Monolithic integrated semiconductor main oscillation power amplifier laser

Abstract

The invention provides a monolithic integrated semiconductor main oscillation power amplifier laser, which relates to the technical field of semiconductor photoelectronics, and comprises a main oscillation region and a power amplifier region which are integrated on the same substrate by adopting the same active region process of a standard semiconductor, the power amplifier region adopts an active 1 * 1 multimode interference coupler structure; the laser adopts a monolithic integrated structure. The problem of flat light spots can be solved, so that coupling with optical fibers or waveguide devices is facilitated, the system coupling process is simplified, and large-scale production and application are facilitated.

Description

Technical Field

[0001] The invention relates to the field of semiconductor optoelectronic technology, and in particular to a monolithic integrated semiconductor master oscillator power amplifier laser. Background Art

[0002] High-power monolithic integrated semiconductor master oscillator power amplifier (MOPA) lasers in the 1.55μm band are widely used in free space optical (FSO) communications, coherent optical communications, silicon photonics (SiPh) co-packaging, and lidar systems. The 1.55μm band is the window with the lowest loss in the field of optical fiber communications, and has a higher safety factor for human eyes. Compared with 0.85μm band lasers, its damage threshold is more than 10,000 times higher.

[0003] At present, high-power semiconductor MOPA lasers usually consist of two parts: the master oscillator (MO) region and the power amplifier (PA) region. The MO region acts as a resonant cavity and provides seed light. The PA region acts as a gain structure for optical amplification and provides optical amplification for the laser mode. The PA region is usually a tapered structure with a gradually varying width. This tapered MOPA laser can solve problems such as multi-mode lasing and catastrophic optical mirror damage (COMD) caused by increasing the width of the ridge waveguide to increase the output power of the laser. It can effectively increase the area of ​​the active region and reduce the optical power density, thereby reducing the threshold of COMD. In addition, based on the above-mentioned resonant cavity and optical amplification gain structure, the tapered MOPA laser can achieve single transverse mode high-power output with high beam quality. However, the conical MOPA laser still faces some problems: since the lateral size of the light-emitting surface of the conical optical amplifier is much larger than the size in the epitaxial direction, the divergence angles of the fast axis and the slow axis are greatly different, and the light spot presents a flat ellipse. It must undergo beam shaping before it can be coupled into other devices or optical fibers, which limits the application of the conical MOPA laser. Summary of the invention

[0004] The present invention provides a monolithic integrated semiconductor master oscillator power amplifier laser, which is used to improve the problem of flat spot, thereby facilitating coupling with optical fiber or waveguide devices, simplifying the system coupling process, and facilitating large-scale production and application.

[0005] The present invention provides a monolithic integrated semiconductor master oscillator power amplifier laser, comprising: a master oscillator region and a power amplifier region integrated on the same substrate using a standard semiconductor same active region process; the power amplifier region adopts an active 1×1 multi-mode interference coupler structure; and the laser adopts a monolithic integrated structure.

[0006] According to a monolithically integrated semiconductor master oscillator power amplifier laser provided by the present invention, the master oscillator region and the power amplifier region are made of the same epitaxial material.

[0007] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, the master oscillation region is composed of a distributed feedback laser or a distributed Bragg reflection laser, which is used to provide single-mode seed light.

[0008] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, the distributed feedback laser comprises, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, three pairs of dilute waveguide layers with alternating structures of N-InP and N-InGaAsP, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, multiple pairs of P-InP and P-InGaAsP alternating structures of P-InGaAsP grating layers, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer; in the dilute waveguide layer, N-InP and N-InGaAsP are alternately arranged along the vertical direction; in the P-InGaAsP grating layer, P-InP and P-InGaAsP are alternately arranged along the horizontal direction.

[0009] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, the active 1×1 multimode interference coupler structure comprises, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, three pairs of dilution waveguide layers of alternating structures of N-InP and N-InGaAsP, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InP layer, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer; in the dilution waveguide layer, N-InP and N-InGaAsP are alternately arranged along the vertical direction.

[0010] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, the distributed feedback laser comprises, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, an InGaAsP large optical cavity layer, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InGaAsP grating layer with multiple pairs of P-InP and P-InGaAsP alternating structures, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer; in the P-InGaAsP grating layer, P-InP and P-InGaAsP are alternately arranged along the horizontal direction.

[0011] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, the active 1×1 multi-mode interference coupler structure comprises, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, an InGaAsP large optical cavity layer, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InP layer, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer.

[0012] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, the material of the multi-quantum well active layer is InGaAsP or AlGaInAs.

[0013] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, all layers except the N-InP substrate layer are lattice matched with the InP, and the composition ratio of Al and In in the multi-quantum well active layer is configured so that the emission wavelength of the material matching the InP lattice is in the range of 1.2~1.7um.

[0014] According to a monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention, one end of the main oscillator region is plated with a high-reflection film, and one end of the power amplifier region is plated with an anti-reflection film.

[0015] The monolithic integrated semiconductor master oscillator power amplifier laser provided by the present invention comprises: a master oscillator region and a power amplifier region integrated on the same substrate using a standard semiconductor same active region process; the power amplifier region adopts an active 1×1 multimode interference coupler structure; the laser adopts a monolithic integrated structure. The power amplifier region of the present invention adopts an active 1×1 multimode interference coupler structure, which can improve the problem of flat spot, thereby facilitating coupling with optical fiber or waveguide devices, simplifying the system coupling process, and facilitating large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the structure of a monolithic integrated semiconductor master oscillator power amplifier laser provided in an embodiment of the present invention.

[0018] Figure 2 It is a schematic diagram of the epitaxial structure of active region materials of a distributed feedback laser provided in an embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of active MMI simulation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Combine the following Figure 1-Figure 3 The monolithically integrated semiconductor master oscillator power amplifier laser of the present invention is described.

[0022] Please refer to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of the structure of a monolithic integrated semiconductor master oscillator power amplifier laser provided by an embodiment of the present invention. Figure 1 As shown, the laser comprises: a main oscillator region 100 and a power amplifier region 200 integrated on the same substrate using a standard semiconductor active region process. The laser operates near the 1.55 μm band, and the output power is expected to be above 1W.

[0023] The laser adopts a monolithic integrated structure and has the advantages of high stability, small size, low power consumption and easy large-scale production.

[0024] The power amplifier region 200 adopts an active 1×1 multimode interference coupler (Multimode Interference, MMI) structure, which can improve the problem of flat spot, thereby facilitating coupling with optical fiber or waveguide devices, simplifying the system coupling process, and facilitating large-scale production and application.

[0025] The working principle of the monolithic integrated semiconductor master oscillator power amplifier laser provided in the embodiment of the present invention includes: when the monolithic integrated semiconductor master oscillator power amplifier laser is working, an appropriate forward bias working current is injected into the main oscillation region 100, and the main oscillation region 100 will generate a wide-spectrum gain light with a central wavelength of about 1.55μm; a large forward bias working current is injected into the power amplifier region 200, so that the seed light output by the main oscillation region 100 passes through the power amplifier region 200 for optical power amplification.

[0026] The cavity surface of the monolithic integrated semiconductor master oscillator power amplifier laser is formed by a natural cleavage surface. Optionally, one end of the main oscillation region 100 is coated with a high reflection film (HR), and one end of the power amplifier region 200 is coated with an anti-reflection film (AR). The seed light output by the main oscillation region 100 can be amplified through the power amplifier region 200 to further improve the output power of the laser.

[0027] The monolithic integrated semiconductor master oscillator power amplifier laser provided in the embodiment of the present invention comprises: a master oscillator region and a power amplifier region integrated on the same substrate using a standard semiconductor same active region process; the power amplifier region adopts an active 1×1 multimode interference coupler structure; the laser adopts a monolithic integrated structure. The power amplifier region of the embodiment of the present invention adopts an active 1×1 multimode interference coupler structure, which can improve the problem of flat spot, thereby facilitating coupling with optical fiber or waveguide devices, simplifying the system coupling process, and facilitating large-scale production and application.

[0028] In addition, the power amplifier region of the embodiment of the present invention adopts an active 1×1 multimode interference coupler structure, which can utilize the self-imaging effect of the waveguide, and at the same time, a reasonable design of the multimode interference coupler structure can achieve single transverse mode output. Compared with traditional ridge waveguide and tapered waveguide optical amplifiers, the active 1×1 multimode interference coupler structure can provide more sufficient gain for the laser by increasing the gain zone area, thereby improving the electro-optical conversion efficiency and saturated output power. At the same time, it can also solve the problem of poor beam quality of tapered optical amplifiers. In this way, both high power and high beam quality output can be taken into account, greatly reducing the coupling cost of the laser with optical fiber or other devices.

[0029] Furthermore, the monolithic integrated semiconductor master oscillator power amplifier laser provided by the embodiment of the present invention has the advantages of simple manufacturing process, compact structure, low cost, high stability, small size, low power consumption, and easy large-scale production.

[0030] Optionally, the main oscillation region 100 and the power amplifier region 200 are made of the same epitaxial material, and the manufacturing process is simple.

[0031] Optionally, the master oscillation region 100 is composed of a distributed feedback (DFB) laser or a distributed Bragg reflector (DBR) laser, and is used to provide single-mode seed light.

[0032] Optionally, the length of the DFB laser is 1000 μm, the length of the MMI structure is 1250 μm, and the width of the MMI structure is 25 μm. At the same time, adding a tapered structure to the input port and output port of the 1×1 MMI can reduce the light reflection in the cavity.

[0033] In one embodiment, if Figure 2 As shown, the distributed feedback laser includes, from bottom to top, a metal negative electrode layer 0, an N-InP substrate layer 1, an N-InP buffer layer 2, three pairs of dilute waveguide layers (3, 4, 5, 6, 7, 8, 9) of alternating structures of N-InP and N-InGaAsP, an N-AlGaInAs lower confinement layer 10, a multi-quantum well active layer 11, a P-AlGaInAs upper confinement layer 12, a plurality of pairs of P-InP and P-InGaAsP alternating structures of P-InGaAsP grating layers 13, a P-InGaAsP etch stop layer 14, a P-InP cap layer 15, a P-InGaAs ohmic contact layer 16, and a metal positive electrode layer 17. In the dilute waveguide layer (3, 4, 5, 6, 7, 8, 9), N-InP (3, 5, 7, 9) and N-InGaAsP (4, 6, 8) are alternately arranged along the vertical direction. In the P-InGaAsP grating layer 13 , P-InP and P-InGaAsP are alternately arranged along the horizontal direction.

[0034] The N-InP substrate layer 1 shares the same metal negative electrode 0 through thinning, polishing, and evaporation of negative electrodes in standard semiconductor processes, and the metal positive electrode layer 17 is made into a graphic electrode through a selective wet etching process or a lift-off process, and the InGaAs contact layer between the main oscillation area 100 and the power amplifier area 200 is etched away to achieve electrical isolation between the main oscillation area 100 and the power amplifier area 200, thereby ensuring separate driving of the main oscillation area 100 and the power amplifier area 200.

[0035] In this embodiment, three pairs of dilute waveguide layers with alternating structures of N-InP and N-InGaAsP are used to pull the light field down and reduce the light confinement factor, thereby effectively reducing the light field waveguide loss and achieving high power output. In addition, compared with the InGaAsP large optical cavity layer, the three pairs of dilute waveguide layers with alternating structures of N-InP and N-InGaAsP can also show better heat dissipation performance.

[0036] Based on the previous embodiment, in one embodiment, the active 1×1 multimode interference coupler structure includes, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, three pairs of dilute waveguide layers of alternating structures of N-InP and N-InGaAsP, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InP layer, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer. In the dilute waveguide layer, N-InP and N-InGaAsP are alternately arranged along the vertical direction.

[0037] In this embodiment, the main oscillation region 100 and the power amplifier region 200 are made of the same epitaxial material, and the only difference is that the main oscillation region 100 has a grating structure, while the power amplifier region 200 does not have a grating structure.

[0038] In another embodiment, the distributed feedback laser includes, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, an InGaAsP large optical cavity layer, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InGaAsP grating layer with multiple pairs of P-InP and P-InGaAsP alternating structures, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer. In the P-InGaAsP grating layer, P-InP and P-InGaAsP are alternately arranged along the horizontal direction.

[0039] In this embodiment, a large InGaAsP optical cavity layer can also be used to achieve high power output.

[0040] Based on the previous embodiment, in one embodiment, the active 1×1 multimode interference coupler structure includes, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, an InGaAsP large optical cavity layer, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InP layer, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer.

[0041] In this embodiment, the main oscillation region 100 and the power amplifier region 200 are made of the same epitaxial material, and the only difference is that the main oscillation region 100 has a grating structure, while the power amplifier region 200 does not have a grating structure.

[0042] Optionally, the material of the multi-quantum well active layer is InGaAsP or AlGaInAs. In addition, the design of four pairs of quantum wells can reduce the internal loss generated in the active region.

[0043] Optionally, all layers except the N-InP substrate layer are lattice-matched with InP, and the composition ratio of Al and In in the multi-quantum well active layer is configured so that the emission wavelength of the material matching with InP lattice is in the range of 1.2-1.7 um.

[0044] For the design of the power amplifier region 200, it is mainly to determine the length and width of the active 1×1 multimode interference coupler structure. The larger the width of the active 1×1 multimode interference coupler structure, the more modes the active 1×1 multimode interference coupler structure accommodates, and the greater the gain that can be provided by the gain region. However, the larger the width of the active 1×1 multimode interference coupler structure, the longer the active 1×1 multimode interference coupler structure increases. The relationship between the length and width of the active 1×1 multimode interference coupler structure can be expressed by the following expression.

[0045] (1) in, represents the length of the active 1×1 multimode interference coupler structure, represents the width of the active 1×1 multimode interference coupler structure, represents the propagation constant of the fundamental mode, represents the propagation constant of the first-order mode, represents the equivalent refractive index, Indicates the wavelength of the laser.

[0046] According to expression (1), it can be seen that the length of the active 1×1 multimode interference coupler structure is proportional to the square of the width. Therefore, as the width of the active 1×1 multimode interference coupler structure increases, the length of the active 1×1 multimode interference coupler structure will inevitably increase.

[0047] like Figure 3 As shown in the figure, the three-dimensional beam propagation method (3-D-BPM) is used to simulate the length of the active 1×1 multimode interference coupler structure. By analyzing the light field intensity, the waveguide output is performed at the maximum point of the light intensity, that is, the position of the self-image point of the active 1×1 multimode interference coupler structure. Considering that the temperature increase of the laser caused by carrier injection leads to a change in the refractive index of about one thousandth, this will cause the length of the output end of the active 1×1 multimode interference coupler structure to shift by tens of microns. Therefore, it is necessary to optimize the length of the active 1×1 multimode interference coupler structure to ensure stable single-mode output.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A monolithically integrated semiconductor master oscillator power amplifier laser, characterized in that: include: The main oscillator region and the power amplifier region are integrated on the same substrate using a standard semiconductor same active region process; the power amplifier region uses an active 1×1 multi-mode interference coupler structure; The laser adopts a monolithic integrated structure.

2. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 1, characterized in that: The main oscillation region and the power amplifier region are made of the same epitaxial material.

3. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 2, characterized in that: The main oscillation region is composed of a distributed feedback laser or a distributed Bragg reflection laser, and is used to provide single-mode seed light.

4. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 3, characterized in that: The distributed feedback laser comprises, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, three pairs of dilute waveguide layers with alternating structures of N-InP and N-InGaAsP, an N-AlGaInAs lower limiting layer, a multi-quantum well active layer, a P-AlGaInAs upper limiting layer, multiple pairs of P-InP and P-InGaAsP alternating structures of P-InGaAsP grating layers, a P-InGaAsP etching stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer; in the dilute waveguide layer, N-InP and N-InGaAsP are alternately arranged along the vertical direction; in the P-InGaAsP grating layer, P-InP and P-InGaAsP are alternately arranged along the horizontal direction.

5. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 4, characterized in that: The active 1×1 multimode interference coupler structure includes, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, three pairs of dilution waveguide layers with alternating structures of N-InP and N-InGaAsP, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InP layer, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer; in the dilution waveguide layer, N-InP and N-InGaAsP are alternately arranged along the vertical direction.

6. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 3, characterized in that: The distributed feedback laser comprises, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, an InGaAsP large optical cavity layer, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InGaAsP grating layer with multiple pairs of P-InP and P-InGaAsP alternating structures, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer; in the P-InGaAsP grating layer, P-InP and P-InGaAsP are alternately arranged along the horizontal direction.

7. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 6, characterized in that: The active 1×1 multimode interference coupler structure includes, from bottom to top, a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, an InGaAsP large optical cavity layer, an N-AlGaInAs lower confinement layer, a multi-quantum well active layer, a P-AlGaInAs upper confinement layer, a P-InP layer, a P-InGaAsP etch stop layer, a P-InP cap layer, a P-InGaAs ohmic contact layer and a metal positive electrode layer.

8. The monolithically integrated semiconductor master oscillator power amplifier laser according to any one of claims 4 to 7, characterized in that: The material of the multi-quantum well active layer is InGaAsP or AlGaInAs.

9. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 8, characterized in that: All layers except the N-InP substrate layer are lattice-matched with the InP layer, and the composition ratio of Al and In in the multi-quantum well active layer is configured so that the emission wavelength of the material matching the InP layer is within the range of 1.2-1.7 um.

10. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 1, characterized in that: One end of the main oscillation area is plated with a high reflection film, and one end of the power amplifier area is plated with an anti-reflection film.

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