All-solid-state high-power single-frequency laser based on optical fiber-lath mixed structure

Abstract

The invention provides an all-solid-state high-power single-frequency laser based on an optical fiber-slab mixed structure, and relates to the technical field of solid lasers, and the all-solid-state high-power single-frequency laser comprises an all-solid-state continuous single-frequency seed module, an optical fiber pulse modulation module, an optical fiber pre-amplification module, a slab laser pre-amplification module, a slab laser main amplification module and a frequency multiplication module which are sequentially arranged; the lath laser pre-amplifier and the lath laser main amplifier are used for compensating thermally induced aberration generated by lath laser through multi-pass amplification designed according to the spherical aberration self-compensation principle, and then the quality of light beams is improved. In addition, a discrete mirror group is adopted to replace a complete amplifier cavity mirror, spontaneous radiation and parasitic oscillation in the working process of the amplifier are effectively restrained, nearly hundred mJ-magnitude single-frequency pulse laser with excellent light beam quality can be obtained, and application to laser radar detection or industry can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state lasers, and particularly to an all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure. Background Art

[0002] High-power single-frequency lasers have important application values in the fields of precision machining, optical communication, remote sensing detection, and national defense technology. In traditional technologies, the realization of single-frequency lasers mainly relies on fiber lasers or solid-state slab lasers. Fiber lasers, with their excellent beam quality, high optical-optical conversion efficiency (the electro-optical efficiency can reach 25%), and compact structure, have become the mainstream choice for high-precision applications. However, their output power is limited by the nonlinear effects of fibers (such as stimulated Raman scattering and photon darkening effects), and it is difficult to break through the kilowatt-level limit. On the other hand, although solid-state slab lasers (such as Yb:YAG slab structures) can achieve high average power output, they are bulky, have complex thermal management, and poor single-frequency stability, making it difficult to meet the requirements of high beam quality and miniaturization. In the prior art, the performance shortcomings of the two make it difficult to balance high power and single-frequency characteristics, and there is an urgent need for a new structure to break through the comprehensive bottleneck of power, stability, and compactness. Summary of the Invention

[0003] To overcome the deficiencies of the prior art, the present invention provides an all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure. The system can output pulsed lasers with a single-pulse energy of nearly a hundred mJ magnitude, narrow pulse width, adjustable repetition frequency (50 Hz to 10 kHz), compact structure, and excellent beam quality, and can be widely applied in the field of lidar detection.

[0004] The technical solution of the present invention is: an all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure, comprising a full-solid-state continuous single-frequency seed module, a fiber pulse modulation module, a fiber pre-amplification module, a slab laser pre-amplification module, a slab laser main amplification module, and a frequency doubling module arranged in sequence;

[0005] The full-solid-state continuous single-frequency seed module generates single-frequency continuous laser and outputs it to the fiber pulse modulation module. The fiber pulse modulation module modulates the incident single-frequency continuous laser pulse into a single-frequency high-repetition-frequency pulsed laser and outputs it to the fiber pre-amplification module. The fiber pre-amplification module amplifies the incident single-frequency high-repetition-frequency laser by an order of magnitude and outputs it to the slab laser pre-amplification module. The slab laser pre-amplification module amplifies the incident single-frequency high-repetition-frequency laser by an order of magnitude and outputs it to the slab laser main amplification module. The slab laser main amplification module receives the single-frequency high-repetition-frequency laser and further amplifies it by an order of magnitude and outputs it to the frequency doubling module. The frequency doubling module receives the single-frequency high-repetition-frequency laser and performs frequency doubling and then outputs the laser.

[0006] Compared with the prior art, the advantages of the present invention are as follows:

[0007] The synergistic improvement of high power and single-frequency characteristics is achieved. Through fiber pulse modulation and fiber pre-amplification, combined with the high-power amplification ability of the slab amplifier, not only the narrow linewidth and high coherence characteristics of single-frequency lasers are retained, but also the power limitation of traditional fiber lasers is broken through; in addition, efficient heat dissipation and preheating management optimization are realized. The slab amplifier adopts microchannel water cooling technology, which effectively reduces the thermal lens effect of the crystal and avoids the deterioration of the beam quality caused by thermal distortion in traditional slab lasers; finally, the repetition frequency is adjustable. By using a fiber-optic electro-optic modulator to pulse-modulate the input continuous laser, a repetition frequency adjustable from 50 Hz to 10 kHz is achieved. The present invention provides a all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure. In the present invention, both the slab laser pre-amplifier and the slab laser main amplifier use multi-pass amplification designed based on the spherical aberration self-compensation principle to compensate for the thermally induced aberration generated by the slab laser, thereby improving the beam quality. In addition, in the present invention, a discrete mirror group is used to replace the complete amplifier cavity mirror, effectively suppressing the spontaneous emission and parasitic oscillation during the operation of the amplifier, and a single-frequency pulsed laser with excellent beam quality in the order of nearly 100 mJ can be obtained, which can meet the applications in lidar detection or industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of an all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure provided by an embodiment of the present invention;

[0009] Figure 2 is a measured spot image of the output of the fiber pre-amplification module provided in this embodiment.

[0010] The reference numerals in the figure are: all-solid-state continuous single-frequency seed module 1, fiber pulse modulation module 2, fiber pre-amplification module 3, slab laser pre-amplification module 4, slab laser main amplification module 5, frequency doubling module 6, polarization-maintaining fiber coupler 7, polarization-maintaining fiber collimator 8, shaping module 9, mirror 10, discrete cavity mirror 11, discrete cavity mirror 12, discrete cavity mirror 13, discrete cavity mirror 14, laser crystal 15, cavity mirror 16, mirror 17, shaping mirror group 18, mirror 19, discrete cavity mirror 21, discrete cavity mirror 22, discrete cavity mirror 23, discrete cavity mirror 24, laser crystal 25, cavity mirror 26, shaping mirror group 27, discrete cavity mirror 28, discrete cavity mirror 29, discrete cavity mirror 30, discrete cavity mirror 31, laser crystal 32, cavity mirror 33, mirror 34, shaping mirror group 35, mirror 36, discrete cavity mirror 37, discrete cavity mirror 38, discrete cavity mirror 39, laser crystal 40, shaping mirror group 41, mirror 42, cavity mirror 43. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0012] The present invention provides an all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure, which includes a sequentially arranged all-solid-state continuous single-frequency seed module 1, a polarization-maintaining fiber coupler 7, a fiber pulse modulation module 2, a fiber pre-amplification module 3, a slab laser pre-amplification module 4, a polarization-maintaining fiber collimator 8, a shaping module 9, a slab laser main amplification module 5, and a frequency doubling module 6.

[0013] The all-solid-state continuous single-frequency seed module 1 generates 10 mW of single-frequency linearly polarized laser, which is output to the fiber pulse modulation module 2 through the polarization-maintaining fiber coupler 7. The fiber pulse modulation module 2 performs pulse modulation on the incident single-frequency linearly polarized laser to obtain single-frequency high-repetition-rate pulsed laser with an adjustable repetition rate of 50 Hz to 10 kHz and a pulse width < 35 ns, and outputs it to the fiber pre-amplification module 3. The fiber pre-amplification module 3 amplifies the incident single-frequency high-repetition-rate pulsed laser to the nJ or even pJ level, and the laser output through the polarization-maintaining fiber collimator 8 and the shaping module 9 is transmitted to the slab laser pre-amplification module 4 through a mirror 10. The slab laser pre-amplification module 4 amplifies the incident laser to the mJ level based on spherical aberration self-compensation and a discrete mirror structure, and outputs it to the slab laser main amplification module 5 through a mirror 17 and a mirror 19. The slab laser main amplification module 5 can further amplify the received laser to nearly 100 mJ level and then output it to the frequency doubling module 6. The frequency doubling module 6 receives the laser and performs frequency doubling to generate 532 nm laser.

[0014] The all-solid-state continuous single-frequency seed module 1 is based on a four-mirror ring cavity configuration and can output continuous single-frequency linearly polarized laser.

[0015] The polarization-maintaining fiber coupler 7 is used to couple the single-frequency linearly polarized laser output by the all-solid-state continuous single-frequency seed module 1 into a polarization-maintaining fiber.

[0016] The fiber pulse modulation module 2 is used to modulate the continuous single-frequency linearly polarized laser into a single-frequency high-repetition-rate pulsed laser, and the fiber pulse modulation module 2 operates based on a fiber electro-optic modulator.

[0017] The fiber pre-amplification module 3 is used to amplify the low-power single-frequency high-repetition-rate pulsed laser to the μJ level.

[0018] The polarization-maintaining fiber collimator 8 is used to collimate and output the single-frequency high-repetition-rate pulsed laser as spatial laser.

[0019] The shaping module 9 is used to shape the laser output by the fiber collimator so that it can enter the laser crystal for amplification later.

[0020] The slab laser pre-amplification module 4 includes a shaping mirror group 18, a laser crystal 15, a cavity mirror 16, and a discrete cavity mirror group composed of discrete cavity mirrors 11, 11, 13, and 14. Among them, the shaping mirror group 18 is used to shape the laser to be output by the slab laser pre-amplification module 4, the laser crystal 15 serves as the laser gain medium, and the cavity mirror 16 and the discrete cavity mirror group together form the amplifier cavity mirror.

[0021] The slab laser main amplification module 5 includes three-stage main amplifiers: the first-stage main amplifier, the second-stage main amplifier, and the third-stage main amplifier. The laser output by the first-stage main amplifier enters the second-stage main amplifier after being reflected by the mirror 34, the laser output by the second-stage main amplifier enters the third-stage main amplifier after being reflected by the mirror 36, and the laser output by the third-stage main amplifier is output to the cavity mirror 43 after being reflected by the mirror 42 and further frequency-doubled by the frequency-doubling module 6 and then output. Among them, it is used for the optical path deflection of the 1064nm laser.

[0022] The first-stage main amplifier includes a shaping mirror group 27, a laser crystal 25, a cavity mirror 26, and a discrete cavity mirror group composed of discrete cavity mirrors 21, 22, 23, and 24. Among them, the shaping mirror group 27 is used to shape the output laser, the laser crystal 25 serves as the laser gain medium, and the cavity mirror 26 and the discrete cavity mirror group together form the amplifier cavity mirror.

[0023] The second-stage main amplifier includes a shaping mirror group 35, a laser crystal 32, a cavity mirror 33, and a discrete cavity mirror group composed of discrete cavity mirrors 28, 29, 30, and 31. Among them, the shaping mirror group 35 is used to shape the output laser, the laser crystal 32 serves as the laser gain medium, and the cavity mirror 33 and the discrete cavity mirror group together form the amplifier cavity mirror.

[0024] The third-stage main amplifier includes a shaping mirror group 41, a laser crystal 40, a cavity mirror 43, and a discrete cavity mirror group composed of discrete cavity mirrors 37, 38, and 39. Among them, the shaping mirror group 41 is used to shape the output laser, the laser crystal 40 serves as the laser gain medium, and the cavity mirror 43 and the discrete cavity mirror group together form the amplifier cavity mirror.

[0025] The frequency-doubling module 6 is used to frequency-double the 1064nm laser into a 532nm laser.

[0026] The discrete cavity mirrors 11 - 14, 21 - 24, 28 - 31, 37 - 39 adopt a discrete configuration to suppress ASE, and the side close to the laser crystal is coated with a 1064nm total reflection film.

[0027] The laser crystal 15 uses Nd:YVO4 with a doping concentration of 0.3 at.%, and is cut in the a-cut manner.

[0028] The laser crystals 25, 32, and 40 use Nd:YAG with a doping concentration of 0.7 at.%, and are cut in the <111> cutting manner.

[0029] The mirrors 10, 17, 19, 34, 36, and 42 are used to deflect the 1064 nm laser optical path.

[0030] As Figure 1 shown, the schematic diagram of a all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure provided by the present invention includes an all-solid-state continuous single-frequency seed module 1 that can output single-frequency continuous 1064 nm. The spatial light is coupled into the polarization-maintaining fiber through the polarization-maintaining fiber coupler 7, modulated into a high-repetition-rate pulsed laser through the fiber, amplified to the μJ level of single-frequency pulsed laser through the fiber pulse amplification, and then collimated and output to the slab laser pre-amplification module by the polarization-maintaining fiber collimator 8, amplified to the mJ level through the Nd:YVO4 laser crystal, and then shaped into the slab laser main amplification module 5 and amplified to nearly 100 mJ level. The laser gain medium of the slab laser main amplification module 5 is Nd:YAG, and finally the 532 nm laser is output by the frequency doubling module 6.

[0031] The fiber pulse modulation module 2 is based on a polarization-maintaining fiber electro-optic modulator and is used to modulate continuous laser into pulsed laser.

[0032] The fiber pre-amplification module 3 is usually selected as a ytterbium-doped fiber amplifier.

[0033] The shaping module 9 is used to shape the laser output from the fiber to match the pump light mode distribution in the laser crystal.

[0034] The Nd:YVO4 laser crystal is in a slab shape. Compared with Nd:YAG, Nd:YVO4 has a higher absorption coefficient for pump light and a larger stimulated emission cross-section, which is suitable for the gain amplification of small-signal lasers.

[0035] The Nd:YAG laser crystal is in a slab shape. Compared with Nd:YVO4, the high thermal conductivity of Nd:YAG is beneficial to efficient heat transfer, enabling the crystal to withstand high-power laser operation.

[0036] As Figure 2 shown, it is the measured spot picture output by the slab fiber pre-amplification module 4 provided in this embodiment.

[0037] The specific embodiments described above have elaborated in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, supplements, equivalent replacements, etc. made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure, characterized in that, It includes a fully solid-state continuous single-frequency seed module, a fiber pulse modulation module, a fiber pre-amplification module, a slab laser pre-amplification module, a slab laser main amplification module, and a frequency doubling module, which are arranged in sequence. The fully solid-state continuous single-frequency seed module generates single-frequency linearly polarized laser and outputs it to the fiber pulse modulation module. The fiber pulse modulation module modulates the incident single-frequency linearly polarized laser pulse into a single-frequency high-repetition-rate pulsed laser and outputs it to the fiber pre-amplification module. The fiber pre-amplification module amplifies the incident single-frequency high-repetition-rate laser by an order of magnitude and then outputs it to the slab laser pre-amplification module. The slab laser pre-amplification module amplifies the incident single-frequency high-repetition-rate laser by an order of magnitude and then outputs it to the slab laser main amplification module. The slab laser main amplification module receives the single-frequency high-repetition-rate laser, further amplifies it by an order of magnitude, and then outputs it to the frequency doubling module. The frequency doubling module receives the single-frequency high-repetition-rate laser, performs frequency doubling, and then outputs the laser.

2. The all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, wherein The fully solid-state continuous single-frequency seed module is based on a four-mirror ring cavity configuration and outputs continuous single-frequency linearly polarized laser.

3. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, A polarization-maintaining fiber coupler is arranged between the fully solid-state continuous single-frequency seed module and the fiber pulse modulation module and is used to couple the single-frequency laser output by the fully solid-state continuous single-frequency seed module into the polarization-maintaining fiber.

4. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The single-frequency high-repetition-rate pulsed laser has an adjustable repetition rate of 50 Hz to 10 kHz, and the fiber pulse modulation module operates based on a fiber electro-optic modulator.

5. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The fiber pre-amplification module is used to amplify the single-frequency high-repetition-rate laser to the pJ level.

6. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The laser output by the fiber pre-amplification module sequentially passes through a polarization-maintaining fiber collimator and a shaping module and then enters the slab laser pre-amplification module. The polarization-maintaining fiber collimator is used to collimate the laser and output it as spatial laser, and the shaping module is used to shape the spatial laser.

7. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The slab laser pre-amplification module includes a shaping mirror group, a laser crystal, a cavity mirror, and a discrete cavity mirror group. The shaping mirror group is used to shape the laser output by the slab laser pre-amplification module. The laser crystal serves as the laser gain medium, and the cavity mirror and the discrete cavity mirror group together form the amplifier cavity mirror.

8. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The slab laser main amplification module includes three-stage main amplifiers: a first-stage main amplifier, a second-stage main amplifier, and a third-stage main amplifier. The laser output by the first-stage main amplifier is reflected by a mirror and then enters the second-stage main amplifier. The laser output by the second-stage main amplifier is reflected by a mirror and then enters the third-stage main amplifier. The laser output by the third-stage main amplifier is reflected by a mirror and then further frequency-doubled by the frequency doubling module and then output.

9. The all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 8, characterized in that The first-stage main amplifier includes a shaping mirror group, a laser crystal, a cavity mirror, and a discrete cavity mirror group. The shaping mirror group is used to shape the output laser. The laser crystal serves as the laser gain medium, and the cavity mirror and the discrete cavity mirror group together form the amplifier cavity mirror.

10. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 9, characterized in that, The second-stage main amplifier includes a shaping mirror group, a laser crystal, a cavity mirror, and a discrete cavity mirror group. The shaping mirror group is used to shape the output laser. The laser crystal serves as the laser gain medium, and the cavity mirror and the discrete cavity mirror group together form the amplifier cavity mirror.

11. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 10, characterized in that, The third-stage main amplifier includes a shaping mirror group, a laser crystal, a cavity mirror, and a discrete cavity mirror group; among them, the shaping mirror group is used to shape the output laser, the laser crystal serves as a laser gain medium, and the cavity mirror and the discrete cavity mirror group together form the amplifier cavity mirror.

12. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The laser output from the shaping module is reflected by a reflecting mirror to the slab laser pre-amplification module; the laser output from the slab laser pre-amplification module is output to the slab laser main amplification module through two reflecting mirrors.

13. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 8 or 11, characterized in that, The reflecting mirror is used for reflecting and deflecting the 1064nm optical path.

14. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 1, characterized in that, The frequency doubling module is used to double the frequency of the 1064nm laser to a 532nm laser.

15. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 11, characterized in that, The discrete mirror groups of the first-stage main amplifier, the second-stage main amplifier, and the third-stage main amplifier all include multiple discrete mirrors. The discrete mirrors are in a discrete configuration and are coated with a 1064nm total reflection film on the side close to the laser crystal.

16. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 7, characterized in that, The laser crystal of the slab laser pre-amplification module uses Nd:YVO4, with a doping concentration of 0.3at.%, and is cut in the a-cut mode.

17. A all-solid-state high-power single-frequency laser based on a fiber-slab hybrid structure according to claim 11, characterized in that, The laser crystals of the first-stage main amplifier, the second-stage main amplifier, and the third-stage main amplifier use Nd:YAG, with a doping concentration of 0.7at.%, and are cut in the <111> mode.

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