阅读说明：本技术 一种基于脉冲激光器泵浦的光学参量振荡器及工作方法 (Optical parametric oscillator based on pulse laser pumping and working method ) 是由 杨克建 郭磊 聂鸿坤 张百涛 何京良 于 2020-07-15 设计创作，主要内容包括：本发明公开了一种基于脉冲激光器泵浦的光学参量振荡器及工作方法,包括：依次设置的半导体泵浦源、耦合透镜、平面输入镜、激光晶体、电光调制单元、凹面输出镜、第一半波片、隔离器、第二半波片、凸透镜、OPO平面输入镜、PPLN晶体以及OPO平面输出镜；半导体泵浦源产生的泵浦光经过耦合透镜和平面输入镜聚焦到激光晶体上,输出激光经过电光调制单元产生脉冲激光,所述脉冲激光经过凹面输出镜输出,经过第一半波片、隔离器和第二半波片,使偏振方向与PPLN晶体达到最佳相位匹配；输出的偏振激光经过凸透镜进入PPLN晶体,在小于100℃的温度下产生3.8μm波段激光。本发明可以在室温下实现简并点波长输出。(The invention discloses an optical parametric oscillator based on pulse laser pumping and a working method thereof, wherein the optical parametric oscillator comprises the following steps: the device comprises a semiconductor pumping source, a coupling lens, a plane input mirror, a laser crystal, an electro-optical modulation unit, a concave output mirror, a first half-wave plate, an isolator, a second half-wave plate, a convex lens, an OPO plane input mirror, a PPLN crystal and an OPO plane output mirror which are sequentially arranged; pump light generated by a semiconductor pump source is focused on a laser crystal through a coupling lens and a plane input mirror, output laser generates pulse laser through an electro-optical modulation unit, the pulse laser is output through a concave output mirror and passes through a first half-wave plate, an isolator and a second half-wave plate, and the polarization direction is matched with the optimal phase of the PPLN crystal; the output polarized laser enters the PPLN crystal through the convex lens, and generates 3.8 μm wave band laser at the temperature less than 100 ℃. The invention can realize the wavelength output of the degenerate point at room temperature.)

1. An optical parametric oscillator based on pulsed laser pumping, comprising: the device comprises a semiconductor pumping source, a coupling lens, a plane input mirror, a laser crystal, an electro-optical modulation unit, a concave output mirror, a first half-wave plate, an isolator, a second half-wave plate, a convex lens, an OPO plane input mirror, a PPLN crystal and an OPO plane output mirror which are sequentially arranged;

the pump light generated by the semiconductor pump source is focused on the laser crystal through the coupling lens and the plane input mirror, the output laser generates pulse laser through the electro-optical modulation unit, the pulse laser is output through the concave output mirror and passes through the first half-wave plate, the isolator and the second half-wave plate, and the polarization direction is matched with the PPLN crystal to the best phase; the output polarized laser enters the PPLN crystal through the convex lens, and generates 3.8 μm wave band laser at the temperature less than 100 ℃.

2. The pulsed laser pumping-based optical parametric oscillator of claim 1, wherein the electro-optical modulation unit comprises: the YAG polarizer, the LGS electro-optic crystal and the 1/4 wave plate are arranged in sequence; the LGS electro-optic crystal is connected with an electro-optic modulation power supply.

3. An optical parametric oscillator based on pulsed laser pumping, comprising: the two-dimensional acousto-optic Q-switch is sequentially provided with a semiconductor pumping source, a coupling lens, a planar input mirror, a laser crystal, a two-dimensional acousto-optic Q-switch, a concave output mirror, a first half-wave plate, an isolator, a second half-wave plate, a convex lens, an OPO planar input mirror, a PPLN crystal and an OPO planar output mirror;

the pump light generated by the semiconductor pump source is focused on the laser crystal through the coupling lens and the plane input mirror, the output laser generates pulse laser through the two-dimensional acousto-optic Q-switch, the pulse laser is output through the concave output mirror and passes through the first half-wave plate, the isolator and the second half-wave plate, and the polarization direction is optimally matched with the PPLN crystal; the output polarized laser enters the PPLN crystal through the convex lens, and generates 3.8 μm wave band laser at the temperature less than 100 ℃.

4. An optical parametric oscillator based on pulsed laser pumping according to claim 1 or 2, characterized in that the semiconductor pump source is a 792nm continuously operating semiconductor laser with adjustable temperature of 15 to 30 degrees.

5. The pulsed laser pumping-based optical parametric oscillator of claim 1 or 2, wherein the pump light generated by the semiconductor pump source is focused on the laser crystal through the coupling lens and the planar input mirror, and outputs laser light with a wavelength of 1937 nm.

6. A pulsed laser pump-based optical parametric oscillator according to claim 1 or 2, wherein the period of the PPLN crystal is 30.2 μm.

7. A pulsed laser pumped optical parametric oscillator as claimed in claim 1 or 2, wherein a 45 ° plane mirror is arranged between the second half-wave plate and the convex lens to change the optical path direction.

8. The pulse laser pumping-based optical parametric oscillator of claim 1 or 2, wherein the PPLN crystal is disposed on a temperature controlled furnace, and the temperature of the PPLN crystal is changed by the temperature controlled furnace; the temperature of the PPLN crystal is tuned between 25 ℃ and 50 ℃.

9. A working method of an optical parametric oscillator based on pulse laser pumping is characterized by comprising the following steps:

pump light generated by a semiconductor pump source is focused on a laser crystal through a coupling lens and a plane input mirror, laser with the wavelength of 1937nm is output, the laser generates pulse laser through an electro-optical modulation unit, the pulse laser is output through a concave output mirror, and the polarization direction is optimally matched with the PPLN crystal through a first half-wave plate, an isolator and a second half-wave plate; the output polarized laser enters a PPLN crystal with the period of 30.2 μm through a convex lens, and generates 3.8 μm wave band laser at the temperature of less than 100 ℃.

10. A working method of an optical parametric oscillator based on pulse laser pumping is characterized by comprising the following steps:

pump light generated by a semiconductor pump source is focused on a laser crystal through a coupling lens and a plane input mirror, laser with the wavelength of 1937nm is output, the laser generates pulse laser through a two-dimensional acousto-optic Q-switch, the pulse laser is output through a concave output mirror, and the polarization direction is matched with the optimal phase of the PPLN crystal through a first half-wave plate, an isolator and a second half-wave plate; the output polarized laser enters a PPLN crystal with the period of 30.2 μm through a convex lens, and generates 3.8 μm wave band laser at the temperature of less than 100 ℃.

Technical Field

The invention relates to the technical field of all-solid-state nonlinear frequency conversion, in particular to an optical parametric oscillator based on pulse laser pumping and a working method.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

An Optical Parametric Oscillator (OPO) is an optical frequency conversion device that converts input laser light (so-called pump light, fundamental light) into two output lights (signal light and idler light) of lower frequencies through second-order nonlinear optical interaction.

The wave band of 3-5 mu m is in the atmospheric transmission window interval and the molecular fingerprint area, and has important application value in the fields of environmental monitoring, medical diagnosis, laser radar, photoelectric countermeasure and the like, and especially the 3.8 mu m laser has important application in free space optical communication.

Currently, an Optical Parametric Oscillator (OPO) based on periodically poled lithium niobate crystals (PPLN) is one of the most commonly used means for generating 3-5 μm laser light. However, most of the existing pump sources use 1 μm-band laser, and due to the large quantum loss, the signal light and the idler frequency light cannot be simultaneously in the 3-5 μm-band interval, so that the conversion efficiency is low.

By using a 2-micron pump source and based on the MgO PPLN OPO technology, the signal light and the idler frequency light can be simultaneously converted in a wavelength range of 3-5 microns, and particularly, the output at a degenerate point is obtained, and the conversion efficiency is expected to be greatly enhanced. However, the current scheme based on 2 μm laser pumping of MgO: PPLN OPO can obtain lower output power (below W level), and to realize the output of degenerate point wavelength, the MgO: PPLN crystal needs to be heated to a high temperature of more than 100 ℃, which brings great inconvenience to practical application.

To date, achieving optical parametric laser output at a 3.8 μm degenerate point at room temperature based on an active tuning QTm YAP laser pumping MgO PPLNOPO scheme has not been reported.

Disclosure of Invention

In view of this, the present invention provides an optical parametric oscillator based on pulse laser pumping and a working method thereof, which respectively use LGS electro-optic Q-switched and acousto-optic QTm: YAP lasers as pumping sources to successfully realize optical parametric laser output at a degenerated point of 3.8 μm at room temperature.

In some embodiments, the following technical scheme is adopted:

a pulsed laser pumping based optical parametric oscillator comprising: the device comprises a semiconductor pumping source, a coupling lens, a plane input mirror, a laser crystal, an electro-optical modulation unit, a concave output mirror, a first half-wave plate, an isolator, a second half-wave plate, a convex lens, an OPO plane input mirror, a PPLN crystal and an OPO plane output mirror which are sequentially arranged;

the pump light generated by the semiconductor pump source is focused on the laser crystal through the coupling lens and the plane input mirror, the output laser generates pulse laser through the electro-optical modulation unit, the pulse laser is output through the concave output mirror and passes through the first half-wave plate, the isolator and the second half-wave plate, and the polarization direction is matched with the PPLN crystal to the best phase; the output polarized laser enters the PPLN crystal through the convex lens, and generates 3.8 μm wave band laser at the temperature less than 100 ℃.

Wherein the electro-optical modulation unit includes: the YAG polarizer, the LGS electro-optic crystal and the 1/4 wave plate are arranged in sequence; the LGS electro-optic crystal is connected with an electro-optic modulation power supply.

In other embodiments, the following technical solutions are adopted:

a pulsed laser pumping based optical parametric oscillator comprising: the two-dimensional acousto-optic Q-switch is sequentially provided with a semiconductor pumping source, a coupling lens, a planar input mirror, a laser crystal, a two-dimensional acousto-optic Q-switch, a concave output mirror, a first half-wave plate, an isolator, a second half-wave plate, a convex lens, an OPO planar input mirror, a PPLN crystal and an OPO planar output mirror;

the pump light generated by the semiconductor pump source is focused on the laser crystal through the coupling lens and the plane input mirror, the output laser generates pulse laser through the two-dimensional acousto-optic Q-switch, the pulse laser is output through the concave output mirror and passes through the first half-wave plate, the isolator and the second half-wave plate, and the polarization direction is optimally matched with the PPLN crystal; the output polarized laser enters the PPLN crystal through the convex lens, and generates 3.8 μm wave band laser at the temperature less than 100 ℃.

As a further scheme, the semiconductor pump source adopts a 792nm continuously-operating semiconductor laser with adjustable temperature of 15-30 degrees.

As a further scheme, the pump light generated by the semiconductor pump source is focused on the laser crystal through the coupling lens and the planar input mirror, and laser with the 1937nm wavelength is output.

As a further alternative, the period of the PPLN crystal is 30.2 μm.

As a further scheme, a 45 ° plane mirror is arranged between the second half-wave plate and the convex lens to change the direction of the light path.

As a further scheme, the PPLN crystal is arranged on a temperature control furnace, and the temperature of the PPLN crystal is changed through the temperature control furnace; the temperature of the PPLN crystal is tuned between 25 ℃ and 50 ℃.

In other embodiments, the following technical solutions are adopted:

a working method of an optical parametric oscillator based on pulse laser pumping comprises the following steps:

pump light generated by a semiconductor pump source is focused on a laser crystal through a coupling lens and a plane input mirror, laser with the wavelength of 1937nm is output, the laser generates pulse laser through an electro-optical modulation unit, the pulse laser is output through a concave output mirror, and the polarization direction is optimally matched with the PPLN crystal through a first half-wave plate, an isolator and a second half-wave plate; the output polarized laser enters a PPLN crystal with the period of 30.2 μm through a convex lens, and generates 3.8 μm wave band laser at the temperature of less than 100 ℃.

In other embodiments, the following technical solutions are adopted:

a working method of an optical parametric oscillator based on pulse laser pumping comprises the following steps:

pump light generated by a semiconductor pump source is focused on a laser crystal through a coupling lens and a plane input mirror, laser with the wavelength of 1937nm is output, the laser generates pulse laser through a two-dimensional acousto-optic Q-switch, the pulse laser is output through a concave output mirror, and the polarization direction is matched with the optimal phase of the PPLN crystal through a first half-wave plate, an isolator and a second half-wave plate; the output polarized laser enters a PPLN crystal with the period of 30.2 μm through a convex lens, and generates 3.8 μm wave band laser at the temperature of less than 100 ℃.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention uses LGS electro-optic Q-switch and acousto-optic Q-switch QTm YAP laser as pumping source, based on the combination of 1937nm fundamental frequency light and 30.2 μm PPLN crystal, successfully realizes optical parametric laser output at 3.8 μm degenerate point at room temperature, and can realize maximum output power of 1.2W at 35 ℃ of MgO: PPLN, which is the highest output power realized based on 2 μm laser pumping scheme at present, the invention has huge application prospect in realizing miniaturization, full curing middle and low power middle infrared laser output.

Drawings

FIG. 1 is a schematic diagram of an electro-optical Q-switched Tm-YAP laser pumped PPLN optical parametric oscillator in accordance with an embodiment of the present invention;

FIG. 2 is a schematic diagram of an acousto-optic Q-switched Tm-YAP laser pumped PPLN optical parametric oscillator in accordance with an embodiment of the present invention;

FIG. 3 is a degenerate point spectrum of an Optical Parametric Oscillator (OPO) output in an embodiment of the present invention;

the tunable acousto-optic tunable laser comprises an 101.792nm semiconductor pumping source, 102 an optical fiber, 201.1:3 coupling lenses, 301 a planar input mirror, 302 a concave output mirror, 303 Tm: YAP crystals, 401 YAG polarizers, 402 LGS electro-optic crystals, 403.1/4 wave plates, 404 an electro-optic modulation power supply, 501 a first half wave plate, 502 an isolator, 503 a second half wave plate, 601.45 DEG planar mirror, 602 a convex lens with 100mm of curvature, 701 OPO planar input mirror, 702 OPO planar output mirror, 801 MgO: PPLN crystals, 802 temperature control furnace and 901.2 mu m two-dimensional acousto-optic Q-switch.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

Interpretation of terms:

the degeneracy point, which is generally the parametric and idler wavelengths of the optical parametric output, is different, but by tuning the PPLN crystal temperature, the two wavelengths can be made the same at a particular temperature, a condition known as the degeneracy point.