Silicon-assisted packaging of high power integrated semiconductor optical amplifier array

Abstract

To solve the problems in which conventional LiDAR systems use mechanical moving components and bulk optical lens elements to steer a laser beam and thus are too bulky, costly, and unreliable.SOLUTION: A light detection and ranging (LiDAR) system for a vehicle comprises a semiconductor optical amplifier (SOA) chip. The SOA chip comprises: at least one first SOA emitting amplified light passing through the SOA chip in a first direction; at least one second SOA emitting amplified light passing through the SOA chip in a second direction; and a particular chip facet, where an optical input of the SOA chip and optical outputs of the SOAs are positioned on the particular chip facet. The at least one first SOA and the at least one second SOA are configured to provide different amounts of amplification.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62 / 960,688, filed January 13, 2020, all of which are incorporated by reference in their entireties.

[0002] The subject matter of this disclosure relates generally to Frequency Modulated Continuous Wave (FMCW) Light Detection and Ranging (LiDAR), and more particularly to solid-state FMCW LiDAR systems. [Background technology]

[0003] Conventional LiDAR systems use mechanical moving parts and bulk optical lens elements (i.e., refractive lens systems) to steer the laser beam, and are too bulky, expensive, and unreliable for many applications (e.g., automotive). Summary of the Invention

[0004] The photonic integrated circuit (PIC) assembly includes a semiconductor optical amplifier (SOA) and a U-turn chip. The input SOA and multiple SOAs are arranged parallel to one another. The U-turn chip includes an optical splitter and a waveguide assembly. The optical splitter is configured to receive amplified input light propagating in a first direction from the input SOA and split the amplified light into multiple beams. The waveguide assembly is configured to guide each of the multiple beams to a corresponding SOA of the multiple SOAs. The waveguide assembly also adjusts the propagation direction of each guided beam to be substantially parallel to a second direction substantially opposite the first direction. Each of the multiple SOAs is configured to amplify a respective beam to generate multiple amplified output beams. The PIC assembly may be part of, for example, a frequency modulated continuous wave (FMCW) LiDAR system.

[0005] In some embodiments, the PIC assembly includes a semiconductor optical amplifier (SOA) module. The SOA module includes an SOA array and may further include a U-turn chip (in an alternative embodiment, the U-turn chip may be part of the PIC chip to which the SOA module is coupled). The SOA array is on the SOA chip. The SOA array includes an input SOA and multiple SOAs, which are arranged parallel to one another. The U-turn chip is coupled to the SOA chip and includes an optical splitter and a waveguide assembly. The optical splitter is configured to receive amplified input light propagating in a first direction from the input SOA and split the amplified light into multiple beams. The waveguide assembly is configured to guide each of the multiple beams to a corresponding SOA of the multiple SOAs, and the waveguide assembly adjusts the propagation direction of each of the guided beams to be substantially parallel to a second direction substantially opposite the first direction. Each of the multiple SOAs is configured to amplify a respective beam to generate multiple amplified output beams. [Brief explanation of the drawings]

[0006] Other advantages and features of the embodiments of the present disclosure will become more clearly apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawing examples.

[0007] [Figure 1] 1 illustrates a top-down view of an integrated optical circuit assembly including two SOA array chips and two corresponding U-turn chips coupled to a PIC chip according to one or more embodiments.

[0008] [Figure 2] 1 illustrates a cross section of one embodiment of an SOA array module according to one or more embodiments.

[0009] [Figure 3] 10 illustrates another embodiment of a cross section of an SOA array module coupled to a PIC chip.

[0010] [Figure 4a] An exemplary fabrication process according to one or more embodiments will be described. [Figure 4b] An exemplary fabrication process according to one or more embodiments will be described.

[0011] [Figure 5a] PIC assemblies including suspended U-turn chips according to one or more embodiments are described. [Figure 5b] PIC assemblies including suspended U-turn chips according to one or more embodiments are described.

[0012] [Figure 6] A PIC assembly including a suspended U-turn chip and multiple comb drives according to one or more embodiments is described.

[0013] [Figure 7] 1 illustrates a top-down view of a PIC assembly including an external cavity laser according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0014] The SOA module includes an SOA array (on an SOA array chip) and may include a U-Turn chip (in other embodiments, the U-Turn chip is part of the PIC circuit to which the SOA module couples), and the SOA module may be coupled to a Photonic Integrated Circuit (PIC) chip. The SOA array includes an input SOA and multiple SOAs. In some embodiments, the input SOA is the same as one or more of the multiple SOAs. In alternative embodiments, the input SOA and the multiple SOAs may be different (e.g., have different amplification levels). In some embodiments, each of the multiple SOAs is configured to provide the same amplification level. In other embodiments, at least one of the multiple SOAs provides an amplification level that is different from the input SOA and / or other SOAs of the multiple SOAs. The input SOA and the multiple SOAs may be arranged in parallel with each other. The PIC chip, U-turn chip, or some combination thereof can be made of silicon, silicon nitride, silicon dioxide, or some combination thereof, while the SOA array chip can be made of III-V compound semiconductor materials consisting of Al, Ga, In, N, P, As, and other elements.

[0015] The U-turn chip includes an optical splitter and a waveguide assembly. The optical splitter is configured to receive amplified input light propagating in a first direction from an input SOA and split the amplified light into multiple beams. The waveguide assembly guides each of the multiple beams to a corresponding SOA of the multiple SOAs. The waveguide assembly also adjusts the propagation direction of each guided beam to be substantially parallel to a second direction substantially opposite the first direction. In this manner, the light guided by the waveguide assembly performs another "U-turn" toward the SOA array.

[0016] Each of the multiple SOAs is configured to amplify its respective beam to generate multiple amplified output beams. The SOA module can be part of a photonic integrated circuit (PIC) assembly, so that the amplified output beams can be provided to the PIC assembly for use in, for example, a frequency-modulated continuous wave (FMCW) LiDAR system. FMCW LiDAR directly measures the distance and velocity of an object by directing a frequency-modulated collimated light beam at the object. Light reflected from the object is combined with a tapped version of the beam. The frequency of the resulting beat tone, once corrected for the Doppler shift required by a second measurement, is proportional to the object's distance from the LiDAR system. The two measurements, which may or may not be made simultaneously, provide both range and velocity information.

[0017] Note that a PIC assembly can include multiple SOA modules, light sources, and multiple waveguides to provide light from the light source to multiple SOA modules. Multiple waveguides can also be arranged to provide a similar U-turn function. This, combined with a parallel arrangement of SOA and U-turn chips, facilitates easy integration and packaging of the SOA module and PIC chip. On the other hand, typical high-power SOA arrays have optical inputs and outputs on opposite sides of the III-V chip. This can make packaging the SOA with other photonic chips expensive and difficult.

[0018] 1 illustrates a top-down view of a photonic integrated circuit (PIC) assembly 100 that includes two SOA array chips 110 (also referred to as SOA chips) and two corresponding U-turn chips 113 coupled to a PIC chip 102 in accordance with one or more embodiments. The PIC chip 102, the SOA array chip 110, the U-turn chip 113, or some combination thereof, may be made of silicon, silicon nitride, silicon dioxide, or some combination thereof.

[0019] The output optical power of an integrated laser source 101 is located on top of the PIC chip 102. Light from this source is coupled into a waveguide 103 that is patterned on the PIC chip 102.

[0020] The optical power in the waveguides is split evenly into two output waveguides 105 and 106 by an optical splitter 104. The optical splitter 104 may be, for example, a beam splitter. In this example, two SOA modules (i.e., 107 and 108) are described, but in other embodiments, a different number of SOA modules may be used. Each of the SOA modules 107 and 108 includes an SOA array chip 110 (also referred to as an SOA chip) and a U-turn chip 113 disposed in a recessed cavity etched into the top surface of the PIC 102.

[0021] As shown, output waveguide 105 is configured to provide a first beam to SOA module 107 (and specifically the corresponding SOA array), and output waveguide 106 is configured to provide a second beam to SOA module 108 (and specifically the corresponding SOA array). Note that, as shown, the direction of propagation of light at the entrances to output waveguides 105 and 106 is substantially opposite to the direction of propagation at the outputs of output waveguides 105 and 106.

[0022] Each SOA array chip includes an SOA array. The SOA array includes an input SOA (e.g., input SOA 111) and multiple SOAs (e.g., SOA 116). As shown, the input SOA and multiple SOAs are arranged parallel to one another. In other embodiments, the input SOA and multiple SOAs may be positioned relative to one another in different ways.

[0023] In the context of the SOA module 107 , the output waveguide 105 is edge-coupled to the SOA array chip 110 via the front chip facet 109 .

[0024] This light passes through the input SOA 111, which acts as a preamplifier to offset losses associated with chip-to-chip coupling. The light to be amplified propagates in a first direction.

[0025] The pre-amplified light exits the SOA through the back facet 112 of the SOA chip 110 where it is edge-coupled into a U-turn chip 113 .

[0026] The light in the input waveguide passes through a 1×M splitter 114 (where M is equal to 1 minus the total number of SOAs, including the input SOA, in SOA array 110), which distributes the pre-amplified optical power equally among M waveguides (e.g., waveguide 115) in the waveguide assembly. Each waveguide in the waveguide assembly contains a guided beam corresponding to a portion of the pre-amplified optical power.

[0027] The waveguide assembly adjusts the propagation direction of each of the guided beams to be substantially parallel to a second direction substantially opposite the first direction. For example, the waveguide bends, and the light is coupled back into the SOA array chip 110 via the rear facet 112. Each optical channel passes through an individual SOA 116 on the SOA array chip, amplifying the light to a desired output level (i.e., each of the multiple SOAs is configured to amplify a respective beam to generate multiple amplified output beams). In some embodiments, each SOA 116 in the SOA array chip is configured to provide the same amplification level. In other embodiments, at least two of the SOAs 116 have different amplification levels. Similarly, in some embodiments, the multiple SOA modules on the PIC chip 102 are the same. And, in other embodiments, at least one SOA module on the PIC chip 102 is different from the other SOA modules on the PIC chip 102. For example, one SOA module may have a different number of SOAs than the other SOA modules on the PIC chip 102.

[0028] The amplified light is edge-coupled back into the PIC chip 102 via the front chip facet 109 and into the waveguide 117. Light from the output waveguide 106 to the SOA module 108 is amplified within the SOA module 108 in a manner substantially similar to that described above for the SOA module 107 and output into the waveguide 118. The waveguides 117, 118 within the PIC chip 102 carry light from the packaged SOA array to the optical circuitry contained within the PIC chip 102.

[0029] 2 shows a cross-section of one embodiment of an SOA array module 200 (also referred to as an SOA module) coupled to a PIC chip 205 in accordance with one or more embodiments. The SOA array chip 201 is bonded to a carrier 203, which provides structural support and thermal management. The carrier 203 can be fabricated from silicon, other thermally conductive ceramics such as AlN or Al2O3, or some combination thereof. The SOA array chip 201 can be one embodiment of the SOA array chip 110.

[0030] The U-turn chip 202 is actively bonded to the SOA array chip 201 with the aid of a shim 204, which provides the necessary mechanical offset relative to the carrier 203. The shim 204 can be made of any material, although it is advantageous to use a material with a thermal expansion coefficient similar to that of the SOA 201, so that the alignment between the SOA 201 and the U-turn 202 is better preserved against temperature swings. The U-turn chip 202 is one embodiment of the U-turn chip 113. The U-turn chip 202 is thinned so that the combined module fits into a recess etched in the PIC chip 205. This arrangement of the bonded SOA array chip 201, carrier 203, shim 204, and U-turn chip 202 forms the SOA array module 200.

[0031] The SOA array module 200 is placed on a PIC chip 205 that uses optical power provided by the SOA array chip 201. The PIC chip 205 includes patterned pedestals 206 that provide mechanical support, precise out-of-plane alignment, and a means for securing the SOA array chip 201 to the PIC chip 205. The SOA array module is placed on top of these pedestals 206, with its front facet attached closely to the chip facet 207 and actively aligned to provide efficient optical coupling between the SOA array chip 201 and the PIC chip 205. Note that in the illustrated embodiment, the U-turn chip 202 is on the opposite side of the SOA array chip 201 from the chip facet 207. In other embodiments, the position of the chip facet 207 relative to the U-turn chip 202 may vary.

[0032] If needed for additional support, the U-turn chip 202 can be bonded to a silicon optical chip with a Low-Shrinkage Adhesive 208.

[0033] 3 shows another embodiment of a cross section of an SOA array module 300 coupled to a PIC chip 304. The SOA array module 300 simplifies the chip assembly process and reduces costs for mass production.

[0034] In this embodiment, the PIC chip 304 and the U-turn chip 302 are fabricated on the same wafer, and the waveguide 310 in the PIC chip 304 and the waveguide 311 in the U-turn chip 302 are vertically self-aligned. That is, they are at the same depth below the chip surface (e.g., aligned in the same plane). Additionally, patterned pedestals (e.g., pedestal 305) in the PIC chip 304 and patterned pedestals (e.g., pedestal 303) in the U-turn chip 302 are formed such that when the SOA chip 301 is placed on these pedestals, the waveguide 309 in the SOA chip 301 is vertically aligned with the waveguides 310 and 311. Because precise vertical alignment during the chip assembly process impacts performance, the mechanical constraints provided by the self-aligned waveguides 309, 310, and 311 and properly formed pedestals can significantly improve the yield and quality of the final chip assembly, potentially leading to higher throughput and lower manufacturing costs.

[0035] 4a and 4b illustrate an exemplary fabrication process according to one or more embodiments. The processes shown in FIGS. 4a and 4b may be performed by components of a circuit manufacturing system. Other entities may perform some or all of the steps of other embodiments of FIGS. 4a and 4b. Embodiments may include different and / or additional steps or perform steps in a different order.

[0036] As shown in FIG. 4a, the PIC 404 and U-turn 402 are fabricated on the same wafer. The wafer can be fabricated from silicon, silicon nitride, silicon dioxide, some other suitable material, or some combination thereof. The waveguides 410, 411 are at the same depth below the wafer surface. Similarly, the pedestals 405 and 403 are formed so that the top of the pedestal 405 and the top of the pedestal 403 are at the same depth below the wafer surface. Note that in the illustrated embodiment, there are four pedestals 405 and two pedestals 403. In other embodiments, there may be more or fewer pedestals 405 and / or more or fewer pedestals 403.

[0037] Figure 4b shows how to assemble an SOA module 400, which includes an SOA array chip 401 and a U-turn chip 402. The U-turn chip 402 can be cut and thinned from the wafer shown in Figure 4a.

[0038] The SOA array chip 401 is bonded to a carrier 406. The carrier 406 may be one embodiment of the carrier 203. The U-turn chip 402 is then flipped upside down, aligned, and bonded to the SOA array chip 401 with a pedestal 403 touching the top surface of the SOA array chip 401 to provide vertical mechanical constraint. Primary adhesion is provided by adhesive 408 (e.g., solder or glue) around the pedestal 403, and secondary adhesion can be added between the U-turn chip 402 and the carrier 406 for better mechanical stability using low-shrinkage glue 408′, optionally with shims 407. Because the height of the pedestal 403 is precisely controlled, this method allows for manual alignment between the SOA array chip 401 and the U-turn chip 402.

[0039] Next, the SOA module 400 is flipped upside down and bonded to the PIC chip 404. For example, as shown in Figure 3, the SOA module 400 is flipped upside down, aligned with the waveguide 310 of the PIC 304, and bonded with adhesive 308 in a recessed cavity that accommodates the pedestal (e.g., pedestal 305) of the PIC chip 304 as a mechanical stop to ensure vertical alignment of the assembly.

[0040] 5a and 5b illustrate a PIC assembly 500 including a suspended U-turn chip 502 according to one or more embodiments. The PIC assembly 500 includes a PIC chip 505 connected to the suspended U-turn chip 500 and an SOA module. The SOA module includes an SOA array chip 501 and a carrier 503. FIG. 5a is a cross-sectional view of the PIC assembly 500, and FIG. 5b is a top-down view of the PIC assembly 500. The PIC chip 505 and the U-turn chip 502 are fabricated on the same wafer (e.g., similar to the embodiment described above in connection with FIG. 4a). If the bottom of the U-turn chip 502 is hollow as a cavity or through via 510, instead of cutting the wafer, the U-turn chip 502 is attached and suspended by a flexure 509. The U-turn chip 502 is constrained in out-of-plane motion but has a small amount of freedom to move in-plane. This ensures vertical alignment between the PIC 505, SOA array chip 501, and U-turn chip 502, but allows the U-turn chip 502 to move left or right to accommodate changes in the length of the SOA array chip 501. During assembly, the pre-assembled SOA 501 on the carrier 503 is inverted, aligned, and bonded to the pedestal (e.g., pedestal 506) of the PIC chip 505. The U-turn chip 502 is then pushed toward the SOA array chip 501 and permanently secured in place with adhesive 508 to form the PIC assembly 500.

[0041] FIG. 6 illustrates a PIC assembly 600 including a U-turn chip 602 from which a PIC chip 605 is suspended and multiple comb drives 611 according to one or more embodiments. The comb drives 611 are added to use electrostatic forces to move the U-turn chip 602 in a plane. As shown, the comb drives 611 are configured to control the translation of the U-turn chip 602 relative to the SOA array chip 601 in two orthogonal directions. The comb drives 611 are formed from portions of the U-turn chip 602 and the PIC chip 605 and are configured to position the U-turn chip 602 relative to the SOA array chip 601. Once the waveguides of the SOA array chip 601 are aligned with the waveguides of the U-turn chip 602, adhesive 608 is applied to permanently secure the U-turn chip 602 in place. While three comb drives 611 are shown, in other embodiments, the PIC chip 605 may include one or more comb drives 611.

[0042] 7 shows a top-down view of a PIC assembly 700 including an external cavity laser according to one or more embodiments. The PIC assembly 700 includes one SOA array chip 110 and one gain medium chip 701 packaged in a PIC chip 702 that includes a resonator 718 with the aid of a U-turn chip 113. The gain medium chip 701 and resonator 718 form an external cavity laser (ECL), which is the laser source in this embodiment. The resonator 718 and gain medium chip 701 collectively select and amplify a specific band of emitted light.

[0043] Light from the ECL source is coupled into the SOA array chip 110 via a waveguide 705. The SOA array chip 110 operates with in-coupled light in the manner described above in connection with FIG.

[0044] Additional configuration information The drawings and the foregoing description relate to preferred embodiments by way of example only. As noted above, it should be noted that alternative embodiments of the structures and methods disclosed herein are readily recognized as viable alternatives that may be employed without departing from the principles of the claims.

[0045] Although the detailed description contains numerous details, these should not be construed as limiting the scope of the invention, but merely as illustrating different examples. It should be understood that the scope of the present disclosure includes other embodiments not described in detail above. Various other modifications, changes, and alterations, which are obvious to those of ordinary skill in the art, may be made in the arrangement, operation, and details of the methods and apparatus disclosed herein without departing from the spirit and scope defined by the appended claims. Therefore, the scope of the invention should be determined by the appended claims and their legal equivalents.

[0046] Alternative embodiments may be implemented in computer hardware, firmware, software, and / or combinations thereof. An example implementation may be implemented as a computer program product substantially embodied in a machine-readable storage device for execution by a programmable processor, with method steps being performed by the programmable processor executing an instruction program to perform functions by operating on input data and generating output. Embodiments may advantageously be implemented as one or more computer programs executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each computer program may be implemented in a high-level procedural or object-oriented programming language, or assembly or machine language as appropriate; in any case, the language may be compiled or interpreted. Suitable processors include, by way of example, general-purpose and special-purpose microprocessors. Typically, a processor receives instructions and data from read-only memory (ROM) and / or random access memory (RAM). Generally, a computer will include one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, and optical disks. Suitable storage devices for substantially embodying computer program instructions and data include, by way of example, all forms of non-volatile memory, including semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices, magnetic disks, such as internal hard disks and removable disks, magneto-optical disks, and CD-ROM disks. All of the foregoing may be supplemented by, or incorporated in, application-specific integrated circuits (ASICs) and other forms of hardware.

Claims

1. As an optical integrated circuit (PIC) assembly, an SOA array including an input SOA (Semiconductor Optical Amplifier) and a plurality of SOAs, the input SOA and the plurality of SOAs being arranged in parallel to each other; an optical integrated circuit assembly comprising: an optical splitter configured to receive amplified input light propagating in a first direction from the input SOA and split the amplified light into a plurality of beams; and a U-turn chip including a waveguide assembly configured to guide each of the plurality of beams to a corresponding SOA of the plurality of SOAs, the waveguide assembly adjusting the propagation direction of each of the guided beams to be substantially parallel to a second direction that is substantially opposite to the first direction, and each of the plurality of SOAs configured to amplify a respective beam to generate a plurality of amplified output beams.

2. 2. The optical integrated circuit assembly of claim 1, wherein the SOA array is on an SOA chip including a front facet and a rear facet opposite the front facet, input light is edge coupled into the front facet before being amplified by the input SOA, the amplified input light is edge coupled into the U-turn chip through the rear facet, the guided beam is edge coupled from the U-turn chip to the rear facet, and the multiple amplified output beams are edge coupled from the front facet to outside of the SOA chip.

3. 2. The optical integrated circuit assembly of claim 1, wherein the SOA array is on an SOA chip coupled to a plurality of pedestals of a PIC chip, the PIC chip including a front facet, and the SOA chip is configured to output the plurality of amplified output beams to the front facet.

4. 4. The optical integrated circuit assembly of claim 3, wherein the U-turn chip is on an opposite side of the SOA array chip from the front facet of the PIC chip.

5. 4. The optical integrated circuit assembly of claim 3, further comprising a carrier coupled to a first side of the SOA chip and a first side of the shim, wherein a second side of the SOA chip is coupled to a plurality of pedestals of the PIC chip and a second side of the shim is coupled to the U-turn chip, and the carrier is configured to provide thermal and structural support to the SOA chip.

6. 4. The optical integrated circuit assembly of claim 3, wherein the U-turn chip and the PIC chip are fabricated on the same wafer such that the waveguides of the waveguide assembly are aligned with the waveguides of the PIC chip.

7. 4. The optical integrated circuit assembly of claim 3, wherein the U-turn chip and the PIC chip are fabricated on the same wafer, and the U-turn chip is coupled to the PIC chip via one or more flexures fabricated on the same wafer and is floating.

8. 8. The optical integrated circuit assembly of claim 7, wherein there are one or more comb drives formed from portions of the U-turn chip and the PIC chip, the one or more comb drives configured to position the U-turn chip relative to the SOA chip.

9. 9. The optical integrated circuit assembly of claim 8, wherein the one or more comb drives control translation of the U-turn chip relative to the SOA chip in two orthogonal directions.

10. 2. The optical integrated circuit assembly of claim 1, further comprising a second SOA array including a second input SOA and a second plurality of SOAs, the second input SOA and the second plurality of SOAs being arranged parallel to each other and to the SOAs of the SOA array.

11. a laser source configured to emit light; 11. The optical integrated circuit assembly of claim 10, further comprising: an optical splitter configured to split the light into at least a first beam and a second beam, the first beam being provided to the SOA array and the second beam being provided to the second SOA array.

12. 12. The optical integrated circuit assembly of claim 11, further comprising a first waveguide and a second waveguide, wherein the first waveguide is configured to provide the first beam to the SOA array and the second waveguide is configured to provide the second beam to the second SOA array, and wherein a propagation direction of the light at an entrance of the first waveguide and the second waveguide is substantially opposite to a propagation direction at an output of the first waveguide and the second waveguide.

13. the SOA array is on an SOA chip that is coupled to a PIC chip; The PIC is further comprising an external cavity laser (ECL) source coupled to the PIC chip, the ECL laser source configured to provide light to the SOA chip; The ECL source is a light source that emits light; a gain medium chip; a resonator; 10. The optical integrated circuit assembly of claim 1, wherein the resonator and the gain medium chip collectively select and amplify a particular band of the emitted light.

14. The optical integrated circuit assembly of claim 1 , wherein each of the plurality of SOAs provides the same amplification level.

15. 2. The optical integrated circuit assembly of claim 1, wherein the plurality of SOAs includes a first SOA and a second SOA, the first SOA and the second SOA being configured to provide different amounts of amplification from each other.

16. 10. The optical integrated circuit assembly of claim 1, wherein the PIC is part of a frequency modulated continuous wave (FMCW) LiDAR system.

17. As a semiconductor optical amplifier (SOA) module, an SOA array on an SOA chip, the SOA array including an input SOA and a plurality of SOAs, the input SOA and the plurality of SOAs being arranged parallel to each other; and a U-turn chip coupled to the SOA chip; The U-turn tip is an optical splitter configured to receive amplified input light propagating in a first direction from the input SOA and split the amplified light into multiple beams; a waveguide assembly configured to guide each of the plurality of beams to a corresponding SOA of the plurality of SOAs, the waveguide assembly adjusting a propagation direction of each of the guided beams to be substantially parallel to a second direction substantially opposite to the first direction, and each of the plurality of SOAs configured to amplify a respective beam to generate a plurality of amplified output beams.

18. 18. The semiconductor optical amplifier module of claim 17, further comprising a carrier and a shim, wherein the carrier is separated from the U-turn chip by the shim.

19. 20. The semiconductor optical amplifier module of claim 18, wherein the shim is sized so that the waveguides of the SOA array and the waveguides of the U-turn chip are aligned in the same plane.

20. 20. The semiconductor optical amplifier module of claim 18, wherein the SOA module is configured to couple to an integrated optical circuit chip.

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