EP-4740276-A2 - REFLECTIVE OPTICAL AMPLIFIER ARRAY WITH SHARED DRIVE

Abstract

An integrated optical device (20, 70, 80, 90, 100) includes an amplifier chip (22), which includes a plurality of multi-pass semiconductor optical gain media (60, 92) having respective reflective ends (61) and respective transmissive ends (63) and multiple first optical couplers (58) optically coupled respectively to the transmissive ends of the optical gain media. A photonics chip (24) includes multiple second optical couplers (50), which are aligned respectively with the first optical couplers on the amplifier chip, and optical circuitry (51), which directs a coherent seed beam through the second optical couplers for input via the first optical couplers to the multi-pass semiconductor optical gain media and to receive amplified beams from the multi-pass semiconductor optical gain media via the first and second optical couplers.

Inventors

• SUTTON, Andrew J.H.

Assignees

• Lyte AI, Inc.

Dates

Publication Date

20260513

Application Date

20240709

Claims (20)

1. 1. An integrated optical device, comprising: an amplifier chip, comprising: a plurality of multi-pass semiconductor optical gain media having respective reflective ends and respective transmissive ends; and multiple first optical couplers optically coupled respectively to the transmissive ends of the optical gain media; and a photonics chip, comprising: multiple second optical couplers, which are aligned respectively with the first optical couplers on the amplifier chip; and optical circuitry configured to direct a coherent seed beam through the second optical couplers for input via the first optical couplers to the multi-pass semiconductor optical gain media and to receive amplified beams from the multi-pass semiconductor optical gain media via the first and second optical couplers.
2. 2. The device according to claim 1, wherein the amplifier chip comprises a substrate comprising a III-V semiconductor compound, on which the multi-pass semiconductor optical gain media are disposed.
3. 3. The device according to claim 2, wherein the photonics chip comprises a silicon photonic integrated circuit (SPIC).
4. 4. The device according to claim 1 , and comprising a laser configured to generate the coherent seed beam for input to the optical circuitry.
5. 5. The device according to claim 4, wherein the laser is disposed on the photonics chip.
6. 6. The device according to claim 4, and comprising: an interferometer disposed on the photonics chip, which is configured to sense a frequency variation in the seed beam; and control circuitry configured to drive the laser responsively to the sensed frequency variation.
7. 7. The device according to claim 1, wherein the multi-pass semiconductor optical gain media comprise reflective semiconductor optical amplifiers.
8. 8. The device according to claim 1, wherein the multi-pass semiconductor optical gain media comprise semiconductor lasers.
9. 9. The device according to claim 1, and comprising an array of microlenses disposed between the first and second optical couplers.
10. 10. The device according to any of claims 1-9, and comprising an optical isolator configured to pass the seed beam from the second optical couplers to the first optical couplers and to pass the amplified beams from the first optical couplers to the second optical couplers while attenuating back-reflections from the photonics chip to the amplifier chip.
11. 11. The device according to claim 10, wherein the optical isolator comprises a waveplate and a polarization rotator, and wherein the seed beam is directed through the second optical couplers with a first linear polarization, which is rotated by the polarization rotator to a second linear polarization, orthogonal to the first linear polarization, for input through the first optical couplers to the multi-pass semiconductor optical gain media.
12. 12. The device according to claim 11, wherein the waveplate comprises a half-wave plate, and the polarization rotator comprises a Faraday rotator.
13. 13. The device according to any of claims 1-9, wherein the optical circuitry comprises: an input waveguide configured to convey the coherent seed beam across the photonics chip; multiple taps coupled to extract respective fractions of the seed beam from the input waveguide; multiple output waveguides; and multiple splitters, coupled to direct the respective fractions of the seed beam from the respective taps to the second optical couplers for input to the multi-pass semiconductor optical gain media and to convey the amplified beams output by the multi-pass semiconductor optical gain media from the second optical couplers to the output waveguides.
14. 14. The device according to claim 13, and comprising an optical isolator comprising a halfwave plate a Faraday rotator disposed between the first and second optical couplers.
15. 15. The device according to claim 14, wherein the coherent seed beam propagates through the input waveguide with a first linear polarization, while the amplified beams received through the second optical couplers have a second linear polarization, orthogonal to the first linear polarization, and wherein the splitters comprise polarization splitters.
16. 16. The device according to claim 14, wherein both the coherent seed beam propagating through the input waveguide and the amplified beams received through the second optical couplers have a first linear polarization, and wherein the splitters comprise polarization splitters and rotators, which rotate the seed beam from the first linear polarization to a second linear polarization, orthogonal to the first linear polarization.
17. 17. The device according to claim 13, wherein the splitters comprise directional couplers, having a first coupling ratio for conveying the seed beam from the respective taps to the second optical couplers and a second coupling ratio, which is at least twice the first coupling ratio, for conveying the amplified beams output by the multi-pass semiconductor optical gain media from the second optical couplers to the output waveguides.
18. 18. A method for optical beam generation, comprising: providing an amplifier chip, comprising: a plurality of multi-pass semiconductor optical gain media having respective reflective ends and respective transmissive ends; and multiple first optical couplers optically coupled respectively to the transmissive ends of the optical gain media; and aligning multiple second optical couplers on a photonics chip with the first optical couplers on the amplifier chip so as to direct a coherent seed beam from the photonics chip through the second optical couplers for input via the first optical couplers to the multi-pass semiconductor optical gain media and to receive amplified beams in the photonics chip from the multi-pass semiconductor optical gain media via the first and second optical couplers.
19. 19. The method according to claim 18, wherein the amplifier chip comprises a substrate comprising a III-V semiconductor compound, on which the multi-pass semiconductor optical gain media are disposed.
20. 20. The method according to claim 19, wherein the photonics chip comprises a silicon photonic integrated circuit (SPIC).

Description

REFLECTIVE OPTICAL AMPLIFIER ARRAY WITH SHARED DRIVE CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application 63/512,629, filed July 9, 2023, and U.S. Provisional Patent Application 63/589,640, filed October 12, 2023. Both of these related applications are incorporated herein by reference. FIELD The present invention relates generally to integrated optoelectronic devices, and particularly to integrated sources of coherent optical radiation. BACKGROUND Silicon photonic integrated circuits (SPICs) are commonly used in optical transmitter and transceiver arrays. Some active optoelectronic components, however, such as semiconductor lasers and semiconductor optical amplifiers (SOAs), comprise III-V semiconductor compounds (such as GaAs or InP). These components are typically fabricated on a III-V wafer. After fabrication, the III-V wafer is diced to produce singulated III-V chiplets, which are then aligned and mounted in the appropriate locations on the SPIC. The terms “optical radiation” and “light” are used synonymously in the present description and in the claims to refer to electromagnetic radiation in any or all of the visible, infrared, and ultraviolet spectral ranges. SUMMARY Embodiments of the present invention that are described hereinbelow provide improved integrated sources of coherent optical radiation. There is therefore provided, in accordance with an embodiment of the invention, an integrated optical device, which includes an amplifier chip, including a plurality of multi-pass semiconductor optical gain media having respective reflective ends and respective transmissive ends and multiple first optical couplers optically coupled respectively to the transmissive ends of the optical gain media. A photonics chip includes multiple second optical couplers, which are aligned respectively with the first optical couplers on the amplifier chip, and optical circuitry configured to direct a coherent seed beam through the second optical couplers for input via the first optical couplers to the multi-pass semiconductor optical gain media and to receive amplified beams from the multi-pass semiconductor optical gain media via the first and second optical couplers. In a disclosed embodiment, the amplifier chip includes a substrate including a III-V semiconductor compound, on which the multi-pass semiconductor optical gain media are disposed, and the photonics chip includes a silicon photonic integrated circuit (SPIC). In some embodiments, the device includes a laser configured to generate the coherent seed beam for input to the optical circuitry. In one embodiment, the laser is disposed on the photonics chip. Additionally or alternatively, the device includes an interferometer disposed on the photonics chip, which is configured to sense a frequency variation in the seed beam, and control circuitry configured to drive the laser responsively to the sensed frequency variation. In a disclosed embodiment, the multi-pass semiconductor optical gain media include reflective semiconductor optical amplifiers. Alternatively, the multi-pass semiconductor optical gain media include semiconductor lasers. In a disclosed embodiment, the device includes an array of microlenses disposed between the first and second optical couplers. Additionally or alternatively, the device includes an optical isolator configured to pass the seed beam from the second optical couplers to the first optical couplers and to pass the amplified beams from the first optical couplers to the second optical couplers while attenuating back- reflections from the photonics chip to the amplifier chip. In some embodiments, the optical isolator includes a waveplate and a polarization rotator, and wherein the seed beam is directed through the second optical couplers with a first linear polarization, which is rotated by the polarization rotator to a second linear polarization, orthogonal to the first linear polarization, for input through the first optical couplers to the multi-pass semiconductor optical gain media. For example, the waveplate includes a half-wave plate, and the polarization rotator includes a Faraday rotator. In some embodiments, the optical circuitry includes an input waveguide configured to convey the coherent seed beam across the photonics chip, multiple taps coupled to extract respective fractions of the seed beam from the input waveguide, multiple output waveguides, and multiple splitters, coupled to direct the respective fractions of the seed beam from the respective taps to the second optical couplers for input to the multi-pass semiconductor optical gain media and to convey the amplified beams output by the multi-pass semiconductor optical gain media from the second optical couplers to the output waveguides. In some embodiments, the device includes an optical isolator including a half-wave plate and a Faraday rotator disposed between the first and second optical couplers. In a disclo