Monolithic integrated semiconductor master oscillator power amplifier laser

Abstract

This invention provides a monolithically integrated semiconductor master oscillator power amplifier laser, relating to the field of semiconductor optoelectronics technology. The laser comprises a master oscillator region and a power amplifier region integrated on the same substrate using standard semiconductor active region technology; the power amplifier region employs an active 1×1 multimode interference coupler structure; and the laser adopts a monolithically integrated structure. This invention can improve the problem of beam flattening, thereby facilitating coupling with optical fibers or waveguide devices, simplifying the system coupling process, and enabling large-scale production applications.

Description

Technical Field

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

[0002] High-power monolithic integrated semiconductor master oscillator (MOPA) lasers in the 1.55μm band have wide applications in free-space optical (FSO) communication, coherent optical communication, silicon photonics (SiPh) co-packaging, and lidar systems. The 1.55μm band represents the lowest loss window in fiber optic communication and offers a significantly higher safety factor for the human eye; its damage threshold is more than ten thousand times higher than that of 0.85μm band lasers.

[0003] Currently, high-power semiconductor MOPA lasers typically consist of two parts: a master oscillator (MO) region and a power amplifier (PA) region. The MO region acts as a resonant cavity, providing seed light. The PA region, as the gain structure for optical amplification, provides optical amplification for the laser modes. The PA region is usually a tapered structure with a gradually varying width. This tapered structure of MOPA lasers can solve problems such as multimode lasing and catastrophic optical mirror damage (COMD) caused by increasing the width of the ridge waveguide to improve the laser's output power. It can effectively increase the area of ​​the active region, reduce the optical power density, and thus lower the COMD threshold. Furthermore, based on the aforementioned resonant cavity and optical amplification gain structure, the tapered MOPA laser can achieve high beam quality and high power output in a single transverse mode. However, the tapered MOPA laser also faces some problems: because the lateral dimension of the output surface of the tapered optical amplifier is much larger than the dimension in the epitaxial direction, the divergence angle between the fast axis and the slow axis is large, and the spot appears as a flat ellipse. It must be beam shaped before it can be coupled into other devices or optical fibers, which limits the application of tapered MOPA lasers. Summary of the Invention

[0004] This invention provides a monolithic integrated semiconductor master oscillator power amplifier laser to improve the problem of beam flattening, thereby facilitating coupling with optical fiber or waveguide devices, simplifying the system coupling process, and making it easy to mass-produce and apply.

[0005] This invention provides a monolithically integrated semiconductor master oscillator power amplifier laser, comprising: a master oscillator region and a power amplifier region integrated on the same substrate using standard semiconductor active region technology; the power amplifier region adopts an active 1×1 multimode interference coupler structure; and the laser adopts a monolithically integrated structure.

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

[0007] According to the present invention, a monolithic integrated semiconductor master oscillation power amplifier laser is provided, wherein 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 the present invention, a monolithic integrated semiconductor master oscillator power amplifier laser is provided, wherein the distributed feedback laser comprises, from bottom to top: a metal negative electrode layer, an N-InP substrate layer, an N-InP buffer layer, a diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures, 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 alternating P-InP and P-InGaAsP structures, a P-InGaAsP etch stop layer, a P-InP capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer; in the diluted waveguide layer, N-InP and N-InGaAsP are arranged alternately in the vertical direction; in the P-InGaAsP grating layer, P-InP and P-InGaAsP are arranged alternately in the horizontal direction.

[0009] According to the present invention, a monolithic integrated semiconductor master oscillator power amplifier laser is provided, wherein 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, a diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures, 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 capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer; wherein the N-InP and N-InGaAsP in the diluted waveguide layer are arranged alternately along the vertical direction.

[0010] According to the present invention, a monolithic integrated semiconductor master oscillator power amplifier laser is provided, wherein 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 alternating P-InP and P-InGaAsP structures, a P-InGaAsP etch stop layer, a P-InP capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer; wherein the P-InP and P-InGaAsP in the P-InGaAsP grating layer are arranged alternately along the horizontal direction.

[0011] According to the present invention, a monolithic integrated semiconductor master oscillator power amplifier laser is provided, wherein 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, 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 capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer.

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

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

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

[0015] The monolithically integrated semiconductor master oscillator power amplifier laser provided by this invention includes: a master oscillator region and a power amplifier region integrated on the same substrate using standard semiconductor active region technology; the power amplifier region adopts an active 1×1 multimode interference coupler structure; the laser adopts a monolithically integrated structure. The active 1×1 multimode interference coupler structure in the power amplifier region of this invention can improve the problem of beam flattening, thereby facilitating coupling with optical fibers or waveguide devices, simplifying the system coupling process, and making it easy for large-scale production applications. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This 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 This is a schematic diagram of the active region material epitaxial structure of the distributed feedback laser provided in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of active MMI simulation provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] The following is combined with Figures 1-3 The present invention describes a monolithic integrated semiconductor master oscillator power amplifier laser.

[0022] Please refer to Figure 1 , Figure 1 This 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. Figure 1 As shown, the laser includes a main oscillation region 100 and a power amplifier region 200 integrated on the same substrate using standard semiconductor active region technology. The laser operates in the vicinity of 1.55 μm and is expected to have an output power of over 1 W.

[0023] This laser adopts a monolithic integrated structure, which has the advantages of high stability, small size, low power consumption and easy mass production.

[0024] The power amplifier section 200 adopts an active 1×1 multimode interference (MMI) structure, which can improve the problem of beam flattening, thereby facilitating coupling with optical fiber or waveguide devices, simplifying the system coupling process, and making it easy to mass-produce and apply.

[0025] The working principle of the monolithic integrated semiconductor master oscillator power amplifier laser provided in this embodiment of the invention includes: when the monolithic integrated semiconductor master oscillator power amplifier laser is working, an appropriate forward bias working current is injected into the master oscillation region 100, and the master oscillation region 100 will generate broadband gain light with a center wavelength around 1.55μm; a larger forward bias working current is injected into the power amplifier region 200, so that the seed light output from the master oscillation region 100 is amplified by the power amplifier region 200.

[0026] The cavity surface of the monolithically integrated semiconductor master oscillator power amplifier laser is formed by natural cleavage. Optionally, one end of the master 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). This allows the seed light output from the master oscillation region 100 to be amplified by the power amplifier region 200, thereby further improving the output power of the laser.

[0027] The monolithically integrated semiconductor master oscillator power amplifier laser provided in this embodiment of the invention includes: a master oscillator region and a power amplifier region integrated on the same substrate using standard semiconductor active region technology; the power amplifier region adopts an active 1×1 multimode interference coupler structure; the laser adopts a monolithically integrated structure. The active 1×1 multimode interference coupler structure in the power amplifier region of this embodiment of the invention can improve the beam flattening problem, thereby facilitating coupling with optical fibers or waveguide devices, simplifying the system coupling process, and making it easy for large-scale production applications.

[0028] Furthermore, the power amplifier region of this embodiment employs an active 1×1 multimode interference coupler structure, which can utilize the self-image effect of the waveguide. Simultaneously, a well-designed multimode interference coupler structure can achieve single-transverse mode output. Compared to traditional ridge waveguide and tapered waveguide optical amplifiers, the active 1×1 multimode interference coupler structure can provide more sufficient gain to the laser by increasing the gain region area, thereby improving electro-optical conversion efficiency and saturated output power. Simultaneously, it can also solve the problem of poor beam quality in tapered optical amplifiers. Thus, it can achieve both high power and high beam quality output, significantly reducing the coupling cost between the laser and optical fiber or other devices.

[0029] Furthermore, the monolithic integrated semiconductor master oscillator power amplifier laser provided in this embodiment of the invention has advantages such as simple manufacturing process, compact structure, low cost, high stability, small size, low power consumption, and ease of mass production.

[0030] Optionally, the main oscillation region 100 and the power amplifier region 200 use the same epitaxial material, which simplifies the manufacturing process.

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

[0032] Optionally, the DFB laser has a length of 1000 μm, the MMI structure has a length of 1250 μm, and the MMI structure has a width of 25 μm. Additionally, adding tapered structures to the input and output ports of the 1×1 MMI can reduce intracavity light reflection.

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

[0034] The N-InP substrate 1 shares the same metal negative electrode 0 through standard semiconductor processes such as thinning, polishing, and evaporation of negative electrodes. The metal positive electrode layer 17 is patterned using selective wet etching or lift-off processes. The InGaAs contact layer between the main oscillation region 100 and the power amplifier region 200 is etched away to achieve electrical isolation between the main oscillation region 100 and the power amplifier region 200, ensuring independent driving of the main oscillation region 100 and the power amplifier region 200.

[0035] In this embodiment, a diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures is used to pull the optical field downward, reducing the optical confinement factor and thus effectively reducing the optical waveguide loss, achieving high-power output. Furthermore, compared to large InGaAsP optical cavity layers, the diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures also exhibits superior heat dissipation performance.

[0036] Based on the previous embodiment, in one embodiment, 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, a diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures, 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 capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer. In the diluted waveguide layer, N-InP and N-InGaAsP are arranged alternately along the vertical direction.

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

[0038] In another embodiment, 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 alternating P-InP and P-InGaAsP structures, a P-InGaAsP etch stop layer, a P-InP capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer. The P-InP and P-InGaAsP structures in the P-InGaAsP grating layer are arranged alternately 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 capping 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 use the same epitaxial material. The only difference is that the main oscillation region 100 contains 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. Furthermore, employing a four-pair quantum well design can reduce internal losses generated in the active region.

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

[0044] The design of power amplifier region 200 primarily involves determining the length and width of the active 1×1 multimode interference coupler structure. A larger width allows the active 1×1 multimode interference coupler structure to accommodate more modes, resulting in greater gain within that region. However, a larger width also increases the length of the active 1×1 multimode interference coupler structure. The relationship between the length and width of the active 1×1 multimode interference coupler structure can be expressed by the following formula.

[0045] (1)

[0046] in, This indicates the length of the active 1×1 multimode interference coupler structure. This represents the width of the active 1×1 multimode interference coupler structure. Represents the propagation constant of the fundamental mode. This represents the propagation constant of the first-order mode. Indicates the equivalent refractive index. This indicates the wavelength of the laser.

[0047] According to expression (1), the length of the active 1×1 multimode interference coupler structure is proportional to the square of its 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 as well.

[0048] like Figure 3 As shown, the length of the active 1×1 multimode interference coupler structure is simulated using the three-dimensional beam propagation method (3-D-BPM). Through analysis of the light field intensity, waveguide output is implemented at the point of maximum light intensity, i.e., the self-image point of the active 1×1 multimode interference coupler structure. Considering that the change in refractive index due to the increase in laser temperature caused by carrier injection is approximately one-thousandth, this will lead to a length shift of tens of micrometers at the output end of the active 1×1 multimode interference coupler structure. Therefore, the length of the active 1×1 multimode interference coupler structure needs to be optimized to ensure stable single-mode output.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A monolithic integrated semiconductor master oscillator power amplifier laser, characterized in that, include: The main oscillation region and the power amplifier region are integrated on the same substrate using standard semiconductor active region technology; the power amplifier region adopts an active 1×1 multimode interference coupler structure; The laser adopts a monolithic integrated structure; 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, a diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures, 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 capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer; in the diluted waveguide layer, N-InP and N-InGaAsP are arranged alternately along the vertical direction.

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 use 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 reflector laser, 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, a diluted waveguide layer with three pairs of alternating N-InP and N-InGaAsP structures, 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 alternating P-InP and P-InGaAsP structures, a P-InGaAsP etch stop layer, a P-InP capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer; in the diluted waveguide layer, N-InP and N-InGaAsP are arranged alternately in the vertical direction; in the P-InGaAsP grating layer, P-InP and P-InGaAsP are arranged alternately in the horizontal direction.

5. 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 alternating P-InP and P-InGaAsP structures, a P-InGaAsP etch stop layer, a P-InP capping 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 arranged alternately along the horizontal direction.

6. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 5, characterized in that, 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, 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 capping layer, a P-InGaAs ohmic contact layer, and a metal positive electrode layer.

7. The monolithically integrated semiconductor master oscillator power amplifier laser according to any one of claims 4 to 6, characterized in that, The active layer of the multi-quantum well is made of InGaAsP or AlGaInAs.

8. The monolithically integrated semiconductor master oscillator power amplifier laser according to claim 7, characterized in that, All layers except the N-InP substrate are matched with the lnP lattice, and the composition ratio of Al and In in the multi-quantum-well active layer is configured such that the emission wavelength of the material matched with the lnP lattice is in the range of 1.2~1.7 μm.

9. The monolithic integrated semiconductor master oscillator power amplifier laser according to claim 1, characterized in that, One end of the main oscillation region is coated with a high-reflection film, and one end of the power amplifier region is coated with an anti-reflection film.

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