CN210007100U - kinds of optical parametric oscillator - Google Patents

Abstract

optical parametric oscillator comprises a pump laser source device for generating pump light, a pump light control device for receiving the pump light and adjusting the spot size and polarization direction of the pump light, including a dichroic mirror, and guiding out the adjusted pump light through the dichroic mirror, a resonant cavity device including a nonlinear optical crystal, a high-reflectivity cavity mirror and an output coupling mirror, wherein the nonlinear optical crystal is arranged between the high-reflectivity cavity mirror and the output coupling mirror, the nonlinear optical crystal is used for receiving the pump light guided out by the dichroic mirror and generating signal light and idle frequency light and guiding out the signal light and the idle frequency light to the high-reflectivity cavity mirror, a preset included angle is formed between the normal direction of the high-reflectivity cavity mirror and the direction of the pump light and used for reflecting the pump light to the nonlinear optical crystal so that the reflected pump light and the incident pump light form quasi-collinearity in the crystal, and the signal light and the idle frequency light are output through the dichroic mirror and the output coupling mirror in sequence.

Description

An Optical Parametric Oscillator

technical field

The utility model relates to the field of lasers, in particular to an optical parametric oscillator.

Background technique

The structure of the laser mainly includes: gain medium, resonator and pump source. The working principle of the general laser is based on the population inversion of the gain medium, and the coherent laser is output after the stimulated radiation is amplified by the frequency selection and feedback of the resonator. In principle, the optical parametric oscillator is a second-order nonlinear optical conversion based on a nonlinear medium. The pump laser is converted into two laser beams in the nonlinear medium, one beam is signal light and the other is idler light, and then passes through resonance. The frequency selection and feedback of the cavity perform nonlinear optical conversion and amplification and then output coherent laser light. Optical parametric oscillator light source has the advantages of wide wavelength tuning range, high energy conversion efficiency, can generate two entangled coherent beams at the same time, all-solid-state structure, etc., and has a wide range of applications in laser chemistry, quantum coherence, medicine and other fields. High-energy optical parametric oscillators have great application requirements in the fields of lidar, medical photoacoustic imaging, and the frequency expansion of the laser itself. In recent years, thanks to the maturity of nonlinear optical crystal growth technology, important progress has been made in the design of optical parametric oscillators.

The output energy of the optical parametric oscillator is mainly limited by the energy conversion efficiency and the maximum pump laser energy. The maximum pump laser energy is limited by the power density damage threshold of the nonlinear optical crystal and each optical element, so improving the output energy is the key. It lies in the reasonable design of the resonant cavity to improve the energy conversion efficiency of the optical parametric oscillator.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

Based on the above problems, the present utility model provides an optical parametric oscillator, which can generate two beams of quasi-collinear pump light from the pump light by reasonably configuring the resonator cavity and other structures. The rational design of the resonator cavity can improve the energy conversion efficiency. In addition to improving the conversion efficiency of the single-pulse output energy, we should also consider how to increase the maximum pump energy without exceeding the damage threshold. Increasing the pump energy can also improve the conversion efficiency to a certain extent, so as to overcome the existing high-energy pulsed optical parametric oscillation. The output energy and energy conversion efficiency of the device are insufficient.

(2) Technical solutions

The utility model provides an optical parametric oscillator, which comprises: a pump laser source device 100 for generating pump light; a pump light control device 200 for receiving the pump light and controlling the spot size of the pump light and the polarization direction is adjusted, including a dichroic mirror 208, and the adjusted pump light is exported through the dichroic mirror 208; the resonant cavity device 300 includes a nonlinear optical crystal 301, a high reflectivity cavity mirror 302, and an output coupling mirror 303, wherein , the nonlinear optical crystal 301 is set between the high reflectivity cavity mirror 302 and the output coupling mirror 303, the dichroic mirror 208 is set between the output coupling mirror 303 and the nonlinear optical crystal 301, and the nonlinear optical crystal 301 is used to receive the dichroic mirror 208 and realize nonlinear optical conversion to generate signal light and idler light, and export them to the high reflectivity cavity mirror 302; the normal direction of the high reflectivity cavity mirror 302 and the pump light direction are preset The included angle is used to reflect the pump light to the nonlinear optical crystal 301, so that the reflected pump light and the incident pump light form quasi-collinearity inside the crystal, and the signal light generated by the two beams of quasi-collinear pump light and the The idler light is output through the dichroic mirror 208 and the output coupling mirror 303 in sequence.

Optionally, the pump light control device 200 further includes a high-energy absorption diaphragm 202, a polarization beam splitter cube 204, and a lens 207 in sequence along the optical path, and the polarization beam splitter cube 204 is provided with a half-wave plate 203 before and after the first half-wave, respectively. The first half-wave plate and the second half-wave plate are rotatable, and an optical path calibration aperture 206 is set before and after the lens 207, respectively for the first optical path calibration aperture and the second optical path calibration light diaphragm, wherein, the high-energy absorption diaphragm 202 is used to limit the spot size of the pump light and absorb the pump light deviated from the optical path of the resonator, so as to protect the pump laser source device 100 from being damaged by the returned pump light; The half-wave plate 203 is used to rotate the linear polarization direction of the pump light; the polarization beam splitter cube 204 is used to separate the horizontal polarization component and the vertical polarization component of the pump light, and send the vertical polarization component of the pump light to the Two half-wave plates; the optical path calibration aperture 206 is used to calibrate the pump optical path; the lens 207 is used to adjust the spot size of the pump light;

Optionally, the lens 207 includes a plano-convex lens 2071 and a plano-concave lens 2072, and the plane parts of the plano-convex lens 2071 and the plano-concave lens 2072 are relatively parallel and the distance between them is the sum of the focal lengths of the plano-convex lens 2071 and the plano-concave lens 2072.

Optionally, a preset angle between the normal direction of the high reflectivity cavity mirror 302 and the pump light direction is set to be less than or equal to 0.3°.

Optionally, the resonant cavity device 300 further includes an electric actuator system 304, the upper surface of which is provided with a nonlinear optical crystal 301 for driving the nonlinear optical crystal 301 to rotate.

Optionally, the electric actuator system 304 includes a crystal fixing column 3041, a rotating arm 3042, a rotating table 3043, a DC servo electric actuator 3044, a return spring 3045 and a sapphire spacer 3046, wherein the crystal fixing column 3041 is used for carrying The nonlinear optical crystal 301, the crystal fixing column 3041 is fixed on one end of the rotating arm 3042, the rotating arm 3042 is axially connected to the rotating table 3043, the DC servo electric actuator 3044 is vertically connected with the other end of the rotating arm 3042 through the sapphire gasket 3046, One end of the return spring 3045 is vertically connected to one end of the rotating arm 3042, and the other end of the return spring 3045 is fixed.

Optionally, the light output by the output coupling mirror 303 also includes residual pump light, the optical parametric oscillator further includes a monitoring control system 400, and the monitoring control system 400 includes a first color filter 401, a second color filter 402 and an idler high reflector. 403, wherein the first color filter 401 is used to filter the residual pump light, and the filtered light beam is sent to the second color filter 402, and the second color filter 402 is used to separate the idler light and the signal light, and send the idler light to The idler light is highly reflective mirror 403 .

Optionally, the monitoring and control system 400 further includes a beam sampling mirror 404, a fiber optic spectrometer 405, a control computer 406 and an actuator controller 407, wherein the beam sampling mirror 404 is used to reflect part of the signal light to the fiber optic spectrometer 405, and the fiber optic spectrometer 405 For measuring the wavelength of the signal light, the control computer 406 is used to display the wavelength in real time and use the actuator controller 407 to control the rotation of the electric actuator system 304 .

Optionally, the pump light control device 200 further includes a laser energy collector 205 for collecting the residual pump light and the horizontally polarized pump light split by the polarization beam splitting cube 204 .

Optionally, the pump light control device 200 further includes a plurality of high reflection mirrors 201 for changing the direction of the pump light.

(3) Beneficial effects

The utility model provides an optical parametric oscillator, which at least has the following beneficial effects:

(1) On the premise that the power density of the pump light is not greater than the damage threshold of the nonlinear optical crystal and each optical element, the pump light control device 200 capable of continuously adjusting the energy of the pump light is used to obtain the highest possible pump light power density, improve the energy conversion efficiency of nonlinear optical conversion;

(2) On the premise of ensuring that the power density of the pump light is not greater than the damage threshold of the nonlinear optical crystal and each optical element, the pump light control device 200 capable of regulating the size of the pump light spot is used to obtain a large pump light spot diameter, thereby increasing the maximum pump light spot diameter. Single pulse pump energy and output pulse energy;

(3) The optical path design of quasi-collinear double-pass pump is adopted to improve the conversion efficiency of pump laser energy;

(4) Using the output coupling mirror 303 with the optimal reflectivity determined by experiments to ensure the optimal pump light energy conversion efficiency;

(5) Under the premise of ensuring no reverse nonlinear optical conversion (that is, the reverse sum-frequency conversion of signal light and idler light into pump light), large-size (optical path length) nonlinear optical crystals are used to improve nonlinear optical conversion. process optical energy gain and compresses the spectral linewidth of the output pump light.

Description of drawings

FIG. 1 schematically shows a schematic structural diagram of an optical parametric oscillator according to an embodiment of the present disclosure;

FIG. 2 schematically shows a top view of the structure of the electric actuator system 304 according to the embodiment of the present disclosure;

FIG. 3 schematically shows a right side view of the structure of the electric actuator system 304 according to the embodiment of the present disclosure.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The present invention provides an optical parametric oscillator, see FIG. 1 , including: a pump laser source device 100 for generating pump light; a pump light control device 200 for receiving the pump light and controlling the pump light The spot size and polarization direction of the light are adjusted, including a dichroic mirror 208, and the adjusted pump light is exported through the dichroic mirror 208; the resonant cavity device 300 includes a nonlinear optical crystal 301, a high reflectivity cavity mirror 302, and an output coupling Mirror 303, wherein the nonlinear optical crystal 301 is arranged between the high reflectivity cavity mirror 302 and the output coupling mirror 303 placed in parallel and compactly, and the dichroic mirror 208 is arranged between the output coupling mirror 303 and the nonlinear optical crystal 301. The optical crystal 301 is used to receive the pump light derived from the dichroic mirror 208 and realize nonlinear optical conversion to generate signal light and idler light, and export them to the high reflectivity cavity mirror 302; the normal direction of the high reflectivity cavity mirror 302 is the same as The pump light direction is provided with a preset angle, which is used to reflect the pump light to the nonlinear optical crystal 301, so that the reflected pump light and the incident pump light are quasi-collinear inside the crystal, and the two beams are quasi-collinear The signal light and idler light generated by the pump light are output through the dichroic mirror 208 and the output coupling mirror 303 in sequence. The solution will be described in detail below by taking the pumping light wavelength of 532 nm and the nonlinear optical crystal 301 being a KTP crystal as an example.

a pump laser source device 100 for generating pump light;

Specifically, in the embodiment of the present invention, the pulse repetition frequency of the pump laser source device 100 is 10 Hz, the pulse width is 10 ns, and the Nd:YAG laser spot diameter is 10 mm. The laser is used as the pump source for the nonlinear optical conversion process of the optical parametric oscillator.

The pump light control device 200 is used for receiving the pump light and adjusting the spot size and polarization direction of the pump light, including a dichroic mirror 208, and exporting the adjusted pump light through the dichroic mirror 208;

Specifically, the pump light control device 200 is disposed behind the pump laser source device 100, and is used to receive and control the pump light generated by the pump laser source device 100 to obtain a certain spot size, a certain polarization, and a continuously adjustable energy. The pump light is introduced into the resonator device 300 , and the pump light returned after being deviated from the optical path of the resonator device 300 can be absorbed to prevent the returning pump laser from damaging the pump laser source device 100 . Along the propagation direction of the pump light, a high-energy absorption diaphragm 202, a polarization beam splitter cube 204, a lens 207, and a dichroic mirror 208 are included in sequence, and the polarization beam splitter cube 204 is provided with a half-wave plate 203 before and after the first half-wave plate and the second half-wave plate respectively. A half-wave plate, and the first half-wave plate and the second half-wave plate are rotatable; an optical path calibration aperture 206 is set before and after the lens 207 respectively, which are the first optical path calibration aperture and the second optical path calibration aperture, wherein the high-energy absorption The outer diameter of the diaphragm 202 is 40mm, and the clear aperture is 9mm. On the one hand, it is used to limit the spot size of the pump light, and on the other hand, it is used to absorb the pump light returning after the optical path of the resonator device 300 is deviated, preventing the return of the pump light. The pump laser damages the pump laser source device 100; the half-wave plate 203 can continuously rotate the linear polarization direction of the pump light. There are two half-wave plates 203 in the embodiment of the present invention, which are the first half-wave plate and the second Two half-wave plates, respectively arranged in front of and behind the polarization beam splitter cube 204, are used to rotate the pump light entering the polarization beam splitter cube 204 and the linear polarization direction of the pump light emitted from the polarization beam splitter cube 204; The beam cube 204 can separate the horizontal polarization component and the vertical polarization component of the pump light, and send the vertical polarization component of the pump light to the second half-wave plate. The first half-wave plate 203 together constitutes a pump light energy attenuator, which realizes continuous adjustment of the vertically polarized pump light energy, and ensures that the polarization of the pump light with a wavelength of 532 nm guided to the next optical element is practical. The vertical polarization required by the phase matching conditions of the KTP crystal in the new embodiment, while guiding the redundant horizontal polarization component to the laser energy collector 205 for collection, preventing the useless pump light from exiting the free space outside the optical path; the optical path calibration light The diaphragm 206 is used for calibrating the pump light path. In the embodiment of the present invention, the number of the optical path calibration diaphragms 206 is two, which are respectively the first optical path calibration diaphragm and the second optical path calibration diaphragm, which are respectively arranged before and after the lens 207; The lens 207 is used to adjust the spot size of the pump light. The lens 207 includes a plano-convex lens 2071 and a plano-concave lens 2072. The plano-convex lens 2071 and the plano-concave lens 2072 together form a Galilean telescope system. The distance between them is the sum of the focal lengths of the plano-convex lens 2071 and the plano-convex lens 2072. Optionally, the distance between the plano-convex lens 2071 and the plano-concave lens 2072 can be fine-tuned so that the outgoing light is parallel light, and the incident pump light enters from the convex surface of the plano-convex lens 2071, from The concave surface of the plano-concave lens 2072 is emitted; the dichroic mirror 208 is arranged in the resonator device 300, and the reflectivity of the pump light with a wavelength of 532 nm is greater than 99%, and the wavelength of the signal light and idler light newly generated in the resonator device 300 is reflected. The transmittance is greater than 96%, which is used to export the pump light emitted from the second optical path calibration aperture to the resonator device 300 , and does not affect the optical feedback and laser oscillation in the resonator device 300 . On the premise of ensuring that the power density of the pump light is not greater than the nonlinear optical crystal 301 and the damage threshold of each optical element, the highest possible power density of the pump light is used to improve the energy conversion efficiency of nonlinear optical conversion, and a large pump spot is used. diameter, increasing the highest single-pulse pump energy and output pulse energy.

The pump light control device 200 also includes a plurality of high reflection mirrors 201 for changing the direction of the pump light. In the embodiment of the present invention, the pump light generated by the pump laser source device 100 is changed by the three high reflection mirrors 201 The vertical polarization of the pump light emitted from the polarization beam splitter cube 204 is perpendicular to the second half-wave plate after passing through a high-reflection mirror 201, and the pump light emitted from the second half-wave plate The pump light passes through a high reflection mirror 201 and then perpendicularly strikes the first optical path calibration aperture, and the pump light emitted from the second optical path calibration aperture passes through a high reflection mirror 201 and then strikes the dichroic mirror 208 .

The resonant cavity device 300 includes a nonlinear optical crystal 301, a high reflectivity cavity mirror 302 and an output coupling mirror 303, wherein the nonlinear optical crystal 301 is arranged between the high reflectivity cavity mirror 302 and the output coupling mirror 303, and the dichroic mirror 208 Set between the output coupling mirror 303 and the nonlinear optical crystal 301, the nonlinear optical crystal 301 is used to receive the pump light derived from the dichroic mirror 208 and realize nonlinear optical conversion to generate signal light and idler light, and export them to high The reflectivity cavity mirror 302; the normal direction of the high reflectivity cavity mirror 302 has a preset angle with the direction of the pump light, which is used to reflect the pump light to the nonlinear optical crystal 301, so that the reflected pump light and the incident light are The pump light generated by the two beams forms a quasi-collinear within the crystal, and the signal light and idler light generated by the two beams of quasi-collinear pump light are output through the dichroic mirror 208 and the output coupling mirror 303 in turn.

Specifically, the resonant cavity device 300 is used to realize wavelength selection of pump light, optical energy gain and feedback of nonlinear optical conversion, and generate oscillation, and finally output laser light stably. The high reflectivity cavity mirror 302 and an output coupling mirror 303 whose reflectivity is measured and optimized through experiments form a resonant cavity, and the high reflectivity cavity mirror 302 and the output coupling mirror 303 are placed in parallel and compactly. The nonlinear optical crystal 301 is placed in the resonant cavity to obtain the optical energy gain of the nonlinear optical conversion. On the premise of ensuring that no reverse nonlinear optical conversion occurs, a nonlinear optical crystal with a large optical path length is used to improve the nonlinear optical conversion. The optical energy gain in the conversion process and the spectral line width of the output pump light are compressed. The material of the nonlinear optical crystal 301 can be KTP (KTiOPO ₄ ), LNB (LiNbO ₃ ), etc. The material of the optical crystal 301 is KTP crystal. The nonlinear optical crystal 301 is set between the high reflectivity cavity mirror 302 and the output coupling mirror 303 to realize nonlinear optical conversion light energy gain. The KTP crystal has high damage threshold, nonlinear According to the advantages of high coefficient and low temperature sensitivity coefficient, according to the required output wavelength range, two KTP crystals that can be replaced with each other are used in the embodiment of the present utility model. The smooth surface and the clear surface are coated with broadband anti-reflection coating, the main axis planes are all xz planes, the cutting angles are Φ=0 degrees, θ=70 degrees and θ=53 degrees, using class II phase matching; dichroic mirror 208 is set Between the output coupling mirror 303 and the nonlinear optical crystal 301, the nonlinear optical crystal 301 is used to receive the pump light derived from the dichroic mirror 208 and realize nonlinear optical conversion to generate signal light and idler light, and export them to highly reflective The cavity mirror 302 with high reflectivity; the cavity mirror 302 with high reflectivity has high reflectivity at the wavelength of the pump light, which can make the pump light pass through the nonlinear optical crystal 301 back and forth twice, realize the double-pass pumping of the optical parametric process, and improve the energy conversion efficiency , while eliminating the optical path departure caused by the refractive index of the nonlinear optical crystal, ensuring the spatial stability of the output beam in the entire wavelength tuning range, the normal direction of the high reflectivity cavity mirror 302 and the pump light derived from the nonlinear optical crystal 301 There is a preset included angle in the direction, the size of the included angle is generally not greater than 0.3°, and the high reflectivity cavity mirror 302 is as close as possible to the nonlinear optical crystal 301, so that the pump light reflected by the high reflectivity cavity mirror 302 returns at The interior of the nonlinear optical crystal 301 is nearly coincident with the incident pump light to realize quasi-collinear double-pass pumping, that is, two beams of quasi-collinear pump light are generated. The generated signal light and idler light can both be subjected to nonlinear optical conversion and amplification, and the generated signal light and idler light are output through the dichroic mirror 208 and the output coupling mirror 303 in turn. At the same time, the pump light reflected by the high reflectivity cavity mirror 302 obtains a deviation distance greater than the diameter of the pump light spot in the pump light control device 200, so that it can be absorbed by a high-energy absorption diaphragm 202 to prevent the returned pump light from being damaged. Pump laser source device 100 . In the embodiment of the present invention, the high reflectivity cavity mirror 302 has a reflectivity greater than 96% for the pump light with a wavelength of 532 nm, the newly generated signal light and the idler light, and the output coupling mirror 303 is an output device for the signal light , the transmittance of the signal light is about 50%, and the transmittance of the idler light is not more than 50%. The high reflectivity cavity mirror 302 and the output coupling mirror 303 are placed in parallel with a distance of 7cm, forming a resonant cavity with high reflection The rate cavity mirror 302 returns the pump light with a wavelength of 532 nm, so that the pump light with a wavelength of 532 nm passes through the KTP crystal twice back and forth to achieve double-pass pumping, and eliminates the optical path departure caused by the refractive index of the KTP crystal, Ensure the spatial stability of the output laser beam over the entire wavelength tuning range. The distance between the reflection surface of the high reflectivity cavity mirror 302 and the KTP crystal, that is, the end face of the nonlinear optical crystal 301 is 8 mm, and the angle between the normal direction of the high reflectivity cavity mirror 302 and the pump light direction derived from the nonlinear optical crystal 301 is 0.2°, the returned pump light with a wavelength of 532 nm approximately coincides with the incident pump light with a wavelength of 532 nm inside the KTP crystal, realizing quasi-collinear two-way pumping, and the returned pump light with a wavelength of 532 nm is absorbed in the high-energy An offset distance of 12 mm is obtained at the diaphragm 202, which is completely absorbed by the high-energy absorption diaphragm 202 to ensure that the pump laser source device 100 is not damaged by the returning pump light with a wavelength of 532 nm.

The resonant cavity device 300 further includes an electric actuator system 304, the upper surface of which is provided with a nonlinear optical crystal 301 for driving the nonlinear optical crystal 301 to rotate.

As shown in FIGS. 2 and 3 , the electric actuator system 304 includes a crystal fixing column 3041 , a rotating arm 3042 , a rotating table 3043 , a DC servo electric actuator 3044 , a return spring 3045 and a sapphire spacer 3046 , wherein the crystal is fixed The column 3041 is used to carry the nonlinear optical crystal 301. The crystal fixing column 3041 is fixed to one end of the rotating arm 3042. The rotating arm 3042 is connected to the rotating table 3043. The rotating arm is made of SS304 stainless steel. The DC servo electric actuator 3044 The sapphire gasket 3046 is vertically connected to the other end of the rotating arm 3042, one end of the return spring 3045 is vertically connected to one end of the rotating arm 3042, and the other end of the return spring 3045 is fixed. The DC servo electric actuator 3044 combined with the return spring 3045 pushes the rotating arm 3042 to drive the rotating table 3043, thereby realizing the precise adjustment of the angle between the optical axis direction of the KTP crystal and the direction of the pump beam, and realizing the wavelength tuning of the output laser. The rotating arm 3042 There is a sapphire gasket 3046 at the contact position with the DC servo electric actuator 3044 to prevent the precession of the top of the DC servo electric actuator 3044 from damaging the contact surface of the rotating arm 3042 during long-term operation, and to ensure long-term tuning of the optical axis of the KTP crystal. job stability.

The light output by the output coupling mirror 303 also includes residual pump light, and the optical parametric oscillator further includes a monitoring control system 400, which includes a first color filter 401, a second color filter 402 and an idler high reflector 403, wherein In the embodiment of the present invention, the first color filter 401 is preferably a long-wave-pass color filter for filtering the residual pump light. The reflectivity of the first color filter 401 to the residual pump light with a wavelength of 532 nm is greater than 99%, and the reflected residual pump light The light is sent to the laser energy collector 205 for collection, the transmittance of the signal light and idler light generated by nonlinear optical conversion is greater than 96%, and the filtered light beam is sent to the second color filter 402; The second color filter 402 is preferably a short-wave-pass color filter for separating the idler light and the signal light. The reflectivity of the second color filter 402 to the idler light is greater than 99%, and the transmittance to the signal light is greater than 98%, so as to realize the signal light and the idler light. It separates the frequency light, and sends the idler light to the idler high reflector 403 for reflection output.

The monitoring and control system 400 further includes a beam sampling mirror 404, a fiber optic spectrometer 405, a control computer 406 and an actuator controller 407, wherein the beam sampling mirror 404 is used for reflecting part of the signal light to the fiber optic spectrometer 405, and the fiber optic spectrometer 405 is used for measuring For the wavelength of the signal light, the control computer 406 is used to display the wavelength in real time and use the actuator controller 407 to control the rotation of the electric actuator system 304 to realize real-time online positioning and continuous scanning of the wavelength.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention, and are not intended to limit the present invention. In the utility model, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims (10)

1. An optical parametric oscillator of , comprising:

   a pump laser source device (100) for generating pump light;

   the pumping light control device (200) is used for receiving the pumping light, adjusting the spot size and the polarization direction of the pumping light, comprises a dichroic mirror (208), and leads out the adjusted pumping light through the dichroic mirror (208);

   the resonant cavity device (300) comprises a nonlinear optical crystal (301), a high-reflectivity cavity mirror (302) and an output coupling mirror (303), wherein the nonlinear optical crystal (301) is arranged between the high-reflectivity cavity mirror (302) and the output coupling mirror (303), the dichroic mirror (208) is arranged between the output coupling mirror (303) and the nonlinear optical crystal (301), and the nonlinear optical crystal (301) is used for receiving pump light led out by the dichroic mirror (208), realizing nonlinear optical conversion to generate signal light and idler frequency light and leading the signal light and the idler frequency light out to the high-reflectivity cavity mirror (302); the normal direction of the high-reflectivity cavity mirror (302) and the direction of the pump light are provided with a preset included angle and used for reflecting the pump light to the nonlinear optical crystal (301) so that the reflected pump light and the incident pump light form two beams of quasi-collinear pump light in the crystal, and signal light and idler frequency light generated by the two beams of quasi-collinear pump light are output through the dichroic mirror (208) and the output coupling mirror (303) in sequence.
2. 2. The optical parametric oscillator according to claim 1, wherein the pump light control device (200) further comprises a high energy absorption diaphragm (202), a polarization beam splitting cube (204) and a lens (207) in sequence along the optical path direction, the polarization beam splitting cube (204) is provided with half-wave plates (203) respectively as a half-wave plate and a second half-wave plate, the half-wave plate and the second half-wave plate are rotatable, the lens (207) is provided with optical path calibration diaphragms (206) respectively as a optical path calibration diaphragm and a second optical path calibration diaphragm, wherein the high energy absorption diaphragm (202) is used for limiting the spot size of the pump light and absorbing the pump light deviated through the resonant cavity optical path to protect the pump laser source device (100) from being damaged by the returned pump light, the half-wave plate (203) is used for rotating the linear polarization direction of the pump light, the polarization beam splitting cube (204) is used for separating the horizontal polarization component and the vertical polarization component of the pump light and transmitting the vertical polarization component of the pump light to the second half-wave plate (206), the calibration diaphragm (207) is used for adjusting the emergent size of the pump light from the calibration optical path (207).
3. 3. The optical parametric oscillator of claim 2, the lens (207) comprising a plano-convex lens (2071) and a plano-concave lens (2072), the planar portions of the plano-convex lens (2071) and the plano-concave lens (2072) being disposed relatively parallel and the distance therebetween being the sum of the focal lengths of the plano-convex lens (2071) and the plano-concave lens (2072).
4. 4. The optical parametric oscillator according to claim 1, wherein the normal direction of the high reflectivity cavity mirror (302) and the pump light direction have a predetermined angle smaller than or equal to 0.3 °.
5. 5. The optical parametric oscillator according to claim 2, the resonator device (300) further comprising an electric actuator system (304) having the nonlinear optical crystal (301) disposed on an upper surface thereof for rotating the nonlinear optical crystal (301).
6. 6. The optical parametric oscillator according to claim 5, wherein the electric actuator system (304) comprises a crystal fixing column (3041), a rotating arm (3042), a rotating platform (3043), a dc servo electric actuator (3044), a return spring (3045) and a sapphire pad (3046), wherein the crystal fixing column (3041) is used for carrying the nonlinear optical crystal (301), the crystal fixing column (3041) is fixed at an end of the rotating arm (3042), the rotating arm (3042) is coupled to the rotating platform (3043), the dc servo electric actuator (3044) is vertically connected to another end of the rotating arm (3042) through the sapphire pad (3046), a end of the return spring (3045) is vertically connected to a end of the rotating arm (3042), and another end of the return spring (3045) is fixed.
7. 7. The optical parametric oscillator according to claim 5, the light output by the output coupling mirror (303) further comprising a residual pump light, the optical parametric oscillator further comprising a monitor and control system (400), the monitor and control system (400) comprising th color filter (401), a second color filter (402), and an idler high mirror (403), wherein th color filter (401) is configured to filter the residual pump light and send the filtered beam to the second color filter (402), and the second color filter (402) is configured to split the idler and signal light and send the idler to the idler high mirror (403).
8. 8. The optical parametric oscillator according to claim 7, the monitoring and control system (400) further comprising a beam sampling mirror (404), a fiber optic spectrometer (405), a control computer (406) and an actuator controller (407), wherein the beam sampling mirror (404) is configured to reflect a portion of the signal light to the fiber optic spectrometer (405), the fiber optic spectrometer (405) is configured to measure a wavelength of the signal light, and the control computer (406) is configured to display the wavelength in real time and control the rotation of the electric actuator system (304) by the actuator controller (407).
9. 9. The optical parametric oscillator according to claim 7, the pump light control device (200) further comprising a laser energy collector (205) for collecting the residual pump light and a horizontally polarized component of the pump light split by the polarization beam splitter cube (204).
10. 10. The optical parametric oscillator according to claim 1, the pump light control device (200) further comprising a plurality of highly reflective mirrors (201) for redirecting the pump light.

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