A multi-cell back-to-back multi-wavelength vertical emission laser source array
By using a multi-unit spine design and the application of a composite functional grating on the upper surface, the limitations of side emission in DFB lasers and the performance deficiencies of VCSELs are solved, realizing a high-efficiency, low-cost multi-wavelength laser source array that meets the requirements of high-density wavelength division multiplexing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JUGUANG KEXIN (HEFEI) OPTOELECTRONICS CO LTD
- Filing Date
- 2026-01-21
- Publication Date
- 2026-06-05
AI Technical Summary
Existing DFB lasers suffer from limitations such as edge emission, high cost of secondary epitaxy with deeply buried gratings, complex processes, poor performance consistency, and low integration, making it difficult to achieve efficient integration and vertical plane emission of multi-wavelength lasers. Furthermore, VCSEL devices have relatively wide linewidths and low output power, which cannot meet the requirements of high-density wavelength division multiplexing.
Employing a multi-unit spine design, utilizing a composite functional grating and quasi-resonant cavity structure on the upper end face, combined with vertical and angled HR end faces, it avoids secondary epitaxial processes, achieving vertical emission and precise multi-wavelength control, and integrating filtering, electrode, and coupling output functions to simplify the fabrication process.
A high-density wavelength division multiplexing (WDM) multi-wavelength laser source array has been realized, featuring narrow linewidth, high stability, and low cost. It meets the ITU-Grid standard, improves the integration and performance of the device, and reduces the manufacturing and application costs.
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Figure CN122159056A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor laser technology, specifically to a multi-unit spine-type multi-wavelength vertical emission laser source array. Background Technology
[0002] Multi-wavelength laser source arrays are core devices in fields such as high-density wavelength division multiplexing (WDM) and integrated photonic chips. Traditional multi-wavelength source arrays are mostly based on DFB laser architecture. Existing DFB lasers have several technical bottlenecks: First, they emit from the side rather than the vertical plane. The laser gain chip resonator adopts an end-face design of "HR coating at one end + AR coating at the other end," which can only achieve side emission and is difficult to achieve large-area two-dimensional vertical plane emission. Second, the core filter grating is deeply buried inside the semiconductor optical waveguide. The fabrication process requires complex and costly secondary epitaxial processes, which are not only difficult to implement but also prone to lattice defects, resulting in low device yield. Third, traditional DFB gratings only have a single filtering function, requiring additional electrode structures and optical coupling output structures, resulting in low device integration and a cumbersome fabrication process. Fourth, single wavelength tuning depends on wafer-level process optimization, making it difficult to achieve precise multi-wavelength matching of each unit in the array and failing to efficiently meet the high-density integration requirements of the ITU-Grid wavelength standard.
[0003] Existing VCSELs have the following key technical shortcomings: 1) The linewidth is too wide (typical value 5MHz); 2) The operating wavelength is concentrated in 800–1000nm, and the performance and cost of 1550nm band devices are limited by the difference in material refractive index, which is far from commercialization; 3) The output power of a single tube is too low (typical value 0.2mW), making it difficult to use in AI optical computing chips and long-distance application scenarios; 4) The array unit has a single wavelength, making it difficult to achieve the DWDM wavelength division multiplexing wavelength distribution series required by ITU-Grid.
[0004] To address these issues, the industry has attempted to optimize the grating structure and resonant cavity design, but none of these efforts have broken through the architectural limitations of traditional DFB lasers. They have failed to achieve integrated functionality of filtering, electrodes, and coupled output, nor have they been able to avoid the defects of secondary epitaxial processes. The problem of switching from edge emission to vertical plane emission remains unsolved, which restricts the performance improvement and cost control of multi-wavelength laser source arrays. Summary of the Invention
[0005] This invention addresses the core pain points of existing DFB lasers, such as limited edge emission, high cost of secondary epitaxy of deeply buried DFB gratings, susceptibility to localized melting and deformation of the grating structure during reflow, complex manufacturing processes, poor performance consistency, limited output direction, and low integration of multi-wavelength lasers. It provides a novel multi-unit spine-type multi-wavelength surface-emitting laser array (1×N one-dimensional or N×M two-dimensional) with an external metal grating on the upper surface and a horizontal-cavity vertical-emission resonant cavity. Through an integrated composite functional grating design and an internal cavity quasi-resonant cavity architecture, it avoids secondary epitaxy processes, combining the low cost and high yield advantages of FP lasers with the narrow linewidth performance of DFB lasers. This achieves vertical emission and precise multi-wavelength control, improving device stability and integration, and providing a high-performance, low-cost multi-wavelength light source solution for high-density wavelength division multiplexing and other fields. It also overcomes the problems of wide linewidth, low power, and single wavelength in existing VCSELs. This invention provides a multi-unit spine-type multi-wavelength vertical-emission laser array to solve the problems mentioned in the background.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A multi-unit spine-type multi-wavelength vertical emission laser source array, consisting of N rows × M columns of spine-type semiconductor lasers;
[0008] N and M are positive integers, and each of the spine-type semiconductor lasers corresponds to a unique coordinate (N, M) and a matching grating constant Λ. (N,M) and output wavelength λ (N,M) .
[0009] As a preferred embodiment of the above technical solution, the spine-type semiconductor laser includes:
[0010] Substrate;
[0011] A ridge-type optical waveguide is disposed on the upper end face of the substrate;
[0012] The vertical HR end face is machined on the left side of the spine-type optical waveguide;
[0013] An angled HR end face is machined on the right side of the back ridge optical waveguide, and the angle φ of the angled HR end face is 10°-26°.
[0014] The back-ridge type optical waveguide includes, from bottom to top, a light-emitting quantum well layer, a PN junction, and an upper end face composite functional grating;
[0015] The upper end face composite functional grating includes a second-order grating disposed in the middle for achieving upward output of light coupling while also taking into account some filtering effect, and a first-order filtering grating disposed on both sides of the second-order grating for achieving filtering function while also acting as laser electrode.
[0016] Each of the first-order filter gratings has a λ in its center. (N,M) A / 4 phase shift structure is used to realize that the first-order filter grating is symmetrically divided into sections with a spacing of λ. (N,M) / 4 two-segment grating.
[0017] As a preferred embodiment of the above technical solution, the upper surface of the second-order grating is coated with a layer, which is a silicon dioxide protective layer or an AR anti-reflective film.
[0018] As a preferred embodiment of the above technical solution, the substrate is an InP or GaAs substrate.
[0019] As a preferred embodiment of the above technical solution, both the vertical HR end face and the angled HR end face are coated with an HR optical film.
[0020] As a preferred embodiment of the above technical solution, the upper surface composite functional grating is any one of the following: a surface-reflective metal optical comb grating, a semiconductor / SiO2 etched grating with a reflective optical film deposited on the upper surface, and a vapor-deposited planar metal optical comb grating.
[0021] As a preferred embodiment of the above technical solution, the resonant structure of the spine semiconductor laser (1) is composed of a quasi-resonant cavity formed by the composite functional grating of the vertical HR end face and the upper end face; by means of the reflection wavelength selection characteristics of the first-order filter grating, the resonant cavity has narrow linewidth optical quality characteristics.
[0022] As a preferred embodiment of the above technical solution, the grating constant of the second-order grating in the same spine semiconductor laser is twice the grating constant of the first-order filter grating.
[0023] As a preferred embodiment of the above technical solution, the grating constant Λ of each unit is adjusted. (N,M) This enables each of the spine semiconductor lasers in the array to output a specific wavelength that conforms to the ITU-T standard wavelength spacing, thereby achieving the multi-wavelength integration required for high-density wavelength division multiplexing.
[0024] As a preferred embodiment of the above technical solution, the upper surface composite functional grating is an arbitrary shape grating, and its filtering function satisfies the λ of BRAGG. (N,M) / 2 grating constant; the material of the upper surface composite functional grating is metal, semiconductor, dielectric, lithium niobate, piezoelectric ceramic or plastic; the type of the upper surface composite functional grating is high reflectivity, transmission refraction or semi-transmission semi-reflection.
[0025] This invention provides a multi-unit spine-type multi-wavelength vertical emission laser source array, which has the following beneficial effects:
[0026] 1. Disruptive innovation in structure and principle: The upper-side composite functional grating is used to replace the traditional deeply buried DFB grating, avoiding the high-cost and low-yield secondary epitaxial process; combined with the resonant cavity design of "vertical HR end face + oblique HR end face", the conversion from traditional DFB edge emission to vertical surface emission in the gain chip area is realized, breaking through the limitation of optical field output direction.
[0027] 2. High functional integration: The composite functional grating on the upper surface has three functions: filtering, electrode, and vertical coupling output. No additional corresponding structure is required, which simplifies the overall structure and fabrication process of the device and reduces the complexity of the process.
[0028] 3. Precise and efficient multi-wavelength control: By adjusting the grating constant Λ of each unit... (N,M) This allows each laser unit in the array to output a specific wavelength that conforms to the ITU-T standard wavelength spacing, realizing the multi-wavelength integration required for high-density wavelength division multiplexing and adapting to the needs of different application scenarios.
[0029] 4. Excellent optical quality characteristics: Through the λ / 4 phase shift design of the first-order filter grating and the resonant coordination of the vertical HR end face and the upper end face composite functional grating, narrow linewidth output is achieved. At the same time, the angled HR end face design eliminates lateral resonance interference, further improving the output optical stability and quality.
[0030] 5. Significant cost advantages: By avoiding complex processes such as secondary epitaxy, the fabrication process is simplified, the device yield is improved, and the functional integration reduces the number of parts, significantly reducing the cost of device fabrication and application, providing a feasible path for high-performance, low-cost integrated photonic chips. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of an N (number of rows) × M (number of columns) array structure of a spine semiconductor laser, where N and M are positive integers; each spine semiconductor laser corresponds to a specific output wavelength λ. (N,M) and grating constant Λ (N,M) ;
[0032] Figure 2 A schematic diagram of the front cross-section of a spine-back semiconductor laser;
[0033] Figure 3 for Figure 2 Top view;
[0034] Figure 4 for Figure 2 The left view.
[0035] In the figure: 1. Ridge-back semiconductor laser; 2. Substrate; 3. Ridge-back optical waveguide; 31. Light-emitting quantum well layer; 32. PN junction; 33. Top-side composite functional grating; 331. Second-order grating; 332. First-order filter grating; 333. λ(N,M) / 4 Phase shift structure; 334, coating; 4, vertical HR end face; 5, angled HR end face. Detailed Implementation
[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0037] Example
[0038] A multi-unit spine-type multi-wavelength vertical emission laser source array is composed of N rows × M columns of spine-type semiconductor lasers 1;
[0039] N and M are positive integers, and each of the spine semiconductor lasers 1 corresponds to a unique coordinate (N, M) and a matching grating constant Λ. (N,M) and output wavelength λ (N,M) .
[0040] As a preferred embodiment of the above technical solution, the spine-type semiconductor laser 1 includes:
[0041] Substrate 2;
[0042] A back-ridge type optical waveguide 3 is disposed on the upper end surface of the substrate 2;
[0043] The vertical HR end face 4 is machined on the left side of the spine-type optical waveguide 3;
[0044] The beveled HR end face 5 is machined on the right side of the back ridge optical waveguide 3, and the bevel angle φ of the beveled HR end face 5 is 10°-26°.
[0045] The back-ridge type optical waveguide 3 includes, from bottom to top, a light-emitting quantum well layer 31, a PN junction 32, and an upper end face composite functional grating 33;
[0046] The upper end face composite functional grating 33 includes a second-order grating 331 disposed in the middle for realizing upward output of light coupling while also taking into account part of the light filtering effect, and a first-order filter grating 332 disposed on both sides of the second-order grating 331 for realizing the light filtering function while also serving as laser electrode.
[0047] Each of the first-order filter gratings 332 has a λ in its center. (N,M) A / 4 phase shift structure is used to realize that the first-order filter grating 332 is symmetrically divided into sections with a spacing of λ. (N,M) The grating has two segments of λ / 4; for example, for a unit with a target wavelength of 1550nm, the grating constant Λ=387.5nm; a λ / 4 phase shift structure is set in the middle of the first-order filter grating 332, with a phase shift spacing of 387.5nm, so that the grating is symmetrically divided into two segments to ensure narrow linewidth output.
[0048] The upper surface of the second-order grating 331 is coated with a coating layer 334, which is a silicon dioxide protective layer or an AR anti-reflective film.
[0049] The substrate 2 is an InP or GaAs substrate.
[0050] Both the vertical HR end face 4 and the oblique HR end face 5 are coated with SiO2 / TiO2 multilayer HR optical films with a reflectivity >99.9%; effectively eliminating interference from the transverse end face resonant cavity and ensuring stable oscillation of the resonant light.
[0051] The upper surface composite functional grating 33 is any one of the following: a surface-reflective metal comb grating, a semiconductor / SiO2 etched grating with a reflective optical film deposited on the upper surface, and a vapor-deposited planar metal comb grating.
[0052] The resonant structure of the spine semiconductor laser 1 is a quasi-resonant cavity formed by the vertical HR end face 4 and the upper end face composite functional grating 33; by means of the reflection wavelength selection characteristics of the first-order filter grating 332, the resonant cavity has narrow linewidth optical quality characteristics.
[0053] The grating constant of the second-order grating 331 in the same spine semiconductor laser 1 is twice the grating constant of the first-order filter grating 332.
[0054] By adjusting the grating constant Λ of each unit (N,M) This enables each of the spine semiconductor lasers 1 in the array to output a specific wavelength that conforms to the ITU-T standard wavelength spacing, thereby achieving the multi-wavelength integration required for high-density wavelength division multiplexing.
[0055] The upper surface composite functional grating 33 is an arbitrary shape grating, and its filtering function satisfies the λ of BRAGG. (N,M) / 2 grating constant; the material of the upper surface composite functional grating 33 is metal, semiconductor, dielectric, lithium niobate, piezoelectric ceramic or plastic; the type of the upper surface composite functional grating 33 is high reflectivity, transmission refraction or semi-transmission semi-reflection.
[0056] The laser emission process in this embodiment is as follows: a forward bias voltage is applied to the electrodes of the first-order filter grating 332 of the upper end face composite functional grating 33, and electrons and holes are injected into the light-emitting quantum well layer 31 to emit light. The generated light oscillates in the quasi-resonant cavity formed by the vertical HR end face 4 and the upper end face composite functional grating 33. After being filtered by the first-order filter grating 332 and narrowed by the λ / 4 phase shift structure, part of the light passes through the opening of the middle second-order grating 331 and is emitted vertically upward to achieve specific wavelength output. By adjusting the grating constant of each unit, the array output can be made to conform to the ITU-Grid 100GHz spacing multi-wavelength laser, which meets the requirements of high-density wavelength division multiplexing.
[0057] Tests showed that the output wavelength of each laser unit in this embodiment accurately matches the ITU-Grid standard, with a linewidth ≤2kHz, a vertical emission efficiency >85%, excellent thermal stability (wavelength drift <0.03pm / ℃ from -40℃ to 85℃), and the fabrication process is more than 40% simpler and the cost is reduced by more than 50% compared to traditional DFB multi-wavelength arrays.
[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A multi-unit spine-type multi-wavelength vertical emission laser source array, characterized in that, It consists of N rows × M columns of spine-back semiconductor lasers (1); N and M are positive integers, and each of the spine semiconductor lasers (1) corresponds to a unique coordinate (N, M) and a matching grating constant Λ. (N,M) and output wavelength λ (N,M) ; The spine-type semiconductor laser (1) includes: Substrate (2); A back-ridge type optical waveguide (3) is disposed on the upper end surface of the substrate (2); The vertical HR end face (4) is machined on the left side of the back ridge optical waveguide (3); The angled HR end face (5) is machined on the right side of the back ridge optical waveguide (3), and the angle φ of the angled HR end face (5) is 10°-26°. The back-shaped optical waveguide (3) includes, from bottom to top, a light-emitting quantum well layer (31), a PN junction (32), and an upper-side composite functional grating (33). The upper surface composite functional grating (33) includes a second-order grating (331) disposed in the middle for realizing upward output of light coupling while also taking into account some filtering effect, and a first-order filtering grating (332) disposed on both sides of the second-order grating (331) for realizing filtering function while also serving as laser electrode. The first-order filter grating (332) is provided with λ in the middle. (N,M) A / 4 phase shift structure is used to realize that the first-order filter grating (332) is symmetrically divided into sections with a spacing of λ. (N,M) / 4 two-segment grating.
2. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: The upper surface of the second-order grating (331) is coated with a coating (334), which is a silicon dioxide protective layer or an AR anti-reflective film.
3. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: The substrate (2) is an InP or GaAs substrate.
4. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: Both the vertical HR end face (4) and the oblique HR end face (5) are coated with HR optical film.
5. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: The upper surface composite functional grating (33) is any one of the following: a surface-reflective metal comb grating, a semiconductor / SiO2 etched grating with a reflective optical film deposited on the upper surface, and a vapor-deposited planar metal comb grating.
6. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: The resonant structure of the spine semiconductor laser (1) is a quasi-resonant cavity formed by the vertical HR end face (4) and the upper end face composite functional grating (33); by means of the reflection wavelength selection characteristics of the first-order filter grating (332), the resonant cavity has narrow linewidth optical quality characteristics.
7. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: The grating constant of the second-order grating (331) in the same spine semiconductor laser (1) is twice the grating constant of the first-order filter grating (332).
8. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that, By adjusting the grating constant Λ of each unit (N,M) This enables each of the spine semiconductor lasers (1) in the array to output a specific wavelength that conforms to the ITU-T standard wavelength spacing, thereby achieving the multi-wavelength integration required for high-density wavelength division multiplexing.
9. The multi-unit spine-type multi-wavelength vertical emission laser source array according to claim 1, characterized in that: The upper surface composite functional grating (33) is an arbitrary grating, and its filtering function satisfies the λ of BRAGG. (N,M) / 2 grating constant; the material of the upper surface composite functional grating (33) is metal, semiconductor, dielectric, lithium niobate, piezoelectric ceramic or plastic; the type of the upper surface composite functional grating (33) is high reflectivity, transmission refraction or semi-transmission semi-reflection.