquely seating the relative positions of the optical connector having the first array of alignment features and the base having the second array of alignment features to couple the optical connector to the base in a predetermined intended relative position. 5. A passive optical alignment coupling as described in any of embodiments 2 to 4, characterized in that the array of discrete protrusions is a rectangular array of (M+1) x (N+1) discrete protrusions, and the first network of intersecting grooves includes M x N orthogonal longitudinal grooves, and for a coupling interface between the optical connector and the base having a planar area of ​​approximately 3 mm x 3 mm, M is preferably in the range of 3 to 10 and N is in the range of 3 to 10 to achieve a coupling accuracy of less than 1 micrometer between the optical connector and the base. 6. A passive optical alignment coupling as described in any one of embodiments 2 to 5, characterized in that a protrusion surface of the longitudinal cylindrical protrusion makes line contact with the groove surface to define an array of line contacts when the optical connector is coupled to the base, the longitudinal grooves are V-shaped grooves, and each of the discrete protrusions has a substantially flat surface corresponding to the groove surface, and defines the line contact with the protrusion surface when the optical connector is coupled to the base. 7. A passive optical alignment coupling as described in any one of embodiments 2 to 5, characterized in that a protrusion surface of the longitudinal cylindrical protrusion makes point contact with the groove surface to define an array of point contacts when the optical connector is coupled to the base, and each of the discrete protrusions has a convex curved surface corresponding to the groove surface and defines the point contact with the protrusion surface when the optical connector is coupled to the base. 8. A passive optical alignment coupling described in any one of embodiments 2 to 7, characterized in that when the optical connector is coupled to the base, the discrete protrusions defined by the longitudinal grooves contact corresponding ones of the first surface and the second surface. 9. A passive optical alignment coupling as described in any one of embodiments 1 to 8, characterized in that the second network of cylindrical protrusions comprises a network of intersecting longitudinal cylindrical protrusions. 10. The passive optical alignment coupling of embodiment 9, wherein the second network of cylindrical protrusions includes M×N orthogonal longitudinal cylindrical protrusions and matches the first network of intersecting longitudinal grooves. 11. A passive optical alignment coupling as described in any one of embodiments 1 to 10, wherein each of the second networks of cylindrical protrusions is substantially semicircular in cross section. 12. A passive optical alignment coupling as described in any of embodiments 1 to 11, characterized in that the first base comprises a first malleable metal material, and a first array of alignment features of the optical connector are integrally defined on the first base by stamping the malleable metal material, and the second base comprises a second malleable material, and a second array of alignment features are integrally defined on the base by stamping the second malleable metal material. 13. The optical connector comprises a first micromirror optical bench, the first micromirror optical bench comprising: said first base; a first array of mirrors defined on the first base, each mirror including a structured reflective surface profile that redirects light between a first optical path along a first direction in a first plane substantially parallel to the first surface of the first base and a second optical path along a second direction outside the first plane; and an array of fiber grooves defined on the first base, each groove receiving a section of an optical fiber with its longitudinal axis along the first optical path and an end optically aligned with a corresponding mirror along the first optical path; 13. The passive optical alignment coupling according to any one of embodiments 1 to 12, comprising: 14. The base includes a second micromirror optical bench, the second micromirror optical bench comprising: the second base; and a second array of mirrors defined on the second base, each mirror in the second array of mirrors including a structured reflective surface profile that redirects light between a third optical path along a third direction in a second plane substantially parallel to the second surface of the second base and a fourth optical path along a fourth direction outside the second plane. 14. The passive optical alignment coupling according to any one of embodiments 1 to 13, comprising: 15. A passive optical alignment coupling as described in any one of embodiments 1 to 12, characterized in that the optical connector comprises a first array of mirrors defined on the first base, the base comprises a second array of mirrors defined on the second base, the first array of mirrors being defined on the first base simultaneously with the first array of alignment features, and the second array of mirrors being defined on the second base simultaneously with the second array of alignment features. 16. A passive optical alignment coupling described in any of embodiments 1 to 15, characterized in that the optical connector and the base define a free space coupling without any refractive optical elements disposed between the optical connector and the base. 17. A passive optical alignment coupling described in any of embodiments 1 to 16, characterized in that the detachable coupling between the optical connector and the base is defined without the use of any complementary alignment pins and alignment holes. 18. A passive optical alignment coupling as described in any of embodiments 1 to 17, characterized in that the first base of the optical connector has a first reference surface on a first side of the first base and the second base of the platform has a second reference surface on a second side of the second base, and the first reference surface and the second reference surface are generally aligned by a compliant clip that biases the first base relative to the second base with the first array of alignment features facing the second array of alignment features. 19. A passive optical alignment coupling described in any one of embodiments 1 to 18, characterized in that the base is coupled to a photonic integrated circuit PIC, and the first base of the optical connector supports an optical fiber array. 20. Support; an optoelectronic device attached to a top surface of the support; and The passive optical alignment coupling according to any one of the first to nineteenth embodiments Equipped with the base is positioned relative to the optoelectronic device, either on the optoelectronic device and / or on the support; The base defines an alignment position for the optoelectronic device to communicate optical signals with the optical connector that is detachably / removably coupled to the base. A photonic device comprising: 21. The photonic apparatus of embodiment 20, wherein the optoelectronic device comprises a photonic integrated circuit (PIC) chip having optical elements as an optical interface to the outside of the PIC chip, and the base is optically aligned with the optical elements of the PIC chip. 22. The photonic device of embodiment 21, wherein the base comprises an edge coupler optically aligned with the PIC chip and supported on the support, the optical elements of the PIC chip directing light to an edge of the PIC chip, the edge coupler comprising an array of mirrors optically aligned with the optical elements of the PIC chip, and light being transmitted along an optical path between mirrors in the array of mirrors and corresponding optical elements in the PIC chip. 23. A method for providing a connection between an optical connector and an optoelectronic device, comprising: providing a support; mounting the optoelectronic device on a top surface of the support; and Providing a passive optical alignment bond according to any one of embodiments 1 to 22. Including, the base is positioned relative to the optoelectronic device, either on the optoelectronic device and / or on the support; The base defines an alignment position for the optoelectronic device to communicate optical signals with the optical connector removably coupled to the base. A method comprising:

Claims

1. a first body defining a first base; a second body providing an alignment reference for the first body; A passive optical alignment coupling comprising: the first base having a first plane defined by a first two-dimensional planar array of alignment features integrally defined on a first surface of the first base; the second body defines a second base having a second plane defined by a second two-dimensional planar array of alignment features integrally defined on a second surface of the second base; one of the first array of alignment features and the second array of alignment features comprises a first network of orthogonal longitudinal grooves, and the other of the first array of alignment features and the second array of alignment features comprises a second network of longitudinal cylindrical projections, each having a longitudinal axis parallel to a corresponding one of a first surface of the first base or a second surface of the second base; the second network of cylindrical projections is received within the first network of grooves with projection surfaces of the cylindrical projections in contact with groove surfaces of the grooves; and The first body is removably attached to the second body to define a releasable bond, and the first array of alignment features defines an elastic average bond with the second array of alignment features, thereby aligning the first body to the second body. A passive alignment bond, characterized in that

2. 2. The passive alignment coupling of claim 1, wherein the first network of orthogonal grooves defines an array of discrete protrusions separated and isolated from one another by the orthogonal grooves on a corresponding one of the first surface of the first base or the second surface of the second base, each of the discrete protrusions being generally square pyramidal in shape with a truncated apex.

3. 3. The passive alignment coupling of claim 2, wherein the array of discrete protrusions comprises raised structures, each of the raised structures being symmetrical about a first vertical reference plane orthogonal to a corresponding one of the first surface of the first base and the second surface of the second base, and further symmetrical about a second vertical reference plane orthogonal to the first vertical reference plane and orthogonal to the corresponding one of the first surface and the second surface.

4. 4. The passive alignment coupling of claim 3, wherein the array of discrete projections further comprises a plurality of guide key projections having raised structures located along a perimeter / edge of a corresponding one of the first and second surfaces, the guide key projections having a different surface profile on a surface facing away from the perimeter / edge compared to a surface profile of the symmetrical discrete projections located inside the perimeter / edge, thereby initially guiding the relative positions of the first and second arrays of alignment features and uniquely seating the relative positions of the first body having the first array of alignment features and the second body having the second array of alignment features for coupling the first body to the second body in a predetermined intended relative position.

5. 5. The passive alignment coupling of claim 2, wherein the array of discrete protrusions is a rectangular array of (M+1)×(N+1) discrete protrusions, the first network of orthogonal grooves comprises M×N orthogonal grooves, and M is in the range of 3 to 10 and N is in the range of 3 to 10 to achieve a coupling accuracy of less than 1 micrometer between the first body and the second body for a coupling interface between the first body and the second body having a planar area of ​​approximately 3 mm×3 mm.

6. 6. The passive alignment bond of claim 2, wherein a protrusion surface of the longitudinal cylindrical protrusion makes line contact with the groove surface to define an array of line contacts when the first body is bonded to the second body, the longitudinal grooves being V-shaped grooves, and each of the discrete protrusions comprises a substantially flat surface corresponding to the groove surface, and defines the line contact with the protrusion surface when the first body is bonded to the second body.

7. 6. The passive alignment bond of claim 2, wherein a protrusion surface of the longitudinal cylindrical protrusion makes point contact with the groove surface to define an array of point contacts when the first body is bonded to the second body, and each of the discrete protrusions comprises a convex curved surface corresponding to the groove surface to define the point contact with the protrusion surface when the first body is bonded to the second body.

8. 8. The passive alignment coupling of claim 2, wherein when the first body is coupled to the second body, the discrete projections defined by the longitudinal grooves contact corresponding ones of the first surface and the second surface.

9. A passive alignment coupling according to any one of claims 1 to 8, characterized in that the second network of cylindrical projections comprises a network of orthogonal longitudinal cylindrical projections.

10. 10. The passive alignment coupling of claim 9, wherein the second network of cylindrical projections includes M x N orthogonal longitudinal cylindrical projections and matches the first network of orthogonal longitudinal grooves.

11. A passive alignment coupling according to any one of claims 1 to 10, characterized in that each of the second networks of cylindrical projections is substantially semicircular in cross section.

12. 12. The passive alignment bond of claim 1, wherein the first base comprises a first malleable metal material, and a first array of alignment features of the first body are integrally defined on the first base by stamping the malleable metal material, and the second base comprises a second malleable metal material, and a second array of alignment features are integrally defined on the base by stamping the second malleable metal material.

13. The first body includes a first micromirror optical bench, the first micromirror optical bench comprising: the first base; a first array of mirrors defined on the first base, each mirror including a structured reflective surface profile that redirects light between a first optical path along a first direction in a first horizontal reference plane substantially parallel to the first surface of the first base and a second optical path along a second direction outside of the first horizontal reference plane; and an array of fiber grooves defined on the first base, each groove receiving a section of an optical fiber with its longitudinal axis along the first optical path and an end optically aligned with a corresponding mirror along the first optical path; A passive alignment coupling according to any one of claims 1 to 12, characterized in that it comprises:

14. The second body includes a second micromirror optical bench, the second micromirror optical bench including: the second base; and a second array of mirrors defined on the second base, each mirror in the second array of mirrors including a structured reflective surface profile that redirects light between a third optical path along a third direction in a second horizontal reference plane substantially parallel to the second surface of the second base and a fourth optical path along a fourth direction outside of the second horizontal reference plane. A passive alignment coupling according to any one of claims 1 to 13, characterized in that it comprises:

15. 13. A passive alignment coupling according to any one of claims 1 to 12, characterized in that the first body comprises a first array of mirrors defined on the first base, and the second body comprises a second array of mirrors defined on the second base, the first array of mirrors being defined on the first base simultaneously with the first array of alignment features, and the second array of mirrors being defined on the second base simultaneously with the second array of alignment features.

16. A passive alignment coupling according to any one of claims 1 to 12, characterized in that at least one of the first body and the second body comprises at least one optical waveguide.

17. 17. The passive alignment coupling of claim 1, wherein the first body and the second body define a free space coupling without any refractive optical element disposed between the first body and the second body.

18. 18. A passive alignment coupling according to any one of claims 1 to 17, characterized in that the detachable coupling between the first body and the second body is defined without the use of any complementary alignment pins and alignment holes.

19. 19. The passive alignment coupling of claim 1, further comprising a compliant clip that biases the first base against the second base with the first array of alignment features facing the second array of alignment features.

20. A passive alignment coupling according to any one of claims 1 to 19, characterized in that the second body is coupled to a photonic integrated circuit PIC and the first base of the first body supports an optical fiber array.

21. A passive alignment coupling according to any one of claims 1 to 20, characterized in that the first body is included in an optical connector for transmitting an optical signal.

22. A passive alignment coupling according to any one of claims 1 to 21, characterized in that the second body is included in a base providing an optical alignment reference.

23. Support; an optoelectronic device attached to a top surface of the support; and The passive alignment bond according to any one of claims 1 to 20. Equipped with the first body is included in an optical connector that transmits an optical signal; the second body is included in a base that provides an optical alignment reference; the base is positioned relative to the optoelectronic device; The base defines an alignment position for the optoelectronic device to communicate optical signals with the optical connector that is detachably / removably coupled to the base. A photonic device comprising:

24. 24. The photonic apparatus of claim 23, wherein the optoelectronic device comprises a photonic integrated circuit chip (PIC chip) having optical elements as an optical interface to the outside of the PIC chip, and the base is optically aligned with the optical elements of the PIC chip.

25. 25. The photonic device of claim 24, wherein the base comprises an edge coupler supported on the support in optical alignment with the PIC chip, the optical elements of the PIC chip directing light to an edge of the PIC chip, the edge coupler comprising an array of mirrors optically aligned with the optical elements of the PIC chip, and light being transmitted along an optical path between mirrors in the array of mirrors and corresponding optical elements in the PIC chip.

26. 1. A method for providing a connection between an optical connector and an optoelectronic device, comprising: Providing a support; mounting the optoelectronic device on a top surface of the support; and 21. A process for providing a passive alignment coupling according to any one of claims 1 to 20, wherein the first body is included in an optical connector for transmitting an optical signal and the second body is included in a base that provides an optical alignment reference. Including, the base is positioned relative to the optoelectronic device, either on the optoelectronic device and / or on the support; The base defines an alignment position for the optoelectronic device to communicate optical signals with the optical connector removably coupled to the base. A method comprising:

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