Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
  • G02B6/4214—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26F—PERFORATING; PUNCHING; CUTTING-OUT; STAMPING-OUT; SEVERING BY MEANS OTHER THAN CUTTING
  • B26F1/00—Perforating; Punching; Cutting-out; Stamping-out; Apparatus therefor
  • B26F1/38—Cutting-out; Stamping-out
  • B26F1/40—Cutting-out; Stamping-out using a press, e.g. of the ram type
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
  • G02B6/4228—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements
  • G02B6/423—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements using guiding surfaces for the alignment
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/3628—Mechanical coupling means for mounting fibres to supporting carriers
  • G02B6/3648—Supporting carriers of a microbench type, i.e. with micromachined additional mechanical structures
  • G02B6/3652—Supporting carriers of a microbench type, i.e. with micromachined additional mechanical structures the additional structures being prepositioning mounting areas, allowing only movement in one dimension, e.g. grooves, trenches or vias in the microbench surface, i.e. self aligning supporting carriers
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/3628—Mechanical coupling means for mounting fibres to supporting carriers
  • G02B6/3684—Mechanical coupling means for mounting fibres to supporting carriers characterised by the manufacturing process of surface profiling of the supporting carrier
  • G02B6/3696—Mechanical coupling means for mounting fibres to supporting carriers characterised by the manufacturing process of surface profiling of the supporting carrier by moulding, e.g. injection moulding, casting, embossing, stamping, stenciling, printing, or with metallic mould insert manufacturing using LIGA or MIGA techniques
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
  • G02B6/4236—Fixing or mounting methods of the aligned elements
  • G02B6/424—Mounting of the optical light guide
  • G02B6/4243—Mounting of the optical light guide into a groove
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
  • G02B6/4236—Fixing or mounting methods of the aligned elements
  • G02B6/4245—Mounting of the opto-electronic elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4246—Bidirectionally operating package structures
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4249—Packages, e.g. shape, construction, internal or external details comprising arrays of active devices and fibres
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4251—Sealed packages

Definitions

• the present invention relates to optical bench subassemblies, particularly optical fiber subassemblies based on optical benches, and more particularly hermetic optical fiber
• optical fiber waveguides There are many advantages of transmitting light signal via optical fiber waveguides and the use thereof is diverse. Single or multiple fiber waveguides may be used simply for transmitting visible light to a remote location. Complex telephony and data communication systems may transmit multiple specific optical signals.
• the data communication systems involve devices that couple fibers in an end-to-end relationship, including optoelectronic or photonic devices that include optical and electronic components that source, detect and/or control light, converting between light signals and electrical signals.
• a transceiver is an optoelectronic module comprising both a transmitter (Tx) and a receiver (Rx) which are combined with circuitry within a module housing, which is known in the art as a package.
• the package may be hermetically sealed to protect its contents from the environment.
• the transmitter includes a light source (e.g., a VCSEL or DFB laser), and the receiver includes a light sensor (e.g., a photodiode (PD)).
• a transceiver's circuitry e.g., including a laser driver, trans-impedance amplifier (TIA), etc. is soldered onto a printed circuit board.
• Such a transceiver generally has a substrate that forms the bottom or floor of the package (either hermetic or non-hermetic), and then optoelectronic devices such as lasers and photodiodes are soldered onto the substrate.
• Optical fibers are connected to the exterior of the package or fed through the wall of the package using a hermetic feedthrough (see, US20130294732A1, which had been commonly assigned to the Assignee/ Applicant of the present application, and is fully incorporated as if fully set forth herein).
• the end of the optical fiber is optically coupled to the optoelectronic devices held within the housing.
• a feedthrough element supports the portion of the optical fiber through the wall opening.
• an optoelectronic device supported on a printed circuit board needs to efficiently couple light to an external optical fiber.
• Some optoelectronic devices require single-mode optical connections that require stringent alignment tolerances between optical fibers and the devices, typically less than 1 micrometer. This is challenging especially for multiple fiber applications, where multiple optical fibers need to be optically aligned to multiple optoelectronic devices using an active optical alignment approach in which the position and orientation of the optical fiber(s) is adjusted by machinery until the amount of light transferred between the fiber and optoelectronic is maximized.
• Figs. 1 A and IB depict a hermetically sealed optoelectronic package 500, having a hermetic multi-fiber feedthrough 502, in which the hermetic feedthrough 502 is actively aligned with the photonic device 504 mounted on a submount 506 supported by the floor of the package 500.
• the feedthrough 502 resembles the optical coupling device disclosed in US2016/0016218A1, which had been commonly assigned to the Assignee/ Applicant of the present application, and is fully incorporated as if fully set forth herein).
• the photonic device 504 may include a VCSEL array and/or PD array, which is supported on the package floor, e.g., via a submount 506 and a printed circuit board 508.
• the printed circuit board 508 is populated with other electronic components and circuits, and the package 500 may include several printed circuit boards.
• the feedthrough 504 is inserted through an opening 503 defined by a snout 50 on the sidewall of the housing 501 of the package 500.
• the array of optical fibers 20 of an optical fiber cable 21 is supported by the feedthrough 502, and are actively aligned with the photonic device 504, to achieve the desired optical coupling efficiency between the photonic device and the array of optical fibers 20. This process requires the photonic device 504 and associated electronics (not shown) to be preassembled into the package 500.
• the photonic device 504 is activated/energized to transmit/receive an optical signal 22 to/from the array of optical fibers 20. Essentially, optical signals to/from the optical fibers 20 are optimally coupled to the photonic device 504 when the signal 22 transferred between the optical fibers 20 and the photonic device 504 is maximized.
• the feedthrough 502 is then soldered into the snout 50 at the package sidewall of the housing 501 in the optically aligned state.
• Active optical alignment involves relatively complex, low throughput processes since the VCSEL or PD must be energized during the active alignment process. Manufacturers of integrated circuits often have expensive capital equipment capable of sub-micron alignment (e.g. wafer probers and handlers for testing integrated circuits), whereas companies that package chips generally have less capable machinery (typically several micron alignment tolerances which is not adequate for single-mode devices) and often use manual operations.
• the current state of the art is expensive due to the inclusion of a package, excludes the use of common electronics and assembly processes, and/or often not suited to single-mode applications.
• the package is a relatively more expensive assembly (which includes expensive circuit components, such as ICs, etc.) as compared to the hermetic feedthrough subassembly.
• the required preassembly of components in the package to support active optical alignment and further given the active alignment and soldering process involve high risk steps towards the end of the overall packaging process, failure to achieve active alignment because of defective components, which may be induced in the active alignment process, would lead to the entire package being discarded, including the photonic devices and other components already packaged therein.
• VCSEL and PD components may be tested in a static state prior to assembly, however they cannot be tested in an operational state until assembled in the package along with the electronics to drive these components. Accordingly, burn-in process (to identify earlier-life component failures under simulated load conditions) of the VCSEL and PD components can only be conducted after assembly of these components into the package. This would lead to further waste of packages (i.e., low yield of packages) that are relatively more expensive module as assembled, as a result of defective but relatively inexpensive VCSEL and PD components. VCSEL and PD components are known to contribute to a relatively high number of failures of assembled packages.
• a further failure mode leading to waste of assembled packages is caused by the relatively larger and more compliant structural loop (represented by dotted line L in Fig. IB) that maintains optical alignment between the photonic device and the feedthrough, as shown in Fig. IB.
• the long structural loop is more sensitive to thermal-mechanical deformations, which could render the package to stray outside of intended design specification, thus resulting in failure mode.
• What is needed is an improved structure to couple the input/output of optical fibers in optical alignment to optoelectronic components/photonic devices, which improves throughput, tolerance, manufacturability, ease of use, functionality and reliability at reduced costs.
• the present invention provides an improved structure to facilitate optical alignment of photonic device to an optical bench, which overcomes the drawbacks of the prior art.
• the present invention combines a photonic device with an optical bench in a subassembly, so that alignment of the optical coupling of the photonic device with the optical bench can be performed outside of the optoelectronic package assembly.
• the photonic device is attached to a base of the optical bench, with its optical input/output in optical alignment with the optical output/input of the optical bench.
• the optical bench supports an optical component in the form of an optical wave guide (e.g., an optical fiber).
• the base of the optical bench defines an alignment structure in the form of at least one groove to precisely support the end section of an optical fiber.
• An optical element e.g., a lens, a prism, a reflector, a mirror, etc.
• the optical element comprises a structured surface, which may be planar reflective or concave reflective (e.g., an aspherical mirror surface).
• the photonic device may be mounted on a submount, which is attached to the base of the optical bench in optical alignment with the optical bench.
• the submount may be provided with circuits, electrical contact pads, circuit components (e.g., a driver for VCSEL, a TIA for a PD), and other components and/or circuits associated with the operation of the photonic device.
• the photonic device may be passively aligned with the optical bench (e.g., relying on alignment indicia provided on the base of the bench).
• the photonic device and the optical bench may be actively aligned by passing an optical signal between the optical waveguide in the optical bench and the photonic device.
• the photonic device e.g., a VCSEL and/or PD
• the photonic device can be activated to allow for active alignment with the optical waveguide (e.g., an optical fiber) supported in the optical bench, without relying on the other components within the package.
• the submount of the photonic device is fixedly attached to the base of the optical bench.
• the base of the optical bench is preferably formed by stamping a malleable material (e.g., metal), to form precise geometries and features of the optical bench.
• the optical bench subassembly can be structured to be hermetically sealed.
• the optical bench is structured to support multiple waveguides (e.g., multiple optical fiber), and structure reflective surfaces (e.g., an array of mirrors), to work with an array of photonic devices (VCSELs and/or PDs) mounted on a submount.
• multiple waveguides e.g., multiple optical fiber
• structure reflective surfaces e.g., an array of mirrors
• VCSELs and/or PDs photonic devices
• the present invention preassemblies optical elements and components and photonic devices precisely in an optical bench subassembly, prior to assembling into the larger
• the subassembly can be functionally tested, including burn-in tests, in a subassembly level, outside of a optoelectronic package, thus reducing waste of more expensive optoelectronic packages arising from early failure in the photonic devices installed therein.
• Fig. 1 A illustrates a hermetic optoelectronic package including a hermetic optical fiber feedthrough
• Fig. IB is a sectional view taken along line IB-IB in Fig. 1 A.
• FIG. 2A illustrates an optical bench subassembly in the form of a hermetic feedthrough, including an integrated photonic device, in accordance with one embodiment of the present invention
• Fig. 2B is a sectional view taken along line 2B-2B in Fig. 2A, shown as installed in a hermetic optoelectronic package.
• FIG. 3 A is an expanded view of the optical bench in the optical bench subassembly in Fig. 2, in accordance with one embodiment of the present invention
• Fig. 3B is an assembled view of the optical bench.
• FIG. 4A is an expanded view of the optical bench in the optical bench subassembly, in accordance with another embodiment of the present invention
• Fig. 4B is an assembled view of the optical bench.
• Fig. 5 illustrates an alternate embodiment of a submount for the photonic device in the optical bench subassembly.
• Figs. 6A to 6C illustrate the sequence of assembly of a hermetic optoelectronic package, wherein Fig. 6A depicts assembly of a photonic device assembly; Fig. 6B depicts assembly of the photonic device assembly to the optical bench and active alignment; Fig. 6C depicts assembly of the hermetic optoelectronic package.
• Fig. 7 illustrates the hermetic feedthrough as installed in the hermetic optoelectronic package.
• the present invention provides an improved structure to facilitate optical alignment of photonic device to an optical bench, which overcomes the drawbacks of the prior art.
• the present invention combines a photonic device with an optical bench in a subassembly, so that alignment of the optical coupling of the photonic device with the optical bench can be performed outside of the optoelectronic package assembly.
• the photonic device is attached to a base of the optical bench, with its optical input/output in optical alignment with the optical output/input of the optical bench.
• Various embodiments of the present invention incorporate some of the inventive concepts developed by the Assignee of the present invention, nanoPrecision Products, Inc., including various proprietary including optical bench subassemblies for use in connection with optical data transmissions, including the concepts disclosed in the patent publications discussed below, which have been commonly assigned to the Assignee. The priority of pending applications had been claimed herein.
• U.S. Patent Application Publication No. US2013/0322818A1 discloses an optical coupling device for routing optical signals, which is in the form of an optical bench having a stamped structured surface for routing optical data signals.
• the optical bench comprising a metal base having a structured surface defined therein, wherein the structured surface has a surface profile that bends, reflects, and/or reshapes an incident light.
• the base further defines an alignment structure, which is configured with a surface feature to facilitate precisely positioning an optical component (e.g., an optical fiber) on the base in precise optical alignment with the structured surface to allow light to be transmitted along a defined path between the structured surface and the optical component, wherein the structured surface and the alignment structure are integrally defined on the base by stamping a malleable metal material to form an optical bench.
• an optical coupling device for routing optical signals for use in an optical communications module in particular an optical coupling device in the form of an optical bench, in which defined on a metal base is a structured surface having a surface profile that bends, reflects and/or reshapes an incident light.
• An alignment structure is defined on the base, configured with a surface feature to facilitate positioning an optical component (e.g., an optical fiber) on the base in optical alignment with the structured surface to allow light to be transmitted along a defined path between the structured surface and the optical component.
• the structured surface and the alignment structure are integrally defined on the base by stamping a malleable metal material of the base.
• the alignment structure facilitates passive alignment of the optical component on the base in optical alignment with the structured surface to allow light to be transmitted along a defined path between the structured surface and the optical component.
• U.S. Patent Application Publication No. US2013/0294732A1 further discloses a hermetic optical fiber alignment assembly having an integrated optical element, in particular a hermetic optical fiber alignment assembly including an optical bench that comprises a metal ferrule portion having a plurality of grooves receiving the end sections of optical fibers, wherein the grooves define the location and orientation of the end sections with respect to the ferrule portion.
• the assembly includes an integrated optical element for coupling the input/output of an optical fiber to optoelectronic devices in an optoelectronic module.
• the optical element can be in the form of a structured reflective surface.
• the end of the optical fiber is at a defined distance to and aligned with the structured reflective surface.
• the structured reflective surfaces and the fiber alignment grooves can be formed by stamping a malleable metal to define those features on a metal base.
• U.S. Patent No. 9,213, 148 further discloses a similar hermetic optical fiber alignment assembly, but without an integrated structured reflective surface.
• U.S. Patent No. 7,343,770 discloses a novel precision stamping system for manufacturing small tolerance parts.
• inventive stamping system can be implemented in various stamping processes to produce the devices disclosed in the above-noted patent publications. These stamping processes involve stamping a bulk material (e.g., a metal blank), to form the final overall geometry and geometry of the surface features at tight (i.e., small) tolerances, including reflective surfaces having a desired geometry in precise alignment with the other defined surface features.
• U.S. Patent Application Publication No. US2016/0016218 Al further discloses a composite structure including a base having a main portion and an auxiliary portion of dissimilar metallic materials.
• the base and the auxiliary portion are shaped by stamping.
• relatively less critical structured features can be shaped on the bulk of the base with less effort to maintain a relatively larger tolerance, while the relatively more critical structured features on the auxiliary portion are more precisely shaped with further considerations to define dimensions, geometries and/or finishes at relatively smaller tolerances.
• the auxiliary portion may include a further composite structure of two dissimilar metallic materials associated with different properties for stamping different structured features.
• This stamping approach improves on the earlier stamping process in U.S. Patent No. 7,343,770, in which the bulk material that is subjected to stamping is a homogenous material (e.g., a strip of metal, such as Kovar, aluminum, etc.)
• the stamping process produces structural features out of the single homogeneous material.
• different features would share the properties of the material, which may not be optimized for one or more features.
• a material that has a property suitable for stamping an alignment feature may not possess a property that is suitable for stamping a reflective surface feature having the best light reflective efficiency to reduce optical signal losses.
• U.S. Patent No. 8,961,034 discloses a method of producing a ferrule for supporting an optical fiber in an optical fiber connector, comprising stamping a metal blank to form a body having a plurality of generally U-shaped longitudinal open grooves each having a longitudinal opening provided on a surface of the body, wherein each groove is sized to securely retain an optical fiber in the groove by clamping the optical fiber.
• the optical fiber is securely retained in the body of the ferrule without the need for additional fiber retaining means.
• PCT Patent Application Publication No. WO2014/011283A2 discloses a ferrule for an optical fiber connector, which overcomes many of the drawbacks of the prior art ferrules and connectors, and further improves on the above noted pin-less alignment ferrules.
• the optical fiber connector includes an optical fiber ferrule, which has a generally oval cross-section for aligning an array of multiple optical fibers to optical fibers held in another ferrule using a sleeve.
• hermetic optical fiber feedthrough for hermetic optoelectronic packages, which includes an optical bench subassembly with an integrated photonic device.
• FIGs. 2A and 2B illustrate one embodiment of a hermetic optical fiber feedthrough, in the form of an optical bench subassembly 10 that includes an optical bench 11 having an integrated photonic device 12 in accordance with one embodiment of the present invention.
• the photonic device 12 is mounted on a submount 14, which is attached to the optical bench 11, at a location in alignment with the optical input/output of the optical bench 11 (see optical signal 22 in Fig. 2B).
• Figs. 3 A and 3B illustrate more clearly the structure of the optical bench 11 in the optical bench subassembly 10.
• the optical bench 11 resembles the hermetic multi- fiber alignment subassembly disclosed in Assignee's US2016/0016218 Al referenced above.
• the optical bench supports one or more optical waveguides, which in the illustrated embodiment is a plurality of optical fibers 20 of an optical fiber cable 21.
• the base 13 of the optical bench 11 defines a plurality of open grooves 16 supporting the optical fibers 20, and defines or supports an optical element (e.g., a lens, a prism, a reflector, a mirror, etc.).
• the optical element comprises an array of structured reflective surfaces 17, each corresponding to an optical fiber 20.
• the reflective surface may be planar reflective or contoured to be concave reflective (e.g., an aspherical mirror surface) or convex reflective.
• the base 13 comprises a composite structure, including an auxiliary portion 30 of a material dissimilar to the material of the rest of the base 13 (i.e., the main portion 13').
• the base 13 including the auxiliary portion 30 are stamped from malleable materials to form the body geometry and the desired surface features.
• the auxiliary portion is shaped by stamping a malleable metallic material to form the array of structured reflective surfaces 17 and grooves 18, while the base 13 is stamped from a different malleable metallic material to form the grooves 16 and the other structures shown.
• the auxiliary portion 17 is stamped, it interlocks with the base 13, resembling a rivet, and at the same time forming the desired structured features on the auxiliary portion 30, including the array of structured reflective surfaces 17, and optical fiber alignment grooves 18 for supporting the end sections of the optical fibers 20, such that each reflective surface 17 and an end face (i.e., the input/output) of a corresponding optical fiber 20 are maintained in precise relationship.
• the auxiliary portion 17 and the main portion 13' are stamped using dissimilar metallic materials.
• the open grooves 16 and 18 may be configured and formed in accordance with the stamped open grooves disclosed in U.S. Patent No. 8,961,034, which clamps the optical fibers in securely in the groove without requiring additional securing means (e.g., no epoxy, etc.).
• a cover 15 is provided to cover the base 13 without covering the structured reflective surfaces 17.
• a hermetic sealing epoxy e.g., glass epoxy
• FIGs. 4A and 4B illustrate another embodiment of an optical bench 11 ', which is similar to the optical bench 11 in Figs. 3 A and 3B, with the exception of the fiber cable 21.
• the optical bench 11 ' is provided with a demountable connection in the form of a ferrule 30.
• the ferrule 30 supports the rear end sections of short sections of optical fibers 20, with the distal front end sections of the optical fibers supported by the grooves 16 and 18 within the optical bench 1 ⁇ .
• the ferrule 30 may be structured to have a generally oval cross-section, as disclosed in
• a sleeve (not shown) can be used to couple to, for example, an optical fiber cable (e.g., a patch cable) that is terminated with a similar ferrule.
• an optical fiber cable e.g., a patch cable
• the connecting optical fiber if it becomes defective, it can be disconnected and replaced, without having to replace the entire optoelectronic package to which the optical bench 11 ' is permanently or fixedly attached.
• the photonic device 12 is mounted on a submount 14 to form a photonic device assembly 23.
• the submount 14 may be provided with circuits, electrical contact pads, circuit components (e.g., a driver for VCSEL, a TIA for a PD), and other components and/or circuits associated with the operation of the photonic device 12.
• Figs. 6A to 6C illustrate the sequence of assembly of a hermetic optoelectronic package.
• Fig. 6A depicts assembly of a photonic device (a transmitter or a receiver or a transceiver) assembly
• Fig. 6B depicts assembly of the photonic device assembly to the optical bench and active alignment
• Fig. 6C depicts assembly of the hermetic optoelectronic package.
• the photonic device 12 is a transmitter, such as a VCSEL, it is mounted on the submount 14, along with a driver chip.
• the VCSEL may be wirebonded to the circuit on the submount 14.
• Test may be performed to confirm that the VCSEL is operative to transmit an optical signal after assembly.
• the photonic device 12 is a receiver, such as a PD, it is mounted on the submount 14, along with a TIA chip.
• the PD may be wirebonded to the circuit on the submount 14.
• Test may be performed to confirm that the PD is operative to receive an optical device and output an electrical signal after assembly.
• a transceiver the above procedures are combined to test the separate receiving and transmitting functions.
• the photonic device 12 may include a plurality of receivers, transmitters and/or transceivers mounted on the submount 14.
• the submount 14 of the photonic device assembly is attached to the opposing surface of the base 13 of the optical bench 11, at a position in which the photonic device 12 is in optical alignment with the optical bench 11, where the input/output of the photonic device 12 is optically aligned with the output/input of the optical bench 11, so that the optical path 22 achieves the desired optical coupling efficiency between the photonic device 12 and the optical fiber 20.
• the optical path 22 is between the input/output end face of an optical fiber 20 and the output/input of a corresponding optical device 12, which is bent and reshaped by the reflective surface 17 (e.g., an aspherical mirror surface).
• the optical path is in a direction out of the plane of the base 13, which is generally perpendicular to the plane of the base 13.
• the plane of the submount 24 is parallel to the plane of the base 13.
• a frame 32 is provided as a spacer between the submount 14 and the opposing surface of the base 13, to provide a space to accommodate the photonic device 12 between the submount 14 and the base 13.
• the photonic device 12 may be passively aligned with the optical bench 11 (e.g., by relying on alignment indicia (not shown) provided on the base of the bench 11).
• the photonic device 12 and the optical bench 11 may be actively aligned by passing an optical signal between the optical waveguide (i.e., the optical fibers 20) in the optical bench 11 and the photonic device 12, and measuring the strength of the optical signal in the optical path to determine the optical coupling that indicates an optically aligned state.
• the photonic device 12 (e.g., a VCSEL and/or PD) can be activated to allow for active alignment with the optical fibers supported in the optical bench 11, without having to rely on the other components within the optoelectronic package to which the optical bench subassembly 10 is to be installed.
• the photonic device 12 is a transmitter (e.g., a VCSEL)
• it is energized to emit light to the reflective surface 17 to be directed to the end face of the corresponding optical fiber 20.
• the strength of the optical signal transmitted via the reflective surface 17 and through the corresponding optical fiber is measured to determine optical coupling between the transmitter and the optical bench 11.
• the photonic device is a receiver (e.g., PD)
• an optical signal is supplied through the optical fiber, which is reflected by the reflective surface to a corresponding receiver.
• the extent of optical coupling between the optical fiber and the receiver can be determined from the electrical output of the receiver (which corresponds to strength of the optical signal received), so as to identify the aligned state.
• the active alignment process involves moving the photonic device 12 in the plane of the submount
• electrically conductive pads are provided on the surface of the submount that face away from the base 13.
• the submount 14 of the photonic device 12 is fixedly attached to the base of the optical bench, e.g., by laser welding, soldering or epoxy.
• the foregoing embodiments of the optical bench subassembly 10 that include the integrated photonic device 12 are hermetic feedthrough with the integrated photonic device 12.
• an optoelectronic package 500' e.g., by soldering
• the optoelectronic package 500' is populated with various components (e.g., ICs, chips, submounts, circuit boards, etc.).
• the optical bench subassembly 10 as a hermetic feedthrough is inserted through the opening of the snout 50 in the sidewall of the housing 501 ' of the package 500' and hermetically sealed (e.g., by soldering).
• the position of this feedthrough with respect to the package 500' is not as critical since there is no optical alignment required between the feedthrough and an external photonic device within the package 500'.
• the submount 14 may be solder bonded to a printed circuit board 39 (which could be a flexible printed circuit board) within the package 500', with vias 36 provided through the substrate of the submount 14 to connect to the photonic device 12 on the other side of the submount 14.
• a ball-grid array (BGA) with micro solder ball joints may be configured on the submount 14.
• Other electrical connections may include the optical bench subassembly 10' in the embodiment of Fig. 5, in which wrap-around traces 38 provided on the side of the submount 14' are electrically connected to a circuit board (not shown) in the package 500' by a wire bond or flex circuit joint 37.
• spring pins may be configured to make the electrical connections between the submount and a printed circuit board in the package 500' .
• Fig. 7 illustrates the hermetic feedthrough/optical bench subassembly 10 as installed in the hermetic optoelectronic package 500' .
• the other electronics and circuit components are omitted from view in Fig. 7.
• the hermetic cover of the hermetic optoelectronic package 500' is also omitted from view.
• the package 500' can be burned-in to eliminate early-life failures and further functionally tested. [0055] Given the present invention preassemblies optical elements and components and photonic devices precisely in an optical bench subassembly prior to assembling into the larger
• the optical bench subassembly can be functionally tested, including burn-in tests, in a subassembly level, outside of an optoelectronic package, thus reducing waste of more expensive packages (which includes expensive circuit components, such as ICs, etc.) arising from early failure in the photonic devices installed therein.
• the active alignment process for the optical bench subassembly is much easier. Further, much smaller and more robust structural loop is present between the optical bench and the photonic device. Thus overall higher yield, higher reliability and lower manufacturing costs can be achieved for optoelectronic packages incorporating the hermetic feedthrough in accordance with the present invention.

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• 2016
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