Semiconductor laser beam quality self-optimization beam combining device and method

Abstract

The present invention belongs to the technical field of dense spectrum beam combining, and in particular, relates to a semiconductor laser beam quality self-optimizing beam combining device and method. The device includes a semiconductor laser group, a fast axis collimator group, a slow axis collimator group, a reflector group, a volume Bragg grating group and an external cavity mirror. A resonant external cavity is formed between the rear cavity surface of each semiconductor laser and the external cavity mirror. After diffraction by the volume Bragg grating, part of the laser transmitted to the external cavity mirror is reflected again by the external cavity mirror to the volume Bragg grating. The spectral selection characteristics of the volume Bragg grating diffract the laser mode that meets the Bragg diffraction condition into the chip of the semiconductor laser, and the mode competition characteristics of the semiconductor laser enhance this part of the laser mode to the main lasing mode, suppress other stray modes, thereby reducing the slow axis divergence angle of the semiconductor laser and improving the beam quality of the combined laser. In addition, the volume Bragg grating automatically adjusts the wavelength of the semiconductor laser to the wavelength with the highest diffraction efficiency according to the angle of the optical path.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor laser intensive spectrum combining, and in particular relates to a semiconductor laser beam quality self-optimizing combining device and method. Background Art

[0002] Semiconductor laser beam combining can significantly improve laser power and beam quality. Among the many semiconductor laser beam combining technologies, the dense spectrum beam combining technology based on volume Bragg grating has shown significant advantages in achieving high power and high brightness. In the traditional beam combining method, it is necessary to first use a transmissive volume Bragg grating to lock the wavelength of the laser, and then use a reflective volume Bragg grating to combine the optical path. This beam combining method increases the output brightness of the combined laser by increasing the power, and does not improve the beam quality of the combined laser, which results in the beam quality of the combined laser being close to but unable to exceed the beam quality of the unit laser; in addition, each semiconductor laser participating in the beam combining needs to first pass through a transmissive volume Bragg grating to lock the wavelength, and a reflective volume Bragg grating is used to diffract the wavelength-locked laser at a specific angle. Once the locked wavelength of the semiconductor laser deviates from the actual optical path angle, it will have a huge impact on the diffraction efficiency; finally, the traditional beam combining method uses a large number of volume Bragg gratings, which increases the beam combining cost. Summary of the invention

[0003] In view of this, the present invention aims to provide a semiconductor laser beam quality self-optimizing beam combining device and method to solve the shortcomings of traditional dense spectrum beam combining technology that can only improve the beam combining power but cannot improve the beam quality. The present invention has the advantages of high beam combining efficiency and low cost.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A semiconductor laser beam quality self-optimizing beam combining device comprises a semiconductor laser group, a fast axis collimating mirror group, a slow axis collimating mirror group, a reflecting mirror group, a volume Bragg grating group and an external cavity mirror;

[0006] The semiconductor laser group emits a light beam group with the same wavelength, and the light beam group is emitted after passing through a fast axis collimator group, a slow axis collimator group, a reflector group, a volume Bragg grating group and an external cavity mirror in sequence;

[0007] The fast-axis collimator group reduces the divergence angle of the light beam group in the fast-axis direction, the slow-axis collimator group reduces the divergence angle of the light beam group in the slow-axis direction, the reflector group reflects the light beam group emitted from the slow-axis collimator group to the volume Bragg grating group, the volume Bragg grating group diffracts the light beam group, and makes part of the laser that meets the Bragg diffraction condition in the entire semiconductor laser spectrum incident on the external cavity mirror, the external cavity mirror feeds back the laser that meets the Bragg diffraction condition to the chips of each semiconductor laser in the semiconductor laser group through the volume Bragg grating group, the reflector group, the slow-axis collimator group and the fast-axis collimator group in the original path, so as to realize mode competition and automatic wavelength adjustment, the adjusted light beam group is combined again through the fast-axis collimator group, the slow-axis collimator group, the reflector group and the volume Bragg grating group in turn, and the combined light beam is output through the external cavity mirror.

[0008] Furthermore, the semiconductor laser group includes no less than two semiconductor lasers, the fast-axis collimator group includes no less than two fast-axis collimators, and each fast-axis collimator is arranged corresponding to each semiconductor laser, the slow-axis collimator group includes no less than two slow-axis collimators, and each slow-axis collimator is arranged corresponding to each semiconductor laser, and the reflector group includes no less than two reflectors, and each reflector is arranged corresponding to each semiconductor laser.

[0009] Furthermore, the semiconductor laser group is a single-tube semiconductor laser, the front cavity surface of the single-tube semiconductor laser is coated with an anti-reflection film, and the wavelength range of the single-tube semiconductor laser emission is 800nm-1500nm.

[0010] Furthermore, the volume Bragg grating group includes at least two volume Bragg gratings, each volume Bragg grating is arranged corresponding to each reflector, and the wavelength of the target light beam and the incident laser angle of each volume Bragg grating satisfy the following formula:

[0011] ;

[0012] in, φ 0 is the incident laser angle of the volume Bragg grating, Λ is the grating period, n av is the grating refractive index, and λ is the wavelength of the target beam.

[0013] Furthermore, the light transmitted and diffracted by each Bragg grating is combined and then emitted through an external cavity mirror.

[0014] Furthermore, the wavelength of the target light beam satisfies the Bragg diffraction condition, and the volume Bragg grating diffracts the target light beam and transmits light beams of other wavelengths except the target light beam.

[0015] Furthermore, the external cavity mirror and the back cavity surface of each single-tube semiconductor laser included in the semiconductor laser group form a resonant external cavity of each single-tube semiconductor laser.

[0016] Furthermore, the reflectivity of the external cavity mirror is between 5% and 20%.

[0017] Furthermore, the grating wavelength range of the volume Bragg grating is 320nm-2700nm, the grating period range of the volume Bragg grating is 500l / mm-3000l / mm, the spectral bandwidth range of the volume Bragg grating is 0.2nm-100nm, and the volume Bragg grating performs spectral selection on the laser beam of 700nm-2500nm.

[0018] A semiconductor laser beam quality self-optimizing beam combining method is implemented using a semiconductor laser beam quality self-optimizing beam combining device, and specifically comprises the following steps:

[0019] S1: The semiconductor laser group emits a light beam group with the same wavelength, and the light beam group is incident on the volume Bragg grating group through the fast axis collimator group, the slow axis collimator group and the reflector group in sequence;

[0020] S2: The volume Bragg grating group diffracts the light beam group, and makes the part of the laser that meets the Bragg diffraction condition in the entire semiconductor laser spectrum incident on the external cavity mirror. The external cavity mirror feeds back the laser that meets the Bragg diffraction condition to the chips of each semiconductor laser in the semiconductor laser group through the volume Bragg grating group, the reflector group, the slow axis collimator group and the fast axis collimator group in the original path, so as to realize mode competition and automatic wavelength adjustment;

[0021] S3: The adjusted light beam group is combined again through a fast axis collimator group, a slow axis collimator group, a reflector group and a volume Bragg grating group in sequence, and the combined light beam is output through an external cavity mirror.

[0022] Compared with the prior art, the invention can achieve the following beneficial effects:

[0023] (1) The present invention creates the semiconductor laser beam quality self-optimizing beam combining device and method, so that the quality of the combined beam is optimized. The present invention forms an external cavity between the back cavity surface of the semiconductor laser and the external cavity mirror. The external cavity mirror will reflect part of the diffracted laser beam onto the volume Bragg grating again, and use its spectral selection characteristics to diffract the laser mode that meets the Bragg diffraction condition into the laser chip. Through the mode competition characteristics of the semiconductor laser, this laser mode will be enhanced and become the main mode for lasing, while the mode that does not meet the Bragg diffraction condition cannot be fed back into the chips of each semiconductor laser in the semiconductor laser group, and the partial mode that cannot be fed back into the laser chip is gradually suppressed during the mode competition process. The reduction of laser modes will effectively reduce the slow axis divergence angle, optimize the quality of the combined beam, and make the combined beam quality better than the level of single-channel devices.

[0024] (2) The present invention creates the semiconductor laser beam quality self-optimizing beam combining device and method, which improves the efficiency of dense spectrum beam combining. In the dense spectrum beam combining process of the present invention, the semiconductor laser modulates the output spectrum according to the spectral selection characteristics of the volume Bragg grating, compresses the output spectrum and automatically adjusts it to the corresponding wavelength with the highest diffraction efficiency. Therefore, even if there is an optical path deviation, the light beam can be diffracted at the theoretically designed angle, thereby optimizing and improving the efficiency of dense spectrum beam combining. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0026] Figure 1 A schematic diagram of the structure of a semiconductor laser beam quality self-optimizing beam combining device according to an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the beam combining principle of the volume Bragg grating described in the embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the process of the semiconductor laser beam quality self-optimization combining method described in an embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1. Semiconductor laser group; 2. Fast axis collimator group; 3. Slow axis collimator group; 4. Reflector group; 5. Volume Bragg grating group; 6. External cavity mirror; 7. First laser beam; 8. Second laser beam; 9. Combined beam. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0034] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0036] like Figure 1 As shown, a semiconductor laser beam quality self-optimizing beam combining device provided by the present invention comprises a semiconductor laser group 1, a fast axis collimating mirror group 2, a slow axis collimating mirror group 3, a reflecting mirror group 4, a volume Bragg grating group 5 and an external cavity mirror 6 (the reflectivity of the external cavity mirror 6 is between 5% and 20%);

[0037] The semiconductor laser group 1 emits a light beam group with the same wavelength. The spectral width of the laser light beam contained in the light beam group is in the range of 5nm-10nm. The light beam group is emitted after passing through the fast axis collimator group 2, the slow axis collimator group 3, the reflector group 4, the volume Bragg grating group 5 and the external cavity mirror 6 in sequence.

[0038] The light beam group is collimated by the fast axis collimator group 2 and the slow axis collimator group 3 in sequence. The fast axis collimator group 2 reduces the divergence angle of the light beam group in the fast axis direction. The slow axis collimator group 3 reduces the divergence angle of the light beam group in the slow axis direction. The reflector group 4 reflects the light beam group emitted from the slow axis collimator group 3 to the volume Bragg grating group 5. The volume Bragg grating group 5 diffracts the light beam group and makes part of the laser light that meets the Bragg diffraction condition incident on the external cavity mirror 6. The external cavity mirror 6 sequentially passes the laser light that meets the Bragg diffraction condition through the volume Bragg grating group 5, the reflector group 4, the slow axis collimator group 3 and the fast axis collimator. The mirror group 2 is fed back in the original path to the chips of each semiconductor laser of the semiconductor laser group 1. Based on the mode competition characteristics of the semiconductor laser, the semiconductor laser group 1 enhances the laser mode fed back in the original path to the semiconductor laser group 1 as the main lasing mode, suppresses other stray modes, realizes mode competition and automatic wavelength adjustment, and reduces the slow axis divergence angle of the light beam group emitted by the semiconductor laser group 1. The adjusted light beam group is combined again through the fast axis collimator mirror group 2, the slow axis collimator mirror group 3, the reflector group 4 and the volume Bragg grating group 5 in sequence, and the combined light beam 9 is output through the external cavity mirror 6.

[0039] The semiconductor laser group 1 includes at least two semiconductor lasers, the fast-axis collimator group 2 includes at least two fast-axis collimators, the focal length of the fast-axis collimator is generally 0.1-1 mm, and each fast-axis collimator is arranged corresponding to each semiconductor laser, the slow-axis collimator group 3 includes at least two slow-axis collimators, the focal length of the slow-axis collimator is generally 5-20 mm, and each slow-axis collimator is arranged corresponding to each semiconductor laser, and the reflector group 4 includes at least two reflectors, and each reflector is arranged corresponding to each semiconductor laser.

[0040] The semiconductor laser group 1 is a single-tube semiconductor laser. The front cavity surface of the single-tube semiconductor laser is coated with an anti-reflection film (with a transmittance greater than 99%). The wavelength range of the single-tube semiconductor laser emission is 800nm-1500nm.

[0041] The volume Bragg grating group 5 includes at least two volume Bragg gratings, and each volume Bragg grating is arranged corresponding to each reflector. The placement angles of each volume Bragg grating are slightly different, and the wavelength of the target light beam and the incident laser angle of each volume Bragg grating satisfy the following formula:

[0042] ;

[0043] in, φ 0 is the incident laser angle of the volume Bragg grating, Λ is the grating period, n av is the grating refractive index, and λ is the wavelength of the target beam.

[0044] The light transmitted and diffracted by each Bragg grating is combined and then emitted through the external cavity mirror 6 .

[0045] The wavelength of the target beam meets the Bragg diffraction condition, and the volume Bragg grating diffracts the target beam and transmits beams of other wavelengths except the target beam. That is, each volume Bragg grating diffracts the laser light that meets the diffraction equation in the laser spectrum emitted by the corresponding semiconductor laser, and transmits the laser beam diffracted by the previous volume Bragg grating (having a certain wavelength difference with the current volume Bragg grating), thereby combining the beams into one beam and transmitting them to the external cavity mirror 6, thereby obtaining the final combined beam 9.

[0046] The external cavity mirror 6 and the back cavity surface of each single-tube semiconductor laser included in the semiconductor laser group 1 form a resonant external cavity of each single-tube semiconductor laser. This structure allows the laser to be reflected multiple times between the semiconductor laser and the external cavity mirror 6, thereby increasing the interaction between the laser and the volume Bragg grating.

[0047] Volume Bragg grating has good spectral selectivity. In conventional dense spectral beam combining, the spectral selectivity of volume Bragg grating is reflected in the change of diffraction angle of different laser modes. The laser modes within its spectral selection bandwidth are diffracted with higher diffraction efficiency, while the laser modes beyond the spectral selection bandwidth will be emitted with a certain directivity deviation, thereby reducing the beam quality.

[0048] The present invention sets an external cavity mirror 6 in the laser emission direction of the dense spectrum beam, and forms an external cavity feedback mechanism with the semiconductor laser, combines the spectral selectivity of the volume Bragg grating with the mode competition effect of the semiconductor laser, effectively reduces the number of transverse modes of the semiconductor laser, and then reduces the divergence angle, fundamentally improves the beam quality of the beam-combining light source, and breaks the bottleneck that the beam quality of the current dense spectrum beam-combining light source is limited by the unit device. Specifically, in the present invention, the volume Bragg grating only allows lasers of a specific wavelength that meet the Bragg diffraction condition to pass. Only lasers of a specific wavelength can be reflected back to the semiconductor laser, while lasers of other wavelengths are filtered out. Semiconductor lasers with mode competition characteristics will enhance the laser mode that meets the Bragg diffraction condition to the main lasing mode. These laser modes are fed back from the external cavity mirror 6, thereby being strengthened inside the laser. The laser mode that does not meet the Bragg diffraction condition cannot be fed back into the laser chip of the semiconductor laser, and therefore is suppressed and reduced during the mode competition process. This results in a reduction in the laser mode output by the semiconductor laser, and the reduction in the laser mode will reduce the slow axis divergence angle of the semiconductor laser and improve the beam quality.

[0049] After the self-optimization process, the laser modes of the semiconductor laser are reduced, the slow axis divergence angle is reduced, the output spectrum of each semiconductor laser is narrowed, and it is automatically adjusted to the wavelength with the highest diffraction efficiency of the volume Bragg grating.

[0050] Due to the spectral selectivity of the volume Bragg grating, a self-regulating effect can be achieved, the necessity of external interference is reduced, and the efficiency of dense spectrum beam combining is improved. Compared with the traditional dense spectrum beam combining technology, the present invention reduces the number of volume Bragg grating devices used, saves costs, and because the use of volume Bragg gratings is reduced, the possibility of affecting the diffraction efficiency due to the position deviation of the volume Bragg grating is also reduced.

[0051] In the present invention, the grating wavelength range of the volume Bragg grating is 320nm-2700nm, the grating period range of the volume Bragg grating is 500l / mm-3000l / mm, the spectral bandwidth range of the volume Bragg grating is 0.2nm-100nm, and the volume Bragg grating performs spectral selection on the laser beam of 700nm-2500nm.

[0052] Example 1

[0053] Select three semiconductor lasers with a light emission wavelength of 940nm and a light emission width of 95μm to construct a laser group, select three volume Bragg gratings with a diffraction center wavelength of 976nm to form volume Bragg grating group 5, and the center wavelengths of the three target light beams that the user ultimately wants to obtain are 974.5nm, 976nm and 977.5nm respectively. Other indicators of the grating are: grating period Λ is 3000 l / mm, and grating refractive index nav is 1.485. Using the above indicators, the incident angles of the three volume Bragg gratings are calculated to be 15.743°, 15° and 14.221° respectively. Place the reflectors corresponding to the three volume Bragg gratings respectively, so that the incident angles of the laser incident on the three volume Bragg gratings are 15.743°, 15° and 14.221° respectively.

[0054] The volume Bragg grating here can realize the laser beam combination of two laser beams with a wavelength interval of 1.5nm, such as Figure 2 As shown, the beam combining principle is: the first laser beam 7 must be incident on the volume Bragg grating to meet the Bragg condition, and is output with an efficiency of 99% after diffraction by the volume Bragg grating. The wavelength of the second laser beam 8 differs by 1.5 nm from the first laser beam 7 after diffraction. After the second laser beam 8 is transmitted through the volume Bragg grating, it overlaps with the first laser beam 7 after diffraction in space to achieve beam combining.

[0055] Finally, part of the laser light transmitted to the external cavity mirror 6 after diffraction by the volume Bragg grating is reflected by the external cavity mirror 6 onto the volume Bragg grating. The spectral selection characteristic of the volume Bragg grating diffracts the laser mode that meets the Bragg diffraction condition into the laser chip, while the laser mode that does not meet the Bragg diffraction condition cannot be fed back into the laser chip, thereby being suppressed and reduced, and finally the wavelength of the semiconductor laser is modulated to 974.5nm, 976nm and 977.5nm.

[0056] like Figure 3 As shown, the present invention provides a semiconductor laser beam quality self-optimizing beam combining method, which is implemented by using a semiconductor laser beam quality self-optimizing beam combining device, and specifically includes the following steps:

[0057] S1: The semiconductor laser group 1 emits a light beam group with the same wavelength, and the light beam group is incident on the volume Bragg grating group 5 through the fast axis collimator group 2, the slow axis collimator group 3 and the reflector group 4 in sequence.

[0058] S2: The volume Bragg grating group 5 diffracts the light beam group, and makes part of the laser light that meets the Bragg diffraction condition in the entire semiconductor laser spectrum incident on the external cavity mirror 6. The external cavity mirror 6 feeds back the laser light that meets the Bragg diffraction condition to the chips of each semiconductor laser of the semiconductor laser group 1 through the volume Bragg grating group 5, the reflector group 4, the slow axis collimator group 3 and the fast axis collimator group 2 in turn, so as to realize mode competition and automatic wavelength adjustment.

[0059] S3: The adjusted light beam group is combined again through the fast axis collimator group 2, the slow axis collimator group 3, the reflector group 4 and the volume Bragg grating group 5 in sequence, and the combined light beam 9 is output through the external cavity mirror 6.

[0060] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0061] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A semiconductor laser beam quality self-optimizing beam combining device, characterized in that: It includes a semiconductor laser group, a fast axis collimator group, a slow axis collimator group, a reflector group, a volume Bragg grating group and an external cavity mirror; The semiconductor laser group emits a light beam group with the same wavelength, and the light beam group is emitted after passing through the fast axis collimator group, the slow axis collimator group, the reflector group, the volume Bragg grating group and the external cavity mirror in sequence; The fast-axis collimator group reduces the divergence angle of the light beam group in the fast-axis direction, and the slow-axis collimator group reduces the divergence angle of the light beam group in the slow-axis direction. The reflector group reflects the light beam group emitted from the slow-axis collimator group to the volume Bragg grating group. The volume Bragg grating group diffracts the light beam group, and makes part of the laser light that meets the Bragg diffraction condition in the entire semiconductor laser spectrum incident on the external cavity mirror. The external cavity mirror feeds back the laser light that meets the Bragg diffraction condition to the chips of each semiconductor laser of the semiconductor laser group through the volume Bragg grating group, the reflector group, the slow-axis collimator group and the fast-axis collimator group in the original path in turn, so as to realize mode competition and automatic wavelength adjustment. The adjusted light beam group is combined again through the fast-axis collimator group, the slow-axis collimator group, the reflector group and the volume Bragg grating group in turn, and the combined light beam is output through the external cavity mirror. The semiconductor laser group includes at least two semiconductor lasers, the fast-axis collimator group includes at least two fast-axis collimators, and each fast-axis collimator is arranged corresponding to each semiconductor laser, the slow-axis collimator group includes at least two slow-axis collimators, and each slow-axis collimator is arranged corresponding to each semiconductor laser, and the reflector group includes at least two reflectors, and each reflector is arranged corresponding to each semiconductor laser; The volume Bragg grating group includes at least two volume Bragg gratings, each volume Bragg grating is arranged corresponding to each reflector, and the wavelength of the target light beam and the incident laser angle of each volume Bragg grating satisfy the following formula: ； in, is the incident laser angle of the volume Bragg grating, Λ is the grating period, n av is the grating refractive index, and λ is the wavelength of the target beam.

2. The semiconductor laser beam quality self-optimizing beam combining device according to claim 1, characterized in that: The semiconductor laser group is a single-tube semiconductor laser, the front cavity surface of the single-tube semiconductor laser is coated with an anti-reflection film, and the wavelength range of the single-tube semiconductor laser emission is 800nm-1500nm.

3. The semiconductor laser beam quality self-optimizing beam combining device according to claim 1, characterized in that: The light transmitted and diffracted by each volume Bragg grating is combined and then emitted through the external cavity mirror.

4. The semiconductor laser beam quality self-optimizing beam combining device according to claim 1, characterized in that: The wavelength of the target light beam satisfies the Bragg diffraction condition, and the volume Bragg grating diffracts the target light beam and transmits light beams of other wavelengths except the target light beam.

5. The semiconductor laser beam quality self-optimizing beam combining device according to claim 2, characterized in that: The external cavity mirror and the back cavity surface of each single-tube semiconductor laser included in the semiconductor laser group form a resonant external cavity of each single-tube semiconductor laser.

6. The semiconductor laser beam quality self-optimizing beam combining device according to claim 1, characterized in that: The reflectivity of the external cavity mirror is between 5% and 20%.

7. The semiconductor laser beam quality self-optimizing beam combining device according to claim 1, characterized in that: The grating wavelength range of the volume Bragg grating is 320nm-2700nm, the grating period range of the volume Bragg grating is 500l / mm-3000l / mm, the spectral bandwidth range of the volume Bragg grating is 0.2nm-100nm, and the volume Bragg grating performs spectral selection on the laser beam of 700nm-2500nm.

8. A semiconductor laser beam quality self-optimizing beam combining method, implemented by using the semiconductor laser beam quality self-optimizing beam combining device according to any one of claims 1 to 7, characterized in that: The specific steps include: S1: the semiconductor laser group emits a light beam group with the same wavelength, and the light beam group is incident on the volume Bragg grating group through the fast axis collimator group, the slow axis collimator group and the reflector group in sequence; S2: the volume Bragg grating group diffracts the light beam group, and makes part of the laser light that meets the Bragg diffraction condition in the entire semiconductor laser spectrum incident on the external cavity mirror, and the external cavity mirror feeds back the laser light that meets the Bragg diffraction condition to the chips of each semiconductor laser in the semiconductor laser group through the volume Bragg grating group, the reflector group, the slow axis collimator group and the fast axis collimator group in the original path in sequence, so as to realize mode competition and automatic wavelength adjustment; S3: The adjusted light beam group is combined again through the fast axis collimator group, the slow axis collimator group, the reflector group and the volume Bragg grating group in sequence, and the combined light beam is output through the external cavity mirror.

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