Laser array integrated on photonic device and methods of making the same

Abstract

A device includes a photonic integrated circuit (PIC) and a laser module. A surface of the PIC defines a recess in the PIC. The PIC comprises: first waveguides partially disposed in the recess, optical splitters, second waveguides at least partially disposed in the PIC, and electrical contacts. The laser module is mounted on the surface of the PIC and comprises: a substrate spanning the recess and supported by the PIC at two opposing edges of the recess, and lasers each having an output port, the lasers being supported by the substrate and at least partially disposed in the recess and optically coupled to a respective first waveguide of the PIC. The electrical contacts electronically connect the lasers to a voltage source. Portions of the PIC comprise an optically nonlinear material coupled to the second waveguides and configured to generate a frequency comb from optical signals received from the lasers.

Description

[0001] Attorney Ref.: 56403-0025W01

[0002] LASER ARRAY INTEGRATED ON PHOTONIC DEVICE AND METHODS OF MAKING THE SAME

[0003] BACKGROUND

[0004] Silicon photonic devices utilize silicon as an optical medium. Because silicon is used as a substrate for most integrated circuits, silicon photonic devices can be hybrid devices that integrate both optical and electronic components into a single integrated circuit package.

[0005] Photonic devices can include both a laser assembly and a photonic integrated circuit (PIC) co-packaged on a common substrate, with the laser assembly generating a laser beam to be in-coupled to the PIC.

[0006] SUMMARY

[0007] Recent advances in photonics include integrating individual lasers to photonic integrated circuits (PICs). However, having multiple lasers integrated onto a single PIC can be beneficial in photonic devices that utilize multiple laser wavelengths during operation. The instant disclosure provides devices with laser arrays integrated with a single PIC and methods of making the same.

[0008] The disclosed devices can have precise alignment between an individual laser from the array of lasers and a respective waveguide of an array of waveguides, e.g., hundreds nm or less. The precise alignment leads to more efficient optical coupling between the photonic integrated circuit and the array of lasers and thus reduced energy expenditure.

[0009] Using the disclosed methods provides a relatively low-cost way of coupling an array of lasers to an array of waveguides. For example, by providing passive, isolator-free butt-coupling, the cost of coupling multiple lasers generating different wavelengths of radiation to respective waveguides can be lowered. The disclosed devices can have relatively low noise reflection from the optical signal generated by the laser, due to improved mode profiles on both the laser and PIC sides and by suppressing reflections at the coupling interfaces. Moreover, PIC-level coherence-enhancement techniques can be applied to maintain frequency stability, removing the need for an external isolator.

[0010] Advantageously, the disclosed methods, devices, and systems can be generalized to optical gain media for amplification purposes. By applying the same coupling geometry at the input and output facets of a gain-die array, reflections at both interfaces Attorney Ref.: 56403-0025W01 can be engineered to remain sufficiently low to prevent parasitic cavity formation and self-lasing.

[0011] The details of one or more embodiments of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 A is a planar view of an example of a device with an integrated laser array. FIG. IB is a cross-sectional view of the device and FIG. 1A along line I-F.

[0014] FIG. 2 is a perspective view of an example of a device including a heat sink.

[0015] FIG. 3 A is a cross-sectional view of an example of a device with an integrated laser array configured for evanescent coupling. FIG. 3B is another cross-sectional view of the device of FIG. 3 A along line II-IF.

[0016] FIG. 4A is a cross-sectional view of an example of a device with a lens integrating a laser and a waveguide. FIG. 4B is a cross-sectional view of an example of a device with a photonic wire bond integrating a laser and a waveguide.

[0017] FIG. 5 is a flowchart of an example of a process of forming devices with an integrated laser array.

[0018] Like reference numbers and designations in the various drawings indicate like elements.

[0019] DETAILED DESCRIPTION

[0020] With reference to FIGS. 1 A and IB, a device 100 includes a photonic integrated circuit (PIC) 102 and a laser module 104 mounted on the PIC 102. The surface 102c of the PIC 102 defines a recess 101 in the PIC 102. The laser module 104 spans the recess 101 and is partially disposed within the recess 101 when mounted on the PIC 102.

[0021] Some of the components of the PIC 102 extend into the recess 101 and optically couple to the laser module 104. These components include waveguides 106a, 106b, 106c... 106n, each of which is optically coupled to a respective optical splitter 108. Each optical splitter 108 includes two respective splitter portions 108a, 108b, 108c, 108d, 108e, 108f... 108x, and 108y spaced apart from each other along the Y direction. Each waveguide 106a can be disposed above two splitter portions 108a and 108b, e.g.. each Attorney Ref.: 56403-0025W01 waveguide 106 overlaps two splitter portions along the Z direction. The waveguides 106 and splitters 108 are disposed within a substrate 110.

[0022] In some implementations, at least one of the waveguides 106 or the splitters 108 include silicon nitride (SiN), amorphous silicon (a-Si), or a combination thereof. The splitters 108 can be an elevator or a spot-size converter. In some implementations, the substrate 110 includes a polymer material, silicon oxynitride (SiON), or combination thereof. In some implementations, the substrate 110 is a planar light circuit (PLC) including doped silicon oxide. The material of the substrate 1 10 can be selected for low confinement and / or low-index-contrast relative to the waveguides 106.

[0023] The laser module 104 includes a substrate 112 spanning the recess 101 and supported by the opposing edges 102a and 102b of the recess 101. The substrate 112 supports an array of lasers 114a, 114, 114c... 114n. In some implementations, the lasers 114 are III-IV semiconductor, distributed feedback (DFB) lasers. In some implementations, the substrate 112 is a glass or silicon carrier substrate.

[0024] Each waveguide 106a is optically coupled to a respective laser 114a, such that optical signals from a laser 114 optically couple into the PIC 102. Each splitter 108 is optically coupled to a respective waveguide 116 disposed within the PIC 102, which is optically coupled to a respective portion 118 of optically nonlinear material. In some implementations, there is an index-cladding layer 120 surrounding part of the waveguides 116 to increase the coupling efficiency between the splitter 108 and the waveguide 116. In some implementations, at least one of the waveguides 1 16 or the portions 118 includes a nitride, e.g., silicon nitride (SiN).

[0025] When the portion 118 of the optically nonlinear material receives the in-coupled optical signals, the portion 118 behaves as a frequency comb generator, e.g., generates an optical spectrum including multiple sharp peaks of different wavelengths. Since the PIC 102 includes multiple portions 118 and the laser module 104 includes multiple lasers 114, the device 100 can generate many distinct optical spectra, e.g., frequency combs. Due to there being two splitter portions per waveguide 106. there are twice as many waveguides 116 and portions 118 as there are lasers 114. In some implementations, the portions 118 are frequency comb generators as described in U.S. Patent No. 12,300,963 B2 and U.S. Pub. No. 2024 / 0272364 Al, which are hereby incorporated by reference.

[0026] During operation of the device 100, electrical contacts 122a and 122b provide a voltage to the laser module 104. The electrical contacts (only electrical contact 122a is Attorney Ref.: 56403-0025W01 visible in cross-sectional view of FIG. IB) are disposed on the opposing edges 102a and 102b of the recess 101 on which the laser module 104 is disposed. In some implementations, the laser module 104 includes one or more redistribution layers 124a and 124b and solder balls 126a, 126b, 126c, and 126d to electrically couple the contacts to the laser array. Some of the solder balls 126a and 126d are disposed on the electrical contacts 122a and 122b, and some of the solder balls 126b and 126c are disposed on the lasers 1 14. The redistribution layers 124a and 124b are bonded to the solder balls.

[0027] The components of each of the PIC 102 and the laser module 104 are precisely arranged to provide efficient optical coupling between a laser 114a and a respective portion 118 of the PIC 102 for frequency comb generation. For example, the lasers 114a- 114n are spaced apart from each other along a horizontal direction, e.g., the Y direction, and the waveguides 106a- 106n are spaced apart from each other along the same horizontal direction. The spacing, e.g., the pitch, between adjacent lasers 114 and the spacing between adjacent waveguides 106 can be the same, such that when one pair of a waveguide 106a and an output port 114z of a laser 114a are aligned, the remaining pairs waveguides 106 and output ports of lasers 114 are also aligned. In some implementations, the spacing between adjacent lasers and the spacing between adjacent waveguides 106 is nonuniform.

[0028] Each splitter portion 108a includes a first end 109a coupled to a respective waveguide 106a and a second end 109b coupled to a respective waveguide 116. Although waveguide 1 16 is depicted as entirely disposed within the PIC 102, in some implementations, the waveguides 116 extend into the recess 101.

[0029] In some implementations, the coupling modules, e.g., referring to the substrate 110, the waveguides 106, and the splitters 108, are a part of the PIC 102 and bonded to a side surface 102d of the recess 101. In some limitations, the coupling modules are a part of the laser module 104 and bonded to the substrate 112, which can aid in achieving micron-scale accuracy relative to the laser emission point.

[0030] The devices disclosed herein can include various other components in addition to those depicted in device 100 to provide different features. For example, the device can have dual-side coupling. For example, the device can have coupling modules on both sides of the laser, e.g., on both the right and left side of the laser 114a in FIG. IB.

[0031] As another example, FIG. 2 depicts a device 200 that is similar to device 100, but a laser module 204 further includes a heat sink 201 disposed between an array of lasers Attorney Ref.: 56403-0025W01

[0032] 214 and a substrate 212 supporting the array of lasers 214. A substrate 210 includes waveguides 206, which are each optically coupled to a respective output port 214z of a laser 214. The heat sink 201 helps maintain a constant temperature in the array of lasers 214. The heat sink 201 maintains a constant temperature, which leads to precise wavelengths of the generated laser radiation. For reference, the orientation of the vertical, Z direction is flipped between FIGS. IB and 2.

[0033] FIG. 3 A depicts an example of a device 300 designed to promote evanescent coupling between a PIC 302 and a laser module 304. The surface of the PIC 302 defines a recess 301 in which the laser module 304 is disposed. The laser module 304 includes a substrate 312 supporting an array of lasers 314 and a substrate 310. An array of waveguides 306 is disposed within the substrate 310, which can be a polymer waveguide or a planar lightwave circuit (PLC). The device 300 does not include a splitter, so there are as many waveguides 316 as there are lasers 314.

[0034] The PIC 302 includes an array of waveguides 316. The waveguides 306 and 316 can be sufficiently close and overlap along the vertical direction, e.g.. the Z direction, such that the optical signal generated by the laser 314 can evanescently couple from the waveguide 306 into the waveguide 316. For example, a spacing (along the Z direction) between a lower surface 310a of the substrate 310 and an upper surface 302a of the PIC 302 under the recess 301 can be between hundreds of nanometers to a few microns. To keep this spacing small, the waveguides 316 can be disposed relatively close to the upper surface 302a of the PIC 302, e.g., a distance d between the upper surface 302a and the waveguides 316 can be betw een hundreds of nanometers to a few7microns.

[0035] By using evanescent coupling betw een the w aveguides 306 and 316, the vertical coupling tolerance between the waveguides 306 and 316 is relaxed, e.g., compared to the vertical coupling tolerance between the splitter portion 108a and the waveguide 116 in device 100.

[0036] In some implementations, the PIC 302 is configured for mode expansion and / or scale invariant modes in the waveguide 316. For example, FIG. 3B depicts an example of a cross-sectional view of the PIC 302 along line II-IF. The PIC 302 can include layers 330 alternating with high and low refractive indices. For example, a top layer 330a and a bottom layer 330c can each have a high refractive index, e.g., greater than 1.7, and a middle layer 330b can have a lower refractive index, e.g., less than 1.7. In other words, the lower index layer is sandwiched between the higher index layers, which effectively Attorney Ref.: 56403-0025W01 expands the beam width of in-coupled optical signals along the vertical direction, e.g., expanding from 100s of nm to 10s of microns. In some implementations, each of the layers 330 includes SiN, but with different stoichiometries of Si and N. In some implementations, layers 330 can include a low index material, such as SiON.

[0037] In some implementations, devices include integration between the coupling module and the array of lasers, e.g., semiconductor III-V laser to polymer waveguide integration. For example, FIG. 4A depicts a device 400a including a three-dimensional (3D) printed polymer lens 417 integrating an output port 414z of a laser 414 to a waveguide 406, which is optically coupled to a splitter 408. A PIC 402 includes a waveguide 416, which optically couples to the splitter 408. Although FIG. 4A depicts the lens 417 in an arrangement where the waveguides 406 and 416 do not overlap along the vertical direction, embodiments like FIG. 3A can also include a lens between the coupling module, e.g., substrate 310, and the laser 314.

[0038] As another example, FIG. 4B depicts a device 400b including a photonic wire bond 419 integrating the output port 414z of the laser 414 to the waveguide 406. Although FIG. 4B depicts the photonic wire bond 419 in an arrangement where the waveguides 406 and 416 do not overlap along the vertical direction, embodiments like FIG. 3 A can also include a photonic wire bond between the substrate 310 and the laser 314.

[0039] FIG. 5 is a flow diagram of a process 500 for forming a device, such as any of devices 100, 200, 300, 400a, or 400b.

[0040] The process 500 includes providing a PIC with a surface defining a recess in the PIC (510). For example, PIC 102 includes a surface defining a recess 101.

[0041] The process includes disposing a substrate at two opposing edges of the recess such that an array of lasers and an array of coupling modules supported by the substrate are at least partially disposed within the recess (520). For example, substrate 112 is disposed at opposing edges 102a and 102b of the recess 101. An array of lasers, e.g., lasers 114a-114n, and an array of coupling modules, e.g., waveguides 106a-106n and splitter portions 108a-108y, are at least partially disposed within the recess 101. In some implementations, the array of coupling modules is disposed in a continuous substrate, e.g., substrate 110.

[0042] In some implementations, disposing a substrate on the PIC includes using alignment one or more markers of the substrate 112, the waveguide 106, or the PIC 102. Attorney Ref.: 56403-0025W01

[0043] The process includes forming waveguides in the PIC such that an output of each coupling module of the array of coupling modules is aligned with a respective waveguide (530). For example, waveguides 116 are formed in the PIC 102 such that an output of each coupling module, e.g., output from each splitter portion, is aligned with a respective waveguide 116.

[0044] The process includes forming frequency comb generators in the PIC such that each frequency comb is optically coupled to a respective waveguide (540). For example, the portions 118 are formed as frequency comb generators in the PIC 102 such that each portion 118 is coupled to a respective waveguide 116.

[0045] The order of steps in the process 500 described above is illustrative only, and steps 510, 520. 530, and 540 can be performed in different orders. For example, each of steps 530 and 540 can be performed before disposing a substrate on the PIC, and step 540 can occur before step 530. In some implementations, forming the waveguides in the PIC (step 530) after disposing the substrate on the PIC (step 520) can be advantageous, since then the waveguides can be formed to account for any inconsistency in laser spacing, thereby preventing alignment mismatch between the lasers and waveguides.

[0046] In some implementations, the process 500 can include additional steps, fewer steps, or some of the steps can be divided into multiple steps. For example, before disposing the substrate 112 on tw o opposing edges 102a and 102b of the recess 101, the array of lasers 114 is attached to the substrate 112 using solder balls 126 and redistribution layers 124. In some implementations, attaching the array of lasers 114 to the substrate 112 includes reflow / thermal compression or laser-assisted bonding, e.g., hybrid bonding.

[0047] In some implementations, the process 500 includes forming the recess in the PIC, which can include lithography and / or etching.

[0048] In some implementations, the process 500 includes connecting contacts 112a and 112b to the laser array, w hich electronically couple the array of lasers 114 to a voltage source.

[0049] In some implementations, the process 500 includes forming cladding layers 120 around respective waveguides 116.

[0050] In some implementations, the process 500 includes, before disposing the substrate on the PIC, forming the array of coupling modules. In some cases, forming the array of coupling modules includes disposing a polymer. SiON, or a PLC on the substrate 112. In Attorney Ref.: 56403-0025W01 other cases, the array of coupling modules are formed on a side surface 102d of the PIC, and the polymer, SiON, or a PLC is disposed on the PIC 102. Either way, forming the array of coupling modules continues with forming an array of waveguides 106 and optical splitters 108 within the disposed polymer, SiON, or a PLC.

[0051] In some implementations, process 500 further includes 3D printing lenses, e.g., lens 417, each lens printed on an output port, e.g., output port 414z. of a respective laser in the array of lasers.

[0052] In some implementations, process 500 further includes 3D printing photonic wire bonds, photonic wire bond 419, each photonic wire bond printed on an output port, e.g., output port 414z, of a respective laser in the array of lasers.

[0053] In some implementations, the process 500 further includes disposing a heat sink, e.g., heatsink 201, on the array of lasers, e.g., lasers 214.

[0054] In addition to the embodiments of the attached claims and the embodiments described above, the following numbered embodiments are also innovative.

[0055] Embodiment 1 is a device, the device comprising a photonic integrated circuit (PIC) and a laser module. The PIC has a surface defining a recess in the PIC and comprises: a plurality of first waveguides at least partially disposed in the recess, a plurality of optical splitters, each optical splitter comprising first and second splitter portions, each of the first and second splitter portions being optically coupled to a respective first waveguide at a first end and optically coupled to a respective second waveguide at a second end, a plurality of second waveguides at least partially disposed in the PIC, and a plurality’ of electrical contacts. The laser module is mounted on the surface of the PIC and comprises: a substrate spanning the recess and supported by the surface of the PIC at two opposing edges of the recess, and a plurality of lasers each having an output port, the plurality of lasers being supported by the substrate and at least partially disposed in the recess, each laser being optically coupled to a respective first waveguide of the PIC. The plurality of electrical contacts electronically connect the plurality of lasers to a voltage source. The PIC comprises one or more portions of an optically nonlinear material coupled to the plurality of second waveguides and configured to generate a frequency comb from optical signals received from the plurality’ of lasers.

[0056] Embodiment 2 is the device of embodiment 1, where the PIC comprises a cladding layer disposed around each second waveguide of the plurality of second waveguides. Attorney Ref.: 56403-0025W01

[0057] Embodiment 3 is the device of embodiment 1 or embodiment 2, where the PIC comprises: a plurality’ of first solder balls disposed on each laser of the plurality’ of lasers; a plurality' of second solder balls disposed on the plurality of electrical contacts; and a plurality of redistribution layers bonded to each of the pluralities of first and second solder balls. Each laser of the plurality of lasers is bonded to the two opposing edges of the PIC through the pluralities first and second solder balls and the plurality’ of redistribution layers.

[0058] Embodiment 4 is the device of any of embodiments 1-3, where the plurality7of lasers comprise at least one III-V semiconductor laser.

[0059] Embodiment 5 is the device of any of embodiments 1-4, where the plurality of first waveguides and the plurality of optical splitters comprise at least one of SiN or amorphous Si.

[0060] Embodiment 6 is the device of any of embodiments 1-5, yvhere the PIC comprises a second substrate surrounding the plurality of first waveguides and the plurality of optical splitters, the second substrate comprising a polymer or SiON.

[0061] Embodiment 7 is the device of any of embodiments 1 -6, where the first and second waveguides overlap along a vertical direction and are spaced sufficiently close to each other along the vertical direction for the optical signals from the lasers to evanescently couple from the first waveguide to the second waveguide.

[0062] Embodiment 8 is the device of any of embodiments 1-7. where the plurality of second waveguides comprise SiN.

[0063] Embodiment 9 is the device of any of embodiments 1-8, yvhere the substrate comprises Si.

[0064] Embodiment 10 is the device of any of embodiments 1-9, further comprising a heat sink disposed on respective surfaces of the plurality of lasers and between the substrate and the plurality of lasers.

[0065] Embodiment 11 is the device of any of embodiments 1-10, where a portion of the PIC comprises at least three stacked portions, where a first stacked portion is sandwiched between second and third stacked portions that have a higher index of refraction than that of the first stacked portion.

[0066] Embodiment 12 is the device of any of embodiments 1-11, where the laser module further comprises a lens or a photonic wire bond disposed between a respective output Attorney Ref.: 56403-0025W01 port of each laser of the plurality of lasers and a respective first waveguide of the plurality of first waveguides.

[0067] Embodiment 13 is a device, the device comprising a photonic integrated circuit (PIC) and a laser module. The PIC has a surface defining a recess in the PIC and comprises: a plurality' of first waveguides at least partially disposed in the PIC, a plurality' of electrical contacts, and one or more portions of an optically nonlinear material coupled to the plurality of first waveguides; a laser module mounted on the surface of the PIC. The laser module is mounted on the surface of the PIC and comprises: a substrate spanning the recess and supported by the surface of the PIC at two opposing edges of the recess, a plurality' of lasers each having an output port, the plurality of lasers being supported by the substrate and at least partially disposed in the recess, a plurality of second waveguides at least partially disposed in the recess, each laser being optically coupled to a respective second waveguide, and a plurality' of optical splitters, each optical splitter comprising first and second splitter portions, each of the first and second splitter portions being optically coupled to a respective second waveguide at a first end and optically coupled to a respective second waveguide at a second end. The plurality' of electrical contacts electronically connect the plurality of lasers to a voltage source. The one or more portions of PIC are configured to generate one or more frequency combs from optical signals received from the plurality of lasers.

[0068] Embodiment 14 is a method, the method comprising: providing a photonic integrated circuit (PIC) with a surface defining a recess in the PIC; disposing a substrate at two opposing edges of the recess such that an array of lasers and an array of coupling modules supported by the substrate are at least partially disposed within the recess; forming a plurality of waveguides in the PIC such that an output port of each coupling module of the array of coupling modules is aligned with a respective waveguide of the plurality of waveguides; and forming a plurality' of frequency' comb generators in the PIC such that each frequency comb of the plurality of frequency comb generators is optically- coupled to a respective waveguide of the plurality of waveguides.

[0069] Embodiment 15 is the method of embodiment 14, further comprising, before disposing the substrate on the two opposing edges of the recess, attaching the array' of lasers to the substrate using a plurality of solder balls and a plurality' of redistribution layers. Attorney Ref.: 56403-0025W01

[0070] Embodiment 16 is the method of embodiment 14 or embodiment 15, further comprising providing contacts electronically coupled to a voltage source on the two opposing edges of the PIC, such that voltage source is electronically coupled to the array of lasers.

[0071] Embodiment 17 is the method of any one of embodiments 14-16, further comprising providing a plurality of cladding layers, each cladding layer formed around a respective waveguide of the plurality of waveguides.

[0072] Embodiment 18 is the method of any one of embodiments 14-17, further comprising, before disposing the substrate on the two opposing edges of the PIC, forming the array of coupling modules. Forming the array of coupling modules comprises: disposing a polymer or SiON medium on the substrate; forming an array of SiN or amorphous Si waveguides; and forming an array of optical splitters at least partially overlapping the array of SiN or amorphous Si waveguides.

[0073] Embodiment 19 is the method of any one of embodiments 14-18, further comprising: three-dimensional (3D) printing a plurality of lenses, each lens of the plurality of lenses printed on an output port of a respective laser of the array of lasers, or 3D printing a plurality of photonic wire bonds, each photonic wire bond of the plurality of photonic wire bonds printed on an output port of a respective laser of the array of laser.

[0074] Embodiment 20 is the method of any one of embodiments 14-19, further comprising disposing a heat sink on the array of lasers.

[0075] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what is being claimed, which is defined by the claims themselves, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially be claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claim may be directed to a subcombination or variation of a subcombination. Attorney Ref.: 56403-0025W01

[0076] Similarly, while operations are depicted in the drawings and recited in the claims in a particular order, this by itself should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system modules and components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0077] Particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results.

Claims

Attorney Ref.: 56403-0025W01What is claimed is:

1. A device comprising: a photonic integrated circuit (PIC) with a surface defining a recess in the PIC, the PIC comprising: a plurality of first waveguides at least partially disposed in the recess, a plurality of optical splitters, each optical splitter comprising first and second splitter portions, each of the first and second splitter portions being optically coupled to a respective first waveguide at a first end and optically coupled to a respective second waveguide at a second end, a plurality of second waveguides at least partially disposed in the PIC, and a plurality of electrical contacts; a laser module mounted on the surface of the PIC, the laser module comprising: a substrate spanning the recess and supported by the surface of the PIC at two opposing edges of the recess, and a plurality of lasers each having an output port, the plurality of lasers being supported by the substrate and at least partially disposed in the recess, each laser being optically coupled to a respective first waveguide of the PIC, wherein the plurality7of electrical contacts electronically connect the plurality of lasers to a voltage source, and wherein the PIC comprises one or more portions of an optically nonlinear material coupled to the plurality7of second waveguides and configured to generate a frequency comb from optical signals received from the plurality of lasers.

2. The device of claim 1, wherein the PIC comprises a cladding layer disposed around each second waveguide of the plurality7of second waveguides.

3. The device of claim 1, wherein the PIC comprises: a plurality of first solder balls disposed on each laser of the plurality7of lasers; a plurality of second solder balls disposed on the plurality7of electrical contacts; and a plurality of redistribution layers bonded to each of the pluralities of first and second solder balls, wherein each laser of the plurality of lasers is bonded to the two opposing edgesAttorney Ref.: 56403-0025W01 of the PIC through the pluralities first and second solder balls and the plurality of redistribution layers.

4. The device of claim 1, wherein the plurality of lasers comprise at least one III-V semiconductor laser.

5. The device of claim 1, wherein the plurality of first waveguides and the plurality of optical splitters comprise at least one of SiN or amorphous Si.

6. The device of claim 1, wherein the PIC comprises a second substrate surrounding the plurality of first waveguides and the plurality of optical splitters, the second substrate comprising a polymer or SiON.

7. The device of claim 1, wherein a first waveguide of the plurality of first waveguide and a second waveguide of the plurality of second waveguides overlap along a vertical direction and are spaced sufficiently close to each other along the vertical direction for the optical signals from the lasers to evanescently couple from the first waveguide to the second waveguide.

8. The device of claim 1, wherein the plurality of second waveguides comprise SiN.

9. The device of claim 1, wherein the substrate comprises Si.

10. The device of claim 1, further comprising a heat sink disposed on respective surfaces of the plurality' of lasers and between the substrate and the plurality of lasers.

11. The device of claim 1, wherein a portion of the PIC comprises at least three stacked portions, wherein a first stacked portion is sandwiched between second and third stacked portions that have a higher index of refraction than that of the first stacked portion.

12. The device of claim 1, wherein the laser module further comprises a lens or a photonic wire bond disposed between a respective output port of each laser of the plurality of lasers and a respective first waveguide of the plurality' of first waveguides.Attorney Ref.: 56403-0025W0113. A device comprising: a photonic integrated circuit (PIC) with a surface defining a recess in the PIC, the PIC comprising: a plurality of first waveguides at least partially disposed in the PIC, a plurality of electrical contacts, and one or more portions of an optically nonlinear material coupled to the plurality of first waveguides: a laser module mounted on the surface of the PIC, the laser module comprising: a substrate spanning the recess and supported by the surface of the PIC at two opposing edges of the recess, a plurality of lasers each having an output port, the plurality of lasers being supported by the substrate and at least partially disposed in the recess, a plurality of second waveguides at least partially disposed in the recess, each laser being optically coupled to a respective second waveguide, and a plurality of optical splitters, each optical splitter comprising first and second splitter portions, each of the first and second splitter portions being optically coupled to a respective second waveguide at a first end and optically coupled to a respective second waveguide at a second end, wherein the plurality of electrical contacts electronically connect the plurality of lasers to a voltage source, and wherein the one or more portions of PIC are configured to generate one or more frequency combs from optical signals received from the plurality of lasers.

14. A method comprising: providing a photonic integrated circuit (PIC) with a surface defining a recess in the PIC; disposing a substrate at two opposing edges of the recess such that an array of lasers and an array of coupling modules supported by the substrate are at least partially disposed within the recess; forming a plurality of waveguides in the PIC such that an output port of each coupling module of the array of coupling modules is aligned with a respective waveguide of the plurality of waveguides; and forming a plurality of frequency comb generators in the PIC such that eachAttorney Ref.: 56403-0025W01 frequency comb of the plurality of frequency comb generators is optically coupled to a respective waveguide of the plurality of waveguides.

15. The method of claim 14, further comprising, before disposing the substrate on the two opposing edges of the recess, attaching the array of lasers to the substrate using a plurality of solder balls and a plurality of redistribution layers.

16. The method of claim 14, further comprising providing contacts electronically- coupled to a voltage source on the two opposing edges of the PIC, such that voltage source is electronically coupled to the array of lasers.

17. The method of claim 14, further comprising providing a plurality of cladding layers, each cladding layer formed around a respective waveguide of the plurality' of waveguides.

18. The method of claim 14, further comprising, before disposing the substrate on the two opposing edges of the PIC, forming the array of coupling modules, wherein forming the array of coupling modules comprises: disposing a polymer or SiON medium on the substrate; forming an array of SiN or amorphous Si waveguides; and forming an array of optical splitters at least partially overlapping the array of SiN or amorphous Si waveguides.

19. The method of claim 14, further comprising: three-dimensional (3D) printing a plurality of lenses, each lens of the plurality of lenses printed on an output port of a respective laser of the array of lasers, or3D printing a plurality of photonic wire bonds, each photonic wire bond of the plurality of photonic wire bonds printed on an output port of a respective laser of the array of laser.

20. The method of claim 14, further comprising disposing a heat sink on the array of lasers.

Images