CN114188812B - A temperature-tuned 9μm~11μm long-wave infrared solid-state laser - Google Patents

Abstract

A temperature-tuned 9 μm to 11 μm long-wave infrared solid laser, which relates to a solid laser. It solves the problem of low conversion efficiency from pump light to idler frequency light and beam deviation during wavelength tuning when realizing 9μm~11μm laser output through optical nonlinear frequency conversion method based on existing short-wave pump source. The temperature-tuned 9μm~11μm long-wave infrared solid-state laser includes a first pump source, a first coupling system, a second pump source, a second coupling system, a power control system, a pump light polarization control system, an optical parametric oscillator and its composition filtering system. The invention is used for temperature-tuned 9 μm to 11 μm long-wave infrared solid laser.

Description

A temperature-tuned 9μm~11μm long-wave infrared solid-state laser

Technical field

The invention relates to a solid laser.

Background technique

The long-wave infrared laser in the 9μm ~ 11μm band is located in the atmospheric transmission window and has extensive and important application value in the fields of space communications, infrared guidance, infrared countermeasures, medical treatment and lidar. At present, an effective method to obtain lasers in the 9 μm ~ 11 μm band is to frequency down-convert the 2 μm band laser through optical nonlinear frequency conversion. However, based on the existing short-wave pump source, when achieving 9 μm ~ 11 μm laser output through optical nonlinear frequency conversion method, the angle between the injected pump light wave vector and the main axis of the refractive index of the nonlinear crystal is not zero, resulting in nonlinear The angle (walk-away angle) between the signal light and idler light generated inside the crystal is not equal to zero, which brings negative effects such as low conversion efficiency from pump light to idler light and beam deviation during the wavelength tuning process.

Contents of the invention

The purpose of this invention is to solve the problem of low conversion efficiency from pump light to idler frequency light and beam deviation during the wavelength tuning process when realizing 9 μm ~ 11 μm laser output based on the existing short-wave pump source through optical nonlinear frequency conversion method. To solve the problem, a temperature-tuned 9μm~11μm long-wave infrared solid-state laser is provided.

A temperature-tuned 9 μm to 11 μm long-wave infrared solid laser, which includes a first pump source, a first plano-concave lens, a first plano-convex lens, a second pump source, a second plano-concave lens, a second plano-convex lens, a first 45° Polarizer, first half-wave plate, second 45° polarizer, second half-wave plate, 0° plane OPO input mirror, selenium gallium barium crystal, semiconductor temperature controller, 0° plane OPO output mirror, the first 45° long-wave infrared filter and the second 45° long-wave infrared filter;

The concave surface of the first plano-concave lens is opposite to the convex surface of the first plano-convex lens, forming a first coupling system; the concave surface of the second plano-concave lens is opposite to the convex surface of the second plano-convex lens, forming a second coupling system; The first 45° polarizing plate is a polarization coupling system; the first half-wave plate and the second 45° polarizing plate constitute a power control system; the second half-wave plate is a pump Optical light polarization control system; the 0° plane OPO input mirror, selenium gallium barium crystal, semiconductor temperature controller and 0° plane OPO output mirror constitute an optical parametric oscillator; the described selenium gallium barium crystal is fixed at the semiconductor temperature On the controller; the first 45° long-wave infrared filter and the second 45° long-wave infrared filter form a filtering system;

start the first pump source or the second pump source;

When the first pump source is started, the first pump source emits horizontally polarized pump light. After the horizontally polarized pump light passes through the first coupling system, it forms an angle of 45° with the normal line of the first 45° polarizer. direction and passes through the first 45° polarizing plate, and then enters the power control system to adjust the angle of the first half-wave plate so that the horizontal polarization state changes to the vertical polarization state, and the vertical polarization pump light is obtained. The vertical polarization state The pump light is reflected by the second 45° polarizing plate and then incident on the second half-wave plate. The angle of the second half-wave plate is adjusted to obtain a pump whose polarization direction is parallel to the n _m refractive index main axis of the selenium gallium barium crystal. Puguang;

When the second pump source is started, the second pump source emits vertically polarized pump light. After the vertically polarized pump light passes through the second coupling system, it forms an angle of 45° with the normal line of the first 45° polarizer. The first 45° polarizing plate is incident on the direction, is reflected to the power control system through the first 45° polarizing plate, adjusts the angle of the first half-wave plate, and the vertically polarized pump light passes through the first half-wave plate, and then After being reflected by the second 45° polarizing plate, it is incident on the second half-wave plate, and the angle of the second half-wave plate is adjusted to obtain the pump light whose polarization direction is parallel to the n _m refractive index main axis of the selenium gallium barium crystal;

The pump light with a polarization direction parallel to the main axis of the n _m refractive index of the selenium gallium barium crystal passes through the 0° plane OPO input mirror and is incident on the selenium gallium barium crystal. The partial polarization direction of the selenium gallium barium crystal is parallel to the n _m refractive index of the selenium gallium barium crystal. The pump light of the spindle undergoes optical nonlinear frequency conversion to obtain signal light with a wavelength between 2.5μm and 2.65μm and idler light with a wavelength between 9μm and 11μm;

The signal light with a wavelength between 2.5μm and 2.65μm is incident on the 0° plane OPO output mirror and is completely reflected. After passing through the selenium gallium barium crystal in the reverse direction, it is incident on the 0° plane OPO input mirror, is reflected by the 0° plane OPO input mirror and is reflected again. Through the selenium gallium barium crystal, it repeatedly oscillates in the cavity without output; the idle frequency light with a wavelength between 9 μm and 11 μm is output from the optical parametric oscillator through the 0° planar OPO output mirror; the idle frequency light output from the optical parametric oscillator The pump light whose residual polarization direction is parallel to the n _m refractive index main axis of the selenium gallium barium crystal is incident on the filter system, and the pump light whose residual polarization direction is parallel to the n _m refractive index main axis of the selenium gallium barium crystal passes through the first 45° long-wave infrared filter The idle frequency light output by the optical parametric oscillator is reflected and output by the first 45° long-wave infrared filter and the second 45° long-wave infrared filter in turn, and a 9 μm ~ 11 μm long-wave infrared laser is obtained.

Advantages of the invention:

The present invention provides a new design scheme for obtaining 9 μm to 11 μm long-wave infrared laser under the condition that the nonlinear crystal temperature is 5°C to 45°C without walk-off effect. The present invention realizes free switching of different pump sources with wavelengths ranging from 2.02 μm to 2.12 μm through the polarization coupling method of pump light, and realizes the switching from pump light to idler frequency light when the nonlinear crystal temperature is in the range of 5°C to 45°C. 9μm ~ 11μm long-wave infrared laser output with high conversion efficiency, no walk-off and wide wavelength tuning range.

Experiments show that when the pump light wavelength is 2.05 μm, the temperature of the barium gallium selenide (BGSe) crystal decreases monotonically from 45°C to 5°C, and the center wavelength of the long-wave infrared laser increases monotonically from 9393.3nm to 10627.4nm. When the average input pump light power is 4.0W, the highest laser output of 200mW with a center wavelength of 10.2μm is obtained, the conversion slope efficiency from pump light to idler frequency light reaches 8.03%, and the light-to-light conversion efficiency reaches 5%, indicating the success of the invention. The conversion efficiency from pump light to idle frequency light is improved. When the pump light wavelength is 2.09 μm, the temperature of the barium gallium selenide (BGSe) crystal decreases monotonically from 45°C to 5°C, and the center wavelength of the long-wave infrared laser increases monotonically from 9379.8nm to 11071.7nm. It can be seen that compared with the solution of using a non-linear crystal with a non-zero walk-off angle to obtain a 9 μm-11 μm long-wave infrared band laser, the present invention can achieve 9-11 μm wide wavelength tuning in a non-linear crystal temperature range of 5°C-45°C. Effect.

In the present invention, the pump light wavevector is incident perpendicularly to the end face of the barium gallium selenide (BGSe) crystal and parallel to the n _g refractive index main axis of the crystal. During the process of tuning the idle frequency light, only the nonlinear crystal temperature is changed. According to the law of refraction, it can be seen that the generated The signal light and idler light are collinear with the pump light, and there will be no beam deviation.

Description of the drawings

Figure 1 is a schematic structural diagram of a temperature-tuned 9 μm ~ 11 μm long-wave infrared solid laser of the present invention;

Figure 2 shows the appearance of the barium-gallium-selenium crystal in the temperature-tuned 9 μm to 11 μm long-wave infrared solid-state laser according to the direction of the refractive index main axes n _g , _nm , and n _p in Example 1, and the relative relationship between the injection of pump light into the crystal;

Figure 3 is a comparison chart of the wavelength and line width of the long-wave infrared laser output by the nonlinear crystal at different temperatures when the temperature-tuned 9 μm-11 μm long-wave infrared solid-state laser uses a 2.05 μm nanosecond pulse laser as the pump source in Example 1;

Figure 4 is a graph showing the variation of the long-wave infrared laser power output by the nonlinear crystal at different temperatures with the pump power when the temperature-tuned 9 μm-11 μm long-wave infrared solid-state laser uses a 2.05 μm nanosecond pulse laser as the pump source in Example 1. 5℃, ● is 10℃, ▲ is 15℃, ▼ is 20℃, is 25℃, ◆ is 30℃, + is 35℃, - is 40℃;

Figure 5 is a scatter plot of the variation of the long-wave infrared laser power with the crystal temperature under the condition that the pump power is 4W when the temperature-tuned 9 μm-11 μm long-wave infrared solid-state laser uses a 2.05 μm nanosecond pulse laser as the pump source in Example 1;

Figure 6 is a comparison chart of the long-wave infrared laser wavelength and line width output by the nonlinear crystal at different temperatures when the temperature-tuned 9 μm to 11 μm long-wave infrared solid-state laser uses 2.09 μm nanosecond pulse laser as the pump source in the second embodiment.

Detailed ways

Specific Embodiment 1: The following is explained with reference to Figure 1. This embodiment is a temperature-tuned 9 μm ~ 11 μm long-wave infrared solid laser, which includes a first pump source 1-1, a first plano-concave lens 2-1, and a first plano-convex lens 3 -1. The second pump source 1-2, the second plano-concave lens 2-2, the second plano-convex lens 3-2, the first 45° polarizing plate 4-1, the first half-wave plate 5-1, The second 45° polarizer 4-2, the second half-wave plate 5-2, 0° plane OPO input mirror 6-1, selenium gallium barium crystal 7, semiconductor temperature controller 8, 0° plane OPO output mirror 6-2. The first 45° long-wave infrared filter 9-1 and the second 45° long-wave infrared filter 9-2;

The concave surface of the first plano-concave lens 2-1 and the convex surface of the first plano-convex lens 3-1 are arranged opposite to form a first coupling system; the concave surface of the second plano-concave lens 2-2 and the second plano-convex lens 3-1 are arranged oppositely. The convex surfaces of 2 are arranged relatively to form a second coupling system; the first 45° polarizing plate 4-1 is a polarization coupling system; the first half-wave plate 5-1 and the second 45° polarizing plate 4-2 constitutes a power control system; the second half-wave plate 5-2 is a pump light polarization control system; the 0° plane OPO input mirror 6-1, selenium gallium barium crystal 7, The semiconductor temperature controller 8 and the 0° planar OPO output mirror 6-2 constitute an optical parametric oscillator; the selenium gallium barium crystal 7 is fixed on the semiconductor temperature controller 8; the first 45° long-wave infrared filter 9 -1 and the second 45° long-wave infrared filter 9-2 form a filtering system;

Start the first pump source 1-1 or the second pump source 1-2;

When the first pump source 1-1 is started, the first pump source 1-1 emits horizontally polarized pump light. After the horizontally polarized pump light passes through the first coupling system, it interacts with the first 45° polarizing plate 4 -1 normal is incident at a 45° angle and passes through the first 45° polarizing plate 4-1, and then is incident on the power control system, which adjusts the angle of the first half-wave plate 5-1 so that the horizontal polarization state becomes Vertically polarized state, a vertically polarized pump light is obtained. The vertically polarized pump light is reflected by the second 45° polarizing plate 4-2 and then incident on the second one-half wave plate 5-2, and adjusts the second half-wave plate 5-2. With a wave plate at an angle of 5-2, the pump light with a polarization direction parallel to the main axis of the 7 _nm refractive index of the gallium selenium barium crystal is obtained;

When the second pump source 1-2 is started, the second pump source 1-2 emits vertically polarized pump light. After the vertically polarized pump light passes through the second coupling system, it interacts with the first 45° polarizer 4 -1 normal is incident on the first 45° polarizing plate 4-1 at a 45° angle, and is reflected to the power control system through the first 45° polarizing plate 4-1, which adjusts the angle of the first half-wave plate 5-1 , the vertically polarized pump light passes through the first half-wave plate 5-1, and then is reflected by the second 45° polarizing plate 4-2 before being incident on the second half-wave plate 5-2. Adjust the second The angle of the half-wave plate is 5-2, and the pump light whose polarization direction is parallel to the main axis of the 7n _m refractive index of the barium selenide crystal is obtained;

The pump light whose polarization direction is parallel to the 7n _m refractive index main axis of the selenium gallium barium crystal passes through the 0° plane OPO input mirror 6-1 and is incident on the selenium gallium barium crystal 7. The selenium gallium barium crystal 7 will partially polarize the direction parallel to the selenium gallium barium The pump light on the main axis of the crystal's _7nm refractive index undergoes optical nonlinear frequency conversion to obtain signal light with a wavelength between 2.5μm and 2.65μm and idler light with a wavelength between 9μm and 11μm;

The signal light with a wavelength between 2.5 μm and 2.65 μm is incident on the 0° plane OPO output mirror 6-2 and is completely reflected. After passing through the selenium gallium barium crystal 7 in the reverse direction, it is incident on the 0° plane OPO input mirror 6-1 and passes through 0°. The plane OPO input mirror 6-1 reflects and passes through the selenium gallium barium crystal 7 again, and then repeatedly oscillates in the cavity without output; the idle frequency light with a wavelength between 9 μm and 11 μm passes through the 0° plane OPO output mirror 6-2 and obtains optical parameters from the Oscillator output; the idler frequency light output from the optical parametric oscillator and the pump light with a residual polarization direction parallel to the main axis of the _7nm refractive index of the gallium-selenium barium crystal are incident on the filtering system, and the remaining polarization direction is parallel to the _7nm refraction of the gallium-selenide-barium crystal. The pump light of the rate spindle is output through the first 45° long-wave infrared filter 9-1, and the idle frequency light output by the optical parametric oscillator is sequentially passed through the first 45° long-wave infrared filter 9-1 and the second 45° long-wave infrared filter. The chip 9-2 reflects the output and obtains 9 μm ~ 11 μm long-wave infrared laser.

In this specific embodiment, the first half-wave plate 5-1 is a broadband wave plate. When switching the pump source, the angle of the first half-wave plate 5-1 can be slightly rotated to convert the horizontally polarized The pump light all changes to the vertical polarization state, or the vertical polarization state is directly transmitted and reaches the second one-half wave plate 5-2; similarly, slightly rotate the angle of the second one-half wave plate 5-2 , the polarization direction of the pump light can be parallel to the _nm refractive index main axis of the selenium gallium barium crystal 7 that has been fixed on the semiconductor temperature controller 8; the second pump source 1-2 optical parametric oscillator and filter system structure and The working method is exactly the same as when using the first pump source 1-1.

The beneficial effects of this specific implementation are:

This specific implementation mode provides a new design solution for obtaining 9 μm to 11 μm long-wave infrared laser at a nonlinear crystal temperature of 5°C to 45°C without walk-off effects. The present invention realizes free switching of different pump sources with wavelengths ranging from 2.02 μm to 2.12 μm through the polarization coupling method of pump light, and realizes the switching from pump light to idler frequency light when the nonlinear crystal temperature is in the range of 5°C to 45°C. 9μm ~ 11μm long-wave infrared laser output with high conversion efficiency, no walk-off and wide wavelength tuning range.

Experiments show that when the pump light wavelength is 2.05 μm, the temperature of the barium gallium selenide (BGSe) crystal decreases monotonically from 45°C to 5°C, and the center wavelength of the long-wave infrared laser increases monotonically from 9393.3nm to 10627.4nm. When the average input pump light power is 4.0W, the highest laser output of 200mW with a center wavelength of 10.2μm is obtained, the conversion slope efficiency from pump light to idler frequency light reaches 8.03%, and the light-to-light conversion efficiency reaches 5%, indicating the success of the invention. The conversion efficiency from pump light to idle frequency light is improved. When the pump light wavelength is 2.09 μm, the temperature of the barium gallium selenide (BGSe) crystal decreases monotonically from 45°C to 5°C, and the center wavelength of the long-wave infrared laser increases monotonically from 9379.8nm to 11071.7nm. It can be seen that compared with the solution of using a non-linear crystal with a non-zero walk-off angle to obtain a 9 μm-11 μm long-wave infrared band laser, the present invention can achieve 9-11 μm wide wavelength tuning in a non-linear crystal temperature range of 5°C-45°C. Effect.

In this specific implementation, the pump light wavevector is incident perpendicularly to the end face of the barium gallium selenide (BGSe) crystal and parallel to the n _g refractive index main axis of the crystal. During the process of tuning the idle frequency light, only the nonlinear crystal temperature is changed. According to the law of refraction, it can be seen that The generated signal light and idler light are collinear with the pump light, and there will be no beam deviation.

Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the first pump source 1-1 is a pulse with a wavelength of 2.09 μm or 2.12 μm and a pulse width of femtosecond, picosecond or nanosecond. Laser; the second pump source 1-2 is a pulse laser with a wavelength of 2.02 μm or 2.05 μm and a pulse width of femtosecond, picosecond or nanosecond. Others are the same as the first embodiment.

Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that the first plano-concave lens 2-1, the first plano-convex lens 3-1, the second plano-concave lens 2-2 and the second The light-passing surface of the plano-convex lens 3-2 is coated with an anti-reflection coating of 2.02 μm ~ 2.12 μm; the curvature radius of the first plano-concave lens 2-1 and the second plano-concave lens 2-2 is -50mm ~ -200mm. The diameters are both 10 mm to 100 mm; the focal lengths of the first plano-convex lens 3-1 and the second plano-convex lens 3-2 are both 50 mm to 1000 mm, and the diameters are both 10 mm to 100 mm. Others are the same as the first or second embodiment.

Specific Embodiment 4: The difference between this embodiment and one of the specific Embodiments 1 to 3 is that the surface of the first 45° polarizing plate 4-1 is plated with a reflectivity of greater than 99 for the vertically polarized laser with a wavelength of 2.02 μm ~ 2.05 μm. % and a film with a reflectivity of less than 70% for horizontally polarized lasers with a wavelength of 2.02μm to 2.05μm, and a film with a transmittance of more than 99% for horizontally polarized lasers with a wavelength of 2.09μm to 2.12μm and a vertically polarized laser with a wavelength of 2.09μm to 2.12μm. The state laser transmission rate is less than 20%. Others are the same as the first to third embodiments.

Specific Embodiment 5: The difference between this embodiment and one of the specific Embodiments 1 to 4 is that the surface of the second 45° polarizing plate 4-2 is plated with a vertically polarized laser reflectivity of greater than 99.5 for a wavelength of 2.02 μm to 2.12 μm. % and the film has a transmittance greater than 99.5% for horizontally polarized laser light with a wavelength of 2.02 μm to 2.12 μm. Others are the same as the first to fourth embodiments.

Specific Embodiment Six: The difference between this implementation mode and one of the specific implementation modes one to five is that the first half-wave plate 5-1 and the second half-wave plate 5-2 both have a wavelength of 2.02 μm～2.12μm broadband wave plate, and the clear surface is coated with 2.02μm～2.12μm anti-reflection coating. Others are the same as the specific embodiments one to five.

Specific Embodiment 7: The difference between this embodiment and one of the specific Embodiments 1 to 6 is that the 0° planar OPO input mirror 6-1 and the 0° planar OPO output mirror 6-2 are plated with a wavelength of 2.02 μm~ 2.12 μm pump light and 9 μm ~ 11 μm idle frequency light anti-reflection coating, and the other side is coated with a dielectric film with a reflectivity of greater than 99% for signal light with a wavelength of 2.5 μm ~ 2.65 μm. Others are the same as the specific embodiments one to six.

Specific Embodiment 8: The difference between this embodiment and one of the specific Embodiments 1 to 7 is that the selenium, gallium and barium crystal 7 has a light-passing surface perpendicular to the _ng refractive index main axis of the crystal. Others are the same as the specific embodiments one to seven.

Specific Embodiment 9: The difference between this implementation mode and one of the specific implementation modes 1 to 8 is that the semiconductor temperature controller 8 is a TEC temperature controller, the temperature is continuously tunable in the range of 0°C to 45°C, and the control accuracy is ±0.1℃, control accuracy is ±0.1℃. Others are the same as Embodiments 1 to 8.

The TEC temperature controller described in this specific embodiment uses direct current to pass through a P-type and N-type pair sandwiched between two ceramic electrodes to produce a "hot" side and a "cold" side phenomenon on the ceramic electrodes, thereby converting selenium gallium By placing the barium crystal 7 on the "cold" side, precise control of the temperature of the nonlinear crystal is achieved.

Specific Embodiment 10: The difference between this implementation mode and one of the specific implementation modes 1 to 9 is that the first 45° long-wave infrared filter 9-1 and the second 45° long-wave infrared filter 9-2 are plated on one side. There is an anti-reflection coating for pump light with a wavelength of 2.02μm ~ 2.12μm, and the other side is coated with a dielectric film with a reflectivity of greater than 95% for idle frequency light with a wavelength of 9μm ~ 11μm. Others are the same as the first to ninth embodiments.

The following examples are used to verify the beneficial effects of the present invention:

Example 1:

A temperature-tuned 9 μm to 11 μm long-wave infrared solid laser, which includes a first pump source 1-1, a first plano-concave lens 2-1, a first plano-convex lens 3-1, a second pump source 1-2, a second Plano-concave lens 2-2, second plano-convex lens 3-2, first 45° polarizer 4-1, first half-wave plate 5-1, second 45° polarizer 4-2, second half-wave plate First wave plate 5-2, 0° flat OPO input mirror 6-1, selenium gallium barium crystal 7, semiconductor temperature controller 8, 0° flat OPO output mirror 6-2, first 45° long wave infrared filter 9- 1 and the second 45° long-wave infrared filter 9-2;

The concave surface of the first plano-concave lens 2-1 and the convex surface of the first plano-convex lens 3-1 are arranged opposite to form a first coupling system; the concave surface of the second plano-concave lens 2-2 and the second plano-convex lens 3-1 are arranged oppositely. The convex surfaces of 2 are arranged relatively to form a second coupling system; the first 45° polarizing plate 4-1 is a polarization coupling system; the first half-wave plate 5-1 and the second 45° polarizing plate 4-2 constitutes a power control system; the second half-wave plate 5-2 is a pump light polarization control system; the 0° plane OPO input mirror 6-1, selenium gallium barium crystal 7, The semiconductor temperature controller 8 and the 0° planar OPO output mirror 6-2 constitute an optical parametric oscillator; the selenium gallium barium crystal 7 is fixed on the semiconductor temperature controller 8; the first 45° long-wave infrared filter 9 -1 and the second 45° long-wave infrared filter 9-2 form a filtering system;

The second pump source 1-2 is started, and the second pump source 1-2 emits vertically polarized pump light. After the vertically polarized pump light passes through the second coupling system, it is connected to the first 45° polarizing plate 4-1 The normal line is incident on the first 45° polarizing plate 4-1 at an angle of 45°, and is reflected to the power control system through the first 45° polarizing plate 4-1. Adjust the angle of the first half-wave plate 5-1 vertically. The polarized pump light passes through the first half-wave plate 5-1, and then is reflected by the second 45° polarizing plate 4-2 before being incident on the second half-wave plate 5-2. The second half-wave plate is adjusted to With a wave plate angle of 5-2, the pump light with a polarization direction parallel to the main axis of the _7nm refractive index of the barium selenium gallium crystal is obtained;

The pump light whose polarization direction is parallel to the 7n _m refractive index main axis of the selenium gallium barium crystal passes through the 0° plane OPO input mirror 6-1 and is incident on the selenium gallium barium crystal 7. The selenium gallium barium crystal 7 will partially polarize the direction parallel to the selenium gallium barium The pump light on the main axis of the crystal's _7nm refractive index undergoes optical nonlinear frequency conversion to obtain signal light with a wavelength between 2.5μm and 2.65μm and idler light with a wavelength between 9μm and 11μm;

The signal light with a wavelength between 2.5 μm and 2.65 μm is incident on the 0° plane OPO output mirror 6-2 and is completely reflected. After passing through the selenium gallium barium crystal 7 in the reverse direction, it is incident on the 0° plane OPO input mirror 6-1 and passes through 0°. The plane OPO input mirror 6-1 reflects and passes through the selenium gallium barium crystal 7 again, and then repeatedly oscillates in the cavity without output; the idle frequency light with a wavelength between 9 μm and 11 μm passes through the 0° plane OPO output mirror 6-2 and obtains optical parameters from the Oscillator output; the idler frequency light output from the optical parametric oscillator and the pump light with a residual polarization direction parallel to the main axis of the _7nm refractive index of the gallium-selenium barium crystal are incident on the filtering system, and the remaining polarization direction is parallel to the _7nm refraction of the gallium-selenide-barium crystal. The pump light of the rate spindle is output through the first 45° long-wave infrared filter 9-1, and the idle frequency light output by the optical parametric oscillator is sequentially passed through the first 45° long-wave infrared filter 9-1 and the second 45° long-wave infrared filter. The chip 9-2 reflects the output and obtains 9 μm ~ 11 μm long-wave infrared laser.

The second pump source 1-2 is a pulse laser with a wavelength of 2.05 μm and a pulse width of nanoseconds.

The light-passing surfaces of the first plano-concave lens 2-1, the first plano-convex lens 3-1, the second plano-concave lens 2-2 and the second plano-convex lens 3-2 are all coated with anti-reflection coatings of 2.02 μm to 2.12 μm; The curvature radius of the first plano-concave lens 2-1 and the second plano-concave lens 2-2 is -100mm, and the diameter is 20mm; the first plano-convex lens 3-1 and the second plano-convex lens 3-2 have The focal length is 100mm and the diameter is 20mm.

The surface of the first 45° polarizing plate 4-1 is coated with a film having a reflectivity of greater than 99% for vertically polarized laser light with a wavelength of 2.02 μm to 2.05 μm and less than 70% for a horizontally polarized laser light with a wavelength of 2.02 μm to 2.05 μm. , and is coated with a film whose transmittance for horizontally polarized lasers with a wavelength of 2.09μm to 2.12μm is greater than 99%, and whose transmittance for vertically polarized lasers with a wavelength of 2.09μm to 2.12μm is less than 20%.

The surface of the second 45° polarizing plate 4-2 is coated with a film having a reflectivity of greater than 99.5% for vertically polarized lasers with a wavelength of 2.02 μm to 2.12 μm and a transmittance of greater than 99.5% for horizontally polarized lasers with a wavelength of 2.02 μm to 2.12 μm. .

The first half-wave plate 5-1 and the second half-wave plate 5-2 are both broadband wave plates with wavelengths of 2.02 μm to 2.12 μm, and the clear surfaces are plated with 2.02 μm to 2.12 μm. μm AR coating.

One side of the 0° planar OPO input mirror 6-1 and the 0° planar OPO output mirror 6-2 is coated with an anti-reflection coating for pump light with a wavelength of 2.02 μm to 2.12 μm and an idle frequency light of 9 μm to 11 μm, and the other side is coated with There are dielectric films with a reflectivity greater than 99% for signal light with a wavelength of 2.5 μm to 2.65 μm.

The light-passing surface of the selenium-gallium-barium crystal 7 is perpendicular to the _ng refractive index main axis of the crystal.

The semiconductor temperature controller 8 is a TEC temperature controller, the temperature is continuously tunable in the range of 5°C to 45°C, and the control accuracy is ±0.1°C.

The first 45° long-wave infrared filter 9-1 and the second 45° long-wave infrared filter 9-2 are both coated with a pump light anti-reflection coating for wavelengths of 2.02 μm ~ 2.12 μm on one side, and the other side is coated with A dielectric film with a reflectivity of idle frequency light greater than 95% at a wavelength of 9 μm to 11 μm.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that: the first pump source 1-1 is started, the first pump source 1-1 emits horizontally polarized pump light, and the horizontally polarized pump light passes through the first After coupling to the system, it is incident at an angle of 45° to the normal line of the first 45° polarizing plate 4-1 and passes through the first 45° polarizing plate 4-1, and then is incident on the power control system to adjust the first half The angle of the wave plate 5-1 changes the horizontal polarization state to the vertical polarization state, thereby obtaining the vertically polarized pump light. The vertically polarized pump light is reflected by the second 45° polarizing plate 4-2 and then enters the second half. First wave plate 5-2, adjust the angle of the second half wave plate 5-2 to obtain pump light with a polarization direction parallel to the main axis of the 7 _nm refractive index of the gallium selenide and barium crystal; the first pump source 1- 1 is a pulse laser with a wavelength of 2.09 μm and a pulse width of nanoseconds. Others are the same as the first embodiment.

Figure 2 shows the appearance of the selenium gallium barium crystal in the temperature-tuned 9 μm to 11 μm long-wave infrared solid-state laser according to the direction of the refractive index main axes n _g , _nm , n _p and the relative relationship between pump light injection into the crystal; it can be seen from the figure , the clear surfaces at both ends of the selenium gallium barium crystal are perpendicular to the n _g direction of the main axis of refractive index, the pump light is injected perpendicular to the clear surface of the crystal, and the polarization direction of the pump light is perpendicular to the n _m direction of the main axis of refractive index.

Figure 3 is a comparison chart of the long-wave infrared laser wavelength and line width output by the nonlinear crystal at different temperatures when the temperature-tuned 9 μm-11 μm long-wave infrared solid-state laser uses a 2.05 μm nanosecond pulse laser as the pump source in Example 1; it can be seen from the figure that, When the temperature of the barium selenide crystal 7 decreases monotonically from 45°C to 5°C, the center wavelength of the long-wave infrared laser increases monotonically from 9393.3nm to 10627.4nm, and the full width at half maximum of the linewidth increases monotonically from 71.8nm to 166.1nm.

Figure 4 is a graph showing the variation of the long-wave infrared laser power output by the nonlinear crystal at different temperatures with the pump power when the temperature-tuned 9 μm-11 μm long-wave infrared solid-state laser uses a 2.05 μm nanosecond pulse laser as the pump source in Example 1. 5℃, ● is 10℃, ▲ is 15℃, ▼ is 20℃, is 25℃, ◆ is 30℃, + is 35℃, - is 40℃; it can be seen from the figure that when the temperature of the temperature-tuned barium gallium selenium (BGSe) crystal is 15℃ and the pump power is 4.0W, the highest average power is achieved 200mW, long-wave infrared laser output with a center wavelength of 10.2μm, a slope efficiency of 8.04%, and a light-to-light conversion efficiency of 5.0%.

Figure 5 is a scatter plot of the variation of the long-wave infrared laser power with the crystal temperature under the condition that the pump power is 4W when the temperature-tuned 9 μm-11 μm long-wave infrared solid-state laser uses a 2.05 μm nanosecond pulse laser as the pump source in Example 1; It can be seen from the figure that when the nonlinear crystal temperature is 15°C, the maximum output power of idler light is 200mW.

Figure 6 is a comparison chart of the long-wave infrared laser wavelength and line width output by the nonlinear crystal at different temperatures when the temperature-tuned 9 μm to 11 μm long-wave infrared solid-state laser uses 2.09 μm nanosecond pulse laser as the pump source in the second embodiment. It can be seen from the figure that when the temperature of the temperature-tuned barium gallium selenide (BGSe) crystal decreases monotonically from 45°C to 5°C, the center wavelength of the long-wave infrared laser increases monotonically from 9379.8nm to 11071.7nm, and the full width at half maximum of the linewidth decreases from 139.1nm. to 85.3nm and then monotonically increases to 484.7nm.

Claims (10)

1. The temperature tuning 9-11 mu m long-wave infrared solid laser is characterized by comprising a first pumping source (1-1), a first plano-concave lens (2-1), a first plano-convex lens (3-1), a second pumping source (1-2), a second plano-concave lens (2-2), a second plano-convex lens (3-2), a first 45 DEG polaroid (4-1), a first half-wave plate (5-1), a second 45 DEG polaroid (4-2), a second half-wave plate (5-2), a 0 DEG plane OPO input mirror (6-1), a selenium-gallium-barium crystal (7), a semiconductor temperature controller (8), a 0 DEG plane OPO output mirror (6-2), a first 45 DEG long-wave infrared filter (9-1) and a second 45 DEG long-wave infrared filter (9-2);

the concave surface of the first plano-concave lens (2-1) is opposite to the convex surface of the first plano-convex lens (3-1), so that a first coupling system is formed; the concave surface of the second plano-concave lens (2-2) is opposite to the convex surface of the second plano-convex lens (3-2), so that a second coupling system is formed; the first 45-degree polaroid (4-1) is a polarization coupling system; the first half-wave plate (5-1) and the second 45-degree polaroid (4-2) form a power control system; the second half wave plate (5-2) is a pump light polarization state control system; the 0-degree plane OPO input mirror (6-1), the selenium gallium barium crystal (7), the semiconductor temperature controller (8) and the 0-degree plane OPO output mirror (6-2) form an optical parametric oscillator; the selenium gallium barium crystal (7) is fixed on the semiconductor temperature controller (8); the first 45-degree long-wave infrared filter (9-1) and the second 45-degree long-wave infrared filter (9-2) form a filter system;

starting the first pump source (1-1) or the second pump source (1-2);

when the first pump source (1-1) is started, the first pump source (1-1) emits horizontal polarized pump light, the horizontal polarized pump light enters the first coupling system in a direction forming an angle of 45 degrees with the normal line of the first 45-degree polaroid (4-1) and passes through the first 45-degree polaroid (4-1), then enters the power control system, the angle of the first half wave plate (5-1) is regulated to enable the horizontal polarization state to be changed into a vertical polarization state, so as to obtain vertical polarized pump light, the vertical polarized pump light enters the second half wave plate (5-2) after being reflected by the second 45-degree polaroid (4-2), the angle of the second half wave plate (5-2) is regulated, and the polarization direction is parallel to the selenium gallium barium crystal (7) n _m Pump light of refractive index principal axis;

when the second pump is startedWhen the source (1-2) is in a Pu mode, the second pump source (1-2) emits vertical polarized pump light, the vertical polarized pump light passes through the second coupling system and then enters the first 45-degree polaroid (4-1) in a direction forming an angle of 45 degrees with the normal line of the first 45-degree polaroid (4-1), the vertical polarized pump light is reflected to the power control system through the first 45-degree polaroid (4-1), the angle of the first half wave plate (5-1) is regulated, the vertical polarized pump light passes through the first half wave plate (5-1) and then enters the second half wave plate (5-2) after being reflected by the second 45-degree polaroid (4-2), the angle of the second half wave plate (5-2) is regulated, and the polarized direction is parallel to the selenium gallium barium crystal (7) n-shaped wave is obtained _m Pump light of refractive index principal axis;

the polarization direction is parallel to the selenium gallium barium crystal (7) n _m The pump light with the principal refractive index passes through the 0-degree plane OPO input mirror (6-1) and is incident to the selenium gallium barium crystal (7), and the selenium gallium barium crystal (7) leads part of the polarization direction to be parallel to the selenium gallium barium crystal (7) n _m Performing optical nonlinear frequency conversion on the pump light with the refractive index spindle to obtain signal light with the wavelength of 2.5-2.65 mu m and idler light with the wavelength of 9-11 mu m;

the signal light with the wavelength of 2.5-2.65 μm is incident to the 0-degree plane OPO output mirror (6-2) and totally reflected, reversely passes through the selenium gallium barium crystal (7), then is incident to the 0-degree plane OPO input mirror (6-1), is reflected by the 0-degree plane OPO input mirror (6-1) and passes through the selenium gallium barium crystal (7) again, and then repeatedly oscillates in the cavity without output; idler frequency light with the wavelength of 9-11 μm is output from the optical parametric oscillator through a 0-degree plane OPO output mirror (6-2); idler light and residual polarization direction outputted from the optical parametric oscillator are parallel to the selenium gallium barium crystal (7) n _m The pump light with the main refractive index axis is incident to a filtering system, and the residual polarization direction is parallel to the selenium gallium barium crystal (7) n _m The pump light of the refractive index main shaft is output through a first 45-degree long-wave infrared filter (9-1), and idler frequency light output by the optical parametric oscillator is sequentially reflected and output through the first 45-degree long-wave infrared filter (9-1) and a second 45-degree long-wave infrared filter (9-2), so that 9-11 mu m long-wave infrared laser is obtained.

2. A temperature-tuned 9-11 μm long-wave infrared solid-state laser according to claim 1, characterized in that said first pump source (1-1) is a pulsed laser with a wavelength of 2.09 μm or 2.12 μm, a pulse width of femtosecond, picosecond or nanosecond; the second pump source (1-2) is a pulse laser with a wavelength of 2.02 μm or 2.05 μm and a pulse width of femtosecond, picosecond or nanosecond.

3. The temperature-tuned 9-11 μm long-wave infrared solid laser according to claim 1, wherein the light-passing surfaces of the first plano-concave lens (2-1), the first plano-convex lens (3-1), the second plano-concave lens (2-2) and the second plano-convex lens (3-2) are coated with an antireflection film of 2.02-2.12 μm; the curvature radius of the first plano-concave lens (2-1) and the curvature radius of the second plano-concave lens (2-2) are-50 mm to-200 mm, and the diameters are 10mm to 100mm; the focal lengths of the first plano-convex lens (3-1) and the second plano-convex lens (3-2) are 50 mm-1000 mm, and the diameters of the first plano-convex lens and the second plano-convex lens are 10 mm-100 mm.

4. A temperature-tuned 9-11 μm long-wave infrared solid-state laser according to claim 1, characterized in that the surface of said first 45 ° polarizer (4-1) is coated with a film having a vertical polarization state laser light reflectance of more than 99% for wavelengths 2.02-2.05 μm and a horizontal polarization state laser light reflectance of less than 70% for wavelengths 2.02-2.05 μm, and simultaneously with a film having a horizontal polarization state laser light transmittance of more than 99% for wavelengths 2.09-2.12 μm and a vertical polarization state laser light transmittance of less than 20% for wavelengths 2.09-2.12 μm.

5. A temperature-tuned 9-11 μm long-wave infrared solid-state laser according to claim 1, characterized in that the surface of said second 45 ° polarizer (4-2) is coated with a film having a vertical polarization laser reflectivity of more than 99.5% for wavelengths 2.02-2.12 μm and a horizontal polarization laser transmissivity of more than 99.5% for wavelengths 2.02-2.12 μm.

6. The temperature-tuned 9-11 μm long-wave infrared solid laser according to claim 1, wherein the first half-wave plate (5-1) and the second half-wave plate (5-2) are broadband wave plates with wavelengths of 2.02-2.12 μm, and the light-transmitting surfaces are plated with antireflection films of 2.02-2.12 μm.

7. The temperature-tuned 9-11 μm long-wave infrared solid laser according to claim 1, wherein one surface of the 0-degree plane OPO input mirror (6-1) and one surface of the 0-degree plane OPO output mirror (6-2) are coated with an antireflection film for pumping light with the wavelength of 2.02-2.12 μm and idler light with the wavelength of 9-11 μm, and the other surface is coated with a dielectric film with the signal light reflectivity of more than 99% for the wavelength of 2.5-2.65 μm.

8. The temperature-tuned 9-11 μm long-wave infrared solid laser according to claim 1, characterized in that said selenium gallium barium crystal (7) has a light-passing surface perpendicular to crystal n _g Refractive index principal axis.

9. The temperature-tuned 9-11 μm long-wave infrared solid laser according to claim 1, wherein the semiconductor temperature controller (8) is a TEC temperature controller, the temperature is continuously tunable within the range of 0-45 ℃, and the control precision is +/-0.1 ℃.

10. The temperature-tuned 9-11 μm long-wave infrared solid laser according to claim 1, wherein the first 45 ° long-wave infrared filter (9-1) and the second 45 ° long-wave infrared filter (9-2) are coated with a pumping light antireflection film with the wavelength of 2.02-2.12 μm on one side and a dielectric film with the idler frequency light reflectance of 9-11 μm of more than 95% on the other side.