Method and apparatus for maintaining alignment of optical ports

Abstract

Apparatus and methods for maintaining alignment of optical ports on a photonic device with optical ports of an optical interface are disclosed. The apparatus includes a photonic device having first optical ports and an optical interface having second optical ports. One or more first members are removably rigidly coupled to the photonic device. One or more second members are rigidly coupled to the optical interface. The first and second members each include bonding surfaces to which the settable material can bond. When the first optical ports and the second optical ports are aligned, the first members are proximate to and spaced apart from the second members. The settable material may be placed in gaps between the bonding surfaces of the first and second members. When set, the settable material holds the first and second pluralities of optical ports in alignment.

Description

METHOD AND APPARATUS FOR MAINTAINING ALIGNMENT OF OPTICAL PORTSCross-Reference to Related Application

[0001] This application claims priority from US application No. 63 / 570056 filed 26 March 2024 and entitled METHOD AND APPARATUS FOR MAINTAINING ALIGNMENT OF OPTICAL PORTS which is hereby incorporated herein by reference for all purposes. For purposes of the United States of America, this application claims the benefit under 35 U.S.C. §119 of US application No. 63 / 570056 filed 26 March 2024 and entitled METHOD AND APPARATUS FOR MAINTAINING ALIGNMENT OF OPTICAL PORTS which is hereby incorporated herein by reference for all purposes.Field

[0002] The present technology relates to making optical connections to photonic devices such as photonic chips. Embodiments of the technology relate to methods and apparatus for holding optical ports of a photonic device in alignment with corresponding optical ports of an optical interface.Background

[0003] A photonic device includes elements that generate and / or interact with and / or manipulate light. A photonic device may comprise or consist of a photonic chip. A photonic device typically includes plural optical ports which couple light from optical waveguides external to the photonic device into the photonic device and / or couple light out from the photonic device into optical waveguides external to the photonic device. A photonic device may include a large number of optical ports.

[0004] It can be a problem to align the optical ports of a photonic device with corresponding external waveguides with sufficient accuracy to provide good coupling of light between each of the optical ports and the corresponding external waveguide. Even small misalignments can interfere with the desired coupling. Once the optical ports of a photonic device have been aligned with the corresponding external waveguides, there is a need for ways to maintain the alignment.

[0005] The inventors have recognized a further problem which is to provide a meansfor maintaining alignment of a photonic chip with external waveguides that facilitate reuse of the photonic chip.Summary

[0006] The present technology has a number of aspects. These include, without limitation, methods and apparatus for maintaining alignment between optical ports of photonic devices such as photonic chips and optical interfaces that may include external waveguides.

[0007] A first aspect of the invention provides apparatus that comprises a photonic device and an optical interface. The photonic device comprises a first plurality of first optical ports on a first surface thereof. The optical interface comprises a plurality of second optical ports on a second surface thereof. The first optical ports and the second optical ports have complementary arrangements such that there is a relative position of the optical interface relative to the photonic device in which optical coupling is established between corresponding ones of the first and second optical ports. One or more first members are removably rigidly coupled to the photonic device. The one or more first members have one or more bonding surfaces to which a settable material can bond. One or more second members are rigidly coupled (and optionally removably rigidly coupled) to the optical interface. The one or more second members have one or more bonding surfaces to which the settable material can bond. When the first plurality of optical ports is in alignment with the second plurality of optical ports so that corresponding ones of the first optical ports and the second optical ports are optically coupled, the one or more first members are located proximate to and spaced apart from the one or more second members. The one or more bonding surfaces of the one or more first members and the one or more bonding surface of the one or more second members are separated by one or more gaps into which the settable material can be introduced and allowed to set. When the settable material has set, the first plurality of optical ports is held in alignment with the second plurality of optical ports.

[0008] In some embodiments, one of the one or more first members and the one or more second members comprises one or more recesses; and the other one of the one or more first members and the one or more second members comprises one or more projections that are arranged such that, when the first plurality of optical ports isin alignment with the second plurality of optical ports, each of the projections projects into one of the recesses and is spaced apart from interior surfaces of the one of the recesses.

[0009] In some embodiments, the projections are non-magnetic.

[0010] In some embodiments, the projections are provided by one or more elongated flexures. In some embodiments, the flexures are metallic. In some embodiments, the flexures have a thickness not exceeding % mm. In some embodiments, the flexures are made of stainless steel.

[0011] In some embodiments, the flexures comprise one or more first flexure portions and one or more second flexure portions, and the one or more second flexure portions are oriented to extend in a direction that is transverse to a direction in which the one or more first flexure portions are oriented. In some embodiments, the one or more first flexure portions are oriented in a direction that is substantially perpendicular to the direction in which the one or more second flexure portions are oriented. In some embodiments, the flexures extend around a majority of a perimeter surrounding the photonic device.

[0012] In some embodiments, the projections comprise pins. In some embodiments, the pins have tips that are enlarged radially relative to adjacent portions of the pins. In some embodiments, the recesses comprise cups and each of the pins projects into a corresponding one of the cups.

[0013] In some embodiments, the apparatus comprises a first holder, the photonic device is affixed to the first holder and the first members are removably affixed to the first holder. In some embodiments the photonic device is secured to the first holder by an adhesive.

[0014] In some embodiments, the first holder comprises a thermally conductive block in thermal contact with the photonic device. In some embodiments, the thermally conductive block is also in thermal contact with a temperature controlled element such as a cold head of a cryogenic cooler.

[0015] In some embodiments, the apparatus comprises a second holder, wherein the optical interface is affixed to the second holder and the second members are affixed to the second holder. Coupling between the second holder and the optical interface and / or coupling between the second holder and the second members optionallypermit separation of the second holder from the second members and / or the optical interface.

[0016] In some embodiments, the apparatus comprises the settable material. The settable material bonds the one or more bonding surfaces of the one or more first members to the one or more bonding surfaces of the one or more second members. The settable material thereby holds the first plurality of optical ports in alignment with the second plurality of optical ports.

[0017] In some embodiments, the settable material comprises an epoxy. In some embodiments, the settable material, when set, has a thermal conductivity of at least 0.01W / (m K).

[0018] In some embodiments, the apparatus comprises one or more actuators that are operable to fine tune alignment of the first and second optical ports after the settable material has set. In some embodiments, the one or more actuators are operable to move the photonic device in a plane by translation in the plane, rotation in the plane or combined translation and rotation in the plane relative to the optical interface (e.g. in X, Y and 9 degrees of freedom).

[0019] A second example aspect of the invention provides apparatus which is useful for maintaining alignment of corresponding optical ports of a photonic device and an optical interface where the apparatus does not include the photonic device and / or the optical interface. The apparatus may be provided in the form of a kit, for example. The apparatus may, for example comprise: one or more first members configured for removably rigidly coupling to a photonic device comprising a first plurality of first optical ports and one or more second members configured for rigid coupling to an optical interface comprising a plurality of second optical ports. Each of the one or more first members and the one or more second members comprises one or more bonding surfaces to which a settable material can bond. The configurations of the first and second members is such that, when the one or more first members is coupled to a photonic device and the one or more second members are coupled to an optical interface and the optical ports of the photonic device and the optical interface are aligned, the one or more first members are located proximate to and spaced apart from the one or more second members to form a gap between the one or more bonding surfaces of the one or more first members and the one or more bonding surfaces of the one or more second members into which the settable material can beintroduced and allowed to set to hold the first and second members to keep the first plurality of optical ports in alignment with the second plurality of optical ports.

[0020] It will be appreciated that embodiments described above in respect of the apparatus of the first aspect may also apply to the apparatus of the second aspect, as appropriate. In some embodiments, one of the one or more first members and the one or more second members comprises one or more recesses and the other one of the one or more first members and the one or more second members comprises one or more projections that are arranged such that, when the first plurality of optical ports is in alignment with the second plurality of optical ports, each of the projections projects into and is spaced apart from interior surfaces of one of the recesses. In some embodiments, the settable material is provided together with the apparatus (e.g. the settable material is provided as part of a kit that includes the one or more first members and the one or more second members).

[0021] Another aspect of the invention provides a method for supporting a first plurality of first optical ports of a photonic device in alignment with a plurality of second optical ports of an optical interface. The method comprises removably rigidly coupling one or more first members to the photonic device. The one or more first members have one or more bonding surfaces to which a settable material can bond. The method also comprises rigidly coupling (optionally removably rigidly coupling) one or more second members to the optical interface. The one or more second members have one or more bonding surfaces to which the settable material can bond. The method aligns the first plurality of optical ports and the second plurality of optical ports so that corresponding ones of the first optical ports and the second optical ports are optically coupled. The method introduces the settable material into one or more gaps between the one or more bonding surfaces of the one or more first members and the one or more bonding surface of the one or more second members and allows the settable material to set, thereby holding the first plurality of optical ports in alignment with the second plurality of optical ports.

[0022] Another aspect of the present technology provides apparatus having any new and inventive feature, combination of features, or sub-combination of features as described herein.

[0023] Another aspect of the present technology provides methods having any new and inventive steps, acts, combination of steps and / or acts or sub-combination ofsteps and / or acts as described herein.

[0024] Further aspects and example embodiments are illustrated in the accompanying drawings and / or described in the following description.

[0025] It is emphasized that the invention relates to all combinations of the above features, even if these are recited in different claims, discussed in different paragraphs or sections and / or illustrated in different drawings.Brief Description of the Drawings

[0026] The accompanying drawings illustrate non-limiting example embodiments of the invention.

[0027] Fig. 1A is a schematic illustration showing degrees of freedom in positioning a photonic chip relative to an optical interface.

[0028] Fig. 1 B is a schematic illustration showing alignment of an optical port comprising a grating coupler with an optical port comprising an optical fiber.

[0029] Figure 2 is a flowchart illustrating a method according to an example embodiment of the present technology.

[0030] Figs. 3A to 3D are schematic illustrations showing example apparatus at various stages of the method of Fig. 2.

[0031] Fig. 4A is an isometric view of apparatus that includes an example holder for a photonic device. Fig. 4B is an exploded view of the apparatus of Fig. 4A. Fig. 4C is an isometric view of apparatus that includes an example holder for an optical interface. Fig. 4D is an isometric view of a part of a holder for an optical interface according to an example embodiment.

[0032] Figs. 5A to 5D are respectively: perspective, top plan, first elevation cross section in the plane indicated by line 5C-5C of Fig. 5B, and second elevation cross section in the plane indicated by line 5D-5D of Fig. 5B, views of apparatus according to an example embodiment.

[0033] Figs. 5E and 5F are sketches that illustrate the effects of ferees on flexures in different directions relative to the flexures.

[0034] Figs 6A and 6B are respectively perspective and top plan and elevation views of apparatus according to another example embodiment. Fig. 6C is a cross sectionview in the plane indicated by line 6C-6C of Fig. 6B.

[0035] Figs 7A and 7B are respectively perspective and top plan views of an apparatus according to another example embodiment. Fig. 7C is an elevation cross section view in the plane indicated by line 7C-7C of Fig. 7B.

[0036] Figs. 8A and 8B are schematic illustrations showing some example alternative configurations for bonding surfaces.Detailed Description

[0037] Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense.

[0038] Fig 1A schematically shows a photonic device 10, which may, for example comprise or consist of a photonic chip, having an array of optical ports 11 on a surface 12 thereof. For ease of illustration, photonic device 10 is shown to have 16 optical ports 11 . However, photonic device 10 may include any suitable number of optical ports 11 . For example, a photonic chip may include hundreds or thousands of optical ports 11. Optical ports 11 are illustrated as being arranged in a regular array. However, this is not mandatory. Optical ports 11 may be arranged in any practical arrangement on surface 12.

[0039] An optical interface 14 includes optical ports 15 arranged on a surface 16. It is desired to align some or all of optical ports 11 of photonic device 10 with corresponding ones of optical ports 15 of optical interface 16 to permit coupling of light between the corresponding optical ports 11 and 15. Depending on the application in which photonic device 10 is being used, optical interface 14 may include optical ports 15 that correspond to all or only some of optical ports 11 of photonic device 10.

[0040] Optical interface 14 may, for example, comprise a plate formed with apertures which receive and hold the ends of optical fibers at positions and orientations that are selected such that there is an alignment of the optical interface relative to acorresponding photonic device such that each of a set of optical ports of the photonic device that is required for operation of the photonic device is optically coupled to a corresponding one of the optical fibers. The plate may, for example comprise a glass plate.

[0041] The relative alignment of photonic device 10 and optical interface 14 involves six degrees of freedom. These degrees of freedom may, for example, be expressed as three translational degrees of freedom (e.g. displacements in X, Y and Z directions) and three rotational degrees of freedom (e.g. rotations about axes corresponding to angles 9, cp, and i ).

[0042] In an example implementation, surfaces 12 and 16 are planar and the desired alignment is achieved when surfaces 12 and 16 are spaced apart by a small separation distance (e.g. a separation distance in the range of about 10 pm to about 50 pm), and displacement of optical interface 14 in X and Y directions and rotation of optical interface 14 in angle 9 are selected such that corresponding optical ports 11 and 15 are aligned to allow coupling of light.

[0043] The desired alignment may be achieved, for example, using a 6 degree of freedom (“6 DOF”) positioning system. A 6 DOF positioning system can have any of a wide variety of constructions. As one example, photonic device 10 may be fixed on a rotary table which is supported on an X-Y positioner. Optical interface 14 may be fixed on a support which is movable in a Z direction relative to the rotary table and has two rotational degrees of freedom which allow tilting of optical interface 14 about angles cp and ip.

[0044] Such a 6 DOF positioning system may be used to align corresponding optical ports 11 , 15 by positioning surface 16 to be parallel to surface 12 and then moving optical interface 14 in the Z direction so that surfaces 12 and 16 are spaced apart by a desired distance in the Z direction. This positioning may be verified, for example using cameras located to image the gap between photonic device 10 and optical interface 14 from two sides. The relative positioning of optical interface 14 and photonic device 10 in the X, Y and 9 degrees of freedom may then be adjusted to achieve sufficient optical coupling of corresponding pairs of optical ports 11 , 15. The quality of optical coupling of corresponding optical ports 11 and 15 may be measured, for example, by directing light from a light source (e.g. a laser) to be emitted from an optical port 15 of optical interface 11 toward photonic device 10 and measuring thelight that is reflected back into the same optical port 15 and / or measuring collected at one or more other ones of optical ports 15.

[0045] In some embodiments the 6 DOF positioning system includes adjustment mechanisms that are incorporated into apparatus as described herein. For example, apparatus 50 of Figs. 5A-D includes screws 57 that may be adjusted to set relative positioning of optical interface 14 and photonic device 10 in the Z, cp, and i degrees of freedom.

[0046] In some embodiments, optical ports 11 comprise optical grating couplers for which maximum optical coupling is achieved for light that is incident on the optical port at a specific angle. In some embodiments, optical ports 15 comprise optical fibers, which may be single mode optical fibers for which maximum optical coupling is achieved for light that is incident on the optical port in a direction that is aligned with an optical axis of the optical fiber. Fig. 1 B is a side elevation cross section view that schematically illustrates optimal alignment of an optical grating coupler 17 of an optical port 11 and an optical fiber 18 of an optical port 15. The alignment is indicated by line 19 which coincides with an optical axis of optical fiber 18. The angle y between line 19 and a vector normal to surface 12 depends on characteristics of grating coupler 17.

[0047] The present technology provides methods and apparatus for maintaining alignment of corresponding optical ports of a photonic device 10 (e.g. a photonic chip) and an optical interface 14 once a desired alignment has been achieved. Fig. 2 illustrates an example method 20 according to an example embodiment. Fig. 3 schematically illustrates apparatus at various stages of method 20. Although method 20 is primarily described with respect to the apparatus illustrated in Fig. 3, it will be appreciated that it may be applicable to other apparatus described herein, such as apparatus 50, 60 and 70.

[0048] In block 21 A, one or more first members 31 are removably coupled to a photonic device 10. When coupled to photonic device 10, first member(s) 31 are affixed to photonic device 10 and project laterally outwardly from photonic device 10 (see Fig. 3A).

[0049] In block 21 B, one or more second members 32 are affixed to an optical interface 14 (see Fig. 3B). When affixed to optical interface 14, second member(s) 32project laterally outwardly from optical interface 14.

[0050] In block 22 optical ports 11 of photonic device 10 are aligned with corresponding optical ports 15 of optical interface 14. Block 23 may be performed using a 6 DOF positioning system 39, for example as described above (see Fig. 3C).

[0051] In block 23, first member(s) 31 are affixed to second members 32 by a settable material 33 while the relative positions of photonic device 10 and optical interface 14 are held fixed by 6 DOF positioning system 39 (see Fig. 3D). The portions of members 31 and 32 to which settable material 33 bonds may be called “bonding surfaces”. The bonding surfaces may optionally have a surface treatment (e.g. surface roughness, plasma etching, pits, a coating of an activator for settable material 33, or the like) that enhances bonding of settable material 33 to members 31 and 32.

[0052] Settable material 33 may, for example, comprise a settable material selected from the group consisting of epoxy, heat or light curable adhesive, solder, or the like.

[0053] In applications where photonic device 10 will be operated at an operating temperature that is different from a temperature at which settable material is set, it can be advantageous to select settable material 33 that, when set, has a coefficient of thermal expansion that is matched reasonably closely (e.g. to within 10% or 5% or 1%) to a coefficient of thermal expansion of first members 31 and second members 32.

[0054] In applications where it is desired for heat to be transferred through the settable material (e.g. in cryogenic applications) it is desirable for the settable material to have a sufficiently high thermal conductivity to transfer the heat within a desired time frame. The thermal conductivity of settable material 33 may be temperature dependent. The thermal conductivity of most materials is lower at temperatures that are close to absolute zero (e.g. temperatures of 5K or less) than the thermal conductivity at higher temperatures. In some embodiments, settable material 33, when set, has a thermal conductivity of at least 0.1W / (m K), 0.8W / (m K) or at least 1W / (m K) at room temperature. In some embodiments, settable material 33 has a thermal conductivity of at least 0.01W / (m K) at a temperature of 2K.

[0055] In applications where photonic device 10 will be operated in a vacuum environment it can be advantageous to select a settable material 33 to be a material that, once set, does not outgas.

[0056] In block 24, if necessary, the assembly of photonic device 10 and optical interface 14 which are now fixed relative to one another may be removed from any part of a positioning system that is used in block 23 that is not intended to remain with the assembled photonic device 10 and optical interface 14. The relative alignment of photonic device 10 and optical interface 14 is preserved by first and second members31 , 32 which are held fixed to one another by settable material 33 and which are respectively affixed to photonic device 10 and optical interface 14.

[0057] In optional block 25, the assembly of photonic device 10 and optical interface 14 is brought to an operating temperature (e.g. cooled to a suitable cryogenic operating temperature).

[0058] In optional block 26, the alignment of corresponding optical ports 11 , 15 is fine tuned. The fine tuning may compensate for any shifts in alignment of corresponding optical ports 11 , 15 resulting from thermal effects. An example apparatus 60 for fine tuning is described in more detail below in respect of Figs. 6A to 6C.

[0059] It can be appreciated that photonic device 10 and optical interface 14 may be separated from one another by removing member(s) 31 and / or removing member(s)32. After this has been done, photonic device 10 and optical interface 14 may be reused. This may be particularly advantageous for situations in which the optical interface 14 may need to be separated from the photonic device 10 for maintenance, re-alignment and / or other purposes.

[0060] As illustrated in Fig. 3C, in some embodiments, apparatus 30 includes one or more projections 32A that are dimensioned to project into one or more corresponding recesses 31 A in a member 31 . This construction is particularly advantageous where settable material 33 is flowable. Settable material 33 may, for example, be introduced into recesses 31 A before or after completing the alignment in block 22. The settable material may flow to fill the space between a projection 32A and walls of a recess 31A. Settable material 33 may solidify as it sets to fix projections 32A in the corresponding recess 31A.

[0061] Recesses 31 A and projections 32A may each take a wide variety of forms. For example, projections 32A may comprise posts, pins, flexures, flanges, or the like. Projections 32A may, for example, be provided by shaping of members 32, parts that are attached to project relative to members 32, or the like. Recesses 31 A may, forexample comprise cylindrical recesses, rectangular recesses, slots, grooves, or the like that are positioned and dimensioned to receive projections 32A.

[0062] Projections 32A may be dimensioned so as to leave clearance between the projection 32A and walls of the corresponding recess 31 A when corresponding optical ports 11 ,15 are aligned. Recesses 31 A are shaped and dimensioned to receive the corresponding projections 32A when corresponding optical ports 11 ,15 are aligned. Projections 32A may be dimensioned to project into one or more corresponding recesses 31A in a member 31 without touching interior surfaces of recesses 31 A, both for a configuration of photonic device 10 and optical interface 14 in which corresponding optical ports 11 ,15 are aligned (aligned configuration) and for configurations of photonic device 10 and optical interface 14 which differ from the aligned configuration by displacement in X and / or Y directions and / or a rotations in angle 0 within specified ranges.

[0063] It is not mandatory that projections 32A are provided on members 32 that are affixed relative to optical interface 14 and corresponding recesses 31 A are provided on members 31 that are affixed relative to photonic device 10. In some embodiments, one or more recesses 31 A are provided in one or more member(s) 32 and one or more corresponding projection(s) 32A are provided in one or more member(s) 31.

[0064] In some embodiments, member(s) 31 are affixed to photonic device 10 by affixing a holder 41 to photonic device 10 (see e.g. Fig. 4A,4B) and affixing member(s) 31 to holder 41.

[0065] In the embodiment illustrated in Fig. 4A, holder 41 comprises a body 42 having a surface 43 to which photonic device 10 is affixed. For example, photonic device 10 may be held in place on surface 43 by a suitable adhesive (as in the illustrated example), a clamp (not shown), or the like. Surface 43 may include features that help to locate photonic device 10 in a desired location relative to members 31. For example, surface 43 may include projections against which photonic device 10 can be placed to achieve coarse alignment of photonic device 10 to surface 43. Fig. 4A shows bosses 44 which have edges against which corresponding sides of photonic device 10 may be placed and held while photonic device 10 is affixed to holder 41.

[0066] In some embodiments, body 42 comprises a thermally conductive material that provides a path by way of which heat can be drawn from photonic device 10, forexample to cool photonic device 10 to cryogenic temperatures. For example, body 42 may be made of copper or cupronickel. Body 42 may be thermally coupled to a cold head of a cryogenic cooler so that photonic device 10 may be cooled to cryogenic temperatures in preparation for use. In such embodiments a thermally conductive material may be provided between surface 43 and photonic device 10. For example, an adhesive used to affix photonic device 10 to surface 43 may be selected to have suitable properties which include good thermal conductivity. In some embodiments the adhesive has a thermal conductivity of at least 0.01W / (m K), 0.1W / (m K), 0.8W / (m K) or 1W / (m K).

[0067] In the embodiment of Figs. 4A and 4B, a single member 31 includes recesses 31 A on plural sides of photonic device 10. In general, member(s) 31 may be removably affixed to holder 41 , for example, by bolts, clamps, screws, cam fasteners or the like. In Figs. 4A and 4B, member 31 is attached to body 42 by fasteners (not shown) such as screws which extend through holes 45 in body 42 into member 31 .

[0068] Member 31 can be seen to be an example of one or more first members removably rigidly coupled to photonic device 10. The inner walls of recesses 31 A can be understood to constitute examples of one or more bonding surfaces to which a settable material 33 can bond.

[0069] Depending on the nature of photonic device 10, photonic device 10 may require electrical connections in addition to optical connections. In some embodiments, holder 41 additionally provides mechanical support for electrical connections to photonic device 10. For example, holder 41 may mechanically support electrical terminals, and electrical connections to photonic device 10 may be made by connecting electrical conductors between electrical contacts on photonic device 10 and corresponding ones of the electrical terminals. For example, the electrical conductors may comprise wires that are mechanically and electrically connected to the electrical contacts of photonic device 10 by wire bonding. Such embodiments permit reuse of both photonic device 10 and the electrical connections to photonic device 10 without disturbing the electrical connections.

[0070] In some embodiments, members 31 are not (easily) removable from holder 41. For example, members 31 and body 42 may have a unitary construction or member(s) 31 may be welded to or attached to body 42 by another fastening modality that is not readily undone without damaging body 42. Such embodiments may besuitable in cases where photonic device 10 can be safely removed from holder 41 for reuse (e.g. by affixing photonic device 10 to a new holder 41).

[0071] In some embodiments, member(s) 32 are affixed to optical interface 14 by affixing a holder 46 to optical interface 14 (see, for example, Figs. 4C and 4D). Member(s) 32 may be affixed to holder 46. Holder 46 may, for example comprise a frame dimensioned to extend around all or a part of the periphery of optical interface 14 and configured to be affixed to optical interface 14 so that optical interface 14 is rigidly fixed relative to frame 46. Optical interface 14 may, for example be affixed to holder 46 by one or more clamps, a suitable adhesive, suitable fasteners or the like. Members 32 may be removably affixed to holder 46, for example, by clamps, suitable fasteners such as screws, bolts, pins or the like.

[0072] In some embodiments, holder 46 is integrated with optical interface 14 (i.e. optical interface 14 may include features to which members 32 may be removably rigidly affixed to optical interface 14 and held in positions such that members 32 are affixable to members 31 by settable material 33 as described herein).

[0073] It can be understood that when affixed to optical interface 14 as described herein, members 32 are examples of one or more second members rigidly coupled to optical interface 14. It can also be appreciated that second members 32 include examples of one or more bonding surfaces to which settable material 33 can bond (e.g. portions of members 32 proximate to the lower edges of members 32 as shown in Fig. 4D).

[0074] In the example apparatus shown in Figs 4C and 4D (see also Figs. 6B and 6C) optical interface 14 is supported by ferrule 46A. Holder 46 comprises a ferrule 46A and a member that can be affixed to ferrule 46A and to member(s) 32. This member may for example comprise a frame 46B.

[0075] Frame 46B is configured to be affixed to ferrule 46A, for example, by being clamped to ferule 46A. As best shown in Fig. 6C, optical interface 14 is supported at an end of ferrule 46A.

[0076] In this example, frame 46B comprises clamping parts 46B-1 and 46B-2 that can be clamped around ferrule 46A.When clamped around ferrule 46A, clamping parts 46B-1 and 46B-2 are held rigidly relative to ferrule 46A and optical interface 14.

[0077] In this example, ferrule 46A comprises a flange 47A and frame 46B comprisesa channel 47B that receives flange 47A when frame 46B is clamped around ferrule 46A. After frame 46B is clamped around ferrule 46A, frame 46B may be held in its clamped position by suitable fasteners. In this example, frame 46B is held in its clamped position by a holding member 48A that is held to clamping portions 46B-1 and 46B-2 by screws 48B. In this example, two of members 32 extend between clamping portions 46B-1 and 46B-2. These members 32 also help to keep frame 46B rigidly affixed relative to optical interface 14.

[0078] Some embodiments incorporate a guide and / or a heat shield that serve to guide optical fibers away from optical interface 14 and / or to help to reduce conduction of heat to and / or from optical interface 14 by way of the optical fibers. Ferrule 46A may incorporate a guide that serves one or more of these functions. Other embodiments may include guides and / or heat shields having other constructions.

[0079] Ferrule 46A includes a channel or passage 46A-1 through which optical fibers (not shown) may be routed. The walls surrounding channel 46A-1 may function as a heat shield. For example, ferrule 46A may be in thermal contact with body 42 by way of flexures 52. The walls surrounding channel 46A-1 may function as a guide for optical fibers that connect to optical interface 14.

[0080] In some embodiments, members 32 are not readily separable from holder 46. After apparatus according to such embodiments has been fixed in alignment with a photonic device by a settable material as described herein, optical interface 14 may be reused with the same or another photonic device by replacing the part of holder 46 that includes member(s) 32 with a new part. In some cases this involves replacing all of holder 46 with a new holder 46 that includes members 32 and / or is configured for attachment to member(s) 32.

[0081] From the above, it can be appreciated that members 32 may be removably affixed directly to an optical interface 14; or removably or non-removably affixed to an intermediate member (e.g. a holder 46) that is itself is removably affixable to optical interface 14. Another option if optical interface 14 is expendable is to permanently attach members 32 to optical interface 14. With this option, photonic device 10 may be readily reused, as described herein but optical interface 14 might not be reusable after members 32 have been bonded to settable material 33.

[0082] Figs. 5A through 5D are respectively perspective, top plan, and two crosssection views of an apparatus 50 according to an example embodiment of the invention. In apparatus 50, members 31 are formed with troughs or grooves that serve as recesses 31A and members 32 comprise flexures 52, in which one edge of each flexure 52 serves as a projection 32A.

[0083] Recesses 31 A are dimensioned to allow a range of adjustment of the relative positions of photonic device 10 and optical interface 14 in X, Y and Z directions and a range of relative rotation of optical interface 14 and photonic device 10 in angle 0 sufficient to achieve proper alignment of optical ports 11 , 15 without bringing projections 32A into contact with walls of recesses 31 A.

[0084] Flexures 52 may comprise strips of material that present less resistance to transverse deflections than to in plane deflections. Flexures 52 may for example comprise thin strips of material that present relatively little resistance to transverse deflections (e.g. deflections in response to forces in direction 53A or 53B as shown in Fig. 5E) and are relatively very stiff in plane (e.g. in directions 53C and 53D as shown in Fig. 5F). Flexures 52 may, for example comprise thin strips of metal (e.g. stainless steel). In some embodiments, flexures 52 have a thickness in the range of about 0.1 mm to about 0.5 mm.

[0085] Apparatus 50 includes four flexures 52 (individually identified in Fig. 5B as 52- 1 , 52-2, 52-3 and 52-4) arranged in two pairs. The flexures 52 of each pair are parallel and are on opposing sides of photonic device 10. In the illustrated embodiment flexures 52-1 and 52-3 form one pair and are perpendicular to the flexures of the other pair which is made up of flexures 52-2 and 52-4.

[0086] The arrangement of flexures 52 in apparatus 50 is one example of a case where one or more first flexure portions and one or more second flexure portions are oriented so that the one or more second flexure portions extend in a direction that is transverse to a direction in which the one or more first flexure portions are oriented. Flexures arranged in this manner can advantageously provide very rigid coupling of a photonic device 10 and an optical interface 14 since, when the first and second flexure portions are bonded to one or more members 31 by settable material 33, the first and second flexure portions can each resist high forces in the non-parallel directions in which they are oriented.

[0087] Example arrangements of flexures 52 which come within this description areflexures arranged around the perimeter of a triangle, rectangle or other polygon. It is not mandatory that the flexure portions follow straight lines. In some embodiments, flexures 52 are curved. Another example arrangement provides one or more flexures that are curved to extend along all or a portion of a perimeter of a circle or ellipse. In this case the one or more flexures will include first flexure portions and second flexure portions that are oriented transversely relative to the first flexure portions, thereby helping to provide more rigid support of a photonic device 10 relative to an optical interface 14. In some embodiments, one or more flexures are arranged in such a manner that the flexures extend along at least a majority of a perimeter that surrounds photonic device 10.

[0088] In apparatus 50, flexures 52 are affixed to holder 46 by screws 55. In general, flexures 52 may be affixed to holder 46 by any suitable fasteners. In apparatus 50, members 31 in which recesses 31 A are formed are affixed to holder 41 by fasteners (e.g. screws, not shown in Fig, 5A).

[0089] Screws 57 may be adjusted to set a desired spacing between photonic device 10 and optical interface 14 as well as to achieve parallelism or a desired angle of tilt of optical interface 14 relative to the proximate surface of photonic device 10 (e.g. to set Z displacement and / or rotation in angle cp and / or i as described in relation to Fig. 1 A). Screws 57 may form part of a 6 DOF positioner.

[0090] Once a desired relative position of optical interface 14 and photonic device 10 has been established (e.g. using a 6 DOF positioner), a settable material 33 (not shown in Figs. 5A to 5D) may be allowed to set. Flexures 52 can flex transversely to accommodate any dimensional changes in settable material 33 that may result from the setting of settable material 33. When set, the settable material 33 is rigid and is bonded to flexures 52 and inner surfaces of recesses 31 A. When edge parts of flexures 52 are bonded to members 31 by settable material 33 in recesses 31A, photonic device 10 is held rigidly relative to optical interface 14, thus preserving optical alignment of optical interface 14 to photonic device 10.

[0091] In some embodiments, photonic device 10 is mounted to a body of a thermally conductive material that can be mounted to a temperature controlled surface (e.g. a cold surface of a cryogenic refrigerator). The thermally conductive material provides thermal contact between photonic device 10 and the temperature controlled surface.

[0092] In apparatus 50, holder 41 comprises a body 42. Body 42 may be thermally conductive and in thermal contact with photonic device 10. Body 42 may be placed in thermal contact with a temperature controlled surface, for example, to facilitate control of the temperature of photonic device 10 and / or cooling of photonic device 10 to cryogenic temperatures.

[0093] In some applications, a photonic device 10 may be intended to operate at temperatures (e.g. cryogenic temperatures) that are significantly lower than the temperature of the photonic device 10 while the photonic device 10 is being aligned. For example, a photonic device 10 may operate at temperatures of 5 Kelvin or less. In such cases corresponding optical ports 11 , 15 need to be properly aligned when apparatus comprising the photonic device 10 and affixed optical interface 14 are cooled to the operating temperature of photonic device 10. This may be achieved, for example, by one or both of: designing the apparatus to preserve alignment of corresponding optical ports 11 , 15 through the temperature changes required to bring photonic device 10 to the intended operating temperature of photonic device 10 and / or providing actuators which are operable at the operating temperature of photonic device 10 to fine tune the alignment of corresponding optical ports 11 , 15.

[0094] Figs. 6A to 6C illustrate apparatus 60 which is similar to apparatus 50 with the addition of actuators which permit tuning of the alignment of optical interface 14 to photonic device 10 at the operating temperature of photonic device 10. Apparatus 60 includes actuators operable for tuning the alignment in X, Y and 0 degrees of freedom (see Fig. 1 A) to optimize optical coupling of corresponding pairs of optical ports 11 , 15 after settable material 33 has set. It will be appreciated that the other apparatus described herein may be adapted to include actuators similar to those shown in apparatus 60.

[0095] The adjustment may, for example, be performed after apparatus 60 has been brought to an operating temperature for photonic device 10 (e.g. cooled to a desired cryogenic operating temperature). The adjustment may, for example compensate for changes in alignment resulting from different materials in apparatus 60 having different coefficients of thermal expansion.

[0096] The example apparatus 60 of Figs. 6A to 6C includes actuators 61-X, 61-Y and 61-9 which may be respectively operated to make small adjustments to the X, Y and 9 degrees of freedom.

[0097] Figs 7A to 7C illustrate apparatus 70 which is similar to apparatus 50, 60 except that apparatus 70 includes projections and recesses having an alternative design. Apparatus 70 includes pins 72 which project into interiors of cups 71 when corresponding optical ports of a photonic device 10 and an optical interface 14 are aligned. In some embodiments, pins 72 include features 72A that help to resist pullout of pins 72 from settable material 33 that has set. Features 72A may, for example comprise projections, recesses and / or texturing of pins 72. For example, pins 72 as shown in Figs. 7A to 7C have tips that are enlarged radially relative to adjacent portions of pins 72.

[0098] When corresponding optical ports of a photonic device 10 and an optical interface 14 have been aligned (e.g. as described elsewhere herein), a settable material 33 (not shown in Figs. 7A to 7C) may be introduced into cups 71. Upon setting, the settable material 33 holds pins 72 fixed relative to cups 71 and thereby preserves the alignment of corresponding optical ports of photonic device 10 and optical interface 14.

[0099] Cups 71 may be removably affixed to holder 41 , for example, by clamps actuated by screws 73. Pins 72 may be removably attached to holder 46, for example, by a threaded coupling. Apparatus 70 includes four pins 72 which project into four cups 71 . Other embodiments may include different numbers of pins 72 and cups 71.

[0100] It is not mandatory that projections 32A (whether they be pins, flexures, projection s of other forms or combinations of those) must project onto corresponding recesses 31 A. In some embodiments alignment of photonic device 10 and optical interface 14 may be suitably maintained by other configurations in which a suitable settable material 33 bonds to and forms a substantially rigid connection between members 31 and 32. Figs. 8A and 8B are schematic cross section views of apparatus 80A and 80B that represent example ways to use a settable material 33 to affix holders 41 and 46 to one another. In each of these examples, settable material 33 at least partially fills an aperture 81 in holder 46 and bonds to holder 41 . In apparatus 80B, holder 31 includes an indentation 82 that receives settable material 33.

[0101] Where a component (e.g. a fastener, clamp, assembly, device, optical port, holder, etc.) is referred to herein, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including asequivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.Interpretation of Terms

[0102] Unless the context clearly requires otherwise, throughout the description and the claims:• “aligned” or “in alignment” in reference to an optical port on a photonic device and a corresponding optical port of an optical interface means that the corresponding optical ports on the photonic device and the optical interface are positioned relative to one another such that light emitted from the optical port of the photonic device is coupled into the corresponding optical port of the optical interface and / or light emitted from the optical port of the optical interface is coupled into the corresponding optical port of the photonic device..• “aligned” or “in alignment” in reference to a photonic device and a corresponding optical interface means that the photonic device and optical interface are positioned relative to one another such that plural optical ports of the photonic device are in alignment with plural corresponding optical ports of the optical interface.• “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”, “affixed” or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; unless otherwise stated or necessarily implied, the coupling or connection between the elements can be physical, logical, or a combination thereof;• two elements are “rigidly coupled” or “rigidly affixed” when the elements are coupled in a manner that does not permit relative movement of the components (except for minor movement that is negligible considering the function of the elements).• “herein”, “above”, “below”, and words of similar import, when used to describethis 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.

[0103] 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.

[0104] 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.

[0105] 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 range would 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.

[0106] 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 describedembodiments 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.

[0107] 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.

[0108] Any aspects described above in reference to apparatus may also apply to methods and vice versa.

[0109] 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.

[0110] 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 expressindication 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.

[0111] 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

WHAT IS CLAIMED IS:

1. Apparatus comprising: a photonic device comprising a first plurality of first optical ports on a first surface thereof; an optical interface comprising a plurality of second optical ports on a second surface thereof; one or more first members removably rigidly coupled to the photonic device, the one or more first members having one or more bonding surfaces to which a settable material can bond; and one or more second members rigidly coupled to the optical interface, the one or more second members having one or more bonding surfaces to which the settable material can bond; wherein, when the first plurality of optical ports is in alignment with the second plurality of optical ports so that corresponding ones of the first optical ports and the second optical ports are optically coupled, the one or more first members are located proximate to and spaced apart from the one or more second members to form a gap between the one or more bonding surfaces of the one or more first members and the one or more bonding surface of the one or more second members into which the settable material can be introduced and allowed to set to hold the first plurality of optical ports in alignment with the second plurality of optical ports.

2. The apparatus according to claim 1 wherein: one of the one or more first members and the one or more second members comprises one or more recesses; and the other one of the one or more first members and the one or more second members comprises one or more projections that are arranged such that, when the first plurality of optical ports is in alignment with the second plurality of optical ports, each of the projections projects into one of the recesses and is spaced apart from interior surfaces of the one of the recesses.

3. The apparatus according to claim 2 wherein the projections are non-magnetic.

4. The apparatus according to claim 2 or 3 wherein the projections are provided by one or more elongated flexures.

5. The apparatus according to claim 4 wherein the flexures are metallic.

6. The apparatus according to claim 5 wherein the flexures have a thickness not exceeding % mm.

7. The apparatus according to any of claims 4 to 6 wherein the flexures are made of stainless steel.

8. The apparatus according to any of claims 4 to 7 wherein the flexures comprise one or more first flexure portions and one or more second flexure portions and the one or more second flexure portions are oriented to extend in a direction that is transverse to a direction in which the one or more first flexure portions are oriented.

9. The apparatus according to claim 8 wherein the one or more first flexure portions are oriented in a direction that is substantially perpendicular to the direction in which the one or more second flexure portions are oriented.

10. The apparatus according to any of claims 4 to 9 wherein the flexures extend around a majority of a perimeter surrounding the photonic device.11 . The apparatus according to claim 2 or 3 wherein the projections comprise pins.

12. The apparatus according to claim 11 wherein the pins have tips that are enlarged radially relative to adjacent portions of the pins.

13. The apparatus according to claim 12 wherein the recesses comprise cups and each of the pins projects into a corresponding one of the cups.

14. The apparatus according to any of the preceding claims comprising a first holder wherein the photonic device is affixed to the first holder and the first membersare removably affixed to the first holder.

15. The apparatus according to claim 14 wherein the first holder comprises a thermally conductive block in thermal contact with the photonic device.

16. The apparatus according to any of the preceding claims comprising a second holder wherein the optical interface is affixed to the second holder and the second members are affixed to the second holder.

17. The apparatus according to any of the preceding claims, comprising the settable material, the settable material bonding the one or more bonding surfaces of the one or more first members to the one or more bonding surface of the one or more second members, the settable material thereby holding first plurality of optical ports in alignment with the second plurality of optical ports.

18. The apparatus according to claim 17 wherein the settable material comprises an epoxy.

19. The apparatus according to claim 17 or 18 wherein the settable material, when set, has a thermal conductivity of at least 0.01W / (m K).

20. The apparatus according to any of claims 17 to 19 comprising one or more actuators operable to fine tune alignment of the first and second optical ports after the settable material has set.21 . The apparatus according to claim 20 wherein the one or more actuators are operable to move the photonic device in a plane by translation in the plane, rotation in the plane or combined translation and rotation in the plane relative to the optical interface.

22. Apparatus comprising: one or more first members configured for removably rigidly coupling to a photonic device comprising a first plurality of first optical ports on a first surface thereof; andone or more second members configured for rigid coupling to an optical interface comprising a plurality of second optical ports on a second surface thereof; wherein: each of the one or more first members and the one or more second members comprises one or more bonding surfaces to which a settable material can bond, and the configurations of the first and second members is such that, when the one or more first members is coupled to a photonic device and the one or more second members are coupled to an optical interface and the optical ports of the photonic device and the optical interface are aligned, the one or more first members are located proximate to and spaced apart from the one or more second members to form a gap between the one or more bonding surfaces of the one or more first members and the one or more bonding surfaces of the one or more second members into which the settable material can be introduced and allowed to set to hold the first and second members to keep the first plurality of optical ports in alignment with the second plurality of optical ports.

23. The apparatus according to claim 22 wherein one of the one or more first members and the one or more second members comprises one or more recesses and the other one of the one or more first members and the one or more second members comprises one or more projections that are arranged such that, when the first plurality of optical ports is in alignment with the second plurality of optical ports, each of the projections projects into and is spaced apart from interior surfaces of one of the recesses.

24. A method for supporting a first plurality of first optical ports of a photonic device in alignment with a plurality of second optical ports of an optical interface, the method comprising: removably rigidly coupling one or more first members to the photonic device, the one or more first members having one or more bonding surfaces to which a settable material can bond; removably rigidly coupling one or more second members to the optical interface, the one or more second members having one or more bonding surfaces to which the settable material can bond;aligning the first plurality of optical ports and the second plurality of optical ports so that corresponding ones of the first optical ports and the second optical ports are optically coupled; and introducing the settable material into a gap between the one or more bonding surfaces of the one or more first members and the one or more bonding surfaces of the one or more second members and allowing the settable material to set, thereby holding the first plurality of optical ports in alignment with the second plurality of optical ports.

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