CN-122026231-A - On-chip integrated laser light source and optical coupling integration method thereof

CN122026231ACN 122026231 ACN122026231 ACN 122026231ACN-122026231-A

Abstract

The application provides an on-chip integrated laser light source and an optical coupling integration method thereof, wherein the on-chip integrated laser light source comprises a silicon light substrate and a light source chip assembly integrated on the silicon light substrate, the silicon light substrate comprises a light signal transmission waveguide, the light source chip assembly comprises a surface-emitting distributed feedback laser chip for generating laser beams emitted along the direction vertical to the surface of the chip, the on-chip integrated laser source further comprises a grating coupling structure configured between the surface-emitting distributed feedback laser chip and the light signal transmission waveguide, the light emitting surface of the surface-emitting distributed feedback laser chip faces towards the silicon light substrate, the laser beams generated by the surface-emitting distributed feedback laser chip are directly projected and coupled into the light signal transmission waveguide through the grating coupling structure, and the surface-emitting distributed feedback laser chip is fixedly combined on the silicon light substrate through a flip chip technology so as to convert the high-precision end face alignment requirement of a heterogeneous integrated waveguide into high-efficiency grating coupling based on a surface light emitting mode. In this way, the harsh end-face coupling is converted into efficient grating coupling.

Inventors

ZHOU DELAI
Zhao Sangzhi
XIAO YAN

Assignees

深圳市柠檬光子科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260315

Claims (10)

1. An on-chip integrated laser light source comprises a silicon optical substrate and a light source chip assembly integrated on the silicon optical substrate, wherein the silicon optical substrate comprises an optical signal transmission waveguide, The light source chip assembly comprises a distributed feedback laser chip with surface emission so as to generate a laser beam emitted along the direction vertical to the surface of the chip; the on-chip integrated laser light source further comprises a grating coupling structure configured between the surface-emitting distributed feedback laser chip and the optical signal transmission waveguide; The light emergent surface of the surface-emitted distributed feedback laser chip is arranged towards the silicon optical substrate, and the laser beam generated by the surface-emitted distributed feedback laser chip is directly projected and coupled into the optical signal transmission waveguide through the grating coupling structure; The surface-emitting distributed feedback laser chip is fixedly combined on the silicon optical substrate through a flip chip technology, so that the high-precision end face alignment requirement of the heterogeneous integrated waveguide is converted into high-efficiency grating coupling based on a surface light emitting mode.
2. The integrated laser light source on chip of claim 1, wherein the grating coupling structure comprises a first grating and a second grating, the first grating is composed of a distributed feedback grating arranged in a resonant cavity of the surface-emitting distributed feedback laser chip to control lasing wavelength and form surface light emission, the second grating is composed of a surface-coupled grating arranged on the surface of the silicon optical substrate and physically connected to the optical signal transmission waveguide, and the surface-emitting distributed feedback laser chip is configured such that an optical signal perpendicularly emitted from the first grating is received by the second grating to define a transmission optical path from the laser light source to the optical signal transmission waveguide based on an angle between the light emitting surface and the surface of the silicon optical substrate.
3. The integrated laser light source on chip of claim 1, wherein the light source chip assembly comprises a plurality of the surface-emitting distributed feedback laser chips arranged side by side at intervals in a longitudinal direction or a transverse direction of the silicon optical substrate to achieve parallelized generation of multiple communication optical signals, each of the plurality of surface-emitting distributed feedback laser chips corresponding to a different lasing wavelength, respectively, and the optical signal transmission waveguide corresponding to comprises a plurality of input waveguide branches to receive the laser beams from the respective surface-emitting distributed feedback laser chips of different wavelengths, respectively.
4. The integrated laser light source on chip of claim 3, wherein the silicon optical substrate is further integrated with a combiner connected between the plurality of input waveguide branches and a common transmission main waveguide, the combiner configured to multiplex the laser beams having different emission wavelengths in the plurality of input waveguide branches into the common transmission main waveguide, thereby forming a multi-wavelength arrayed integrated light source suitable for use in a Wavelength Division Multiplexing (WDM) system.
5. The integrated laser light source on a chip of claim 1, wherein one side surface of the surface-emitting distributed feedback laser chip is connected with a metal solder bump, the other side surface of the surface-emitting distributed feedback laser chip is connected with a heat conducting component, when the surface-emitting distributed feedback laser chip is in a physical fixing state, the surface-emitting distributed feedback laser chip is electrically conducted with a feed network on the silicon optical substrate through the metal solder bump, and when the surface-emitting distributed feedback laser chip generates waste heat due to continuous laser, the heat conducting component rapidly conducts heat to an external environment to maintain stability of laser output wavelength.
6. The integrated laser light source on a chip of claim 1, wherein the silicon optical substrate is a silicon-on-insulator (SOI) chip, the optical signal transmission waveguide is a silicon optical waveguide formed based on a top silicon process of the SOI chip, the surface-emitting distributed feedback laser chip is a separate active device fabricated based on a III-V compound semiconductor material, and a light emission wavelength of the surface-emitting distributed feedback laser chip is within an optical communication band.
7. The integrated laser light source on a chip of claim 2, wherein a physical gap is provided between the light exit surface of the surface-emitting distributed feedback laser chip and the second grating, the physical gap is filled with an optical index matching glue material, and the refractive index of the optical index matching glue material is between the refractive index of the material of the first grating and the refractive index of the material of the second grating, and is configured to reduce refractive index abrupt changes at an interface to reduce fresnel reflection loss in a transmission light path.
8. The integrated laser light source on chip of claim 2, wherein the structural parameters of the first grating and the structural parameters of the second grating are cooperatively configured in physical space to match an outgoing optical field mode of the first grating to a received optical field mode of the second grating, wherein the second grating has a waveguide transition region of graded width in a direction toward the optical signal transmission waveguide.
9. The integrated laser light source on chip of claim 1, wherein a mounting alignment tolerance between the surface-emitting distributed feedback laser chip and the silicon photo-substrate achieved by the flip chip process is set in a range of 1 to 3 microns, so that the grating coupling structure still maintains a beam coupling efficiency higher than an end-face coupling efficiency under the mounting alignment tolerance, thereby avoiding sub-micron alignment requirements and yield loss problems caused by heterogeneous wafer bonding.
10. An optical coupling integration method based on an integrated laser light source on chip according to any of claims 1 to 9, characterized by comprising the steps of: Acquiring physical position parameters of the silicon optical substrate and the pre-prepared distributed feedback laser chip emitted by the surface, and establishing an initial mounting alignment reference; acquiring an optical alignment image of a visual system of the chip mounter in real time, placing the light emitting surface of the surface-emitted distributed feedback laser chip downward above a grating coupling structure of the silicon optical substrate based on the initial mounting alignment standard, judging that the alignment is qualified and executing a pressing bonding action if the alignment error is within a preset tolerance range of 1-3 microns; Periodically collecting an applied pressure value and a thermosetting temperature value in the curing process, and monitoring whether the surface-emitted distributed feedback laser chip generates transverse position deviation or not based on the physical position parameter to ensure that the spatial vertical corresponding relation of the grating coupling structure is kept relatively stable; Injecting driving current into the surface-emitted distributed feedback laser chip, and monitoring the optical power transmitted inside the optical signal transmission waveguide, wherein if the injected current shows a stable output trend and the variation rate difference value of the optical power is within a preset error range, the optical path coupling is judged to be successful and the connection is stable; And in response to the multi-wavelength communication requirement of the wavelength division multiplexing system, scanning a plurality of arrayed and distributed mounting nodes on the silicon optical substrate, sequentially flip-mounting a plurality of surface-emitting distributed feedback laser chips with different luminous wavelengths to corresponding positions according to the configuration information of the optical communication frequency bands corresponding to different nodes, and determining the arrayed parallel diffusion range of the multi-wavelength light source on the silicon optical substrate.

Description

On-chip integrated laser light source and optical coupling integration method thereof Technical Field The application relates to the technical field of semiconductor photoelectron integration, in particular to an on-chip integrated laser source and an optical coupling integration method thereof. Background With the development of silicon-based photonic integrated technology, photonic integrated circuits are increasingly used in fields such as optical communication due to the advantage of high integration. However, in the prior art, the integration of the laser light source and the silicon optical waveguide mostly adopts an end-face coupling or evanescent coupling scheme, and the method has the following limitations that on one hand, the requirements on the three-dimensional space alignment precision between the laser chip and the silicon optical waveguide are very strict whether flip-chip bonding or heterogeneous integration are realized, submicron level is usually required to be achieved, the packaging process is complex, the yield is low, the production cost is high, on the other hand, the high-precision alignment requirement also limits the expandability and the production test efficiency of the light source array integration, and the urgent requirements of scenes such as a data center on the low-cost and high-density integrated light source on the chip are difficult to meet. Disclosure of Invention Based on the foregoing, it is necessary to provide an integrated laser light source and an optical coupling integration method thereof, so as to solve at least one of the above-mentioned technical problems. In a first aspect, the present application provides an integrated laser light source on a chip, comprising a silicon optical substrate and a light source chip assembly integrated on the silicon optical substrate, the silicon optical substrate comprising an optical signal transmission waveguide, The light source chip assembly comprises a distributed feedback laser chip with surface emission so as to generate a laser beam emitted along the direction vertical to the surface of the chip; The on-chip integrated laser light source further comprises a grating coupling structure configured between the surface-emitting distributed feedback laser chip and the optical signal transmission waveguide; The light emitting surface of the surface-emitted distributed feedback laser chip is arranged towards the silicon optical substrate, and the laser beam generated by the surface-emitted distributed feedback laser chip is directly projected and coupled into the optical signal transmission waveguide through the grating coupling structure; The distributed feedback laser chip of the surface emission is fixedly combined on the silicon optical substrate through a flip chip technology, so that the high-precision end face alignment requirement of the heterogeneous integrated waveguide is converted into high-efficiency grating coupling based on a surface light emitting mode. In this way, the harsh end-face coupling is converted into efficient grating coupling. The grating coupling structure further comprises a first grating and a second grating, wherein the first grating is formed by the distributed feedback grating which is arranged in a resonant cavity of the surface-emitting distributed feedback laser chip to control the lasing wavelength and form surface light emission, the second grating is formed by the surface-coupling grating which is arranged on the surface of the silicon optical substrate and is physically connected with the optical signal transmission waveguide, and the surface-emitting distributed feedback laser chip is configured to enable an optical signal vertically emitted from the first grating to be received by the second grating based on a certain included angle between the light emitting surface of the surface-emitting distributed feedback laser chip and the surface of the silicon optical substrate so as to define a transmission light path from the laser light source to the optical signal transmission waveguide. In this way, the transmission path of the vertically emitted light to the waveguide is precisely defined. Further, the light source chip assembly comprises a plurality of surface-emitting distributed feedback laser chips which are distributed side by side at intervals along the longitudinal direction or the transverse direction of the silicon optical substrate so as to realize parallelization generation of multipath communication optical signals, each of the plurality of surface-emitting distributed feedback laser chips corresponds to different lasing wavelengths, and the optical signal transmission waveguide corresponds to a plurality of input waveguide branches so as to receive laser beams from the surface-emitting distributed feedback laser chips with different wavelengths. Thus, parallel generation of multiple paths of optical signals with different wavelengths is realized. Further, a combiner is inte