A high-power torsional cavity single-frequency laser based on slab crystal

Abstract

This invention discloses a high-power torsional mode cavity single-frequency laser based on a slab crystal, belonging to the field of solid-state laser technology. It includes: two pump sources, two pump shaping mirror groups, two mirrors, a slab laser crystal, three quarter-wave plates, an electro-optic Q-switched crystal, a polarizer, a total internal reflection plano-concave cavity mirror, and an output cavity mirror. Pump light emitted from the two pump sources passes through the two pump shaping mirror groups, then through the two mirrors, and is injected into the slab laser crystal. The combination of the first and third quarter-wave plates realizes the torsional mode cavity technology. The sequentially arranged electro-optic Q-switched crystal, second quarter-wave plate, and polarizer modulate the continuous light in the resonant cavity into pulsed light. The total internal reflection plano-concave cavity mirror and the output cavity mirror serve as the cavity mirrors of the resonant cavity. This invention can increase the pump power, currently limited to tens of watts, to hundreds of watts, and the single-frequency laser power, currently limited to watts, to tens of watts, achieving a synergistic improvement in high power and single-frequency characteristics.

Description

Technical Field

[0001] This invention belongs to the field of solid-state laser technology, specifically relating to a high-power torsional cavity single-frequency laser based on a slab crystal. Background Technology

[0002] In current high-power single-frequency solid-state lasers, torsional cavities are the mainstream technology for suppressing multi-longitudinal-mode oscillations and achieving single-frequency output. The principle is to create a spatial hole-burning effect within the resonant cavity through polarization selection, forcing the laser to operate in a single longitudinal mode. However, traditional rod-shaped gain media have significant limitations in torsional cavity configurations. For example, under high-power pumping, the radial thermal gradient of the rod-shaped medium leads to severe thermal lensing and thermally induced birefringence, disrupting the polarization selection conditions of the torsional cavity and causing frequency instability or mode skipping. Existing technologies typically employ composite crystal bonding to alleviate thermal effects, but this fails to fundamentally resolve the contradiction between power and single-frequency characteristics. Therefore, a new technical solution is urgently needed to address the limitations imposed on existing torsional cavity configurations by factors such as single-frequency characteristics, output power, stability, and compactness. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0004] A high-power torsional mode cavity single-frequency laser based on a slab crystal includes: a first pump source, a first pump shaping mirror group, a first reflector, a slab laser crystal, a second reflector, a second pump shaping mirror group, a second pump source, a first quarter-wave plate, an electro-optic Q-switched crystal, a second quarter-wave plate, a polarizer, a total internal reflection plano-concave cavity mirror, a third quarter-wave plate, and an output cavity mirror. Pump light emitted from the first and second pump sources is shaped by the first and second pump shaping mirror groups, respectively, and then injected into the slab laser crystal after passing through the first and second reflectors. The first and third quarter-wave plates are combined to realize the torsional mode cavity technology. The electro-optic Q-switched crystal, the second quarter-wave plate, and the polarizer, arranged sequentially, are combined to modulate the continuous light in the resonant cavity into pulsed light. The total internal reflection plano-concave cavity mirror and the output cavity mirror are combined as the cavity mirror of the resonant cavity. The output cavity mirror is used to output a single-frequency pulsed laser.

[0005] The present invention has the following beneficial effects:

[0006] This invention provides a high-power torsional cavity single-frequency laser based on slab crystal. The system outputs an average power that can break through the current watt-level limitation, has a narrow pulse width, adjustable repetition frequency, a compact structure, and excellent beam quality. It can be widely used in the field of lidar detection.

[0007] This invention replaces the rod-shaped crystal in the existing torsional cavity technology with a slab crystal, taking advantage of the large surface area heat dissipation of the slab crystal. This solves the mode skipping phenomenon caused by the crystal thermal effect due to high-power pumping in the laser crystal of the existing torsional cavity technology, which in turn affects the single-frequency characteristics of the laser.

[0008] This invention replaces the fiber pump in the existing torsional cavity technology with a laser diode bar array pump source (arrayed diode), thereby transforming the existing Gaussian-distributed circular pump spot into a bar-shaped pump spot with a one-dimensional flat-top distribution in the horizontal direction and a Gaussian distribution in the vertical direction, which matches the size of the slab crystal and greatly reduces the thermal effect of the laser crystal.

[0009] This invention innovatively introduces slab laser crystals and laser diode bar array pump sources into existing torsional cavity technology, which can increase the pump power from tens of watts to hundreds of watts and the single-frequency laser power from watts to tens of watts. It achieves a synergistic improvement in high power and single-frequency characteristics, retaining the narrow linewidth and high coherence characteristics of single-frequency lasers while breaking through the power limitations of traditional torsional cavities, providing a key method for realizing high-power single-frequency compact lasers. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the high-power torsional mode cavity single-frequency laser based on slab crystal of the present invention, wherein: 01-first pump source, 02-first pump shaping mirror group, 03-first reflector, 04-slab laser crystal, 05-second reflector, 06-second pump shaping mirror group, 07-second pump source, 08-first quarter-wave plate, 09-electro-optic Q-switched crystal, 10-second quarter-wave plate, 11-polarizer, 12-total internal reflection plano-concave cavity mirror, 13-third quarter-wave plate, 14-output cavity mirror. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0012] like Figure 1As shown, the high-power torsional cavity single-frequency laser based on slab crystal of the present invention includes: a first pump source 01, a first pump shaping mirror group 02, a first reflector 03, a slab laser crystal 04, a second reflector 05, a second pump shaping mirror group 06, a second pump source 07, a first quarter-wave plate 08, an electro-optic Q-switching crystal 09, a second quarter-wave plate 10, a polarizer 11, a total internal reflection plano-concave cavity mirror 12, a third quarter-wave plate 13, and an output cavity mirror 14. Pump light emitted from the first pump source 01 and the second pump source 07 is shaped by the first pump shaping mirror group 02 and the second pump shaping mirror group 06, respectively, and then injected into the slab laser crystal 04 after passing through the first reflecting mirror 03 and the second reflecting mirror 05, respectively. The first quarter-wave plate 08 and the third quarter-wave plate 13 are combined to realize the twisted cavity technology. The electro-optic Q-switching crystal 09, the second quarter-wave plate 10 and the polarizer 11 arranged in sequence are combined to modulate the continuous light in the resonant cavity into pulse light. The total internal reflection plano-concave cavity mirror 12 and the output cavity mirror 14 are combined as the cavity mirror of the resonant cavity; wherein, the output cavity mirror 14 is used to output single-frequency pulse laser.

[0013] The polarizer 11 is positioned in the thin-film Brewster orientation and forms a 45° angle with the optical axis of the slab laser crystal 04 to achieve linearly polarized laser output.

[0014] The output cavity mirror 14 is coated with a partial laser reflection and partial laser transmission film.

[0015] The total reflection plano-concave cavity mirror 12 is coated with a laser total reflection film.

[0016] Slab laser crystal 04 is a bonded slab laser crystal, which is a non-birefringent laser crystal, such as Nd:YAG.

[0017] The first quarter-wave plate 08 and the second quarter-wave plate 10 are used to form a torsional cavity configuration, eliminate the spatial hole burning effect, and output single-frequency laser; the third quarter-wave plate 13, combined with the electro-optic Q-switched crystal 09 and the polarizer 11, outputs pulsed linearly polarized laser.

[0018] The first reflecting mirror 03 and the second reflecting mirror 05 are used to reflect the laser beam path and transmit the pump light.

[0019] The first pump shaping mirror group 02 and the second pump shaping mirror group 06 are used to shape the pump light emitted from the first pump source 01 and the second pump source 07 into a one-dimensional flat-top distribution in the horizontal direction and a Gaussian distribution in the vertical direction, respectively.

[0020] The first pump source 01 and the second pump source 07 are used to provide energy to the slab laser crystal 04. They can be stacked diodes and are water-cooled.

[0021] The linearly polarized laser propagating along the optical axis in the resonant cavity becomes a circularly polarized laser after passing through the first quarter-wave plate 08, and then becomes a linearly polarized laser again after passing through the third quarter-wave plate 13. After being reflected by the cavity mirrors of the resonant cavity (a combination of a total internal reflection plano-concave cavity mirror 12 and an output cavity mirror 14), the linearly polarized laser becomes a circularly polarized laser again after passing through the quarter-wave plate 13. However, since the polarization directions of the two circularly polarized lasers propagating to this point (at the quarter-wave plate 13) are 90° different, the light intensity is uniformly distributed after being superimposed in the slab laser crystal 04, thus eliminating the spatial hole burning effect and obtaining high-power single-longitudinal-mode operation.

[0022] The total reflection plano-concave cavity mirror 12 and the output cavity mirror 14 together form a resonant cavity mirror, which can be coated with a corresponding film layer according to the type of laser.

[0023] The slab laser crystal 04 can be processed into laser-bonded slab crystals of different sizes and doping concentrations as needed.

[0024] The actual working process of the high-power torsional cavity single-frequency laser based on slab crystal of the present invention is as follows: place each lens and device in the designed position, turn on the first pump source 01 and the second pump source 07, and then apply voltage to the electro-optic Q-switched crystal 09. The single-frequency pulse laser output can be observed at the output cavity mirror 14.

[0025] The above description is merely an embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the protection scope of the present invention.

[0026] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A high-power torsional mode cavity single-frequency laser based on slab crystal, characterized in that, include: The system comprises a first pump source, a first pump shaping mirror group, a first reflecting mirror, a slab laser crystal, a second reflecting mirror, a second pump shaping mirror group, a second pump source, a first quarter-wave plate, an electro-optic Q-switched crystal, a second quarter-wave plate, a polarizer, a total internal reflection plano-concave cavity mirror, a third quarter-wave plate, and an output cavity mirror. Pump light emitted from the first and second pump sources is shaped by the first and second pump shaping mirror groups, respectively, and then injected into the slab laser crystal after passing through the first and second reflecting mirrors. The first and third quarter-wave plates are combined to achieve torsional cavity technology. The electro-optic Q-switched crystal, the second quarter-wave plate, and the polarizer, arranged sequentially, are combined to modulate the continuous light in the resonant cavity into pulsed light. The total internal reflection plano-concave cavity mirror and the output cavity mirror are combined as the cavity mirrors of the resonant cavity. The output cavity mirror is used to output single-frequency pulsed laser light.

2. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The polarizer is positioned in the thin-film Brewster orientation, forming a 45° angle with the optical axis of the slab laser crystal, to achieve linearly polarized laser output.

3. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The output cavity mirror is coated with a partial laser reflection and partial laser transmission film.

4. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The total reflection plano-concave cavity mirror is coated with a laser total reflection film.

5. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The slab laser crystal is a bonded slab laser crystal and is a non-birefringent laser crystal.

6. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The first and second quarter-wave plates are used to form a torsional cavity configuration, eliminate the spatial hole burning effect, and output single-frequency laser; the third quarter-wave plate, combined with an electro-optic Q-switched crystal and a polarizer, outputs pulsed linearly polarized laser.

7. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The first and second pump sources are configured as stacked diodes to provide energy to the slab laser crystal.

8. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, Slab laser crystals can be processed into laser-bonded slab crystals of different sizes and doping concentrations as needed.

9. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The total reflection plano-concave cavity mirror and the output cavity mirror together form a resonant cavity mirror, which is coated with a corresponding film layer according to the type of laser.

10. The high-power torsional mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that, The linearly polarized laser propagating along the optical axis in the resonant cavity becomes a circularly polarized laser after passing through the first quarter-wave plate, and becomes a linearly polarized laser again after passing through the third quarter-wave plate. After being reflected by the cavity mirror of the resonant cavity, the linearly polarized laser passes through the quarter-wave plate again and becomes a circularly polarized laser. Since the polarization directions of the two circularly polarized lasers propagating to the quarter-wave plate are 90° apart, the light intensity is uniformly distributed after superposition in the slab laser crystal.

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