A semiconductor laser structure of a waveguide-coupled integrated photodiode

Abstract

The present invention discloses a semiconductor laser structure with waveguide-coupled integrated photodiodes, belonging to the field of semiconductor optoelectronic technology, and capable of solving the problem that existing semiconductor lasers cannot achieve real-time power monitoring. The semiconductor laser structure includes: a substrate; a double heterojunction structure formed on the substrate; a P-type cap layer formed on the double heterojunction structure, on the upper surface of which an electrical isolation channel is provided, and the electrical isolation channel divides the top of the P-type cap layer into multiple raised regions; an ohmic contact layer formed on the P-type cap layer, which includes multiple ohmic contact regions, and the ohmic contact regions correspond to the raised regions 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 regions 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. The present invention is used for semiconductor laser structures.

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 scheme 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 achieve 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 the new generation of 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:

[0006] A substrate;

[0007] A double heterojunction structure formed on the substrate;

[0008] 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;

[0009] 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;

[0010] An N-side electrode provided on the surface of the substrate away from the double heterojunction structure;

[0011] The P-side electrode is disposed on the ohmic contact layer and includes a plurality of sub-electrodes that correspond one-to-one with the ohmic contact regions; a forward voltage is applied to one of the sub-electrodes, and a reverse voltage is applied to the remaining sub-electrodes.

[0012] Optionally, it further includes:

[0013] A waveguide coupling layer formed on the substrate;

[0014] A spacer layer formed on the waveguide coupling layer; the double heterojunction structure is formed on the spacer layer.

[0015] Optionally, the raised region corresponding to the sub-electrode with the forward voltage applied is denoted as the first raised region, and the remaining raised regions are denoted as the second raised regions; the first raised region is in a strip shape; the distance between the first raised region and each of the second raised regions is between 0.2 μm and 20 μm.

[0016] Optionally, it further includes:

[0017] An electrical injection blocking layer disposed on the double heterojunction structure for separating the double heterojunction structure into a plurality of double heterojunction regions that correspond one-to-one with the raised regions.

[0018] Optionally, the double heterojunction region corresponding to the sub-electrode with the forward voltage applied 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 in a strip shape; the distance between the first double heterojunction region and each of the second double heterojunction regions is between 0.2 μm and 20 μm.

[0019] Optionally, the second double heterojunction region is in a strip shape.

[0020] Optionally, the refractive index of the waveguide coupling layer is greater than the refractive index of the substrate.

[0021] Optionally, the waveguide coupling layer is a multi-layer structure, and a spacer layer is provided between adjacent two layers of the waveguide coupling layer;

[0022] The double heterojunction structure is formed on the spacer layer of the uppermost layer.

[0023] Optionally, the thickness of a single layer of the waveguide coupling layer is between 0.01 μm and 2 μm.

[0024] Optionally, it further includes:

[0025] A buffer layer formed on the substrate; the waveguide coupling layer is formed on the buffer layer.

[0026] The beneficial effects that can be produced by the present invention include:

[0027] 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, multiple raised 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, 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. Description of the Drawings

[0028] Figure 1 Schematic cross-sectional structure diagram of the semiconductor laser with waveguide-coupled integrated photodiode based on the ridge waveguide structure provided by the embodiment of the present invention;

[0029] Figure 2 Schematic cross-sectional structure diagram of the semiconductor laser with waveguide-coupled integrated photodiode based on the buried heterojunction structure provided by the embodiment of the present invention;

[0030] Figure 3 Schematic top view of the positions of the semiconductor laser and the photodiode provided by the embodiment of the present invention;

[0031] Figure 4 Schematic diagram of the two-dimensional optical field distribution of the cross-section of the semiconductor laser and the photodiode based on the buried heterojunction structure provided by the embodiment of the present invention;

[0032] Figure 5 Schematic diagram of the two-dimensional optical field distribution of the cross-section of the semiconductor laser and the photodiode based on the ridge waveguide structure provided by the embodiment of the present invention;

[0033] Figure 6 Line graph of the normalized mode field distribution along the horizontal direction of the active layer of the cross-section of the semiconductor laser and the photodiode based on the buried heterojunction structure provided by the embodiment of the present invention;

[0034] Figure 7 Line graph of the normalized mode field distribution along the horizontal direction of the active layer of the cross-section of the semiconductor laser and the photodiode based on the ridge waveguide structure provided by the embodiment of the present invention.

[0035] Reference Signs:

[0036] 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 raised region; 62, second raised 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 implementation manners

[0037] The present invention will be described in detail below in conjunction with embodiments, but the present invention is not limited to these embodiments.

[0038] An embodiment of the present invention provides a semiconductor laser structure integrated with a waveguide-coupled photodiode, as Figure 1 shown, including:

[0039] Substrate 10;

[0040] Double heterojunction structure 50, formed on substrate 10;

[0041] P-type capping layer 60, formed on double heterojunction structure 50, on the upper surface of which an electrical isolation channel 63 is provided, and the electrical isolation channel 63 divides the top of the P-type capping layer 60 into multiple raised regions;

[0042] Ohmic contact layer, formed on P-type capping layer 60, which includes multiple ohmic contact regions, and the ohmic contact regions correspond to the raised regions one by one;

[0043] N-side electrode 40, provided on the surface of substrate 10 away from double heterojunction structure 50;

[0044] P-side electrode, provided on the ohmic contact layer, which includes multiple sub-electrodes, and the sub-electrodes correspond to the ohmic contact regions 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.

[0045] In the embodiment of the present invention, two sub-devices are taken as an example for illustration, and the two sub-devices are a semiconductor laser 100 and a photodiode 200 respectively. A forward voltage is applied to the sub-electrode in the semiconductor laser 100, and a reverse voltage is applied to the sub-electrode in the photodiode 200.

[0046] The electrical isolation channel 63 is provided on the upper surface at the connection of the P-type capping layer 60 of the semiconductor laser 100 and the P-type capping layer 60 of the photodiode 200, and is suitable for electrically isolating the photodiode 200 and the semiconductor laser 100 for different current or voltage control.

[0047] Further, the semiconductor laser structure further includes:

[0048] A waveguide coupling layer 20 formed on the substrate 10;

[0049] A spacer layer 30 formed on the waveguide coupling layer 20; A double heterojunction structure 50 is formed on the spacer layer 30.

[0050] In practical applications, the semiconductor laser structure further includes:

[0051] A buffer layer formed on the substrate 10; The waveguide coupling layer 20 is formed on the buffer layer.

[0052] Taking two sub-devices as an example, the isolation channel separates the top of the P-type capping 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 capping 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.

[0053] 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.

[0054] In the present invention, the convex region corresponding to the sub-electrode with the forward voltage 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.

[0055] In the present invention, the semiconductor laser 100 and the photodiode 200 can adopt a buried heterojunction structure or a ridge waveguide structure.

[0056] Among them, the refractive index of the waveguide coupling layer 20 is greater than that of the substrate 10.

[0057] Further, the waveguide coupling layer 20 is a multi-layer structure, and a spacer layer 30 is provided between adjacent two-layer waveguide coupling layers 20; The double heterojunction structure 50 is formed on the topmost spacer layer 30. The thickness of a single-layer waveguide coupling layer 20 is 0.01 μm to 2 μm.

[0058] 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 designed as 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.

[0059] Figure 5 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 ridge waveguide structure.

[0060] As Figure 5 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.

[0061] 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.

[0062] Figure 7 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 ridge waveguide structure along the horizontal direction of the active layer 54.

[0063] 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.

[0064] In another embodiment of the present invention, the semiconductor laser structure further includes:

[0065] 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.

[0066] 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.

[0067] Preferably, the second double heterojunction region 52 is strip-shaped.

[0068] Figure 3 Schematically shows a top view of the positions of the semiconductor laser 100 and the photodiode 200.

[0069] As Figure 3As 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.

[0070] Reference Figure 2 As shown, the semiconductor laser structure with waveguide-coupled integrated photodiode adopts a buried heterostructure. A 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 form 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.

[0071] Figure 4 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 buried heterostructure.

[0072] As Figure 4 As 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 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 coupling strength between the two waveguides.

[0073] 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.

[0074] 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.

[0075] As Figure 6 As 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, and 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.

[0076] 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.

[0077] In an embodiment of the present invention, the shape of the orthographic projection of the photodiode 200 on the N-type substrate 10 is strip-shaped.

[0078] In an embodiment of the present invention, the number of photodiodes 200 is not limited to one, and one or more can be designed according to needs. Specifically, the photodiodes 200 can be located at different positions corresponding to the semiconductor laser 100, so as to realize the optical power monitoring of the front light, rear light or a certain position in the middle of the semiconductor laser 100.

[0079] The semiconductor laser structure with waveguide-coupled integrated photodiodes 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 realize 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.

[0080] For the semiconductor laser structure with waveguide-coupled integrated photodiodes provided by the present invention, the photodiode 200 has basically no influence on the preparation and performance of the semiconductor laser 100.

[0081] The semiconductor laser structure with waveguide-coupled integrated photodiodes 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.

[0082] 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 with preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A semiconductor laser structure with a waveguide-coupled integrated photodiode, characterized in that, Comprising: Substrate; Double heterojunction structure formed on the substrate; P-type capping layer formed on the double heterojunction structure, with an electrically isolated channel provided on its upper surface, and the electrically isolated channel divides the top of the P-type capping layer into multiple raised regions; Ohmic contact layer formed on the P-type capping layer, which includes multiple ohmic contact regions, and the ohmic contact regions correspond to the raised regions one by one; N-side electrode provided on the surface of the substrate on the side away from the double heterojunction structure; P-side electrode provided on the ohmic contact layer, which includes multiple sub-electrodes, and the sub-electrodes correspond to the ohmic contact regions one by one; a forward voltage is applied to one of the sub-electrodes, and reverse voltages are applied to the remaining sub-electrodes; Waveguide coupling layer formed on the substrate; Spacer layer formed on the waveguide coupling layer; The double heterojunction structure is formed on the spacer layer; Electric injection blocking layer provided on the double heterojunction structure for dividing the double heterojunction structure into multiple double heterojunction regions, and the double heterojunction regions correspond to the raised regions one by one; the double heterojunction region corresponding to the sub-electrode with the forward voltage applied 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.

2. The semiconductor laser structure according to claim 1, characterized in that, The raised region corresponding to the sub-electrode with the forward voltage applied is denoted as the first raised region, and the remaining raised regions are denoted as the second raised regions; the first raised region is strip-shaped; the distance between the first raised region and each of the second raised regions is between 0.2 μm and 20 μm.

3. The semiconductor laser structure according to claim 1, characterized in that, The second double heterojunction region is strip-shaped.

4. The semiconductor laser structure according to claim 1, characterized in that, The refractive index of the waveguide coupling layer is greater than that of the substrate.

5. The semiconductor laser structure according to claim 1, wherein 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 topmost spacer layer.

6. The semiconductor laser structure according to claim 5, characterized in that, The thickness of a single-layer waveguide coupling layer is between 0.01 μm and 2 μm.

7. The semiconductor laser structure according to claim 1, wherein Further comprising: Buffer layer formed on the substrate; the waveguide coupling layer is formed on the buffer layer.

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