阅读说明：本技术 一种减缓高功率脉冲光学参量振荡器走离热效应的装置 (Device for slowing down walk-off thermal effect of high-power pulse optical parametric oscillator ) 是由 王静 刘士鹏 夏伟 于 2019-11-26 设计创作，主要内容包括：一种减缓高功率脉冲光学参量振荡器走离热效应的装置,通过采用MoSe<Sub>2</Sub>被动调质材料结合声光调制器实现双损耗调Q光学参量振荡器,可以有效的压缩腔长提高平均输出功率,同样也使得输出信号光脉冲宽的明显压缩,峰值功率显著升高。对于全固态光学参量振荡器,晶体的热效应,以及热效应引起的非线性晶体内的走离效应,对信号光输出特性有很大的影响,甚至在较高泵浦功率下,平均输出功率可能随着泵浦功率的继续升高达到饱和或者下降。通过对MoSe<Sub>2</Sub>二维材料的引入,有效的缓解了热效应,在一定泵浦功率范围内保持平均输出功率的稳步增长。(A device for slowing down the walk-off thermal effect of a high-power pulse optical parametric oscillator adopts MoSe 2 The passive quenching and tempering material is combined with the acousto-optic modulator to realize the double-loss Q-switched optical parametric oscillator, the cavity length can be effectively compressed to improve the average output power, the optical pulse width of an output signal is obviously compressed, and the peak power is obviously improved. For all-solid-state optical parametric oscillator, the thermal effect of the crystal and the walk-off effect in the nonlinear crystal caused by the thermal effect have great influence on the output characteristics of the signal light, even under the condition of higher pumping powerThe output power may saturate or decrease as the pump power continues to increase. By pairing MoSe 2 The introduction of the two-dimensional material effectively relieves the heat effect and keeps the stable increase of the average output power within a certain pumping power range.)

1. An apparatus for mitigating walk-off thermal effects in a high power pulsed optical parametric oscillator, comprising:

the input end of the coupling lens group (3) is connected with the laser diode pumping source (1) through an optical fiber (2), the rear end of the coupling lens group is provided with a laser resonant cavity input mirror (4), and the laser resonant cavity input mirror (4) and the coupling lens group (3) are positioned on the same optical axis;

the laser gain medium (5) is arranged behind the laser resonant cavity input mirror (4), the laser gain medium (5) and the laser resonant cavity input mirror (4) are located on the same optical axis, pump light emitted by the laser diode pumping source (1) is focused to the laser gain medium (5) through the coupling lens group (3), and the pump light is pumped in the laser gain medium (5) to generate population inversion to perform positive feedback oscillation in the fundamental frequency light resonant cavity;

the acousto-optic modulator (6) is arranged behind the laser gain medium (5), and the acousto-optic modulator (6) and the laser gain medium (5) are positioned on the same optical axis;

MoSe ₂two-dimensional material (7), MoSe ₂A two-dimensional material (7) arranged behind the acousto-optic modulator (6), MoSe ₂The two-dimensional material (7) and the acousto-optic modulator (6) are positioned on the same optical axis;

a nonlinear optical crystal (8) disposed on the MoSe ₂Behind the two-dimensional material (7), a nonlinear optical crystal (8) and MoSe ₂The two-dimensional materials (7) are positioned on the same optical axis; and

the optical parametric oscillator comprises an optical parametric oscillator output mirror (9) arranged behind a nonlinear optical crystal (8), a laser resonant cavity input mirror (4) and the optical parametric oscillator output mirror (9) form a fundamental frequency optical resonant cavity, the optical parametric oscillator output mirror (9) and the input end face of the nonlinear optical crystal (8) form a signal optical resonant cavity, the fundamental frequency light is subjected to frequency conversion in the nonlinear optical crystal (8) to generate signal light, and the signal light is subjected to positive feedback oscillation in the signal optical resonant cavity.

2. The apparatus of claim 1 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: the laser gain medium (5) adopts Nd ³⁺：GdVO ₄A crystalline material.

3. The apparatus of claim 1 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: the nonlinear optical crystal (8) is made of KTP crystal material.

4. The apparatus of claim 1 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: the input mirror (4) of the laser resonant cavity is plated with an anti-reflection film with the wavelength of 808nm and a high-reflection film with the wavelength of 1064nm, the reflectivity of the anti-reflection film is less than 0.5%, and the reflectivity of the high-reflection film is more than 98%.

5. The apparatus of claim 1 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: the output mirror (9) of the optical parametric oscillator is a plane mirror coated with a partial transmission film with the thickness of 1.5 mu m, and the transmittance of the partial transmission film is 25 percent.

6. The apparatus of claim 1 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: the length of an acousto-optic modulation crystal of the acousto-optic modulator (6) is 47mm, and two surfaces of the acousto-optic modulation crystal are plated with anti-reflection films of 1064 nm.

7. The apparatus of claim 1 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: MoSe ₂The dimensions of the two-dimensional material (7) are 1.4cm by 2mm, MoSe ₂The thickness of the two-dimensional material is 2.5 nm.

8. The apparatus of claim 2 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: nd (neodymium) ³⁺：GdVO ₄The crystal size of the crystal material is 3mm multiplied by 5mm, the doping concentration is 0.5 percent, and Nd is ³⁺：GdVO ₄One end of the crystal material is plated with a 808nm anti-reflection 1064 high-reflection film, the other end of the crystal material is plated with a 1064nm anti-reflection film, the reflectivity of the anti-reflection film is less than 0.2%, and the reflectivity of the high-reflection film is more than 98%.

9. The apparatus of claim 4 for mitigating thermal effects of walk-off of high power pulsed optical parametric oscillators, wherein: the KTP crystal material has the crystal size of 5mm multiplied by 20mm, one end of the KTP crystal material is plated with a 1064nm anti-reflection film of 1573nm, the other end of the KTP crystal material is plated with anti-reflection films of 1064nm and 1573nm, the reflectivity of the high-reflection film is 99%, and the reflectivity of the anti-reflection film is less than 0.2%.

Technical Field

The invention relates to the technical field of optical parametric oscillators in the laser field, in particular to a device for slowing down the walk-off thermal effect of a high-power pulse optical parametric oscillator.

Background

The single-resonance optical parametric oscillator (SRO) is one of important optical nonlinear frequency conversion technologies for expanding the wavelength range of laser coherent radiation and obtaining a tunable coherent light source, and is also one of main means for obtaining a 1.5-1.6 mu m near-infrared eye-safe waveband coherent light source in an all-solid-state laser. An Intracavity Optical Parametric Oscillator (IOPO) places a nonlinear crystal inside a laser resonant cavity, the conversion efficiency is improved by utilizing the high photon number density in the cavity, the technology of obtaining Q-switched pulses by using a single active modulator in a 1.5-1.6 mu m near-infrared band all-solid-state laser is mature, in addition, the 1.5-1.6 mu m near-infrared human eye safety band is positioned in an atmospheric transmission window, and near-infrared lasers with high peak power, narrow pulse width and high stability have important application value and prospect in the fields of laser radar, remote sensing, environmental monitoring, medical treatment, wind speed detection, unmanned driving of motor vehicles and the like.

The 1.06 micron laser is used as a fundamental frequency light source, and the signal light output of OPO1.5-1.6 μm wave band can be effectively realized under the non-critical phase matching. Thus, the OPO does not operate away from the polarization state of the fundamental light. In the process of optical pumping of a laser medium by using a Laser Diode (LD), high non-radiative heat energy is gathered besides radiation of fundamental frequency laser, and the influence of thermal effect on IOPO can be divided into two aspects, namely refractive index gradient distribution caused by thermal gradient distribution of a fundamental frequency laser crystal and refractive index gradient distribution caused by thermal gradient distribution of a nonlinear crystal. The refractive index gradients of the fundamental light, the signal light and the idler light can shift the energy flow direction, and the phenomenon that the three lights are not collinear, namely the walk-off effect, is caused. Therefore, in order to mitigate the walk-off effect caused by thermal effects, the OPO of all-solid-state laser pumping is often accompanied by a bulky and energy-consuming cooling device. How to slow down or even eliminate the walk-off thermal effect on the basis of reducing power consumption is very important for the effective operation of compact pulse OPO with high peak power.

Disclosure of Invention

In order to overcome the defects of the technology, the invention provides a device for slowing down the walk-off thermal effect of the high-power pulse optical parametric oscillator, which can slow down the thermal effect, obviously shorten the cavity length of a laser resonant cavity and improve various output characteristics of the double-loss modulation optical parametric oscillator.

The technical scheme adopted by the invention for overcoming the technical problems is as follows:

an apparatus for mitigating walk-off thermal effects in a high power pulsed optical parametric oscillator, comprising:

the input end of the coupling lens group is connected with the laser diode pumping source through an optical fiber, and the rear end of the coupling lens group is provided with a laser resonant cavity input mirror which is positioned on the same optical axis as the coupling lens group;

the laser gain medium is arranged behind the input mirror of the laser resonant cavity, the laser gain medium and the input mirror of the laser resonant cavity are positioned on the same optical axis, pump light emitted by a laser diode pumping source is focused to the laser gain medium through a coupling lens group, and the pump light is pumped in the laser gain medium to generate population inversion and perform positive feedback oscillation in the fundamental frequency light resonant cavity;

the acousto-optic modulator is arranged behind the laser gain medium, and the acousto-optic modulator and the laser gain medium are positioned on the same optical axis;

MoSe ₂two-dimensional material, MoSe ₂The two-dimensional material is arranged behind the acousto-optic modulator, MoSe ₂The two-dimensional material and the acousto-optic modulator are positioned on the same optical axis;

a nonlinear optical crystal disposed on the MoSe ₂Rear, nonlinear optical crystal and MoSe of two-dimensional material ₂The two-dimensional materials are positioned on the same optical axis; and

the optical parametric oscillator output mirror is arranged behind the nonlinear optical crystal, the laser resonant cavity input mirror and the optical parametric oscillator output mirror form a fundamental frequency optical resonant cavity, the optical parametric oscillator output mirror and the input end face of the nonlinear optical crystal form a signal optical resonant cavity, the fundamental frequency light is subjected to frequency conversion in the nonlinear optical crystal to generate signal light, and the signal light is subjected to positive feedback oscillation in the signal optical resonant cavity.

Preferably, Nd is used as the laser gain medium ³⁺：GdVO ₄A crystalline material.

Further, the acousto-optic modulation frequency of the acousto-optic modulator is 10 kHz.

Preferably, the nonlinear optical crystal is made of a KTP crystal material.

Preferably, the input mirror of the laser resonant cavity is plated with an antireflection film of 808nm and a high reflection film of 1064nm, the reflectivity of the antireflection film is less than 0.5%, and the reflectivity of the high reflection film is more than 98%.

Preferably, the output mirror of the optical parametric oscillator is a flat mirror coated with a 1.5 μm partially permeable film having a transmittance of 25%.

Preferably, the length of the acousto-optic modulation crystal of the acousto-optic modulator is 47mm, and the two surfaces of the acousto-optic modulation crystal are plated with anti-reflection films of 1064 nm.

Preferably, MoSe ₂The dimensions of the two-dimensional material are 1.4cm × 1.4cm × 2mm, MoSe ₂The thickness of the two-dimensional material is 2.5 nm.

Preferably, Nd ³⁺：GdVO ₄The crystal size of the crystal material is 3mm multiplied by 5mm, the doping concentration is 0.5 percent, and Nd is ³⁺：GdVO ₄One end of the crystal material is plated with a 808nm anti-reflection 1064 high-reflection film, the other end of the crystal material is plated with a 1064nm anti-reflection film, the reflectivity of the anti-reflection film is less than 0.2%, and the reflectivity of the high-reflection film is more than 98%.

Preferably, the crystal size of the KTP crystal material is 5mm multiplied by 20mm, one end of the KTP crystal material is plated with a 1064nm anti-reflection film of 1573nm, the other end of the KTP crystal material is plated with anti-reflection films of 1064nm and 1573nm, the reflectivity of the high-reflection film is 99%, and the reflectivity of the anti-reflection film is less than 0.2%.

The invention has the beneficial effects that: by adopting MoSe ₂The two-dimensional material is combined with the acousto-optic modulator to realize the double-loss Q-switched optical parametric oscillator, the cavity length can be effectively compressed to improve the average output power, the optical pulse width of an output signal is obviously compressed, and the peak power is obviously improved. For the all-solid-state optical parametric oscillator, the thermal effect of the crystal and the walk-off effect in the nonlinear crystal caused by the thermal effect have great influence on the output characteristic of the signal light, and even under the condition of higher pumping power, the average output power can reach saturation or fall along with the continuous rise of the pumping power. By pairing MoSe ₂The introduction of two-dimensional materials effectively relieves heatThe effect is to maintain a steady increase in average output power over a range of pump powers.

Drawings

FIG. 1 is a schematic diagram of an optical parametric oscillator according to the present invention;

FIG. 2 shows MoSe of the present invention ₂A representation of the material;

FIG. 3 is a graph showing the relationship between the pulse width, peak power, and average output power of an optical parametric oscillator according to the present invention and the incident pump power;

in the figure, 1, a laser diode pumping source 2, an optical fiber 3, a coupling lens group 4, a laser resonant cavity input mirror 5, a laser gain medium 6, an acoustic optical modulator 7, MoSe ₂Two-dimensional material 8, nonlinear optical crystal 9, optical parametric oscillator output mirror.

Detailed Description

The invention will be further explained with reference to fig. 1, fig. 2 and fig. 3.

An apparatus for mitigating walk-off thermal effects in a high power pulsed optical parametric oscillator, comprising:

the input end of the coupling lens group 3 is connected with the laser diode pumping source 1 through the optical fiber 2, the rear end of the coupling lens group is provided with a laser resonant cavity input mirror 4, and the laser resonant cavity input mirror 4 and the coupling lens group 3 are positioned on the same optical axis; the laser gain medium 5 is arranged behind the laser resonant cavity input mirror 4, the laser gain medium 5 and the laser resonant cavity input mirror 4 are positioned on the same optical axis, pump light emitted by the laser diode pumping source 1 is focused to the laser gain medium 5 through the coupling lens group 3, the pump light is pumped in the laser gain medium 5 to generate population inversion, and positive feedback oscillation is carried out in the fundamental frequency light resonant cavity; the acousto-optic modulator 6 is arranged behind the laser gain medium 5, and the acousto-optic modulator 6 and the laser gain medium 5 are positioned on the same optical axis; MoSe ₂Two-dimensional material 7 of MoSe ₂Made of a material of MoSe ₂A two-dimensional material 7 of MoSe disposed behind the acousto-optic modulator 6 ₂The two-dimensional material 7 and the acousto-optic modulator 6 are positioned on the same optical axis; acousto-optic modulator 6 and MoSe ₂The two-dimensional material 7 realizes active and passive double-loss modulation on the fundamental frequency light. A nonlinear optical crystal 8, providedIn MoSe ₂Behind the two-dimensional material 7, a nonlinear optical crystal 8 and MoSe ₂The two-dimensional material 7 is positioned on the same optical axis; and an optical parametric oscillator output mirror 9 disposed behind the nonlinear optical crystal 8, wherein the laser resonator input mirror 4 and the optical parametric oscillator output mirror 9 form a fundamental frequency optical resonator, the optical parametric oscillator output mirror 9 and an input end face of the nonlinear optical crystal 8 form a signal optical resonator, the fundamental frequency light is subjected to frequency conversion in the nonlinear optical crystal 8 to generate signal light, and the signal light is subjected to positive feedback oscillation in the signal optical resonator.

When the laser gain medium works, pumping light generated by the laser diode pumping source 1 is transmitted through the optical fiber 2 and focused into the laser gain medium through the coupling lens group 3 to realize the population inversion, the acousto-optic modulator 6 and the MoSe ₂The two-dimensional material 7 realizes double-loss modulation, the quenched and tempered laser is subjected to linear frequency conversion through the nonlinear optical crystal 8, and finally signal pulse light is output through the output mirror 9 of the optical parametric oscillator. By using MoSe ₂The two-dimensional material 7 is combined with the acousto-optic modulator 6 to realize the double-loss Q-switched optical parametric oscillator, the cavity length can be effectively compressed to improve the average output power, the optical pulse width of an output signal is obviously compressed, and the peak power is obviously improved. For the all-solid-state optical parametric oscillator, the thermal effect of the crystal and the walk-off effect in the nonlinear crystal caused by the thermal effect have great influence on the output characteristic of the signal light, and even under the condition of higher pumping power, the average output power can reach saturation or fall along with the continuous rise of the pumping power. By pairing MoSe ₂The introduction of the two-dimensional material 7 effectively relieves the heat effect and keeps the stable increase of the average output power within a certain pumping power range.