Methods and apparatus for high-density optical connections

Abstract

Optical interconnection apparatus optical connect a plurality of photonic integrated circuit (PIC) waveguides to a plurality of optical components spaced apart from the PIC. The apparatus comprises an optical transposer with a plurality of optical transposer waveguides having a fan-out configuration wherein a first end spacing is less than a second end spacing. The apparatus also comprises optical connections between the PIC waveguides and the first ends of the optical transposer waveguides. Each optical connection between a PIC waveguide and a corresponding optical transposer waveguide is provided by one or more optical components fabricated using additive manufacturing.

Description

METHODS AND APPARATUS FOR HIGH-DENSITY OPTICAL CONNECTIONSCross-Reference to Related Applications

[0001] This application claims priority from, and for the purposes of the United States of America the benefit under 35 USC § 119 in connection with, United States patent application No. 63 / 688177 filed 28 August 2024 which is hereby incorporated herein by reference for all purposes.Technical Field

[0002] The present disclosure relates to the field of optics, in particular micro-optics (photonics) and methods and systems for photonics fabrication and implementation. Some embodiments provide methods and systems for optical interconnection between high- density waveguides on a photonics integrated circuit to relatively more spaced apart optical components.Background

[0003] There is a general desire to increase bandwidth density (e.g. spatial density) for connections to data processing units. For example, there is a desire to increase spatial bandwidth density for connection to auxiliary processing units (XPUs) to help meet the requirements for high-performance computing and machine learning. Electrical connections are typically used to connect to such XPUs, but such electrical connections are reaching their limits in terms of microbump pitch, electrical cross-talk, packaging reliability and / or the like when pursuing higher connection density.

[0004] Converting electrical signals to photonic signals and using aggregated transmission via wavelength division multiplexing and / or dual polarization has been proposed as a potential means to achieving relatively high bandwidth density. Optical signals can be transmitted between XPUs or other processors using optical fibers which are relatively low loss.

[0005] While on-chip optical waveguides such as those provided on photonic integrated circuits (PICs) can be spaced relatively close to one another (e.g. at pitches as small as one or two microns) without noticeable cross-talk, off-chip optical fibers are often limited to 127pm spacings or 250pm spacings due to optical fiber standards. Such optical fiber standards and other reasons for the spacing between off-chip waveguides are driven bycriteria, such as manufacturing efficiency, alignment precision, mechanical stability, thermal considerations, optical performance, ease of handling and / or the like. Further, there is typically mode field diameter mismatch between on-chip (PIC) waveguides and off-chip fiber arrays or other off-chip optical components. These differences in pitch and mode field diameter between on-chip (PIC) waveguides and off chip fiber arrays can limit the shoreline density (data transmission capacity per unit length of a chip, package, or board) of optical connections between such components. Although the use of serializers, advanced modulation schemes, multiplexing with greater numbers of wavelengths and higher modulation speeds have been used to increase bandwidth density, these techniques have corresponding adverse effects on latency and power consumption.

[0006] Having regard to the foregoing, there is a desire for high bandwidth optical connection between relatively high density (tightly spaced) waveguides on PICs to other off- chip optical components having relatively low density (less tightly spaced).

[0007] The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.Summary

[0008] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the abovedescribed problems have been reduced or eliminated, while other embodiments are directed to other improvements.

[0009] One aspect of the invention provides an optical interconnection apparatus for optical connection between a plurality of photonic integrated circuit (PIC) waveguides on a PIC and a plurality of optical components spaced apart from the PIC. The optical interconnection apparatus comprises: an optical transposer comprising a plurality of optical transposer waveguides wherein the plurality of optical transposer waveguides comprise a fan-out configuration wherein: first ends of the optical transposer waveguides have a first end spacing between adjacent pairs of the first ends of the optical transposer waveguides; second ends of the optical transposer waveguides, opposite to the first ends, have a secondend spacing between adjacent pairs of the second ends of the optical transposer waveguides; and the first end spacing is less than the second end spacing. The optical interconnection apparatus also comprises optical connections between the PIC waveguides and the first ends of the optical transposer waveguides, each optical connection between a PIC waveguide and the first end of a corresponding optical transposer waveguide provided by one or more optical components fabricated using additive manufacturing.

[0010] For each optical connection, the one or more optical components may comprise a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween. The photonic waveguide may be fabricated by additive manufacturing.

[0011] The photonic wire bond may be attached between a facet of the PIC waveguide and a facet of the first end of the optical transposer waveguide. The photonic wire bond may be fabricated from polymer.

[0012] For each optical connection, the one or more optical components may comprise at least one lens between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween. The at least one lens may be fabricated by additive manufacturing.

[0013] For each optical connection, the one or more optical components may comprise a pair of lenses between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween. The pair of lenses may be fabricated by additive manufacturing.

[0014] One of the pair of lenses may be attached to a facet of the PIC waveguide and the other one of the pair of lenses may be attached to a facet of the first one of the corresponding optical transposer waveguide.

[0015] Each lens may be fabricated from polymer.

[0016] The PIC may comprise a first alignment structure having one of: a protruding shape and a complementary recess-defining shape. The optical transposer may comprise a second alignment structure having the other one of: the protruding shape and the complementary recess-defining shape. The first alignment structure and the second alignment structure may be engaged with one another such that the protruding shapeprotrudes into a complementary recess defined by the complementary recess-defining shape to thereby align the optical transposer to the PIC.

[0017] Surfaces of the first and second alignment structures may form a contact fit when the protruding shape protrudes into the complementary recess defined by the complementary recess-defining shape.

[0018] At least one of the first and second alignment structures may be fabricated by additive manufacturing.

[0019] At least one of the first and second alignment structures may be fabricated by an etching process.

[0020] The second end spacing between adjacent pairs of the second ends of the optical transposer waveguides may be dimensioned to match at least one of: a pitch between fibers of a fiber array, a pitch between cores of a multicore fiber and a pitch between optical connections of an optical connector (e.g. for butt connection).

[0021] Each PIC waveguide may comprise an edge-coupling optical interface (e.g. a facet) on an edge of the PIC (e.g. a vertical edge of the PIC). Each optical connection may be shaped, located and / or fabricated from suitable material(s) to direct light into or receive light from the optical interface.

[0022] Each PIC waveguide may comprise a surface-coupling optical interface (e.g. a grating or mirror) to direct optical energy through, either to or from, a surface of the PIC (e.g. a horizontal surface of the PIC). Each optical connection may be shaped, located and / or fabricated from suitable material(s) to direct light into or receive light from the optical interface.

[0023] Each optical connection may be shaped, located and / or shaped, located and / or fabricated from suitable material(s) to direct light into or receive light from the PIC waveguide by evanescent coupling.

[0024] The optical transposer may comprise a body made up of one or more of: glass, polymer, plastic, silicon and silicon nitride.

[0025] The optical transposer waveguides may be fabricated in the body by one or more of: ion-exchange which changes the crystal structure of the body in the region of the opticaltransposer waveguides and laser inscription which changes the crystal structure of the body in the region of the optical transposer waveguides.

[0026] The optical transposer waveguides may be located on a surface of the body. The optical transposer waveguides may be located within the body.

[0027] The optical transposer may comprise a substrate body and the optical transposer waveguides may be fabricated on the substrate by melting and drawing optical fibers.

[0028] The second end spacing between adjacent pairs of the second ends of the optical transposer waveguides may be a spacing in a single dimension. The spacing in the single dimension may be in a horizontal direction. The spacing in the single dimension may be in a horizontal direction.

[0029] The second end spacing between adjacent pairs of the second ends of the optical transposer waveguides may be a spacing in two orthogonal dimensions. The two orthogonal dimensions may be in a vertical direction and a horizontal direction.

[0030] The PIC may be electrically connected to exchange electronic signals with an electrical integrated circuit (EIC).

[0031] Electrical connections between the PIC and the EIC may be provided at least in part by conductors that extend through vias in a substrate layer (e.g. transposer layer).

[0032] The substrate layer may be made up of one or more of: glass, polymer, plastic, silicon and silicon nitride.

[0033] The EIC, the PIC and the optical transposer may be mounted on the substrate layer.

[0034] The EIC and / or the PIC may be mounted to the substrate layer by ball grid array soldering.

[0035] The optical transposer may be bonded to the substrate layer - e.g. using metal soldering, adhesive and / or fasteners.

[0036] The substrate layer and the optical transposer may be integrally formed.

[0037] The EIC may be mounted atop the PIC or underneath the PIC.

[0038] Electrical connections between the PIC and the EIC may be provided at least in part by conductors that extend through vias in the PIC.

[0039] The PIC and the optical transposer may be spaced apart from one another.

[0040] The PIC and the optical transposer may be in abutting contact with one another.

[0041] The optical transposer may be shaped to define a recess. The recess may be shaped to expose facets of the optical transposer waveguides in a recess-defining surface (e.g. a vertical or edge recess-defining surface) that is spaced apart from the abutting contact with the PIC.

[0042] The recess may be formed by chemical or physical etching.

[0043] For each optical connection, the one or more optical components may comprise a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween. A portion of the recess-defining surface may be located to support the photonic wire bond.

[0044] A body of the PIC may be shaped to provide a recess that is located adjacent to the optical connections and between the PIC waveguides and the substrate - e.g. for minimizing heat conduction between the substrate and the PIC waveguides

[0045] The recess may fabricated by chemical or physical etching.

[0046] The plurality of optical components may comprise a plurality of fibers in a fiber array.

[0047] At least portions of the plurality of fibers that are closest to the optical transposer may be supported by a fiber support body.

[0048] The fiber support body may be shaped (e.g. by micromachining) to provide a plurality of grooves. Each portion of a corresponding one of the plurality of fibers may be located in a corresponding one of the plurality of grooves.

[0049] The optical transposer and the fiber support body may be attached to one another (e.g. by suitable adhesion techniques or by welding).

[0050] The optical transposer and the fiber support body may be integrally formed with one another.

[0051] The fiber support body may be fabricated from a transparent material (e.g. quartz or glass).

[0052] The PIC, the EIC and the optical transposer may be bonded to a sub-mount during fabrication and are subsequently flip-chip mounted to the substrate. The sub-mount maycomprise a heat spreader (e.g. copper, other metal or metal alloy with high thermal conductivity). The heat spreader may comprise or be thermally coupled to a heat sink.

[0053] The PIC, the EIC and the optical transposer may be bonded to the sub-mount using thermally conductive adhesive or metalization.

[0054] The first end spacing may be less than 20pm. The second end spacing may be greater than 100pm or greater than 200pm.

[0055] Another aspect of the invention provides a method for optically connecting a plurality of photonic integrated circuit (PIC) waveguides on a PIC and a plurality of optical components spaced apart from the PIC. The method comprises providing an optical transposer comprising a plurality of optical transposer waveguides wherein the plurality of optical transposer waveguides comprise a fan-out configuration wherein: first ends of the optical transposer waveguides have a first end spacing between adjacent pairs of the first ends of the optical transposer waveguides; second ends of the optical transposer waveguides, opposite to the first ends, have a second end spacing between adjacent pairs of the second ends of the optical transposer waveguides; and the first end spacing is less than the second end spacing. The method also comprises fabricating optical connections between the PIC waveguides and the first ends of the optical transposer waveguides, wherein fabricating each optical connection between a PIC waveguide and the first end of a corresponding optical transposer waveguide comprises fabricating one or more optical components using additive manufacturing.

[0056] For each optical connection, the one or more optical components may comprise a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween.

[0057] The method may comprise attaching the photonic wire bond between a facet of the PIC waveguide and a facet of the first end of the optical transposer waveguide.

[0058] The photonic wire bond may be fabricated from polymer.

[0059] For each optical connection, the one or more optical components may comprise at least one lens between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween.

[0060] For each optical connection, the one or more optical components may comprise a pair of lenses between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween.

[0061] The method may comprise attaching one of the pair of lenses to a facet of the PIC waveguide and attaching the other one of the pair of lenses to a facet of the first one of the corresponding optical transposer waveguide.

[0062] Each lens may be fabricated from polymer.

[0063] The method may comprise: shaping the PIC to comprise a first alignment structure having one of: a protruding shape and a complementary recess-defining shape; shaping the optical transposer to comprise a second alignment structure having the other one of: the protruding shape and the complementary recess-defining shape; and engaging the first alignment structure and the second alignment structure with one another such that the protruding shape protrudes into a complementary recess defined by the complementary recess-defining shape to thereby align the optical transposer to the PIC.

[0064] The method may comprise forming a contact fit between surfaces of the first and second alignment structures when the protruding shape protrudes into the complementary recess defined by the complementary recess-defining shape.

[0065] The method may comprise fabricating at least one of the first and second alignment structures by additive manufacturing.

[0066] The method may comprise fabricating at least one of the first and second alignment structures by an etching process.

[0067] The method may comprise dimensioning the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides to match at least one of: a pitch between fibers of a fiber array, a pitch between cores of a multicore fiber and a pitch between optical connections of an optical connector (e.g. for butt connection).

[0068] Each PIC waveguide may comprise an edge-coupling optical interface (e.g. a facet) on an edge of the PIC (e.g. a vertical edge of the PIC). Fabricating each optical connection may comprise shaping, locating and / or fabricating the optical connection from suitable material(s) to direct light into or receive light from the optical interface.

[0069] Each PIC waveguide may comprise a surface-coupling optical interface (e.g. a grating or mirror) to direct optical energy through, either to or from, a surface of the PIC (e.g. a horizontal surface of the PIC). Fabricating each optical connection may comprise shaping, locating and / or fabricating the optical connection from suitable material(s) to direct light into or receive light from the optical interface.

[0070] The method may comprise shaping, locating and or fabricating from suitable materials each optical connection to direct light into or receive light from the PIC waveguide by evanescent coupling.

[0071] The optical transposer may comprise a body fabricated from one or more of: glass, polymer, plastic, silicon and silicon nitride.

[0072] The method may comprise fabricating the optical transposer waveguides in the body using one or more of: an ion-exchange process which changes the crystal structure of the body in the region of the optical transposer waveguides; and a laser inscription process which changes the crystal structure of the body in the region of the optical transposer waveguides.

[0073] The method may comprise locating the optical transposer waveguides on a surface of the body.

[0074] The method may comprise locating the optical transposer waveguides within the body.

[0075] The optical transposer may comprise a substrate body. The method may comprise fabricating the optical transposer waveguides on the substrate by melting and drawing optical fibers.

[0076] The second end spacing between adjacent pairs of the second ends of the optical transposer waveguides may be a spacing in a single dimension.

[0077] The spacing in the single dimension may be in a horizontal direction. The spacing in the single dimension may be in a vertical direction.

[0078] The second end spacing between adjacent pairs of the second ends of the optical transposer waveguides may be a spacing in two orthogonal dimensions. The two orthogonal dimensions may be in a vertical direction and a horizontal direction.

[0079] The PIC may be electrically connected to exchange electronic signals with an electrical integrated circuit (EIC). Electrical connections between the PIC and the EIC may be provided at least in part by conductors that extend through vias in a substrate layer (e.g. transposer layer).

[0080] The substrate layer may be made up of one or more of: glass, polymer, plastic, silicon and silicon nitride.

[0081] The EIC, the PIC and the optical transposer may be mounted on the substrate layer.

[0082] Mounting the EIC and / or the PIC to the substrate layer may comprise ball grid array soldering.

[0083] The method may comprise bonding the optical transposer to the substrate layer - e.g. using metal soldering, adhesive and / or fasteners.

[0084] The substrate layer and the optical transposer may be integrally formed.

[0085] The EIC may be mounted atop the PIC or underneath the PIC.

[0086] Electrical connections between the PIC and the EIC may be provided at least in part by conductors that extend through vias in the PIC.

[0087] The PIC and the optical transposer may be in abutting contact with one another.

[0088] The method may comprise fabricating the optical transposer to define a recess, the recess shaped to expose facets of the optical transposer waveguides in a recess-defining surface (e.g. a vertical or edge recess-defining surface) that is spaced apart from the abutting contact with the PIC.

[0089] The method may comprise fabricating the recess by chemical or physical etching.

[0090] For each optical connection, fabricating the one or more optical components may comprise: fabricating, by additive manufacturing, a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween; and fabricating a portion of the recess-defining surface to be located to support the photonic wire bond.

[0091] The method may comprise fabricating a body of the PIC to provide a recess that is located adjacent to the optical connections and between the PIC waveguides and the substrate.

[0092] The method may comprise fabricating the recess by chemical or physical etching.

[0093] The plurality of optical components may comprise a plurality of fibers in a fiber array.

[0094] At least portions of the plurality of fibers that are closest to the optical transposer may be supported by a fiber support body.

[0095] The fiber support body may be shaped (e.g. by micromachining) to provide a plurality of grooves and each portion of a corresponding one of the plurality of fibers is located in a corresponding one of the plurality of grooves.

[0096] The method may comprise attaching the optical transposer and the fiber support body to one another (e.g. by suitable adhesion techniques or by welding).

[0097] The optical transposer and the fiber support body may be integrally formed with one another.

[0098] The fiber support body may be fabricated from a transparent material (e.g. quartz or glass).

[0099] The method may comprise bonding the PIC, the EIC and the optical transposer to a sub-mount during fabrication and subsequently flip-chip mounting the bonded PIC, EIC and optical transposer to the substrate.

[0100] The sub-mount may comprise a heat spreader (e.g. copper, other metal or metal alloy with high thermal conductivity). The heat spreader may comprise or may be thermally coupled to a heat sink.

[0101] The method may comprise bonding the PIC, the EIC and the optical transposer to the sub-mount using thermally conductive adhesive or metalization.

[0102] The first end spacing may be less than 20pm. The second end spacing may be greater than 100pm or greater than 200pm.

[0103] Other aspects of the invention provide methods comprising any features, combinations of features and / or subcombinations of features disclosed herein.

[0104] Other aspects of the invention provide apparatus comprising any features, combinations of features and / or subcombinations of features disclosed herein.

[0105] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions.Brief Description of the Drawings

[0106] Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

[0107] Figures 1A and 1 B (collectively and individually Figure 1 ) are side-cross-sectional and top views of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a photonic integrated circuit (PIC) and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0108] Figure 2 is a side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0109] Figure 3 is a side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0110] Figure 4 is a side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0111] Figures 5A and 5B (collectively and individually Figure 5) are a side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) and a partial side-cross-sectional view showing detail of the photonic wire bond connections between the PIC and the optical transposer according to a particular embodiment.

[0112] Figure 6 is a side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0113] Figure 7 is a side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0114] Figure 8 is a partial side cross-sectional view of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides on different layers of a multi-layer PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) on different layers according to a particular embodiment.

[0115] Figure 9 is a partial side cross-sectional view of an optical interconnect apparatus between a PIC waveguide having a surface coupler to an edge coupler of a fiber on an optical transposer according to a particular embodiment.

[0116] Figures 10A and 10B are respectively exploded and assembled side cross-sectional views of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.

[0117] Figures 11 A and 1 1 B (collectively and individually Figure 11 ) show exploded and assembled side-cross-sectional schematic views of an optical interconnect apparatus according to a particular embodiment.

[0118] Figures 12A and 12B (collectively and individually Figure 12) show exploded and assembled side-cross-sectional schematic views of an optical interconnect apparatus according to a particular embodiment.

[0119] Figures 13A and 13B (collectively and individually Figure 13) show exploded and assembled side-cross-sectional schematic views of an optical interconnect apparatus according to a particular embodiment.

[0120] Figures 14A and 14B (collectively and individually Figure 14) show exploded and assembled side-cross-sectional views of an optical interconnect apparatus between the high density (small-pitch or tightly spaced) waveguides of a PIC and a plurality of relatively low density (large-pitch or large spacing) optical components (in the illustrated example, a fiber array) according to a particular embodiment.Description

[0121] Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0122] Aspects of the invention provide optical interconnection apparatus for optical connection between a plurality of photonic integrated circuit (PIC) waveguides on a PIC and a plurality of optical components spaced apart from the PIC. The optical interconnection apparatus comprises an optical transposer with a plurality of optical transposer waveguides having a fan-out configuration wherein: first ends of the optical transposer waveguides have a first end spacing between adjacent pairs of the first ends of the optical transposer waveguides; second ends of the optical transposer waveguides, opposite to the first ends, have a second end spacing between adjacent pairs of the second ends of the optical transposer waveguides; and the first end spacing is less than the second end spacing. The optical interconnection apparatus also comprises optical connections between the PIC waveguides and the first ends of the optical transposer waveguides. Each optical connection between a PIC waveguide and a corresponding optical transposer waveguide is provided by one or more optical components fabricated using additive manufacturing.

[0123] Aspects of the invention also include methods for fabricating optical interconnection apparatus and for making optical interconnections using such optical interconnection apparatus.

[0124] Figures 1A and 1 B (collectively and individually Figure 1 ) are side-cross-sectional and top views of an optical interconnect apparatus 10 for establishing an optical data connection between high density (small-pitch or tightly spaced) waveguides 12A of a photonic integrated circuit (PIC) 12 and a plurality of relatively low density (large-pitch or large spacing) optical components 14 (in the illustrated example, an array 14A of optical fibers 14) according to a particular embodiment. Optical interconnect apparatus 10 of the Figure 1 embodiment is supported by a substrate layer 16 (which may also be referred to as an interposer or interposer layer 16). Substrate layer 16 may be fabricated from any suitable material, including, by way of non-limiting example, glass, polymer, plastic, silicon and / or the like. In the Figure 1 embodiment, PIC 12 is conductively connected to exchange (e.g. send and / or receive) electronic signals with an electronic integrated circuit (EIC) 18 by way of vias 20 which may extend into or through substrate layer 16 and which may be filled or otherwise contain electrically conductive material (e.g. metal) 20A. PIC 12 may be mounted to substrate layer 16 using any suitable technique, including, by way of non-limiting example, ball grid array soldering and / or the like. In the illustrated embodiments, first portions 14B of the fibers 14 in fiber array 14A are mounted to fiber array support 19 and second portions 14C of the fibers 14 in fiber array 14A are spaced apart from fiber array support 19. Fiber support 19 may be coupled to substrate layer 16 using any suitable technique (e.g. adhesives, fasteners, soldering and / or the like). First portions 14B of fibers 14 in fiber array 14A may be mounted in corresponding upwardly (y-direction) opening and longitudinally (z-direction) extending concavities or grooves (not shown) in the body of support 19. Such concavities may be micromachined, for example, although this is not necessary. First portions 14B of fibers 14 may be adhesively bonded within such grooves. In the illustrated embodiment, the second portions 14C of fibers 14 in fiber array 14A are connected to an external optical system or systems by standard fiber connectors 20 (e.g. multifiber push-on (MPO) connectors, multifiber terminal push-on (MPT) connectors and / or the like).

[0125] Optical interconnect apparatus 10 provides an optical data connection between high density waveguides 12A of PIC 12 and relatively low density optical components (e.g. fibers) 14. In some embodiments, PIC waveguides 12A may have a pitch (center-to-center spacing between adjacent waveguides 12A) on the order of 20pm or less. In some embodiments, this PIC waveguide pitch may be on the order of 10pm or less or 5pm orless. In some embodiments, the low-density optical components 14 may have a pitch on the order of 100pm or greater (e.g. 127pm or greater or 250pm or greater). In the particular case of the Figure 1 embodiment, these pitch-spacings are one-dimensional spacings in the x-direction (see Cartesian axes illustrated in Figure 1 ). In other embodiments, these pitchspacings may be in each of two-dimensions (e.g. in the x- and y-directions).

[0126] Optical interconnect apparatus 10 comprises an optical transposer 22 (also referred to as a fan-out 22 or fan-out component 22) which, in the illustrated embodiment, comprises a number of curved waveguides 24 fabricated or otherwise located within (and / or on a surface of) a transposer body 26. The number of waveguides 24 in optical transposer 22 may correspond to the number of optical connections being made (e.g. to the number of PIC waveguides 12A or to the number of optical components 14). This is not necessary, however, as there may be multiple PCI waveguides 12A optically connected to a single optical transposer waveguide 24 or vice versa. Optical transposer waveguides 24 comprise first ends 24A having a relatively small pitch (center-to-center spacing between adjacent waveguides 24) and waveguides 24 may be curved, or otherwise routed, to provide second ends 24B that have a relatively large pitch.

[0127] Transposer body 26 may be fabricated from material that comprises, by way of nonlimiting example, glass, quartz, polymer, plastic, silicon, silicon nitride and / or the like. Transposer body 26 may be fabricated from material that is transparent. Transposer body 26 may be coupled to substrate layer 16 using any suitable technique (e.g. adhesives, fasteners, soldering and / or the like). In some embodiments, transposer body 26 may be integral formed with (e.g. part of) substrate layer 16. Optical transposer waveguides 24 may be fabricated in transposer body 26 (or on a surface of transposer body 26) by processes which change the index of refraction (e.g. by changing the crystal structure or otherwise) in particular regions of transposer body 26. Such optical transposer fabrication techniques include, by way on non-limiting example, ion-exchange, laser (e.g. ultra-fast laser) inscription, and / or the like. In some embodiments, transposer body 26 may be provided as a substrate and transposer waveguides 24 may be fabricated by melting and drawing fibers atop the substrate. Transposer body 26 may abut against support 19 for optical components (e.g. fibers 14). In some embodiments, transposer body 26 may be attached to support 19 by adhesion or welding. In some embodiments, optical transposer 22 may be fabricated such that the first ends 24A of transposer waveguides 24 are located at or near to theheight (i.e. y-direction distance from substrate layer 16) of PIC waveguides 12A. This is not necessary. In some embodiments, the first ends 24A of transposer waveguides 24 may be located at different heights (i.e. y-direction distances from substrate layer 16) than PIC waveguides 12A.

[0128] Optical interconnect apparatus 10 also comprises optical connections 28 which connect optical energy in one or both directions between PIC waveguides 12A and the first ends 24A of optical transposer waveguides 24. In currently preferred embodiments, optical connections 28 are fabricated in situ (e.g. after PIC 12 and optical transposer 22 are mounted to substrate layer 16) by way of additive manufacturing (e.g. two-photon lithography, 3D printing and / or the like). In the case of the illustrated embodiment of Figure 1 , optical connections 28 comprise photonic wire bonds 28A fabricated in situ by additive manufacturing. Each photonic wire bond 28A attaches to a facet of a corresponding PIC waveguide 12A and to a facet of corresponding transposer waveguide 24 for coupling optical energy in one or both directions between the corresponding PIC waveguide 12A and the corresponding transposer waveguide 24. In the illustrated Figure 1 embodiment, PIC 12 and optical transposer 22 are spaced apart from one another in the z-direction. This is not necessary. In some embodiments, PIC 12 and optical transposer 22 can abut against one another. In the illustrated Figure 1 embodiment, the facets of PIC waveguides 12A and facets of optical transposer waveguides 24 are “edge” facets which extend in the x- and y- directions to provide so-called “edge coupling” optical interfaces. This is not necessary. In some embodiments, the facets of PIC waveguides 12A and / or to optical transposer waveguides 24 could be “surface” facets on the surface of the PIC 12 or on the surface of the optical transposer 22 and could extend in x- and z-directions. In some embodiments, optical interfaces to PIC waveguides 12A and / or to optical transposer waveguides 24 could be provided by surface emitting devices (e.g. grating couplers, mirrors and / or the like), evanescent coupling and / or the like. In some embodiments, optical connections 28 may comprise one or more lenses (not shown in Figure 1 ) which may be fabricated by additive manufacturing and which may be attached to the facets of one or both of a corresponding PIC waveguide 12A and a corresponding transposer waveguide 24 for coupling optical energy in one or both directions therebetween.

[0129] Individually fabricating optical connections 28 in situ by additive manufacturing can be advantageous over other techniques such as active alignment between PIC 12 andoptical transposer 22, because the insertion loss (e.g. between PIC waveguides 12A and corresponding transposer waveguides 24) tends to increase with the number of channels due to imperfections (e.g. warpage and / or the like) in PIC 12 and / or optical transposer 22. In contrast, optical connections 28 fabricated by additive manufacturing can be individually tailored and / or optimized, so that insertion loss is less likely to scale with an increase in the number of channels. Additive manufacturing techniques can be used at dimensions on the order of 20pm or less. So, for example, on a PIC 12 having an edge length of 10mm, this would enable the fabrication of several hundred (e.g. 500) individual optical connections 28. In addition, fabricating optical connections 28 (e.g. photonic wire bonds 28A or lens(es)) may be used to provide desired (coupling efficiency maximizing) mode fields at the facets of the first ends 24A of optical transposer waveguides 24.

[0130] Optical transposer waveguides 24 of the Figure 1 embodiment are curved in a “fanout” configuration where the second ends 24B of waveguides 24 have an x-dimension pitch that is greater than that of first ends 24A. This larger x-dimension pitch enables the second ends 24B of optical transposer waveguides 24 to interface with other optical components 14 for which a large pitch is desirable (e.g. fiber array 14A in the case of the illustrated embodiment, one or more multicore fibers, multi-fiber connectors, lasers, LEDs, photodetectors and / or the like). In the illustrated embodiment of Figure 1 , the “fan-out” curvature or configuration of optical transposer waveguides 24 provides a one-dimensional (x-direction) increase in the pitch between first ends 24A and second ends 24B. In other embodiments, this one-dimensional increase in pitch can be in a different direction (e.g. in the y-direction) or the increase in pitch can be in two-dimensions (e.g. in the x-direction and in the y-direction). Curvature of optical transposer waveguides 24 is not necessary to achieve this x-direction pitch spread between first ends 24A and second ends 24B. In some embodiments, transposer waveguides 24 can be otherwise routed (e.g. by positioning waveguides adjacent to one another to facilitate energy transfer between adjacent waveguides) to provide this x-direction pitch spread.

[0131] Connections between second ends 24B of waveguides 24 and optical components 14 (e.g. fibers 14 of fiber array 14A) are shown in the Figure 1 as so-called butt connections, but this is not necessary. Any suitable optical connections can be used between second ends 24B of waveguides 24 and optical components 14.

[0132] In addition to the “fan-out” curvature or configuration of optical transposer waveguides 24, the cross-sectional dimensions (e.g. diameter) of optical transposer waveguides 24 may change along the length (e.g. between first ends 24A and second ends 24B) of optical transposer waveguides 24 to “match” the mode field of the optical components 14 to which second ends 24B are optically coupled. For example, in the case of the illustrated Figure 1 embodiment, optical components 14 are fibers 14 of a fiber array 14A and insertion loss between optical transposer waveguides 24 and these fibers 14 may be minimized if the cross-sections of the second ends 24B of fibers 14 are dimensioned to create a mode field that maximizes coupling efficiency into fibers 14 at the connections between second ends 24B and fibers 14. However, because of spatial constraints at first ends 24A of optical transposer waveguides 24 (i.e. prior to fan-out), it may not be possible to provide first ends 24A with the same cross-sectional dimensions as second ends 24B and, consequently, optical transposer waveguides 24 may be fabricated so that their cross- sectional dimensions change along their length (between first ends 24A and second ends 24B). The cross-sectional dimensions of first ends 24A of optical transposer waveguide 24 may be fabricated to match the mode field of PIC fibers 12A. Additionally or alternatively, any difference in the mode field between the mode field of PIC fibers 12A and first ends 24A may be compensated for by optical connections 28 (e.g. photonic wire bods and / or lenses) fabricated by additive manufacturing.

[0133] In the description of optical interconnect apparatus 10 (Figure 1 ) and the other optical interconnect apparatus described herein, a set of Cartesian axes (having x-, y- and z-directions) are shown in various drawings. Typically, the substrate of a chip / wafer / die or the like is generally planar and is described as having a generally horizontal planar orientation. Accordingly, substrate layer 16 of the Figure 1 embodiment and the substrate layers of the other optical interconnect apparatus described herein comprise surfaces that extend in the x-z directions which may be referred to herein as “horizontal” directions. The positive y-direction (toward the top of the page of the Figure 1 A and out from the page in Figure 1 B) may be referred to as an “upward” direction and / or using similar directional words, whereas the negative y-direction (toward the bottom of the page of the Figure 1 A and into the page in Figure 1 B) may be referred to as an “downward” direction and / or using similar directional words. The y-directions may be referred to herein as vertical directions In the illustrated embodiments, the flow of optical energy is generally in the z-direction(s) and,consequently, the horizontal z-directions may be referred to as longitudinal directions and the orthogonal horizontal x-directions may be referred to as transverse directions. These and other analogous directional words are used herein for simplifying description only. In this description and any accompanying claims (where present), such directional words will depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly.

[0134] Figure 2 is a side cross-sectional view of an optical interconnect apparatus 110 between the high density (small-pitch or tightly spaced) waveguides 12A of a PIC 12 and a plurality of relatively low density (large-pitch or large spacing) optical components 14 (in the illustrated example, the fibers 14 of a fiber array 14A) according to a particular embodiment. In many respects, optical interconnect apparatus 110 is similar to optical interconnect apparatus 10 described elsewhere herein and similar components are provided with similar reference numerals.

[0135] Optical interconnect apparatus 110 differs from optical interconnect apparatus 10 primarily in that optical transposer 122 is integrally formed with substrate layer (interposer) 116. Other than being shaped to provide optical transposer, substrate layer 116 may be substantially similar to substrate layer 16 described elsewhere herein. Optical transposer 122 of the Figure 2 embodiment comprises a transposer body 126 which, other than being integrally formed with substrate layer 116, is substantially similar to transposer body 26 described elsewhere herein. Optical transposer waveguides 124 and their first and second ends 124A, 124B may be substantially similar to optical transposer waveguides 24 and their first and second ends 24A, 24B described elsewhere herein. In other respects, optical interconnect apparatus 110 may be substantially similar to optical interconnect apparatus 10 described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 110 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0136] Figure 3 is a side cross-sectional view of an optical interconnect apparatus 210 between the high density (small-pitch or tightly spaced) waveguides 12A of a PIC 12 and a plurality of relatively low density (large-pitch or large spacing) optical components 14 (in the illustrated example, the fibers 14 of a fiber array 14A) according to a particular embodiment. In many respects, optical interconnect apparatus 210 is similar to optical interconnectapparatus 1 10 described elsewhere herein and similar components are provided with similar reference numerals.

[0137] Optical interconnect apparatus 210 differs from optical interconnect apparatus 110 primarily in that optical connections 228 that provide the optical coupling between PIC waveguides 12A and the first ends 124 of optical transposer waveguides 124 are provided by a pair of lenses 228A, 228B. Lenses 228A, 228B may be fabricated in situ (e.g. after PIC 12 is mounted to substrate layer 116) by additive manufacturing and may be attached to the facets of one or both of a corresponding PIC waveguide 12A and a first end 124A of a corresponding transposer waveguide 124 for coupling optical energy in one or both directions therebetween. Lenses 22A, 228B may be referred to as facet-attached microlenses. In some embodiments, the pair of lenses 228A, 228B shown in the Figure 3 embodiment, can be replaced by a single lens which may provide sufficient coupling efficiency between PUC waveguides 12A and optical transposer waveguides 124. Lenses (or a lens) similar to lenses 228A, 228B may be used in addition to or in the alternative to photonic wire bonds in optical interconnect apparatus 10 or any of the other optical interconnect apparatus described herein. In other respects, optical interconnect apparatus 210 may be substantially similar to optical interconnect apparatus 110 described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 210 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0138] Figure 4 is a side cross-sectional view of an optical interconnect apparatus 310 between the high density (small-pitch or tightly spaced) waveguides 12A of a PIC 12 and a plurality of relatively low density (large-pitch or large spacing) optical components 314 (in the illustrated example, the fibers 314 of a fiber array 314A) according to a particular embodiment. In many respects, optical interconnect apparatus 310 is similar to optical interconnect apparatus 10 described elsewhere herein and similar components are provided with similar reference numerals.

[0139] Optical interconnect apparatus 310 differs from optical interconnect apparatus 10 primarily in that in that transposer body 326 of optical transposer 322 is integrally formed with fiber support 319. Other than being shaped to provide fiber support 319, optical transposer 322 and transposer body 326 may be substantially similar to optical transposer 22 and transposer body 26 described elsewhere herein. Transposer body 326 may befabricated from a transparent material such as quartz, glass and / or the like. Optical transposer waveguides 324 and their first and second ends 324A, 324B may be substantially similar to optical transposer waveguides 24 and their first and second ends 24A, 24B described elsewhere herein. Fibers 314, fiber array 314A and fiber portions 314B, 314C may be substantially similar to fibers 14, fiber array 14A and fiber portions 14B, 14C described elsewhere herein. In other respects, optical interconnect apparatus 310 may be substantially similar to optical interconnect apparatus 10 described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 310 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0140] Figures 5A and 5B (collectively and individually Figure 5) are a side cross-sectional view of an optical interconnect apparatus 410 between the high density (small-pitch or tightly spaced) waveguides 12A of a PIC 12 and a plurality of relatively low density (large- pitch or large spacing) optical components 14 (in the illustrated example, the fibers 14 of a fiber array 14A) and a partial side-cross-sectional view showing detail of the photonic wire bond connections 28A between the waveguides 12A of PIC 12 and the waveguides 424 optical transposer 422 according to a particular embodiment. In many respects, optical interconnect apparatus 410 is similar to optical interconnect apparatus 10 described elsewhere herein and similar components are provided with similar reference numerals.

[0141] Optical interconnect apparatus 410 differs from optical interconnect apparatus 10 primarily in that the x-y oriented (transverse) edges of PIC 12 and optical transposer 422 (in particular transposer body 426) abut against one another and a portion (e.g. a corner portion) of transposer body 426 is removed (e.g. by etching (chemical and / or physical) and / or some other suitable material removal process), or transposer body 426 is otherwise fabricated, to provide a recess 411 which exposes the first ends 424A of optical transposer waveguides 424 to provide space for fabrication and connection of optical connections 28 (e.g. photonic wire bonds 28A or facet attached microlenses). In some embodiments, recess 411 is a relatively shallow recess (in the y-direction), so that a portion of recessdefining surface 411 A can support a portion of photonic wire bonds 28A in the event that such photonic wire bonds 28A deform mechanically. The depth of recess 411 (in the y- direction) may be sufficient that the facets of PIC waveguides 12A are located above (in the y-direction) the height of the portion of recess-defining surface 411 A and are not blocked bythe abutting contact of optical transposer 422. In some embodiments, optical transposer 422 may be fabricated such that the first ends 424A of transposer waveguides 424 are located at or near to the height (i.e. y-direction distance from substrate layer 16) of PIC waveguides 12A. This is not necessary. In some embodiments, the first ends 424A of transposer waveguides 424 may be located at different heights (i.e. y-direction distances from substrate layer 16) than PIC waveguides 12A. Other than being shaped to provide recess 411 , optical transposer 422 and transposer body 426 may be substantially similar to optical transposer 22 and transposer body 26 described elsewhere herein. Other than their first ends 424A being exposed by recess 411 , optical transposer waveguides 424 and their first and second ends 424A, 424B may be substantially similar to optical transposer waveguides 24 and their first and second ends 24A, 24B described elsewhere herein. In other respects, optical interconnect apparatus 410 may be substantially similar to optical interconnect apparatus 10 described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 410 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0142] Figure 6 is a side cross-sectional view of an optical interconnect apparatus 510 between the high density (small-pitch or tightly spaced) waveguides 512A of a PIC 512 and a plurality of relatively low density (large-pitch or large spacing) optical components 14 (in the illustrated example, the fibers 14 of a fiber array 14A) according to a particular embodiment. In many respects, optical interconnect apparatus 510 is similar to optical interconnect apparatus 110 described elsewhere herein and similar components are provided with similar reference numerals.

[0143] Optical interconnect apparatus 510 differs from optical interconnect apparatus 110 primarily in that PIC 512 is located underneath (in the y-direction relative to) EIC 18. EIC 18 and PIC 512 in the Figure 6 embodiment, may be electrically connected (to share electrical signals) by vias 520 which may extend into or through substrate layer 16 and / or PIC 516 and which may be filled or otherwise contain electrically conductive material (e.g. metal) 520A. In some embodiments, PIC 512 could be located on top of EIC 18 and similar vias 520 with conductive materials 520A could be used to communicate electrical signals between EIC 18 and PIC 512. PIC waveguides 512A may be substantially similar to PIUC waveguides 12A described elsewhere herein. In other respects, optical interconnectapparatus 510 may be substantially similar to optical interconnect apparatus 110 described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 510 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0144] Figure 7 is a side cross-sectional view of an optical interconnect apparatus 610 between the high density (small-pitch or tightly spaced) waveguides 612A of a PIC 612 and a plurality of relatively low density (large-pitch or large spacing) optical components 14 (in the illustrated example, the fibers 14 of a fiber array 14A) according to a particular embodiment. In many respects, optical interconnect apparatus 610 is similar to optical interconnect apparatus 510 described elsewhere herein and similar components are provided with similar reference numerals.

[0145] Optical interconnect apparatus 610 differs from optical interconnect apparatus 510 primarily in that a portion (e.g. a corner portion) of PIC 612 is removed (e.g. by etching (chemical and / or physical) and / or some other suitable material removal process), or PIC 612 is otherwise fabricated, to provide a recess 613 under PIC waveguides 612A and / or between PIC waveguides 612A and substrate layer 116 and / or between PIC waveguides 612A and transposer body 126. Relative to the PICs in other embodiments, providing recess 613 may reduce thermal conductivity between substrate layer 116 and optical connections 28 (e.g. photonic wire bonds 28A or facet-attached micro-lenses), especially when standard solder reflow techniques are used to mount substrate layer 116 to an additional support / board (not shown) below. PIC waveguides 612A may be substantially similar to PIUC waveguides 12A described elsewhere herein. In other respects, optical interconnect apparatus 610 may be substantially similar to optical interconnect apparatus 510 described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 610 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0146] Figure 8 is a partial side cross-sectional view of an optical interconnect apparatus 710 between the high density (small-pitch or tightly spaced) waveguides 712A on different layers 715A, 715B of a multi-layer PIC 712 and a plurality of relatively low density (large- pitch or large spacing) optical components 714 (in the illustrated example, the fibers 714 on multiple layers 717A, 717B, 717C of a multi-layer fiber array 714A) on different layersaccording to a particular embodiment. In many respects, optical interconnect apparatus 710 is similar to the other optical interconnect apparatus described elsewhere herein.

[0147] Optical interconnect apparatus 710 differs from the other optical interconnect apparatus described herein primarily in that optical interconnect apparatus 710 comprises an optical transposer 722 that provides curved or otherwise routed transposer waveguides 724 that provide a fan-out or pitch spread in the y-direction (toward or away from the substrate layer (not shown in Figure 8)) within optical transposer body 726. Such y-direction pitch spread may be in addition to or in the alternative to the x-direction pitch spread of the previously described embodiments. In the particular case of the Figure 8 embodiment, optical transposer waveguides 724 are located on several y-direction layers 719A, 719B, 719C and comprise first ends 724A having a relatively small y-direction pitch (center-to- center spacing between adjacent waveguides 724A) and waveguides 724 may be curved or otherwise routed (e.g. by positioning waveguides adjacent to one another to facilitate energy transfer between adjacent waveguides) to provide second ends 724B that have a relatively large y-direction pitch. Optical transposer waveguides 724 may have similar fanout (pitch spreading curvature or routing in the x-direction) although this is not explicitly shown in the Figure 8 view. Second ends 724B may be optically coupled to fibers 714 of a multi-layer fiber array 714 which, in the illustrated Figure 8 embodiment, comprises y- direction layers 717A, 717B, 717C supported by fiber support 719. Second ends 724B of optical transposer waveguides 724 may have a y-direction pitch that allows butt connections to fibers 714. Fiber array 714A may also have multiple fibers 714 spanning an x-direction dimension, although this is not expressly visible in the Figure 8 view. The illustrated embodiment of Figure 8 also shows how it is possible to provide optical connections 728 (e.g. photonic wire bonds 728A and / or facet-attached micro-lenses) that connect a single PIC waveguide 712A to multiple optical transposer waveguides 724.

[0148] Other than having waveguides 712A arranged on multiple y-direction layers 715A, 715B, PIC 712 and PIC waveguides 712A may be substantially similar to any of the other PICs and PIC waveguides described herein. Optical connections 728 may be similar to any of the other optical connections described herein. Other than the y-direction curvature (or y- direction pitch-spread routing) or multi-directional (x- and y-direction) curvature (or x- and y- direction pitch-spread routing) of optical transposer waveguides 724 may be substantially similar to other optical transposer waveguides described herein. Other than having fibers714 arranged on multiple y-direction layers 717A, 717B,717C, fiber support 719, fiber array 714A and fibers 714 may be similar to the other fiber supports, fiber arrays and fibers described herein. In other respects, optical interconnect apparatus 710 may be similar to other optical interconnect apparatus described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 710 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0149] Figure 9 is a partial side cross-sectional view of an optical interconnect apparatus 810 between a plurality of PIC waveguides 812A on a PIC 812 having surface couplers 821 to the edge facet of the first ends 24A of optical transposer fibers 24 on an optical transposer 22 according to a particular embodiment. In many respects, optical interconnect apparatus 810 is similar to the other optical interconnect apparatus described elsewhere herein.

[0150] Optical interconnect apparatus 810 differs from the other optical interconnect apparatus described herein primarily in that PIC 812 provides waveguides having surface couplers 821 . Surface couplers 821 may comprise grating couplers, mirrors and / or the like. Surface couplers 821 may comprise evanescent couplers. Optical connections 828, which may be fabricated using additive manufacturing, provide optical connection between edge facets on the first ends 24A of optical transposer waveguides 24 and surface couplers 821 . Optical connections 828 may comprise photonic wire bonds 828A and / or microlenses. In the particular case of the Figure 9 embodiment, optical transposer 22 (e.g. transposer body 26) abuts against PIC 812, although this is not necessary. In some embodiments, optical transposer 22 may be fabricated so that the y-direction height of first ends 24A or optical transposer waveguides 24 is the same or close to (e.g. just above) the y-direction height of surface couplers 821 and the x-z surface of PIC 812 such that the x-z surface of PCI 812 can provide mechanical support for photonic wire bond 828A. In other respects, optical interconnect apparatus 810 and the components of the Figure 9 embodiment may be similar to the other optical interconnect apparatus and the components of the other embodiments described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 810 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0151] Figures 10A and 10B are respectively exploded and assembled side cross-sectional views of an optical interconnect apparatus 910 between the high density (small-pitch or tightly spaced) waveguides 912A of a PIC 912 and a plurality of relatively low density (large- pitch or large spacing) optical components 914 (in the illustrated example, the fibers 914 of a fiber array 914A) according to a particular embodiment. In many respects, optical interconnect apparatus 910 is similar to optical interconnect apparatus 10 described elsewhere herein and similar components are provided with similar reference numerals.

[0152] Optical interconnect apparatus 810 differs from optical interconnect apparatus 10 primarily in that optical interconnect apparatus 810 comprises a sub-mount (e.g. a heat spreader which may comprise a heat-conducting material (e.g. copper)) 923 on which other components (e.g. EIC 18, PIC 912, optical transposer 922 and / or fiber support 919 may be mounted (e.g. using a bonding agent, which may comprise a heat conductive adhesive, heat conductive bonding agent, metalization and / or the like) prior to connecting such components to substrate layer 16 using a “flip chip” mounting / packaging technique. As is known in the art of semiconductor chip manufacturing a “flip chip” mounting / packaging technique (also referred to flip chip die bonding) is a technique where the active side of the chip (in this case the active sides EIC 18, PIC 912, optical transposer and / or fiber support 919) is / are “flipped” to face downward (in the negative y-direction) bonded to a substrate (e.g. substrate layer 16), typically using solder bumps or other conductive adhesives. Submount 923, which may comprise a heat spreader, may in turn be connected to a heat sink (not shown in Figure 10) which may be physically configured (e.g. with large surface area and suitable material construction) or otherwise configured to dissipate heat. In the illustrated Figure 10 embodiment, the PIC waveguides 912A and optical transposer waveguides 924 are fabricated on the opposite (y-direction) side of PIC 912 and optical transposer body 926 (i.e. closer to substrate layer 16) than in the other embodiments, although this is not necessary. Similarly, optical connections 928 (e.g. photonic wire bonds 928A or microlenses) may be fabricated in situ prior to mounting on substrate layer 16 by additive manufacturing on a (y-direction) side relatively close to where substrate layer 16 will be located after mounting (when compared to other embodiments described herein), although this is not necessary. Similarly, fibers 914 of fiber array 914A are located in fiber mount 919 on a (y-direction) side relatively close to where substrate layer 16 will be located after mounting (when compared to other embodiments described herein), although this isnot necessary. In other respects, optical interconnect apparatus 910 and the components of the Figure 10 embodiment may be similar to the other optical interconnect apparatus and the components of the other embodiments described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 910 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0153] Figures 11A and 1 1 B (collectively and individually Figure 11 ) show exploded and assembled side-cross-sectional schematic views of an optical interconnect apparatus 1010 according to a particular embodiment. Optical interconnect apparatus 1010 provides an optical data connection between high density waveguides 1012A of PIC 1012 and relatively low density optical components (not shown in Figure 11 ). In some embodiments, PIC waveguides 1012A may have a pitch (center-to-center spacing between adjacent waveguides 1012A) on the order of 20pm or less. In some embodiments, this PIC waveguide pitch may be on the order of 10pm or less or 5pm or less. In some embodiments, the low-density optical components 14 may have a pitch on the order of 100pm or greater (e.g. 127pm or greater or 250pm or greater). In the particular case of the Figure 11 embodiment, these pitch-spacings are one-dimensional spacings in the x- direction (see Cartesian axes illustrated in Figure 11 ). In other embodiments, these pitchspacings may be in each of two-dimensions (e.g. in the x- and y-directions).

[0154] Optical interconnect apparatus 1010 comprises an optical transposer 1022 (also referred to as a fan-out 1022 or fan-out component 1022) which, in the illustrated embodiment, comprises a number of curved waveguides 1024 (only one of which is visible in the Figure 11 views) fabricated or otherwise located within (and / or on a surface of) a transposer body 1026. As with the other optical transposer waveguides described herein, optical transposer waveguides 1024 comprise first ends 1024A having a relatively small pitch (center-to-center spacing between adjacent waveguides 1024) and waveguides 1024 may be curved or otherwise routed with pitch-spread routing to provide second ends 1024B that have a relatively large pitch (e.g. for connection to larger pitch optical components - not shown in the Figure 11 views). Optical transposer waveguides 1024 are curved or otherwise routed in a “fan-out” configuration where the second ends 1024B of waveguides 1024 have an x-dimension pitch that is greater than that of first ends 1024A. This larger x-dimension pitch enables the second ends 1024B of optical transposer waveguides 1024 to interfacewith other optical components for which a large pitch is desirable (e.g. fiber arrays, one or more multicore fibers, multi-fiber connectors, lasers, LEDs, photodetectors and / or the like). In the illustrated embodiment of Figure 1 , the “fan-out” curvature or configuration of optical transposer waveguides 24 provides a one-dimensional (x-direction) increase in the pitch between first ends 24A and second ends 24B. In other embodiments, this one-dimensional increase in pitch can be in a different direction (e.g. in the y-direction) or the increase in pitch can be in two-dimensions (e.g. in the x-direction and in the y-direction). In addition to the “fan-out” curvature or pitch-spread routing of optical transposer waveguides 1024, the cross-sectional dimensions (e.g. diameter) of optical transposer waveguides 1024 may change along the length (e.g. between first ends 1024A and second ends 1024B) of optical transposer waveguides 1024 to “match” the mode field of the optical components to which second ends 1024B are optically coupled.

[0155] Transposer body 1026 and transposer waveguides 1024 may be fabricated from materials and using processes similar to other embodiments described herein. Trenches 1025A, 1025B may be respectively formed in PIC 1012 and transposer body 1026 (e.g. by chemical etching, physical etching or some other material removal process) to provide space for in situ fabrication of lenses 1028A, 1028B.

[0156] Optical interconnect apparatus 1010 also comprises optical connections 1028 which connect optical energy in one or both directions between PIC waveguides 1012A and the first ends 1024A of optical transposer waveguides 1024. In currently preferred embodiments, optical connections 1028 are fabricated in situ by way of additive manufacturing (e.g. two-photon lithography, 3D printing and / or the like). In the case of the illustrated embodiment of Figure 11 , optical connections 1028 comprise pairs of lenses 1028A, 1028B fabricated in situ by additive manufacturing. Lens 1028A attaches to a facet of a corresponding PIC waveguide 1012A and lens 1028B attaches to a facet of corresponding transposer waveguide 1024 for coupling optical energy in one or both directions between the corresponding PIC waveguide 1012A and the corresponding transposer waveguide 1024. In the illustrated Figure 11 embodiment, lenses 1028A, 1028B are shaped to provide total internal reflection (TIR) which changes the direction of light between the z-directions of waveguides 1012A, 1024 and the y-direction in the illustrated view.

[0157] In the Figure 11 embodiment, complementary-shaped alignment structures 1027A, 1027B are fabricated on or otherwise formed in or on PIC 1012A and body 1026 of optical transposer 1022 to help with the alignment and spacing of the components of optical interconnect apparatus 1010. In the case of Figure 11 embodiment a protruding (e.g. male) alignment structure 1027A is fabricated (e.g. by additive manufacturing using polymer or other suitable material) on PIC 1012 and a complementary recess (female) alignment structure 1027B is fabricated (e.g. by chemical etching, physical etching or other lithographic material removal technique) in transposer body 1026 of optical transposer 1022. As can be seen from Figures 11 A and 11 B, when optical interconnect apparatus 1010 is assembled, protrusion alignment structure 1027A projects into complementary shaped recess alignment structure 1027B to help align the other components of optical interconnect apparatus 1010, including, without limitation, the coupling interfaces (e.g. facets or other coupling interfaces) of waveguides 1012A of PIC 1012 and waveguides 1024 of optical transposer 1022. When protrusion alignment structure 1027A projects into complementary shaped recess alignment structure 1027B, the surfaces of alignment structures 1027A, 1207B may be shaped to provide a contact fit with one another to help align the other components of optical interconnect apparatus 1010. Because of the aligning functionality of complementary alignment structures 1027A, 1027B, stringent alignment requirements of traditional flip chip bonding waveguide coupling between waveguides can be relaxed, when comparted to prior art techniques.

[0158] It will be appreciated that one pair of complementary alignment structures 1027A, 1027B is shown in the Figure 11 embodiment, but that alignment could be further improved with a plurality of complementary pairs of alignment structures which may be similar to those shown in Figure 1 1 . It will also be appreciated that the locations of the complementary protrusion and recess alignment structures 1027A, 1027B could be reversed - i.e. protruding alignment component 1027A could be provided on optical transposer 1022 and recess alignment component 1027B could be provided on PIC 1012. Although not expressly shown in Figure 11 , in the region of recess alignment structure 1027B it may be desirable to reroute optical transposer waveguides (e.g. in the x-direction (into and / or out of the page in the Figure 12 view) to avoid the area of recess alignment component 1027B.

[0159] In other respects, optical interconnect apparatus 1010 may be similar to any of the other optical interconnect apparatus described herein. Unless the context clearly dictatesotherwise, any of the features of optical interconnect apparatus 1010 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0160] Figures 12A and 12B (collectively and individually Figure 12) show exploded and assembled side-cross-sectional schematic views of an optical interconnect apparatus 1110 according to a particular embodiment. In many respects, optical interconnect apparatus 1110 is similar to optical interconnect apparatus 1010 described elsewhere herein and similar components are provided with similar reference numerals.

[0161] Optical interconnect apparatus 1110 differs from optical interconnect apparatus 1010 primarily in that optical interconnect apparatus 1110 comprises different alignment structures than optical interconnect apparatus 1010. In particular, a first (e.g. male) protruding alignment structure 1129 is fabricated (e.g. by additive manufacturing of polymer or other suitable material) on optical transposer 1022 and a second one or more protruding alignment structures 1131 is / are fabricated (e.g. by additive manufacturing of polymer or other suitable material) on PIC 1012. In the case of the illustrated Figure 12 embodiment, the one or more protruding alignment structures 1131 are shaped to define an alignment recess 1133 (i.e. female alignment structure) that is complimentary to alignment structure 1129. As can be seen from Figures 12A and 12B, when optical interconnect apparatus 1110 is assembled, protrusion structure 1129 projects into complementary shaped recess structure 1133 defined by protrusion structure 1131 to help align the other components of optical interconnect apparatus 1110. When protrusion alignment structure 1129 projects into complementary shaped recess structure 1133 defined by protrusion structure 1131 , the surfaces of alignment structures 1129, 1131 may be shaped to provide a contact fit with one another to help align the other components of optical interconnect apparatus 1110.Advantageously, the alignment structures of the Figure 12 embodiment can be fabricated without etching either of PIC 1012 or optical transposer 1022 and, further, do not require rerouting of transposer waveguides 1024 in transverse directions (which can save surface area and corresponding device size). It will be appreciated that one pair of complementary alignment structures 1129, 1133 is shown in the Figure 12 embodiment, but that alignment could be further improved with a plurality of complementary pairs of alignment structures which may be similar to those shown in Figure 12. It will also be appreciated that the locations of the complementary protrusion and recess alignment structures 1129, 1131could be reversed - i.e. protruding alignment component 1129 could be provided on PIC 1012 and recess alignment component 1133 could be provided on optical transposer 1022.

[0162] In other respects, optical interconnect apparatus 1110 may be similar to optical interconnect apparatus 1010 and / or any of the other optical interconnect apparatus described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 1110 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0163] Figures 13A and 13B (collectively and individually Figure 13) show exploded and assembled side-cross-sectional schematic views of an optical interconnect apparatus 1210 according to a particular embodiment. In many respects, optical interconnect apparatus 1210 is similar to optical interconnect apparatus 1010 described elsewhere herein and similar components are provided with similar reference numerals.

[0164] Optical interconnect apparatus 1210 differs from optical interconnect apparatus 1010 primarily in that PIC waveguides 1212A and optical transposer waveguides 1224 are respectively provided with surface emitting devices 1235A, 1235B (e.g. grating couplers, mirrors and / or the like) which direct optical energy in the y-direction (out of the plane of these waveguides 1212A, 1224). The combination of these surface emitting devices 1235A, 1235B with additive-manufacturing based lenses 1228A (on PIC 1012) and 1228B (on optical transposer 1022) provide optical connections between PIC waveguides 1212A and optical transposer waveguides 1224. Advantageously, lenses 1228A, 1228B can be fabricated using additive manufacturing techniques without having to etch trenches (like trenches 1025A, 1025B of the Figure 11 embodiment).

[0165] In other respects, optical interconnect apparatus 1210 may be similar to optical interconnect apparatus 1010 and / or any of the other optical interconnect apparatus described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 1210 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.

[0166] Figures 14A and 14B (collectively and individually Figure 14) show exploded and assembled side-cross-sectional views of an optical interconnect apparatus 1310 between the high density (small-pitch or tightly spaced) waveguides 1312A (not expressly shown) of a PIC 1312 and a plurality of relatively low density (large-pitch or large spacing) opticalcomponents 1314 (in the illustrated example, the fibers 1314 of a fiber array 1314A) according to a particular embodiment. In many respects, optical interconnect apparatus 1310 is similar to other optical interconnect apparatus described elsewhere herein and similar components are provided with similar reference numerals. In particular, optical interconnect apparatus 1310 combines a number of features of some of the other optical interconnect apparatus described herein to provide a removably “pluggable” optical transposer 1322 which includes a optical fiber array 1314A and external optical connector 20.

[0167] Optical interconnect apparatus 1310 comprises complementary alignment structures 1335A, 1135B, which, in the illustrated embodiment, comprise recess alignment structures 1335A fabricated in PIC 1312 and complementary protruding alignment structures 1335B fabricated on optical transposer 1322. PIC waveguides 1312A may comprise surface emitting devices (e.g. grating couplers, mirrors and / or the like - not expressly shown in Figure 13) which direct optical energy in the y-direction (out of the plane of PIC waveguides 1312A. These surface emitting devices in combination with additive manufacturing based lenses (not expressly shown in Figure 14) which may include lenses mounted on the x-z surface of PIC 1312 and lenses attached to the facets of optical transposer waveguides 1324 provide the optical connections between the waveguides 1312A, 1324 of PIC 1312 and optical transposer 1322 and eventually to fibers 1314 of fiber array 1314A. In part due to the alignment provided by complementary alignment structures 1335A, 1335B, such lenses may be prefabricated on their respective surfaces to facilitate the removably pluggable nature of optical transposer 1322. The removably pluggable nature of optical transposer 1322 and PIC 1312 is not necessary. Adhesive could be provided on the surfaces of alignment structures 1335, 1335B to more permanently physically attach optical transposer 1322 to PIC 1312.

[0168] In other respects, optical interconnect apparatus 1310 may be similar to any of the other optical interconnect apparatus described herein. Unless the context clearly dictates otherwise, any of the features of optical interconnect apparatus 1310 may be combined with, or substituted for, features of the other optical interconnection apparatus described herein and vice versa.Interpretation of Terms

[0169] Unless the context clearly requires otherwise, throughout the description and the claims:• “comprise”, “comprising”, and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”;• “connected”, “coupled”, or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof;• “herein”, “above”, “below”, and words of similar import, when used to describe this specification, shall refer to this specification as a whole, and not to any particular portions of this specification;• “or”, in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list;• the singular forms “a”, “an”, and “the” also include the meaning of any appropriate plural forms. These terms (“a”, “an”, and “the”) mean one or more unless stated otherwise;• “and / or” is used to indicate one or both stated cases may occur, for example A and / or B includes both (A and B) and (A or B);• “approximately” when applied to a numerical value means the numerical value ±10%;• where a feature is described as being “optional” or “optionally” present or described as being present “in some embodiments” it is intended that the present disclosure encompasses embodiments where that feature is present and other embodiments where that feature is not necessarily present and other embodiments where that feature is excluded. Further, where any combination of features is described in this application this statement is intended to serve as antecedent basis for the use of exclusive terminology such as "solely," "only" and the like in relation to the combination of features as well as the use of "negative" limitation(s)” to exclude the presence of other features; and• “first” and “second” are used for descriptive purposes and cannot be understood as indicating or implying relative importance or indicating the number of indicated technical features.

[0170] Words that indicate directions such as “vertical”, “transverse”, “horizontal”, “upward”, “downward”, “forward”, “backward”, “inward”, “outward”, “left”, “right”, “front”, “back”, “top”, “bottom”, “below”, “above”, “under”, and the like, used in this description and any accompanying claims (where present), depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms are not strictly defined and should not be interpreted narrowly.

[0171] Where a range for a value is stated, the stated range includes all sub-ranges of the range. It is intended that the statement of a range supports the value being at an endpoint of the range as well as at any intervening value to the tenth of the unit of the lower limit of the range, as well as any subrange or sets of sub ranges of the range unless the context clearly dictates otherwise or any portion(s) of the stated range is specifically excluded. Where the stated range includes one or both endpoints of the range, ranges excluding either or both of those included endpoints are also included in the invention.

[0172] Certain numerical values described herein are preceded by "about". In this context, "about" provides literal support for the exact numerical value that it precedes, the exact numerical value ±5%, as well as all other numerical values that are near to or approximately equal to that numerical value. Unless otherwise indicated a particular numerical value is included in “about” a specifically recited numerical value where the particular numerical value provides the substantial equivalent of the specifically recited numerical value in the context in which the specifically recited numerical value is presented. For example, a statement that something has the numerical value of “about 10” is to be interpreted as: the set of statements:• in some embodiments the numerical value is 10;• in some embodiments the numerical value is in the range of 9.5 to 10.5; and if from the context the person of ordinary skill in the art would understand that values within a certain range are substantially equivalent to 10 because the values with the rangewould be understood to provide substantially the same result as the value 10 then “about 10” also includes:• in some embodiments the numerical value is in the range of C to D where C and D are respectively lower and upper endpoints of the range that encompasses all of those values that provide a substantial equivalent to the value 10

[0173] Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions, and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and / or acts with equivalent features, elements and / or acts; mixing and matching of features, elements and / or acts from different embodiments; combining features, elements and / or acts from embodiments as described herein with features, elements and / or acts of other technology; and / or omitting combining features, elements and / or acts from described embodiments.

[0174] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any other described embodiment(s) without departing from the scope of the present invention.

[0175] Any aspects described above in reference to apparatus may also apply to methods and vice versa.

[0176] Any recited method can be carried out in the order of events recited or in any other order which is logically possible. For example, while processes or blocks are presented in a given order, alternative examples may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified to provide alternative or subcombinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, simultaneously or at different times.

[0177] Various features are described herein as being present in “some embodiments”. Such features are not mandatory and may not be present in all embodiments. Embodiments of the invention may include zero, any one or any combination of two or more of such features. All possible combinations of such features are contemplated by this disclosure even where such features are shown in different drawings and / or described in different sections or paragraphs. This is limited only to the extent that certain ones of such features are incompatible with other ones of such features in the sense that it would be impossible for a person of ordinary skill in the art to construct a practical embodiment that combines such incompatible features. Consequently, the description that “some embodiments” possess feature A and “some embodiments” possess feature B should be interpreted as an express indication that the inventors also contemplate embodiments which combine features A and B (unless the description states otherwise or features A and B are fundamentally incompatible).This is the case even if features A and B are illustrated in different drawings and / or mentioned in different paragraphs, sections or sentences.

[0178] It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions, and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims

CLAIMS:1 . An optical interconnection apparatus for optical connection between a plurality of photonic integrated circuit (PIC) waveguides on a PIC and a plurality of optical components spaced apart from the PIC, the optical interconnection apparatus comprising: an optical transposer comprising a plurality of optical transposer waveguides wherein the plurality of optical transposer waveguides comprise a fan-out configuration wherein: first ends of the optical transposer waveguides have a first end spacing between adjacent pairs of the first ends of the optical transposer waveguides; second ends of the optical transposer waveguides, opposite to the first ends, have a second end spacing between adjacent pairs of the second ends of the optical transposer waveguides; and the first end spacing is less than the second end spacing; optical connections between the PIC waveguides and the first ends of the optical transposer waveguides, each optical connection between a PIC waveguide and the first end of a corresponding optical transposer waveguide provided by one or more optical components fabricated using additive manufacturing.

2. The apparatus of claim 1 or any other claim herein wherein, for each optical connection, the one or more optical components comprise a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween, the photonic waveguide fabricated by additive manufacturing.

3. The apparatus of claim 2 or any other claim herein wherein the photonic wire bond is attached between a facet of the PIC waveguide and a facet of the first end of the optical transposer waveguide.

4. The apparatus of any one of claims 2 to 3 or any other claim herein wherein the photonic wire bond is fabricated from polymer.

5. The apparatus of claim 1 or any other claim herein wherein, for each optical connection, the one or more optical components comprise at least one lens between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween, the at least one lens fabricated by additive manufacturing.

6. The apparatus of claim 1 or any other claim herein wherein, for each optical connection, the one or more optical components comprise a pair of lenses between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween, the pair of lenses fabricated by additive manufacturing.

7. The apparatus of claim 6 or any other claim herein wherein one of the pair of lenses is attached to a facet of the PIC waveguide and the other one of the pair of lenses is attached to a facet of the first one of the corresponding optical transposer waveguide.

8. The apparatus of any one of claims 5 to 7 or any other claim herein wherein each lens is fabricated from polymer.

9. The apparatus of any one of claims 1 to 8 or any other claim herein wherein: the PIC comprises a first alignment structure having one of: a protruding shape and a complementary recess-defining shape; the optical transposer comprises a second alignment structure having the other one of: the protruding shape and the complementary recess-defining shape; and the first alignment structure and the second alignment structure are engaged with one another such that the protruding shape protrudes into a complementary recess defined by the complementary recess-defining shape to thereby align the optical transposer to the PIC.

10. The apparatus of claim 9 or any other claim herein wherein surfaces of the first and second alignment structures form a contact fit when the protruding shape protrudes into the complementary recess defined by the complementary recess-defining shape.11 . The apparatus of any one of claims 9 to 10 or any other claim herein wherein at least one of the first and second alignment structures is fabricated by additive manufacturing.

12. The apparatus of any one of claims 9 to 11 or any other claim herein wherein at least one of the first and second alignment structures is fabricated by an etching process.

13. The apparatus of any one of claims 1 to 12 or any other claim herein wherein the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides is dimensioned to match at least one of: a pitch between fibers of a fiber array, a pitch between cores of a multicore fiber and a pitch between optical connections of an optical connector (e.g. for butt connection).

14. The apparatus of any one of claims 1 to 13 or any other claim herein wherein each PIC waveguide comprises an edge-coupling optical interface (e.g. a facet) on an edge of the PIC (e.g. a vertical edge of the PIC) and wherein each optical connection is shaped, located and / or fabricated from suitable material(s) to direct light into or receive light from the optical interface.

15. The apparatus of any one of claims 1 to 13 or any other claim herein wherein each PIC waveguide comprises a surface-coupling optical interface (e.g. a grating or mirror) to direct optical energy through, either to or from, a surface of the PIC (e.g. a horizontal surface of the PIC) and wherein each optical connection is shaped, located and / or fabricated from suitable material(s) to direct light into or receive light from the optical interface.

16. The apparatus of any one of claims 1 to 13 or any other claim herein wherein each optical connection is shaped, located and / or shaped, located and / or fabricated from suitable material(s) to direct light into or receive light from the PIC waveguide by evanescent coupling.

17. The apparatus of any one of claims 1 to 16 or any other claim herein wherein the optical transposer comprises a body made up of one or more of: glass, polymer, plastic, silicon and silicon nitride.

18. The apparatus of claim 17 or any other claim herein wherein the optical transposer waveguides are fabricated in the body by one or more of: ion-exchange which changes the crystal structure of the body in the region of the optical transposer waveguides and laser inscription which changes the crystal structure of the body in the region of the optical transposer waveguides.

19. The apparatus of any one of claims 17 to 18 or any other claim herein wherein the optical transposer waveguides are located on a surface of the body.

20. The apparatus of any one of claims 17 to 18 or any other claim herein wherein the optical transposer waveguides are located within the body.21 . The apparatus of any one of claims 1 to 16 or any other claim herein wherein the optical transposer comprises a substrate body and the optical transposer waveguides are fabricated on the substrate by melting and drawing optical fibers.

22. The apparatus of any one of claims 1 to 21 or any other claim herein wherein the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides is a spacing in a single dimension.

23. The apparatus of claim 22 or any other claim herein wherein the spacing in the single dimension is in a horizontal direction.

24. The apparatus of claim 22 or any other claim herein wherein the spacing in the single dimension is in a vertical direction.

25. The apparatus of any one of claims 1 to 21 or any other claim herein wherein the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides is a spacing in two orthogonal dimensions.

26. The apparatus of claim 25 or any other claim herein wherein the two orthogonal dimensions are in a vertical direction and a horizontal direction.

27. The apparatus of any one of claims 1 to 26 or any other claim herein wherein the PIC is electrically connected to exchange electronic signals with an electrical integrated circuit (EIC).

28. The apparatus of claim 27 or any other claim herein wherein electrical connections between the PIC and the EIC are provided at least in part by conductors that extend through vias in a substrate layer (e.g. transposer layer).

29. The apparatus of claim 28 or any other claim herein wherein the substrate layer is made up of one or more of: glass, polymer, plastic, silicon and silicon nitride.

30. The apparatus of any one of clams 28 to 29 or any other claim herein wherein the EIC, the PIC and the optical transposer are mounted on the substrate layer.31 . The apparatus of claim 30 or any other claim herein wherein the EIC and / or the PIC are mounted to the substrate layer by ball grid array soldering.

32. The apparatus of any one of claims 30 to 31 or any other claim herein wherein the optical transposer is bonded to the substrate layer - e.g. using metal soldering, adhesive and / or fasteners.

33. The apparatus of any one of clams 28 to 29 or any other claim herein wherein the substrate layer and the optical transposer are integrally formed.

34. The apparatus of any one of claims 27 to 29 and 33 or any other claim herein wherein the EIC is mounted atop the PIC or underneath the PIC.

35. The apparatus of claim 34 or any other claim herein wherein electrical connections between the PIC and the EIC are provided at least in part by conductors that extend through vias in the PIC.

36. The apparatus of any one of claims 27 to 29 and 33 or any other claim herein wherein the PIC and the optical transposer are spaced apart from one another.

37. The apparatus of any one of claims 27 to 29 and 33 or any other claim herein wherein the PIC and the optical transposer are in abutting contact with one another.

38. The apparatus of claim 37 or any other claim herein wherein the optical transposer is shaped to define a recess, the recess shaped to expose facets of the optical transposer waveguides in a recess-defining surface (e.g. a vertical or edge recessdefining surface) that is spaced apart from the abutting contact with the PIC.

39. The apparatus of claim 38 or any other claim herein where the recess is formed by chemical or physical etching.

40. The apparatus of any one of claims 37 to 38 or any other claim herein wherein: for each optical connection, the one or more optical components comprise a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween, the photonic waveguide fabricated by additive manufacturing; and a portion of the recess-defining surface is located to support the photonic wire bond.41 . The apparatus of any one of claims 28 to 40 or any other claim herein where a body of the PIC is shaped to provide a recess that is located adjacent to the optical connections and between the PIC waveguides and the substrate.

42. The apparatus of claim 41 or any other claim herein wherein the recess is fabricated by chemical or physical etching.

43. The apparatus of any one of claims 1 to 42 or any other claim herein wherein the plurality of optical components comprise a plurality of fibers in a fiber array.

44. The apparatus of clam 43 or any other claim herein wherein at least portions of the plurality of fibers that are closest to the optical transposer are supported by a fiber support body.

45. The apparatus of claim 44 or any other claim herein wherein the fiber support body is shaped (e.g. by micromachining) to provide a plurality of grooves and each portion of a corresponding one of the plurality of fibers is located in a corresponding one of the plurality of grooves.

46. The apparatus of any one of claims 44 to 45 or any other claim herein wherein the optical transposer and the fiber support body are attached to one another (e.g. by suitable adhesion techniques or by welding).

47. The apparatus of any one of claims 44 to 45 or any other claim herein wherein the optical transposer and the fiber support body are integrally formed with one another.

48. The apparatus of any one of claims 44 to 47 or any other claim herein wherein the fiber support body is fabricated from a transparent material (e.g. quartz or glass).

49. The apparatus of any one of claims 28 to 42 or any other claim herein wherein the PIC, the EIC and the optical transposer are bonded to a sub-mount during fabrication and are subsequently flip-chip mounted to the substrate.

50. The apparatus of claim 49 or any other claim herein wherein the sub-mount comprises a heat spreader (e.g. copper, other metal or metal alloy with high thermal conductivity).51 . The apparatus of claim 50 or any other claim herein wherein the heat spreader comprises or is thermally coupled to a heat sink.

52. The apparatus of any one of claims 49 to 51 or any other claim herein wherein the PIC, the EIC and the optical transposer are bonded to the sub-mount using thermally conductive adhesive or metalization.

53. The apparatus of any one of claims 1 to 52 or any other claim herein wherein the first end spacing is less than 20pm.

54. The apparatus of any one of claims 1 to 53 or any other claim herein wherein the second end spacing is greater than 100pm or greater than 200pm.

55. A method for optically connecting a plurality of photonic integrated circuit (PIC) waveguides on a PIC and a plurality of optical components spaced apart from the PIC, the method comprising: providing an optical transposer comprising a plurality of optical transposer waveguides wherein the plurality of optical transposer waveguides comprise a fanout configuration wherein: first ends of the optical transposer waveguides have a first end spacing between adjacent pairs of the first ends of the optical transposer waveguides; second ends of the optical transposer waveguides, opposite to the first ends, have a second end spacing between adjacent pairs of the second ends of the optical transposer waveguides; and the first end spacing is less than the second end spacing; fabricating optical connections between the PIC waveguides and the first ends of the optical transposer waveguides, wherein fabricating each optical connection between a PIC waveguide and the first end of a corresponding optical transposer waveguide comprises fabricating one or more optical components using additive manufacturing.

56. The method of claim 55 or any other claim herein wherein, for each optical connection, the one or more optical components comprise a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween.

57. The method of claim 56 or any other claim herein comprising attaching the photonic wire bond between a facet of the PIC waveguide and a facet of the first end of the optical transposer waveguide.

58. The method of any one of claims 56 to 57 or any other claim herein wherein the photonic wire bond is fabricated from polymer.

59. The method of claim 55 or any other claim herein wherein, for each optical connection, the one or more optical components comprise at least one lens between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween.

60. The method of claim 55 or any other claim herein wherein, for each optical connection, the one or more optical components comprise a pair of lenses between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween.61 . The method of claim 60 or any other claim herein comprising attaching one of the pair of lenses to a facet of the PIC waveguide and attaching the other one of the pair of lenses to a facet of the first one of the corresponding optical transposer waveguide.

62. The method of any one of claims 59 to 61 or any other claim herein wherein each lens is fabricated from polymer.

63. The method of any one of claims 55 to 62 or any other claim herein comprising: shaping the PIC to comprise a first alignment structure having one of: a protruding shape and a complementary recess-defining shape; shaping the optical transposer to comprise a second alignment structure having the other one of: the protruding shape and the complementary recess-defining shape; and engaging the first alignment structure and the second alignment structure with one another such that the protruding shape protrudes into a complementary recessdefined by the complementary recess-defining shape to thereby align the optical transposer to the PIC.

64. The method of claim 63 or any other claim herein comprising forming a contact fit between surfaces of the first and second alignment structures when the protruding shape protrudes into the complementary recess defined by the complementary recess-defining shape.

65. The method of any one of claims 63 to 64 or any other claim herein comprising fabricating at least one of the first and second alignment structures by additive manufacturing.

66. The method of any one of claims 63 to 65 or any other claim herein comprising fabricating at least one of the first and second alignment structures by an etching process.

67. The method of any one of claims 55 to 66 or any other claim herein comprising dimensioning the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides to match at least one of: a pitch between fibers of a fiber array, a pitch between cores of a multicore fiber and a pitch between optical connections of an optical connector (e.g. for butt connection).

68. The method of any one of claims 55 to 67 or any other claim herein wherein each PIC waveguide comprises an edge-coupling optical interface (e.g. a facet) on an edge of the PIC (e.g. a vertical edge of the PIC) and wherein fabricating each optical connection comprising shaping, locating and / or fabricating the optical connection from suitable material(s) to direct light into or receive light from the optical interface.

69. The method of any one of claims 55 to 67 or any other claim herein wherein each PIC waveguide comprises a surface-coupling optical interface (e.g. a grating or mirror) to direct optical energy through, either to or from, a surface of the PIC (e.g. a horizontal surface of the PIC) and wherein fabricating each optical connection comprisesshaping, locating and / or fabricating the optical connection from suitable material(s) to direct light into or receive light from the optical interface.

70. The method of any one of claims 55 to 67 or any other claim herein comprising shaping, locating and or fabricating from suitable materials each optical connection to direct light into or receive light from the PIC waveguide by evanescent coupling.71 . The method of any one of claims 55 to 70 or any other claim herein wherein the optical transposer comprises a body fabricated from one or more of: glass, polymer, plastic, silicon and silicon nitride.

72. The method of claim 71 or any other claim herein comprising fabricating the optical transposer waveguides in the body using one or more of: an ion-exchange process which changes the crystal structure of the body in the region of the optical transposer waveguides; and a laser inscription process which changes the crystal structure of the body in the region of the optical transposer waveguides.

73. The method of any one of claims 71 to 72 or any other claim herein comprising locating the optical transposer waveguides on a surface of the body.

74. The method of any one of claims 71 to 72 or any other claim herein comprising locating the optical transposer waveguides within the body.

75. The method of any one of claims 55 to 70 or any other claim herein wherein the optical transposer comprises a substrate body and the method comprises fabricating the optical transposer waveguides on the substrate by melting and drawing optical fibers.

76. The method of any one of claims 55 to 75 or any other claim herein wherein the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides is a spacing in a single dimension.

77. The method of claim 76 or any other claim herein wherein the spacing in the single dimension is in a horizontal direction.

78. The method of claim 76 or any other claim herein wherein the spacing in the single dimension is in a vertical direction.

79. The method of any one of claims 55 to 76 or any other claim herein wherein the second end spacing between adjacent pairs of the second ends of the optical transposer waveguides is a spacing in two orthogonal dimensions.

80. The method of claim 79 or any other claim herein wherein the two orthogonal dimensions are in a vertical direction and a horizontal direction.81 . The method of any one of claims 55 to 80 or any other claim herein wherein the PIC is electrically connected to exchange electronic signals with an electrical integrated circuit (EIC).

82. The method of claim 81 or any other claim herein wherein electrical connections between the PIC and the EIC are provided at least in part by conductors that extend through vias in a substrate layer (e.g. transposer layer).

83. The method of claim 82 or any other claim herein wherein the substrate layer is made up of one or more of: glass, polymer, plastic, silicon and silicon nitride.

84. The method of any one of clams 82 to 83 or any other claim herein wherein the EIC, the PIC and the optical transposer are mounted on the substrate layer.

85. The method of claim 84 or any other claim herein comprising mounting the EIC and / or the PIC to the substrate layer by ball grid array soldering.

86. The method of any one of claims 84 to 85 or any other claim herein comprising bonding the optical transposer to the substrate layer - e.g. using metal soldering, adhesive and / or fasteners.

87. The method of any one of clams 82 to 83 or any other claim herein wherein the substrate layer and the optical transposer are integrally formed.

88. The method of any one of claims 81 to 83 and 87 or any other claim herein wherein the EIC is mounted atop the PIC or underneath the PIC.

89. The method of claim 88 or any other claim herein wherein electrical connections between the PIC and the EIC are provided at least in part by conductors that extend through vias in the PIC.

90. The method of any one of claims 81 to 83 and 87 or any other claim herein wherein the PIC and the optical transposer are spaced apart from one another.91 . The method of any one of claims 81 to 83 and 87 or any other claim herein wherein the PIC and the optical transposer are in abutting contact with one another.

92. The method of claim 91 or any other claim herein comprising fabricating the optical transposer to define a recess, the recess shaped to expose facets of the optical transposer waveguides in a recess-defining surface (e.g. a vertical or edge recessdefining surface) that is spaced apart from the abutting contact with the PIC.

93. The method of claim 92 or any other claim herein comprising fabricating the recess by chemical or physical etching.

94. The method of any one of claims 91 to 92 or any other claim herein wherein: for each optical connection, fabricating the one or more optical components comprises fabricating, by additive manufacturing, a photonic wire bond between the PIC waveguide and the first end of the corresponding optical transposer waveguide for coupling optical energy therebetween; and fabricating a portion of the recess-defining surface to be located to support the photonic wire bond.

95. The method of any one of claims 82 to 94 or any other claim herein comprising fabricating a body of the PIC to provide a recess that is located adjacent to the optical connections and between the PIC waveguides and the substrate.

96. The method of claim 95 or any other claim herein comprising fabricating the recess by chemical or physical etching.

97. The method of any one of claims 55 to 96 or any other claim herein wherein the plurality of optical components comprise a plurality of fibers in a fiber array.

98. The method of clam 43 or any other claim herein wherein at least portions of the plurality of fibers that are closest to the optical transposer are supported by a fiber support body.

99. The method of claim 98 or any other claim herein wherein the fiber support body is shaped (e.g. by micromachining) to provide a plurality of grooves and each portion of a corresponding one of the plurality of fibers is located in a corresponding one of the plurality of grooves.

100. The method of any one of claims 98 to 99 or any other claim herein comprising attaching the optical transposer and the fiber support body to one another (e.g. by suitable adhesion techniques or by welding).101 . The method of any one of claims 98 to 99 or any other claim herein wherein the optical transposer and the fiber support body are integrally formed with one another.

102. The method of any one of claims 98 to 101 or any other claim herein wherein the fiber support body is fabricated from a transparent material (e.g. quartz or glass).

103. The method of any one of claims 82 to 96 or any other claim herein comprising bonding the PIC, the EIC and the optical transposer to a sub-mount during fabrication and subsequently flip-chip mounting the bonded PIC, EIC and optical transposer to the substrate.

104. The method of claim 103 or any other claim herein wherein the sub-mount comprises a heat spreader (e.g. copper, other metal or metal alloy with high thermal conductivity).

105. The method of claim 104 or any other claim herein wherein the heat spreader comprises or is thermally coupled to a heat sink.

106. The method of any one of claims 103 to 105 or any other claim herein comprising bonding the PIC, the EIC and the optical transposer to the sub-mount using thermally conductive adhesive or metalization.

107. The method of any one of claims 55 to 16 or any other claim herein wherein the first end spacing is less than 20pm.

108. The method of any one of claims 55 to 107 or any other claim herein wherein the second end spacing is greater than 100pm or greater than 200pm.

109. Methods comprising any features, combinations of features and / or subcombinations of features disclosed herein.

110. Apparatus comprising any features, combinations of features and / or subcombinations of features disclosed herein.

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