High-power torsional mode cavity single-frequency laser based on lath crystal

Abstract

The invention discloses a high-power torsional mode cavity single-frequency laser based on a slab crystal, which belongs to the technical field of solid lasers and comprises two pumping sources, two pumping shaping mirror groups, two reflectors, a slab laser crystal, three quarter-wave plates, an electro-optic Q-switched crystal, a polarizer, a total reflection plano-concave cavity mirror and an output cavity mirror. Pump light emitted by the two pump sources passes through the two pump shaping lens sets and then passes through the two reflectors to be injected into the lath laser crystal, and the first quarter-wave plate and the third quarter-wave plate are combined to achieve the torsional mode cavity technology. The electro-optic Q-switched crystal, the second quarter-wave plate and the polarizer which are sequentially arranged are combined to modulate continuous light in the resonant cavity into pulsed light, and the total reflection plano-concave cavity mirror and the output cavity mirror are combined to serve as a cavity mirror of the resonant cavity. According to the invention, the existing pumping power limited to tens of watts can be improved to hundreds of watts, the existing single-frequency laser power limited to watt level can be improved to tens of watts, and the cooperative improvement of high power and single-frequency characteristics is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of solid lasers, and in particular relates to a high-power twisted-mode cavity single-frequency laser based on a slab crystal. Background Art

[0002] In current high-power single-frequency solid-state lasers, twisted mode cavities are the mainstream technology for suppressing multi-longitudinal mode oscillations and achieving single-frequency output. The principle is to form a spatial hole burning effect in 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 twisted mode cavity configurations. For example, under high-power pumping, the rod-shaped medium causes severe thermal lensing and thermally induced birefringence due to radial thermal gradients, destroying the polarization selection conditions of the twisted mode cavity and causing frequency instability or mode hopping. In the existing technology, composite crystal bonding is usually used to alleviate the thermal effect, but it fails to fundamentally solve the contradiction between the power and single-frequency characteristics. Therefore, a new technical solution is urgently needed to solve the problem that the existing twisted mode cavity configuration is limited by factors such as single-frequency characteristics, output power, stability and compactness. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention adopts the following technical solutions:

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

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

[0006] The present invention provides a high-power twisted-mode cavity single-frequency laser based on a slab crystal. The system's average output power can break through the current watt-level limit, and the system has a narrow pulse width, adjustable repetition frequency, compact structure, and excellent beam quality. The pulsed single-frequency laser can be widely used in the field of lidar detection.

[0007] The present invention solves the mode hopping phenomenon of the laser crystal in the existing torsional cavity technology due to the crystal thermal effect caused by high-power pumping in the existing torsional cavity technology by changing the rod-shaped crystal into a slab crystal and taking advantage of the large surface heat dissipation of the slab crystal. This phenomenon affects the single-frequency characteristics of the laser.

[0008] The present invention changes the fiber pump in the existing twisted cavity technology to a laser diode bar array pump source (stacked diode), thereby transforming the Gaussian distributed circular pump spot in the existing technology into a strip 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] The present invention innovatively introduces slab laser crystals and laser diode bar stacked array pump sources into the existing twisted mode cavity technology, which can increase the pump power currently limited to tens of watts to hundreds of watts, and increase the current single-frequency laser power currently limited to watts to tens of watts, thereby achieving a synergistic improvement in high power and single-frequency characteristics. It not only retains the narrow linewidth and high coherence characteristics of single-frequency lasers, but also breaks through the power limitations of traditional twisted mode cavities, providing a key implementation method for realizing high-power single-frequency compact lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of the high-power twisted mode cavity single-frequency laser based on the 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-optical Q-switched crystal, 10-second quarter-wave plate, 11-polarizer, 12-total reflection plano-concave cavity mirror, 13-third quarter-wave plate, and 14-output cavity mirror. DETAILED DESCRIPTION

[0011] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0012] like Figure 1As shown, the high-power twisted mode 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-optical Q-switched crystal 09, a second quarter wave plate 10, a polarizer 11, a total reflection plano-concave cavity mirror 12, a third quarter wave plate 13, and an output cavity mirror 14. The pump light emitted by 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 reflector 03 and the second reflector 05 respectively. The first quarter-wave plate 08 and the third quarter-wave plate 13 are combined to realize the twisted mode cavity technology. The electro-optical Q-switched 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 pulsed light. The total 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 pulsed laser.

[0013] The polarizer 11 is placed in a thin film Brewster orientation, forming an angle of 45° with the optical axis of the slab laser crystal 04, thereby achieving linearly polarized laser output.

[0014] The output cavity mirror 14 is coated with a film layer that partially reflects laser light and partially transmits laser light.

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

[0016] The 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 twisted cavity configuration, eliminate the spatial hole burning effect, and output single-frequency laser; the third quarter wave plate 13 is combined with the electro-optical Q-switched crystal 09 and the polarizer 11 to output pulsed linearly polarized laser.

[0018] The first reflecting mirror 03 and the second reflecting mirror 05 are used to return the laser light 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 by 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 , and can be stacked diodes, using water cooling control.

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

[0022] The total reflection plano-concave cavity mirror 12 and the output cavity mirror 14 together constitute a resonant cavity mirror, which can be coated with corresponding film layers 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 required.

[0024] The actual working process of the high-power twisted mode cavity single-frequency laser based on slab crystal of the present invention is as follows: each lens and device is placed according to the designed position, the first pump source 01 and the second pump source 07 are turned on, and then voltage is applied to the electro-optical Q-switched crystal 09. The single-frequency pulse laser output can be observed at the output cavity mirror 14.

[0025] The above descriptions are merely embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied to other related system fields, are also included in the scope of protection of the present invention.

[0026] The contents not described in detail in the specification of the present invention belong to the prior art known to those skilled in the art.

Claims

1. A high-power twisted-mode cavity single-frequency laser based on a slab crystal, characterized in that: include: 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-optical Q-switched crystal, a second quarter wave plate, a polarizer, a total reflection plano-concave cavity mirror, a third quarter wave plate, and an output cavity mirror; the pump light emitted by the first pump source and the second pump source is shaped by the first pump shaping mirror group and the second pump shaping mirror group respectively, and then injected into the slab laser crystal after passing through the first reflector and the second reflector respectively; the first quarter wave plate and the third quarter wave plate are combined to realize the twisted mode cavity technology; the electro-optical Q-switched crystal, the second quarter wave plate and the polarizer combination arranged in sequence are used to modulate the continuous light in the resonant cavity into pulsed light; the total reflection plano-concave cavity mirror and the output cavity mirror combination serve as the cavity mirror of the resonant cavity; wherein, the output cavity mirror is used to output single-frequency pulsed laser.

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

3. The high-power twisted-mode cavity single-frequency laser based on slab crystal according to claim 1, characterized in that: The output cavity mirror is coated with a film layer that partially reflects the laser and partially transmits the laser.

4. The high-power twisted-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 layer.

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

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

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

8. The high-power twisted-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 twisted-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 constitute the resonant cavity mirror, which is coated with corresponding film layers according to the type of laser.

10. The high-power twisted-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 again. The circularly polarized laser light propagating twice to the quarter-wave plate has a 90° difference in polarization direction. After the light intensity is superimposed in the slab laser crystal, the light intensity is uniformly distributed.

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