Semiconductor laser bar and spectral beam combining device based on quasi-PT symmetry

Abstract

The present disclosure provides a semiconductor laser bar based on quasi-PT symmetry, which is applied to the semiconductor field and includes: a plurality of quasi-PT symmetric semiconductor laser single tubes arranged horizontally and closely, and there is no coupling between the lasers emitted by the plurality of quasi-PT symmetric semiconductor laser single tubes; the quasi-PT symmetric semiconductor laser single tube includes an N-type electrode, an N-type substrate layer, an N-type waveguide cover layer, an N-type waveguide layer, alternately distributed barrier layers and well layers, a P-type waveguide layer, a P-type waveguide cover layer, a P-type contact layer, a P-type insulating layer and a P-type electrode arranged in sequence; wherein, a ridge waveguide region is provided on the P-type waveguide layer, the P-type waveguide cover layer and the P-type contact layer. The present disclosure also provides a spectral beam combining device. By using an optical lens and a grating, the independent light emitted by each semiconductor laser on the bar is combined into a beam of light with a uniformly spaced wavelength distribution, realizing high-power laser output and improving the lateral beam quality of the semiconductor laser bar.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor lasers, and in particular, to a semiconductor laser bar and a spectral beam combining device based on quasi-PT symmetry. Background Art

[0002] Semiconductor lasers have the advantages of high electro-optical conversion efficiency, small size, high reliability, etc., and application requirements have emerged in fields such as radar detection and fiber coupling. This requires that the laser light source can not only achieve high-power output, but also have good beam quality.

[0003] However, wide-strip lasers that achieve high-power output often exhibit multi-lateral mode lasing, resulting in poor beam quality and restricting the further expansion of their application scenarios. Introducing a parity-time (PT) symmetric structure into a strip laser can effectively reduce the lateral modes of the semiconductor laser and achieve single-mode lasing. However, its ridge width is narrow, and catastrophic optical mirror damage (COMD) is likely to occur when operating at high currents. This results in a relatively low output optical power (usually in the hundreds of milliwatts) when the PT symmetric laser achieves single-lateral mode lasing, and increasing the injection current will cause the mode characteristics of the laser to be unstable, which is not conducive to applications in scenarios with high brightness requirements. Summary of the Invention

[0004] In view of this, the present disclosure provides a semiconductor laser bar and a spectral beam combining device based on quasi-PT symmetry.

[0005] In the first aspect of the embodiments of the present disclosure, a semiconductor laser bar based on quasi-PT symmetry is provided, including a plurality of quasi-PT symmetric semiconductor laser single tubes 2, the plurality of quasi-PT symmetric semiconductor laser single tubes 2 are horizontally arranged closely, and there is no coupling between the lasers emitted by the plurality of quasi-PT symmetric semiconductor laser single tubes 2;

[0006] The quasi-PT symmetric semiconductor laser single tube 2 includes an N-type electrode 4, an N-type substrate layer 5, an N-type waveguide capping layer 6, an N-type waveguide layer 7, alternately distributed barrier layers 8 and well layers 9, a P-type waveguide layer 10, a P-type waveguide capping layer 11, a P-type contact layer 12, a P-type insulating layer 13, and a P-type electrode 14 arranged in sequence;

[0007] Wherein, a ridge waveguide region 3 is provided on the P-type waveguide layer 10, the P-type waveguide capping layer 11, and the P-type contact layer 12.

[0008] According to the embodiments of the present disclosure, the ridge waveguide region 3 includes a waveguide array, and the distribution mode of the waveguides in the waveguide array is symmetric distribution or asymmetric distribution;

[0009] The waveguides in the waveguide array include gain waveguides 31 and loss waveguides 32;

[0010] The gain waveguide 31 is the part of the P-type insulating layer 13 that does not completely cover the P-type contact layer 12;

[0011] The loss waveguide 32 is the part of the P-type insulating layer 13 that completely covers the P-type contact layer 12.

[0012] According to an embodiment of the present disclosure, the coupling relationship of the ridge waveguide region:

[0013]

[0014] Wherein, is the Hamiltonian of the waveguide array, is a dimensional tridiagonal matrix, is the number of waveguides in the waveguide array, is an N-dimensional column matrix, is the complex propagation constant of the supermode generated by the coupling of the waveguide array, and N is a positive integer greater than or equal to 1.

[0015] According to an embodiment of the present disclosure, the matrix element of the m-th row and n-th column of the Hamiltonian :

[0016]

[0017] Wherein, is the Kronecker-delta symbol. When then ; when then , is the coupling coefficient generated when the mode field of the m-th waveguide perturbs the mode field of the n-th waveguide, is the complex propagation constant of the fundamental mode of the m-th waveguide, and both m and n are positive integers greater than or equal to 1.

[0018] According to an embodiment of the present disclosure, the arrangement period of the multiple quasi-PT symmetric semiconductor laser single tubes 2 is the width of the quasi-PT symmetric semiconductor laser single tube 2 in the horizontal direction.

[0019] According to an embodiment of the present disclosure, the cavity length of the quasi-PT symmetric semiconductor laser single tube 2 is the length of the quasi-PT symmetric semiconductor laser single tube 2 in the longitudinal direction.

[0020] According to an embodiment of the present disclosure, the thickness of the N-type waveguide layer 7 is greater than that of the P-type waveguide layer 10.

[0021] According to an embodiment of the present disclosure, when the electrical injection gain is less than the gain required for PT breaking, the lasing mode of the semiconductor laser bar based on quasi-PT symmetry is multimode lasing;

[0022] When the electro-injection gain is greater than the gain required for PT breaking, the lasing mode of the quasi-PT-symmetric semiconductor laser bar is single-sided mode lasing.

[0023] The second aspect of the embodiments of the present disclosure provides a spectral beam combining device, including:

[0024] A quasi-PT-symmetric semiconductor laser bar 16, configured to generate a laser beam to be beam combined;

[0025] A first collimating mirror 17, configured to perform fast-axis collimation on the laser beam to be beam combined to obtain a first laser beam;

[0026] A beam converter 18, configured to rotate the fast axis and the slow axis of the first laser beam by 90 degrees to obtain a second laser beam;

[0027] A second collimating mirror 19, configured to perform slow-axis collimation on the second laser beam to obtain a third laser beam;

[0028] A transmission lens 20, configured to converge the third laser beam to obtain a fourth laser beam;

[0029] A zero-order half-wave plate 21, configured to change the polarization state of the fourth laser beam to obtain a fifth laser beam;

[0030] A transmissive grating 22, configured to select lasers with different wavelengths from the fifth laser beam;

[0031] An output coupling mirror 23, configured to feedback any part of the light of the lasers with different wavelengths back to the quasi-PT-symmetric semiconductor laser bar 16 to form a laser oscillation, and output the light after the lasers with different wavelengths form a stable oscillation.

[0032] According to the embodiments of the present disclosure, the spectrum of the remaining light has a plurality of closely arranged spectral peaks, and the number of the spectral peaks is equal to the number of the quasi-PT-symmetric semiconductor laser single tubes 2 on the quasi-PT-symmetric semiconductor laser bar 16.

[0033] According to the provided quasi-PT-symmetric semiconductor laser bar and its spectral beam combining device in the embodiments of the present disclosure, by using an injection current to pump a gain waveguide array and keeping the loss without current injection, the combined action of the two makes the complex refractive index of the laser form a quasi-PT-symmetric distribution laterally. Continuing to apply current causes the PT-symmetric state to break, realizing single-sided mode laser output of each single tube. The spectral beam combining device uses optical lenses and gratings to combine the independent lights emitted by each semiconductor laser on the bar into a beam of light with a uniform wavelength distribution, realizing high-power laser output and improving the lateral beam quality of the semiconductor laser bar. Description of the Drawings

[0034] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0035] Figure 1 A cross-sectional view of a quasi-PT symmetric semiconductor laser bar provided by an embodiment of the present disclosure is schematically shown;

[0036] Figure 2 A side view of a quasi-PT symmetric semiconductor laser bar provided by an embodiment of the present disclosure is schematically shown;

[0037] Figure 3 A cross-sectional view of a spectral beam combining device provided by an embodiment of the present disclosure is schematically shown;

[0038] Figure 4 A far-field distribution diagram of a single quasi-PT symmetric semiconductor laser at a current of 0.5 A provided by an embodiment of the present disclosure is schematically shown;

[0039] Figure 5 A far-field distribution diagram of a single quasi-PT symmetric semiconductor laser at a current of 1.5 A provided by an embodiment of the present disclosure is schematically shown;

[0040] Figure 6 A laser spot diagram after beam combination by the spectral beam combining device provided by an embodiment of the present disclosure is schematically shown. Detailed Embodiments

[0041] To make the objectives, technical solutions, and advantages of the present disclosure clearer and more understandable, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0042] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0043] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0044] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression. For example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc. In the case of using expressions such as "at least one of A, B, or C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression. For example, "a system having at least one of A, B, or C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.

[0045] It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only references to the directions in the drawings and are not used to limit the protection scope of the present disclosure. Throughout the drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in the understanding of the present disclosure, the conventional structures or configurations will be omitted.

[0046] A wide-strip laser for achieving high-power output often exhibits multi-lateral mode lasing, which results in poor beam quality and limits the further expansion of its application scenarios. Introducing a parity-time (PT) symmetric structure into the strip laser can effectively reduce the lateral modes of the semiconductor laser and achieve single-mode lasing. However, its ridge width is relatively narrow, and catastrophic optical mirror damage (COMD) is likely to occur when operating at high currents. This leads to a relatively low output optical power (usually in the order of hundreds of milliwatts) when the PT-symmetric laser achieves single-lateral mode lasing. Moreover, increasing the injection current will cause the mode characteristics of the laser to become unstable, which is not conducive to applications in scenarios with high brightness requirements.

[0047] Accordingly, embodiments of the present disclosure provide a quasi-PT symmetric semiconductor laser bar and a spectral beam combining device. The quasi-PT symmetric semiconductor laser bar includes a plurality of quasi-PT symmetric semiconductor laser single tubes 2, the plurality of quasi-PT symmetric semiconductor laser single tubes 2 are horizontally arranged closely, and there is no coupling between the lasers emitted by the plurality of quasi-PT symmetric semiconductor laser single tubes 2. The quasi-PT symmetric semiconductor laser single tube 2 includes an N-type electrode 4, an N-type substrate layer 5, an N-type waveguide cover layer 6, an N-type waveguide layer 7, alternately distributed barrier layers 8 and well layers 9, a P-type waveguide layer 10, a P-type waveguide cover layer 11, a P-type contact layer 12, a P-type insulating layer 13, and a P-type electrode 14 arranged in sequence. Among them, a ridge waveguide region 3 is provided on the P-type waveguide layer 10, the P-type waveguide cover layer 11, and the P-type contact layer 12. The spectral beam combining device is used to perform spectral beam combining on the lasers emitted by each quasi-PT symmetric semiconductor laser single tube 2 in the quasi-PT symmetric semiconductor laser bar, and obtain a combined laser output.

[0048] In the above-mentioned quasi-PT symmetric semiconductor laser bar and spectral beam combining device, through the action of the ridge waveguide region 3, the complex refractive index of the laser forms a quasi-PT symmetric distribution laterally. Applying current can break the PT symmetry and achieve single-side mode laser output of each single tube 2; and the spectral beam combining device combines the independent lights emitted by each semiconductor laser on the bar into a beam of light with a uniform wavelength distribution through optical lenses and gratings, realizing a laser output with a relatively high power and improving the lateral beam quality of the quasi-PT symmetric semiconductor laser bar.

[0049] The following lists specific embodiments to illustrate the technical solutions of the present disclosure in detail. It should be noted that the specific embodiments below are only for illustration and do not limit the present disclosure.

[0050] Figure 1 is a cross-sectional view of the quasi-PT symmetric semiconductor laser bar according to an embodiment of the present disclosure.

[0051] As Figure 1As shown in the figure, the present disclosure provides a quasi-PT symmetric semiconductor laser bar 1, including: an N-type electrode 4 plated on the bottom of the N-type substrate layer 5 for providing an electrical injection channel; an N-type substrate layer 5 serving as the substrate of the epitaxial layer; an N-type waveguide cover layer 6 disposed between the N-type substrate layer 5 and the N-type waveguide layer 7 for restricting the optical field of the laser; an N-type waveguide layer 7 disposed between the N-type waveguide cover layer 6 and the active region for expanding the lasing optical field, an active region disposed between the N-type waveguide layer 7 and the P-type waveguide layer 10, including alternately distributed barrier layers 8 and well layers 9 to form a quantum well region for generating laser gain; a P-type waveguide layer 10 disposed between the active region and the P-type waveguide cover layer 11 for expanding the optical field of the laser and etched into a waveguide morphology when the etching depth is relatively deep; a P-type waveguide cover layer 11 disposed between the P-type waveguide layer 10 and the P-type contact layer 12 for restricting the optical field of the laser and etched into a waveguide morphology; a P-type contact layer 12 grown on the P-type waveguide cover layer 11, provided as a heavily doped layer and etched into a waveguide morphology; a P-type insulating layer 13 covering the P-type waveguide cover layer 11 and a part of the P-type contact layer 12, made of silicon dioxide material; a P-type electrode 14 disposed on the P-type insulating layer 13 and the P-type contact layer 12 for the electrical injection channel of the laser and forming an ohmic contact with the P-type contact layer 12.

[0052] According to an embodiment of the present disclosure, the quasi-PT symmetric semiconductor laser bar 1 is composed of quasi-PT symmetric semiconductor laser single tubes 2, and the ridge waveguide region 3 of the quasi-PT symmetric semiconductor laser single tube 2 includes a waveguide array. The distribution pattern of the waveguides in the waveguide array is symmetric distribution or asymmetric distribution. The coupling coefficient k between adjacent waveguides is affected by the waveguide width, etching depth, and adjacent waveguide spacing.

[0053] The waveguides in the waveguide array include a gain waveguide 31 and a loss waveguide 32. The loss waveguide 32 is manifested as the part where the P-type insulating layer 13 completely covers the P-type contact layer 12, and the complex propagation constant of the fundamental mode of the loss waveguide 32 has a negative imaginary part. The gain waveguide 31 is manifested as the part where the P-type insulating layer 13 does not completely cover the P-type contact layer 12, and current can be injected into the semiconductor laser through the exposed P-type electrode 14 window, thereby generating gain, and the complex propagation constant of the fundamental mode of the gain waveguide 31 has a positive imaginary part.

[0054] In some embodiments, the number of gain waveguides 31 in a ridge waveguide region 3 can be one or more, and the number of loss waveguides 32 can also be one or more. The present disclosure does not limit this.

[0055] According to an embodiment of the present disclosure, the coupling relationship of the ridge waveguide region 3 satisfies:

[0056]

[0057] Where is the Hamiltonian of the waveguide array, which is represented as an N×N - dimensional tridiagonal matrix, where N is the number of waveguides in the waveguide array. The Hamiltonian of the waveguide array The matrix element in the m - th row and n - th column can be written as:

[0058]

[0059] where is the Kronecker - delta symbol. When then ; when then , is the coupling coefficient generated when the mode field of the m - th waveguide perturbs the mode field of the n - th waveguide, is the complex propagation constant of the fundamental mode of the m - th waveguide. Both m and n are positive integers greater than or equal to 1.

[0060] where is an N - dimensional column matrix, and the m - th element represents the electric - field amplitude of the m - th waveguide; represents the complex propagation constant of the supermode generated by the coupling of the waveguide array. If there are N waveguides, then there are N eigenvalues satisfying the coupling relation , denoted as in the form of

[0061] According to an embodiment of the present disclosure, the spacing, the number of periods, and the cavity length 15 of the quasi - PT - symmetric semiconductor laser single - tube 2 that composes the quasi - PT - symmetric semiconductor laser bar 1 can be varied. Specifically, the cavity length of the quasi - PT - symmetric semiconductor laser single - tube 2 is the length of the quasi - PT - symmetric semiconductor laser single - tube 2 in the longitudinal direction. The cavity length of the quasi - PT - symmetric semiconductor laser single - tube 2 is the length of the quasi - PT - symmetric semiconductor laser single - tube 2 in the longitudinal direction. The number of periods of the quasi - PT - symmetric semiconductor laser single - tube 2 can be the number of periodic arrangements in a quasi - PT - symmetric semiconductor laser bar 1. Figure 2 Schematically shows a side view of the quasi - PT - symmetric semiconductor laser bar provided by an embodiment of the present disclosure. Among them, the number of periods of the bar is only for illustration, and the cavity length 15 of the bar is set to 2 mm.

[0062] According to an embodiment of the present disclosure, the active region between the N - type waveguide layer 7 and the P - type waveguide layer 10 includes: quantum wells or quantum dots.

[0063] According to an embodiment of the present disclosure, on the light - emitting direction z of the quasi - PT - symmetric semiconductor laser bar 1, an antireflection film is required to be plated on the front cavity surface, and a high - reflection film is required to be plated on the rear cavity surface.

[0064] According to an embodiment of the present disclosure, the pumping method of the quasi-PT symmetric semiconductor laser bar is electrical injection.

[0065] According to an embodiment of the present disclosure, the quasi-PT symmetric semiconductor laser bar and its spectral beam combining device are applied in the field of semiconductor lasers.

[0066] According to an embodiment of the present disclosure, the quasi-PT symmetric semiconductor laser bar is fabricated by semiconductor processing techniques such as thin film growth, epitaxial growth, exposure, and etching.

[0067] As Figure 1 shown in the embodiment, the ridge waveguide region 3 of the quasi-PT symmetric semiconductor laser single tube 2 is set as a gain waveguide (left side) and a loss waveguide (right side), and the bar is set as a closely arranged array of 19 single tubes.

[0068] The lasing wavelength is set to 980 nm, and the active region is set as a double quantum well structure. The thicknesses of the quantum well barrier layer 8 and the quantum well well layer 9 are respectively set to 0.01 and 0.007 ; the N-type substrate layer 5 is set to 0.5 , the N-type waveguide capping layer 6 is set to 1 ; the N-type waveguide layer 7 is set to 4.5 ; the P-type waveguide layer 10 is set to 0.7 , the P-type waveguide capping layer 11 is set to 0.8 , the P-type contact layer 12 is set to 0.2 .

[0069] The P-type insulating layer 13 is set as silicon dioxide with a thickness of 0.25 .

[0070] The materials of the N-type electrode 4 and the P-type electrode 14 are gold. In order to reduce the Smile effect of the bar and facilitate the subsequent spectral beam combining process, the electrode thicknesses on both the N-type and P-type sides are set to 4 .

[0071] Figure 3 Schematically shows a cross-sectional view of the spectral beam combining device provided by the embodiment of the present disclosure.

[0072] As Figure 3As shown in the figure, the present disclosure provides a spectral beam combining device, which includes: a quasi-PT symmetric semiconductor laser bar 16 for generating a laser beam to be combined; a first collimating mirror 17 for fast-axis collimation of the laser beam to be combined to obtain a first laser beam; a beam converter 18 for rotating the fast axis and slow axis of the first laser beam by 90 degrees to obtain a second laser beam; a second collimating mirror 19 for slow-axis collimation of the second laser beam to obtain a third laser beam; a transmission lens 20 for converging the third laser beam to obtain a fourth laser beam; a zero-order half-wave plate 21 for changing the polarization state of the fourth laser beam to obtain a fifth laser beam; a transmissive grating 22 as a dispersive element for selecting lasers of different wavelengths from the fifth laser beam; and an output coupling mirror 23 for feeding back any part of the lasers of different wavelengths to the quasi-PT symmetric semiconductor laser bar 16 to form a laser oscillation, and outputting the lasers of different wavelengths to form light after stable oscillation.

[0073] According to an embodiment of the present disclosure, the N-type waveguide capping layer 6, N-type waveguide layer 7, quantum well barrier layer 8, quantum well well layer 9, P-type waveguide layer 10, P-type waveguide capping layer 11, and P-type contact layer 12 are all semiconductor materials.

[0074] According to an embodiment of the present disclosure, the doping, composition, and thickness of the above-mentioned N-type waveguide capping layer 6, N-type waveguide layer 7, quantum well barrier layer 8, quantum well well layer 9, P-type waveguide layer 10, P-type waveguide capping layer 11, and P-type contact layer 12 can be designed according to the required wavelength.

[0075] According to an embodiment of the present disclosure, the optical devices of the spectral beam combining device can be selected according to the wavelength of the laser emitted by the quasi-PT symmetric semiconductor laser bar 16.

[0076] In one embodiment, the size of the beam converter 18 is designed to match the bar period, the rotation angle of the zero-order half-wave plate 21 is designed to be able to convert the P wave emitted by the laser into an S wave, the transmittance of the transmissive grating 22 in the 980 nm band is designed to be 98% for the S wave, and the remaining optical elements are coated with an antireflection film in the 980 nm band.

[0077] Figure 4 Schematically shows the far-field distribution diagram of a single quasi-PT symmetric semiconductor laser provided by an embodiment of the present disclosure under a current of 0.5 A.

[0078] As Figure 4 shown, the far field of the laser presents a double-lobe distribution. According to an embodiment of the present disclosure, the injection current is the gain applied to the laser. When the gain is small, the laser is in a PT symmetric state, and the splitting of the real part of the supermode and the degeneracy of the imaginary part result in a double-lobe far field of the output laser.

[0079] Figure 5The far-field distribution diagram of a single quasi-PT symmetric semiconductor laser tube provided by an embodiment of the present disclosure at a current of 1.5 A is schematically shown.

[0080] like Figure 5 As shown, the far field of the laser presents a single-lobe distribution. According to the embodiment of the present disclosure, the injected current is the gain applied to the laser. When the gain is large, the laser is in a PT symmetry-breaking state, at which time the real part of the supermode is degenerate and the imaginary part is split, resulting in a part of the output laser being emitted in the gain waveguide and the other part being lost in the loss waveguide, thereby outputting a single-lobe far field.

[0081] Figure 6 The schematic diagram shows the laser spot diagram after the laser beam is combined by the spectral beam combining device in the embodiment of the present disclosure. When the PT symmetry is broken by the injected current, the spot after the beam is combined is a single lobe.

[0082] According to the above-mentioned embodiments of the present disclosure, in the quasi-PT symmetric semiconductor laser bar and its spectrum combining device, the gain waveguide array and the loss waveguide array on the quasi-PT symmetric semiconductor laser single tube work together to make the complex refractive index of the laser form a quasi-PT symmetric distribution in the lateral direction, and the current is applied to introduce the gain. When the injected current reaches a certain level, the PT symmetry state can be broken, and the single-side mode laser output of each single tube can be achieved. And through the spectrum combining device provided by the present disclosure, the independent light emitted by each semiconductor laser on the bar is combined into a beam of light with uniform wavelength distribution by using optical lenses and gratings, so as to achieve high-power laser output and improve the lateral beam quality of the semiconductor laser bar, so that the quasi-PT symmetric semiconductor laser bar can be further applied to the use scenarios requiring high power and high beam quality.

[0083] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A semiconductor laser bar based on quasi-PT symmetry, characterized in that: Comprising a plurality of quasi-PT symmetric semiconductor laser single tubes (2), wherein the plurality of quasi-PT symmetric semiconductor laser single tubes (2) are closely arranged horizontally, and there is no coupling between the lasers emitted by the plurality of quasi-PT symmetric semiconductor laser single tubes (2); The quasi-PT symmetric semiconductor laser single tube (2) comprises an N-type electrode (4), an N-type substrate layer (5), an N-type waveguide cover layer (6), an N-type waveguide layer (7), alternately distributed potential barrier layers (8) and potential well layers (9), a P-type waveguide layer (10), a P-type waveguide cover layer (11), a P-type contact layer (12), a P-type insulating layer (13) and a P-type electrode (14) which are arranged in sequence; Wherein, a ridge waveguide region (3) is provided on the P-type waveguide layer (10), the P-type waveguide cover layer (11) and the P-type contact layer (12); The ridge waveguide region (3) comprises a waveguide array, and the waveguides in the waveguide array are distributed in a symmetrical distribution or an asymmetrical distribution; The waveguides in the waveguide array include a gain waveguide (31) and a loss waveguide (32), wherein the gain waveguide and the loss waveguide work together to form a quasi-PT symmetrical distribution of the complex refractive index of the quasi-PT symmetrical semiconductor laser tube (2) in the lateral direction, and the quasi-PT symmetry can be broken when a current is applied, thereby achieving single-side mode laser output of each quasi-PT symmetrical semiconductor laser tube (2); The gain waveguide (31) is a portion of the P-type insulating layer (13) that is not completely covered on the P-type contact layer (12); The lossy waveguide (32) is the portion of the P-type insulating layer (13) that completely covers the P-type contact layer (12).

2. The semiconductor laser bar based on quasi-PT symmetry according to claim 1, characterized in that: The coupling relationship of the ridge waveguide region (3) is: in, is the Hamiltonian of the waveguide array, For one dimensional tridiagonal matrix, is the number of waveguides in the waveguide array, is an N-dimensional column matrix, is the complex propagation constant of the supermode generated by the waveguide array coupling, and N is a positive integer greater than or equal to 1.

3. The semiconductor laser bar based on quasi-PT symmetry according to claim 2, characterized in that: The Hamiltonian The matrix element of the mth row and nth column is: in, is the Kronecker-delta symbol, when hour ;when hour , is the coupling coefficient generated when the mode field of the mth waveguide perturbs the mode field of the nth waveguide, is the complex propagation constant of the fundamental mode of the mth waveguide, and m and n are both positive integers greater than or equal to 1.

4. The semiconductor laser bar based on quasi-PT symmetry according to claim 1, characterized in that: The arrangement period of the plurality of quasi-PT symmetric semiconductor laser tubes (2) is the width of the quasi-PT symmetric semiconductor laser tube (2) in the horizontal direction.

5. The semiconductor laser bar based on quasi-PT symmetry according to claim 1, characterized in that: The cavity length of the quasi-PT symmetric semiconductor laser single tube (2) is the length of the quasi-PT symmetric semiconductor laser single tube (2) in the longitudinal direction.

6. The semiconductor laser bar based on quasi-PT symmetry according to claim 1, characterized in that: The N-type waveguide layer (7) is thicker than the P-type waveguide layer (10).

7. The semiconductor laser bar based on quasi-PT symmetry according to claim 1, characterized in that: When the electrical injection gain is less than the gain required for PT breaking, the lasing mode of the semiconductor laser stripe based on quasi-PT symmetry is multi-mode lasing; When the electrical injection gain is greater than the gain required for PT breaking, the stripe lasing mode of the semiconductor laser based on quasi-PT symmetry is single-side mode lasing.

8. A spectral beam combining device, characterized in that: include: The quasi-PT symmetric semiconductor laser bar (16) according to any one of claims 1 to 7, used to generate laser beams to be combined, wherein the laser beams to be combined are multiple horizontally arranged single-side mode lasers; A first collimator (17) is used to perform fast-axis collimation on the laser beam to be combined to obtain a first laser beam; A beam converter (18), used for rotating the fast axis and the slow axis of the first laser beam by 90 degrees to obtain a second laser beam; A second collimator (19) is used to perform slow-axis collimation on the second laser beam to obtain a third laser beam; A transmission lens (20) is used to converge the third laser beam to obtain a fourth laser beam; A zero-order half-wave plate (21), used for changing the polarization state of the fourth laser beam to obtain a fifth laser beam; A transmission grating (22), used for selecting laser light of different wavelengths from the fifth laser light beam; The output coupling mirror (23) is used to feed back any part of the laser light of different wavelengths to the quasi-PT symmetric semiconductor laser bar (16) to form laser oscillation, and output the laser light of different wavelengths to form stable oscillation light.

9. The spectral beam combining device according to claim 8, characterized in that: The spectrum of the light after stable oscillation has a plurality of closely arranged spectrum peaks, and the number of the spectrum peaks is equal to the number of quasi-PT-symmetric semiconductor laser single tubes (2) on the quasi-PT-symmetric semiconductor laser bar (16).

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