Semiconductor laser structure of waveguide coupling integrated photodiode

Abstract

The invention discloses a semiconductor laser structure of a waveguide coupling integrated photodiode, belongs to the technical field of semiconductor photoelectrons, and can solve the problem that an existing semiconductor laser cannot realize real-time power monitoring. The semiconductor laser structure comprises a substrate; the double heterojunction structure is formed on the substrate; the P-type cover layer is formed on the double-heterojunction structure, an electrical isolation channel is arranged on the upper surface of the P-type cover layer, and the electrical isolation channel divides the top of the P-type cover layer into a plurality of convex regions; the ohmic contact layer is formed on the P-type cover layer and comprises a plurality of ohmic contact regions, and the ohmic contact regions are in one-to-one correspondence with the convex regions; the N-surface electrode is arranged on the surface of one side, far away from the double-heterojunction structure, of the substrate; the P-surface electrode is arranged on the ohmic contact layer and comprises a plurality of sub-electrodes, and the sub-electrodes are in one-to-one correspondence with the ohmic contact areas; wherein forward voltage is loaded on one sub-electrode, and backward voltage is loaded on the other sub-electrodes. The invention is used for the semiconductor laser structure.

Description

Technical Field

[0001] The present invention relates to a semiconductor laser structure with waveguide-coupled integrated photodiodes, belonging to the field of semiconductor optoelectronic technology. Background Art

[0002] High-power semiconductor lasers, with their excellent output power and stable performance, exhibit important application values in fields such as optical information transmission, photonic computing, and biomedical detection. Against the backdrop of the rapid development of silicon-based optoelectronic integration technology and the new generation of communication infrastructure, such laser sources, as the core components of optoelectronic conversion systems, provide key technical support for building high-speed and low-latency information networks. Compared with the system redundancy problems caused by the separate packaging of lasers and supporting components in traditional discrete architectures, the innovative design of monolithic integration of a monitoring photodiode (MPD) can significantly improve the module integration and operation reliability. More notably, the monolithic integration of MPD can monitor the laser output characteristics in real time. Combined with an intelligent control system, it can realize dynamic compensation adjustment of driving parameters, effectively cope with complex working conditions such as temperature fluctuations and current transients, improve the system power stability, and provide an innovative solution for the miniaturization and intelligent development of new-generation optoelectronic devices.

[0003] Therefore, it is necessary to invent a high-power semiconductor laser with monolithic integrated photodiodes that can perform real-time power monitoring while serving as a high-quality light source. Summary of the Invention

[0004] The present invention provides a semiconductor laser structure with waveguide-coupled integrated photodiodes, which can solve the problem that existing semiconductor lasers cannot achieve real-time power monitoring.

[0005] The present invention provides a semiconductor laser structure with waveguide-coupled integrated photodiodes, comprising: A substrate; A double heterojunction structure formed on the substrate; A P-type cap layer formed on the double heterojunction structure, on whose upper surface an electrical isolation channel is provided, and the electrical isolation channel divides the top of the P-type cap layer into multiple raised areas; An ohmic contact layer formed on the P-type cap layer, which includes multiple ohmic contact areas, and the ohmic contact areas correspond to the raised areas one by one; An N-side electrode provided on the surface of the substrate away from the double heterojunction structure; A P-side electrode provided on the ohmic contact layer, which includes multiple sub-electrodes, and the sub-electrodes correspond to the ohmic contact areas one by one; a forward voltage is applied to one of the sub-electrodes, and reverse voltages are applied to the remaining sub-electrodes.

[0006] Optionally, it further includes: A waveguide coupling layer formed on the substrate; A spacer layer formed on the waveguide coupling layer; the double heterojunction structure is formed on the spacer layer.

[0007] Optionally, the convex region corresponding to the sub-electrode loaded with a forward voltage is denoted as the first convex region, and the remaining convex regions are denoted as the second convex regions; the first convex region is strip-shaped; the distance between the first convex region and each of the second convex regions is between 0.2 μm and 20 μm.

[0008] Optionally, it further includes: An electrical injection blocking layer disposed on the double heterojunction structure for separating the double heterojunction structure into a plurality of double heterojunction regions, and the double heterojunction regions correspond to the convex regions one by one.

[0009] Optionally, the double heterojunction region corresponding to the sub-electrode loaded with a forward voltage is denoted as the first double heterojunction region, and the remaining double heterojunction regions are denoted as the second double heterojunction regions; the first double heterojunction region is strip-shaped; the distance between the first double heterojunction region and each of the second double heterojunction regions is between 0.2 μm and 20 μm.

[0010] Optionally, the second double heterojunction region is strip-shaped.

[0011] Optionally, the refractive index of the waveguide coupling layer is greater than the refractive index of the substrate.

[0012] Optionally, the waveguide coupling layer is a multi-layer structure, and a spacer layer is provided between adjacent two-layer waveguide coupling layers; The double heterojunction structure is formed on the spacer layer of the uppermost layer.

[0013] Optionally, the thickness of a single-layer waveguide coupling layer is 0.01 μm to 2 μm.

[0014] Optionally, it further includes: A buffer layer formed on the substrate; the waveguide coupling layer is formed on the buffer layer.

[0015] The beneficial effects that the present invention can produce include: The semiconductor laser structure of the waveguide-coupled integrated photodiode provided by the present invention forms a structure integrating at least one photodiode on the semiconductor laser by sequentially stacking a double heterojunction structure, a plurality of protruding regions, an ohmic contact region, and sub-electrodes on a substrate. Since the semiconductor laser and the photodiode are respectively designed as two adjacent waveguide structures, and the two waveguides are coupled to each other, a part of the optical field in the semiconductor laser can be coupled into the photodiode, and the photodiode performs photoelectric conversion on the coupled light to realize the function of monitoring the output optical power of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic cross-sectional structure diagram of a semiconductor laser with a waveguide-coupled integrated photodiode based on a ridge waveguide structure provided by an embodiment of the present invention; Figure 2 FIG. is a schematic cross-sectional structure diagram of a semiconductor laser with a waveguide-coupled integrated photodiode based on a buried heterojunction structure provided by an embodiment of the present invention; Figure 3 FIG. is a schematic top view of the positions of the semiconductor laser and the photodiode provided by an embodiment of the present invention; Figure 4 FIG. is a schematic diagram of the two-dimensional optical field distribution of the cross section of the semiconductor laser and the photodiode based on a buried heterojunction structure provided by an embodiment of the present invention; Figure 5 FIG. is a schematic diagram of the two-dimensional optical field distribution of the cross section of the semiconductor laser and the photodiode based on a ridge waveguide structure provided by an embodiment of the present invention; Figure 6 FIG. is a normalized mode field distribution line graph of the cross section of the semiconductor laser and the photodiode based on a buried heterojunction structure provided by an embodiment of the present invention along the horizontal direction of the active layer; Figure 7 FIG. is a normalized mode field distribution line graph of the cross section of the semiconductor laser and the photodiode based on a ridge waveguide structure provided by an embodiment of the present invention along the horizontal direction of the active layer.

[0017] REFERENCE SIGNS: 100, semiconductor laser; 200, photodiode; 10, substrate; 20, waveguide coupling layer; 30, spacer layer; 40, N-side electrode; 50, double heterojunction structure; 51, first double heterojunction region; 52, second double heterojunction region; 53, N-region confinement layer; 54, active layer; 55, P-region confinement layer; 60, P-type capping layer; 61, first protruding region; 62, second protruding region; 63, electrical isolation channel; 71, first ohmic contact region; 72, second ohmic contact region; 81, first sub-electrode; 82, second sub-electrode; 90, electrical injection blocking layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention will be described in detail below in conjunction with embodiments, but the present invention is not limited to these embodiments.

[0019] An embodiment of the present invention provides a semiconductor laser structure with a waveguide-coupled integrated photodiode, as Figure 1 shown, including: Substrate 10; A double heterojunction structure 50 formed on the substrate 10; A P-type cap layer 60 formed on the double heterojunction structure 50, on whose upper surface an electrical isolation channel 63 is provided, and the electrical isolation channel 63 divides the top of the P-type cap layer 60 into multiple raised areas; An ohmic contact layer formed on the P-type cap layer 60, which includes multiple ohmic contact areas, and the ohmic contact areas correspond to the raised areas one by one; An N-side electrode 40 provided on the surface of the substrate 10 away from the double heterojunction structure 50; A P-side electrode provided on the ohmic contact layer, which includes multiple sub-electrodes, and the sub-electrodes correspond to the ohmic contact areas one by one; a forward voltage is applied to one of the sub-electrodes, and a reverse voltage is applied to the remaining sub-electrodes.

[0020] In the embodiment of the present invention, two sub-devices are formed on the substrate 10 as an example. The two sub-devices are a semiconductor laser 100 and a photodiode 200 respectively. A forward voltage is applied to the sub-electrodes in the semiconductor laser 100, and a reverse voltage is applied to the sub-electrodes in the photodiode 200.

[0021] The electrical isolation channel 63 is provided on the upper surface at the connection of the P-type cap layer 60 of the semiconductor laser 100 and the P-type cap layer 60 of the photodiode 200, and is suitable for electrically isolating the photodiode 200 and the semiconductor laser 100 to facilitate different current or voltage control.

[0022] Furthermore, the semiconductor laser structure further includes: A waveguide coupling layer 20 formed on the substrate 10; A spacer layer 30 formed on the waveguide coupling layer 20; the double heterojunction structure 50 is formed on the spacer layer 30.

[0023] In practical applications, the semiconductor laser structure further includes: A buffer layer formed on the substrate 10; the waveguide coupling layer 20 is formed on the buffer layer.

[0024] Taking two sub-devices as an example, the isolation trench separates the top of the P-type cap layer 60 into two convex regions, denoted as the first convex region 61 and the second convex region 62 respectively; two ohmic contact regions are formed on the P-type cap layer 60, denoted as the first ohmic contact region 71 and the second ohmic contact region 72 respectively; two sub-electrodes are arranged on the ohmic contact layer, denoted as the first sub-electrode 81 and the second sub-electrode 82 respectively. A forward voltage is applied to the first sub-electrode 81, and a reverse voltage is applied to the second sub-electrode 82.

[0025] Among them, the double heterojunction structure 50 includes an N-region separate confinement layer 53, an active layer 54, and a P-region separate confinement layer 55 that are sequentially stacked on the spacer layer 30.

[0026] In the present invention, the convex region corresponding to the sub-electrode to which the forward voltage is applied is denoted as the first convex region 61, and the remaining convex regions are denoted as the second convex region 62; the first convex region 61 is strip-shaped; the distance between the first convex region 61 and each second convex region 62 is between 0.2 μm and 20 μm.

[0027] In the present invention, the semiconductor laser 100 and the photodiode 200 can adopt a buried heterojunction structure or a ridge waveguide structure.

[0028] Among them, the refractive index of the waveguide coupling layer 20 is greater than the refractive index of the substrate 10.

[0029] Furthermore, the waveguide coupling layer 20 is a multi-layer structure, and a spacer layer 30 is provided between adjacent waveguide coupling layers 20; the double heterojunction structure 50 is formed on the uppermost spacer layer 30. The thickness of a single-layer waveguide coupling layer 20 is 0.01 μm to 2 μm.

[0030] Reference Figure 1 As shown, the semiconductor laser structure of the waveguide-coupled integrated photodiode adopts a ridge waveguide structure. The waveguide coupling layer 20 is designed below the active layer 54, and the waveguide coupling layer 20 can be designed as a single layer, or alternately arranged with the spacer layer 30 to be a multi-layer. The refractive index of the waveguide coupling layer 20 is higher than that of the substrate 10, and the range of the single-layer thickness is 0 μm to 2 μm.

[0031] Figure 5 Schematically shows a two-dimensional optical field distribution diagram of the cross-section of the semiconductor laser 100 and the photodiode 200 based on the ridge waveguide structure.

[0032] As Figure 5As shown, due to the coupling effect between the waveguides, the optical field of the semiconductor laser 100 is coupled into the photodiode 200. The photodiode 200 converts the coupled light into current through the photoelectric effect, realizing the monitoring of the optical power of the semiconductor laser 100. There is a certain distance between the semiconductor laser 100 and the photodiode 200, and different spacings can be designed according to the actual responsivity requirements to control the strength of the coupling between the two waveguides.

[0033] In the embodiment of the present invention, the distance d between the semiconductor laser 100 and the photodiode 200 is between 0.2 μm and 20 μm.

[0034] Figure 7 Schematically shows the normalized mode field distribution line graph of the cross-section of the semiconductor laser 100 and the photodiode 200 based on the ridge waveguide structure along the horizontal direction of the active layer 54.

[0035] As Figure 7 shown, the mode field intensity of the photodiode 200 on the active layer 54 is 26% of that of the semiconductor laser 100. The photodiode 200 can effectively realize the monitoring of the output optical power of the semiconductor laser 100. The waveguide spacing d can be adjusted according to the actual application requirements to reduce or increase the mode field intensity of the photodiode 200.

[0036] In another embodiment of the present invention, the semiconductor laser structure further includes: An electrical injection blocking layer 90, disposed on the double heterojunction structure 50, for separating the double heterojunction structure 50 into multiple double heterojunction regions, and the double heterojunction regions correspond to the raised regions one by one.

[0037] Specifically, the double heterojunction region corresponding to the sub-electrode loaded with the forward voltage is denoted as the first double heterojunction region 51, and the remaining double heterojunction regions are denoted as the second double heterojunction regions 52. The first double heterojunction region 51 is strip-shaped. The distance between the first double heterojunction region 51 and each second double heterojunction region 52 is between 0.2 μm and 20 μm.

[0038] Preferably, the second double heterojunction region 52 is strip-shaped.

[0039] Figure 3 Schematically shows a top view of the positions of the semiconductor laser 100 and the photodiode 200.

[0040] As Figure 3 shown, the semiconductor laser 100 and the photodiode 200 are respectively designed on two adjacent straight waveguides. The two waveguides are coupled to each other, and part of the optical field in the semiconductor laser 100 can be coupled into the photodiode 200, and the photodiode 200 realizes the function of monitoring the output optical power of the semiconductor laser 100.

[0041] Reference Figure 2 As shown, the semiconductor laser structure of the waveguide-coupled integrated photodiode adopts a buried heterostructure. A waveguide-coupling layer 20 is designed below the active layer 54. The waveguide-coupling layer 20 can be designed as a single layer or alternately arranged with the spacer layer 30 into multiple layers. The refractive index of the waveguide-coupling layer 20 is higher than that of the substrate 10. By designing the thickness of the single-layer waveguide-coupling layer 20 to be 0.01 μm to 2 μm, it is convenient for production and has good structural performance.

[0042] Figure 4 Schematically shows a schematic diagram of the two-dimensional optical field distribution of the cross-section of the semiconductor laser 100 and the photodiode 200 based on the buried heterostructure.

[0043] As Figure 4 shown, due to the coupling effect between waveguides, the optical field of the semiconductor laser 100 is coupled into the photodiode 200. The photodiode 200 converts the coupled light into current through the photoelectric effect to realize the monitoring of the optical power of the semiconductor laser 100. There is a certain distance between the semiconductor laser 100 and the photodiode 200, and different spacings can be designed according to the actual responsivity requirements to control the strength of the coupling between the two waveguides.

[0044] In the embodiment of the present invention, the distance d between the semiconductor laser 100 and the photodiode 200 is between 0.2 μm and 20 μm.

[0045] Figure 6 Schematically shows a normalized mode field distribution line graph of the cross-section of the semiconductor laser 100 and the photodiode 200 based on the buried heterostructure along the horizontal direction of the active layer 54.

[0046] As Figure 6 shown, the mode field intensity of the photodiode 200 on the active layer 54 is 43% of that of the semiconductor laser 100. The photodiode 200 can effectively realize the monitoring of the output optical power of the semiconductor laser 100. The waveguide spacing d can be adjusted according to the actual application requirements to reduce or increase the mode field intensity of the photodiode 200.

[0047] In the embodiment of the present invention, the shape of the positive projection of the semiconductor laser 100 on the N-type substrate 10 is strip-shaped.

[0048] In the embodiment of the present invention, the shape of the positive projection of the photodiode 200 on the N-type substrate 10 is strip-shaped.

[0049] In the embodiment of the present invention, the photodiode 200 is not limited to one, and one or more can be designed according to needs. Specifically, the photodiode 200 can be located at different positions corresponding to the semiconductor laser 100, so as to realize the monitoring of the optical power of the front light, rear light or a certain position in the middle of the semiconductor laser 100.

[0050] The semiconductor laser structure of the waveguide-coupled integrated photodiode provided by the present invention monolithically integrates the photodiode 200 and the semiconductor laser 100 in a waveguide-coupled manner, while ensuring the integrity of the main optical path of the laser, an auxiliary monitoring optical path is constructed. This structure can achieve real-time and accurate monitoring of the output optical power of the laser, providing reliable data support for the closed-loop control of the system.

[0051] For the semiconductor laser structure of the waveguide-coupled integrated photodiode provided by the present invention, the photodiode 200 has basically no influence on the preparation and performance of the semiconductor laser 100.

[0052] The semiconductor laser structure of the waveguide-coupled integrated photodiode provided by the present invention can be applied in application fields such as optical interconnection modules, optical I / O chips, and co-packaged optics. Through high-integration design, it helps to enhance the stability and reliability of the system.

[0053] The above are only several embodiments of the present application, and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, making some changes or modifications using the technical content disclosed above is equivalent to equivalent implementation cases, and all belong to the scope of the technical solution.

Claims

1. A semiconductor laser structure with a waveguide-coupled integrated photodiode, characterized in that: include: substrate; A double heterojunction structure is formed on the substrate; A P-type cap layer is formed on the double heterojunction structure, and an electrical isolation channel is provided on its upper surface, wherein the electrical isolation channel separates the top of the P-type cap layer into a plurality of raised areas; An ohmic contact layer, formed on the P-type cap layer, comprising a plurality of ohmic contact regions, wherein the ohmic contact regions correspond one to one to the convex regions; An N-side electrode is arranged on a surface of the substrate away from the double heterojunction structure; The P-side electrode is arranged on the ohmic contact layer, and includes a plurality of sub-electrodes, and the sub-electrodes correspond to the ohmic contact regions one by one; a forward voltage is loaded on one of the sub-electrodes, and a reverse voltage is loaded on the remaining sub-electrodes.

2. The semiconductor laser structure according to claim 1, characterized in that: Also includes: a waveguide coupling layer formed on the substrate; a spacer layer formed on the waveguide coupling layer; The double heterojunction structure is formed on the spacer layer.

3. The semiconductor laser structure according to claim 2, characterized in that: The raised area corresponding to the sub-electrode loaded with a forward voltage is recorded as the first raised area, and the remaining raised areas are recorded as the second raised areas; the first raised area is in the shape of a long strip; the distance between the first raised area and each of the second raised areas is between 0.2 μm and 20 μm.

4. The semiconductor laser structure according to claim 2, characterized in that: Also includes: The electric injection blocking layer is arranged on the double heterojunction structure and is used to separate the double heterojunction structure into a plurality of double heterojunction regions, and the double heterojunction regions correspond to the convex regions one by one.

5. The semiconductor laser structure according to claim 4, characterized in that: The double heterojunction region corresponding to the sub-electrode loaded with a forward voltage is recorded as the first double heterojunction region, and the remaining double heterojunction regions are recorded as the second double heterojunction regions; the first double heterojunction region is in the shape of a long strip; the distance between the first double heterojunction region and each of the second double heterojunction regions is between 0.2 μm and 20 μm.

6. The semiconductor laser structure according to claim 5, characterized in that: The second double heterojunction region is in a strip shape.

7. The semiconductor laser structure according to claim 2, characterized in that: The refractive index of the waveguide coupling layer is greater than the refractive index of the substrate.

8. The semiconductor laser structure according to claim 2, characterized in that: The waveguide coupling layer is a multi-layer structure, and a spacer layer is provided between two adjacent waveguide coupling layers; The double heterojunction structure is formed on the uppermost spacer layer.

9. The semiconductor laser structure according to claim 8, characterized in that: The thickness of a single layer of the waveguide coupling layer is 0.01 μm to 2 μm.

10. The semiconductor laser structure according to claim 2, characterized in that: Also includes: A buffer layer is formed on the substrate; and the waveguide coupling layer is formed on the buffer layer.

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