Optical parametric oscillator

Abstract

The invention relates to an optical parametric oscillator, belongs to the technical field of optical parametric oscillators, and solves the problems of low reliability, low quality of obtained laser beams, large divergence angle and insufficient long-distance measurement of a laser in the prior art. The oscillator comprises a total reflection mirror, a nonlinear crystal, a wedge-shaped mirror and an output mirror which are sequentially arranged along an optical axis. The pump light is transmitted to the nonlinear crystal through the total reflective mirror; the nonlinear crystal is used for carrying out optical parameter conversion and converting the received pump light into signal light; the wedge-shaped mirror can freely rotate around the optical axis and is used for adjusting the light beam output direction; the output mirror is used for coupling and outputting the signal light; a resonant cavity formed by the total reflective mirror and the output mirror is a virtual confocal unstable cavity, and the total reflective mirror, the nonlinear crystal, the wedge mirror and the output mirror jointly form a complete resonant cavity. High-quality signal light can be generated, the divergence angle of emergent signal light is reduced, the requirement for long-distance ranging is met, and the debugging process is greatly optimized by adjusting the wedge-shaped mirror.

Description

Technical Field

[0001] The present invention relates to the technical field of optical parametric oscillators, and in particular to an optical parametric oscillator. Background Art

[0002] The optical parametric oscillator involved in the present invention is a nonlinear optical device, which uses a nonlinear crystal as a working medium. In a typical optical parametric oscillator, three laser wavelengths are mainly involved. Generally, a short-wave laser is incident and two long-wave lasers are generated. The incident short-wave laser is called pump light, and the two long-wave lasers generated are respectively called signal light and idler light. A general optical parametric oscillator requires that the working medium be placed in a resonant cavity, and a parametric conversion process is generated under the action of the pump light, and a laser output with a wavelength different from the pump laser is formed through the oscillation of the resonant cavity.

[0003] The optical parametric oscillator can be integrated into the pump light resonant cavity to form an intracavity optical parametric oscillator. This solution requires placing a nonlinear crystal in the pump light resonant cavity and considering the oscillation requirements of the signal light in the coating of the resonant cavity mirror so that both the pump light and the signal light can form a stable oscillation. A typical example of this structure is described in patent CN 1123950C. Another type of external cavity optical parametric oscillator is more flexible in structure than the intracavity type, allowing the entire laser system to first use an independent resonant cavity to generate pump lasers, and then couple the pump light into the optical parametric oscillator cavity to generate signal light and idler light. A typical example of this structure is described in patent CN 1140024C.

[0004] Optical parametric oscillators are mainly used to generate new laser wavelengths. For example, in laser rangefinders, optical parametric oscillators are used to convert 1.06μm lasers into 1.57μm lasers. Lasers of this wavelength can be absorbed by water molecules and converted into heat when irradiated to the human eye, thus preventing damage to the retina. This is called eye-safe laser. In the existing distance measurement field, laser reliability is not high, the quality of the laser beam obtained is low, and the divergence angle is large, so that the laser energy cannot be concentrated and long-distance distance measurement cannot be performed. Summary of the invention

[0005] In view of the above analysis, an embodiment of the present invention aims to provide an optical parametric oscillator to solve the problems in the prior art of low laser reliability, low quality of the obtained laser beam, large divergence angle, and insufficient long-distance measurement.

[0006] On the one hand, an embodiment of the present invention provides an optical parametric oscillator, the oscillator comprising a total reflection mirror, a nonlinear crystal, a wedge mirror and an output mirror arranged in sequence along an optical axis;

[0007] The pump light is transmitted to the nonlinear crystal through a total reflection mirror;

[0008] The nonlinear crystal is used to perform optical parametric conversion to convert the received pump light into signal light;

[0009] The wedge-shaped mirror can rotate freely around the optical axis to adjust the output direction of the light beam;

[0010] The output mirror is used to couple the signal light out;

[0011] The resonant cavity composed of the total reflection mirror and the output mirror is a virtual confocal unstable cavity. The total reflection mirror, the nonlinear crystal, the wedge mirror and the output mirror together form a complete resonant cavity.

[0012] Furthermore, the wedge-shaped mirror includes one or two wedge-shaped lenses. When the number of the wedge-shaped lenses is two, the wedge angles of the two wedge-shaped lenses are set to be consistent.

[0013] Furthermore, when two wedge-shaped lenses are used, the maximum optical axis adjustment range of the double wedge-shaped mirror should be calculated according to the parallelism error of the mounting surface of the total reflector and output mirror of the lens barrel according to the following formula:

[0014]

[0015] Among them, θ max is the maximum optical axis adjustment range, n is the refractive index of the wedge mirror, and θ is the apex angle of the wedge mirror.

[0016] Furthermore, the oscillator further comprises: a front lens barrel, a wedge-shaped lens edging, and a rear lens barrel;

[0017] The nonlinear crystal is installed in the middle of the front lens barrel, and the total reflection mirror is installed at the front end of the front lens barrel;

[0018] The wedge mirror is mounted on the wedge mirror edging;

[0019] The wedge-shaped mirror edge is installed in the middle of the rear lens barrel, the front end of the rear lens barrel is connected to the rear end of the front lens barrel, and the output mirror is installed at the rear end of the rear lens barrel.

[0020] Furthermore, one side outside the cavity of the total reflection mirror is coated with a film that increases the transmittance of pump light and idler light, and one side inside the cavity is coated with a film that increases the transmittance of pump light and idler light and fully reflects signal light.

[0021] Furthermore, the light-transmitting surface of the nonlinear crystal is coated with a film that increases the transmittance of pump light, signal light and idler light.

[0022] Furthermore, the light-transmitting surface of the wedge-shaped mirror is coated with a film that increases the transmittance of pump light, signal light and idler light.

[0023] Furthermore, one side of the output mirror cavity is coated with a film that increases the transmittance of pump light and idler light and partially reflects signal light, and one side outside the cavity is coated with a film that increases the transmittance of pump light, signal light and idler light.

[0024] Further, the front lens barrel comprises: a first cylindrical lens barrel, a first lens mounting groove, a crystal mounting groove and a connecting flange;

[0025] The lens mounting groove is located at the front end of the first cylindrical lens barrel and is used to mount the total reflection mirror. The crystal mounting groove is located in the middle of the first cylindrical lens barrel and is used to place the nonlinear crystal. The rear end of the first cylindrical lens barrel has a connecting flange for connecting the rear lens barrel.

[0026] Furthermore, the rear lens barrel comprises: a second cylindrical lens barrel, a second lens mounting groove, a mounting limiter, and an edge adjustment groove;

[0027] The second lens mounting groove is located at the rear end of the second cylindrical lens barrel and is used to install the output mirror. Two adjacent edge-wrapping adjustment grooves are set at the middle and rear positions of the lens barrel of the second cylindrical lens barrel. An installation limit is set inside the lens barrel of the second cylindrical lens barrel and in the middle of the two edge-wrapping adjustment grooves. The edge-wrapping of two wedge-shaped mirrors is placed on both sides of the installation limit, and each edge-wrapping of the wedge-shaped mirror corresponds to an edge-wrapping adjustment groove. The wedge-shaped mirror is adjusted by the edge-wrapping adjustment groove to change the direction of the light beam, thereby compensating for the installation tilt error of the total reflection mirror and the output mirror.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] 1. Using a wedge-shaped mirror as an optical path adjustment mechanism in the resonant cavity greatly optimizes the debugging process and enhances the overall stability of the resonant cavity. If a wedge-shaped mirror is not used, the resonant cavity reflector needs to be finely adjusted, and it is necessary to consider how to intervene in the adjustment tooling and the tilting and moving of the lens during the fixing process. It is usually impossible to fix it in a barrel. In this application, a wedge-shaped mirror is used to adjust the light beam direction, thereby achieving fixed installation of the total reflector, output mirror and nonlinear crystal, enhancing system stability and facilitating debugging.

[0030] 2. By bonding and fixing the total reflection mirror, output mirror, nonlinear crystal and wedge mirror to the front and rear lens barrels, the reliability and stability of working in different environments are improved;

[0031] 3. Using an unstable cavity as the optical parametric oscillator cavity type can provide higher high-order mode loss, improve the quality of the optical parametric signal light beam, reduce the divergence angle of the output signal light, and thus increase the ranging distance.

[0032] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0034] Figure 1 This is the optical path principle diagram of the external cavity optical parametric oscillator;

[0035] Figure 2 This is the exploded diagram of the optical parametric oscillator device;

[0036] Figure 3 This is the front structure of the front lens barrel;

[0037] Figure 4 This is the reverse structure of the front lens barrel;

[0038] Figure 5 It is the rear lens barrel structure.

[0039] Reference numerals:

[0040] 1-total reflection mirror; 2-nonlinear crystal; 3-wedge mirror; 4-output mirror; 5-front lens barrel; 6-wedge mirror edging; 7-rear lens barrel; 51-first lens injection port; 52-first lens mounting slot; 53-crystal mounting slot; 54-lens barrel mounting foot; 55-stress relief slot; 56-mounting hole; 57-crystal injection port; 58-V-groove; 59-connecting flange; 71-second lens injection port; 72-second lens mounting slot; 73-installation limit; 74-edging tightening hole; 75-edging injection port; 76-edging adjustment slot; 77 lens barrel tightening hole; 78-lens barrel glue injection hole. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0042] A specific embodiment of the present invention discloses an optical parametric oscillator, such as Figure 1 The oscillator comprises a total reflection mirror 1, a nonlinear crystal 2, a wedge mirror 3 and an output mirror 4 which are arranged in sequence along the optical axis;

[0043] The pump light is transmitted to the nonlinear crystal through a total reflection mirror;

[0044] The nonlinear crystal is used to perform optical parametric conversion to convert the received pump light into signal light;

[0045] The wedge-shaped mirror can rotate freely around the optical axis to adjust the transmission direction of the light beam;

[0046] The output mirror is used to couple the signal light out;

[0047] The resonant cavity composed of the total reflection mirror and the output mirror is a virtual confocal unstable cavity. The total reflection mirror, the nonlinear crystal, the wedge mirror and the output mirror together form a complete resonant cavity.

[0048] Specifically, the incident pump light enters the nonlinear crystal, generating signal light and idler light. The signal light oscillates back and forth multiple times in the resonant cavity and is amplified, gradually establishing a stable oscillation of the signal light. The idler light is directly output from the cavity or absorbed and lost by certain optical materials.

[0049] Specifically, the wavelength generation of the oscillator satisfies the following conditions:

[0050]

[0051] Among them, λ p represents the wavelength of the pump light in optical parametric oscillation, λ s represents the wavelength of the signal light in optical parametric oscillation, λ i Represents the wavelength of the idler light in optical parametric oscillation.

[0052] Virtual confocal unstable cavity can suppress the high-order mode components in the oscillation and produce signal light with high beam quality. The higher the magnification in the unstable cavity, the greater the oscillation loss of the laser, and the higher the threshold for establishing laser oscillation, which requires stronger pumping conditions. In addition, the increase in magnification can increase the loss of high-order modes, so that the mode existing in the cavity is closer to the fundamental mode, and the quality of the output laser beam is improved.

[0053] The curvature of the unstable cavity mirror is calculated as follows:

[0054]

[0055] 2L=R1+R2

[0056] Among them, M is the magnification, R1 is the radius of curvature of one side of the total reflection mirror cavity, R2 is the radius of curvature of one side of the output mirror cavity, and L is the length of the resonant cavity.

[0057] Further, such as Figure 2 As shown, the oscillator further comprises: a front lens barrel 5, a wedge-shaped lens edging 6, and a rear lens barrel 7;

[0058] The nonlinear crystal is installed in the middle of the front lens barrel, and the total reflection mirror is installed at the front end of the front lens barrel;

[0059] The wedge mirror is mounted on the wedge mirror edging;

[0060] The wedge-shaped mirror edge is installed in the middle of the rear lens barrel, the front end of the rear lens barrel is connected to the rear end of the front lens barrel, and the output mirror is installed at the rear end of the rear lens barrel.

[0061] Specifically, the wedge-shaped mirror edge has a plurality of grooves that can be used for adjustment, and the position corresponding to the rear group lens barrel has an edge adjustment groove. After the wedge-shaped mirror edge is installed to the rear group lens barrel, the wedge-shaped mirror edge can be rotated and adjusted from the outside through the edge adjustment groove.

[0062] Furthermore, one side outside the cavity of the total reflection mirror is coated with a film that increases the transmittance of pump light and idler light, and one side inside the cavity is coated with a film that increases the transmittance of pump light and idler light and fully reflects signal light.

[0063] Specifically, the total reflection mirror is an optical lens with a surface coating.

[0064] Furthermore, the light-transmitting surface of the nonlinear crystal is coated with a film that increases the transmittance of pump light, signal light and idler light.

[0065] Specifically, the nonlinear crystal may be PPLN, KTP, etc. The crystal needs to consider the polarization direction of the incident pump light, and be cut according to a certain crystal axis direction and placed in a polarization direction, so as to maximize the conversion efficiency.

[0066] Furthermore, the wedge-shaped mirror includes one or two wedge-shaped lenses. When the number of the wedge-shaped lenses is two, the wedge angles of the two wedge-shaped lenses are set to be consistent.

[0067] Specifically, a wedge lens is an optical lens with a certain wedge angle. When light passes through the wedge lens, due to the principle of light refraction, the light will be deflected, thereby changing the propagation direction of the light. If there are two wedge lenses, each wedge lens can rotate independently.

[0068] Furthermore, when two wedge-shaped lenses are used, the maximum optical axis adjustment range of the double wedge-shaped mirror should be calculated according to the parallelism error of the mounting surface of the total reflector and output mirror of the lens barrel according to the following formula:

[0069]

[0070] Among them, θ max is the maximum optical axis adjustment range, n is the refractive index of the wedge mirror, and θ is the apex angle of the wedge mirror.

[0071] Specifically, the wedge mirror can change the transmission direction of light by rotating around the optical axis, so that the central axis of the outgoing light beam can be continuously adjusted within a cone angle. The required adjustment cone angle range should be calculated based on the parallelism error of the mounting surfaces of the total reflector and the output mirror of the lens barrel.

[0072] Furthermore, the light-transmitting surface of the wedge-shaped mirror is coated with a film that increases the transmittance of pump light, signal light and idler light.

[0073] Furthermore, one side of the output mirror cavity is coated with a film that increases the transmittance of pump light and idler light and partially reflects signal light, and one side outside the cavity is coated with a film that increases the transmittance of pump light, signal light and idler light.

[0074] Specifically, the output mirror is an optical lens with a surface coating, and the surface shapes of the front and rear surfaces are both spherical surfaces with the same curvature.

[0075] Specifically, if the total reflection mirror, wedge mirror, and output mirror are made of lens materials that have an absorption effect on idler light, the increase in transmittance of idler light can be ignored during lens coating.

[0076] The laser damage threshold of the above coatings should be reasonably designed according to the actual laser power density.

[0077] Further, such as Figure 3 and Figure 4 As shown, the front lens barrel comprises: a first cylindrical lens barrel, a first lens mounting groove 52, a crystal mounting groove 53 and a connecting flange 59;

[0078] The lens mounting groove is located at the front end of the first cylindrical lens barrel and is used to mount the total reflection mirror. The crystal mounting groove is located in the middle of the first cylindrical lens barrel and is used to place the nonlinear crystal. The rear end of the first cylindrical lens barrel has a connecting flange for connecting the rear lens barrel.

[0079] Specifically, the front lens barrel further includes: a first lens glue injection port 51, a crystal glue injection port 57, a lens barrel mounting foot 54, a stress relief groove 55, and a mounting hole 56;

[0080] The first lens mounting groove is provided with a first lens glue injection port, and the crystal mounting groove is provided with 8 crystal glue injection ports, which can facilitate glue dispensing and allow the glue to flow into the contact surface between the lens and the lens barrel, and are respectively used to fix the total reflection mirror and the nonlinear crystal. The lens barrel mounting foot is located on the bottom outer wall of the first cylindrical lens barrel, and is used to connect with other external devices. The lens barrel mounting foot is also provided with a mounting hole and a stress relief groove. The mounting hole fixes the optical parametric oscillator and other devices together, and the stress relief groove is used to reduce the stress caused by the insufficient flatness of the mounting surface and the local protrusion against the lens barrel.

[0081] Specifically, the front lens barrel and the rear lens barrel can be an integral structure or designed as a split structure as required. If designed as a split structure, a V-shaped groove 58, a glue injection hole and other mechanisms are required at the root of the connecting flange, and a set screw is used for initial fixation and a glue bonding method is used for final fixation to enhance the convenience and reliability of the assembly process.

[0082] Further, such as Figure 5 As shown, the rear lens barrel includes: a second cylindrical lens barrel, a second lens mounting groove 72, a mounting limiter 73, and an edge adjustment groove 76;

[0083] The second lens mounting groove is located at the rear end of the second cylindrical lens barrel and is used to install the output mirror. Two adjacent edge-wrapping adjustment grooves are set at the middle and rear positions of the lens barrel of the second cylindrical lens barrel. An installation limit is set inside the lens barrel of the second cylindrical lens barrel and in the middle of the two edge-wrapping adjustment grooves. The edge wraps of two wedge-shaped mirrors are placed on both sides of the installation limit, and each wedge-shaped mirror edge wrap corresponds to an edge wrap adjustment groove; the wedge-shaped mirror is adjusted by the edge wrap adjustment groove to change the direction of the light beam, thereby compensating for the installation tilt error of the total reflection mirror and the output mirror.

[0084] Specifically, the rear lens barrel further includes: a plurality of second lens glue injection ports 71, a plurality of edge fixing holes 74, a plurality of edge glue injection ports 75, a plurality of lens barrel fixing holes 77, and a plurality of lens barrel glue injection ports 78;

[0085] The second lens mounting groove is provided with a plurality of second lens glue injection ports, and both sides of the mounting limit are provided with a plurality of edging glue injection ports. The front end of the rear lens barrel is provided with a plurality of lens barrel glue injection ports, which can facilitate glue dispensing and allow the glue to flow into the contact surface between the lens and the lens barrel, and are respectively used to fix the output mirror, the wedge-shaped mirror, and the connection between the front lens barrel and the rear lens barrel. The edging fixing holes are located on both sides of the mounting limit, and the edging of the wedge-shaped mirror is fixed with fixing screws. The lens barrel fixing holes are located at the front end of the rear lens barrel, and are fixed to the front lens barrel with fixing screws.

[0086] Specifically, the total reflection mirror, nonlinear crystal, and output mirror are directly fixed to the front lens barrel and the rear lens barrel by gluing. The corresponding positions of the lens barrel have a support surface and a circular groove, which can realize the mechanical positioning of the lens. After being installed in sequence, it can be guaranteed to be basically coaxial by relying on the machining accuracy. Through the bonding method, the reliability in high and low temperature and vibration environments can be guaranteed.

[0087] Specifically, the wedge mirror is first bonded to the wedge mirror edging by glue, and then installed in the rear lens barrel. The wedge mirror edging has a limiting leaning surface, which can position the wedge mirror by mechanical leaning. The rear lens barrel has an installation limiting structure, which can position the wedge mirror with edging by mechanical leaning, ensuring that the position in the rear lens barrel is correct and does not shift. The wedge mirror edging has a V-groove, which can be fixed in the rear lens barrel with a set screw to complete the initial fixation. The corresponding position of the lens barrel has a glue injection hole, which can be glued and fixed to the edging and the lens barrel to complete the final fixation and ensure reliability.

[0088] Exemplarily, in this embodiment, two wedge mirrors are selected, and the nonlinear crystal is a KTP crystal cut along the X-axis. When the electric vector direction of the incident linearly polarized pump light is parallel to the Y-axis and the energy density of the incident pump light reaches the conversion threshold, the optical parametric oscillation conversion process can begin. The pump light wavelength is 1.06 μm, which is converted into 1.57 μm signal light and 3.29 μm idler light in the nonlinear crystal. It is also applicable to other wavelengths, and some design parameters need to be modified, which will not be discussed in this embodiment.

[0089] According to experience, the magnification M of the unstable cavity is selected as 1.4 times, the length of the resonant cavity is selected as L = 30mm, and the curvature radius of one side of the total reflection mirror cavity is calculated according to the curvature of the unstable cavity mirror to be R1 = 210mm, and the curvature radius of one side of the output mirror cavity is R2 = -150mm.

[0090] The side of the total reflection mirror away from the nonlinear crystal is coated with a 1.06μm anti-reflection film, and the side close to the nonlinear crystal is coated with a 1.06μm anti-reflection film and a 1.57μm total reflection film. The lens material is H-K9L, which has a strong absorption effect on light with a wavelength above 2μm, that is, 3.29μm idle frequency light is absorbed.

[0091] The two light-transmitting end faces of the nonlinear crystal are plated with 1.06 μm and 1.57 μm antireflection films.

[0092] The wedge angle of the wedge mirror is 1 minute, the light-transmitting surface is coated with 1.06μm and 1.57μm anti-reflection films, and the material used is H-K9L.

[0093] The output mirror is coated with 1.06μm and 1.57μm anti-reflection films on the side away from the nonlinear crystal, and 1.57μm partial reflection film and 1.06μm anti-reflection film on the side close to the nonlinear crystal. The lens material is H-K9L. The partial reflectivity of the inner surface of the output mirror (the surface close to the nonlinear crystal) has two functions. One is to reflect a part of the 1.57μm signal light to form feedback and maintain oscillation; the other is to transmit another part of the 1.57μm signal light. The transmitted 1.57μm signal light passes through the output mirror material to the second surface (the surface away from the nonlinear crystal). At this time, it only needs to increase the transmittance as much as possible to allow the 1.57μm signal light to pass through.

[0094] All coating requirements mentioned in this application include an anti-reflection coating for 1.06 μm, because the laser of this wavelength is required to propagate in one direction to avoid reflection.

[0095] In this embodiment, the entire assembly should be installed in accordance with the following steps.

[0096] S1. The nonlinear crystal 2 is installed in the crystal installation groove 53 of the front lens barrel 5. Optical glue is injected from the crystal injection port 57. After the glue is cured, the total reflection mirror 1 is installed in the lens installation groove 52, and glue is injected from the lens injection port 51 to fix it;

[0097] S2. Install the two wedge mirrors 3 in the wedge mirror rim 6 and inject glue from the edge to fix them. Then install the bonded components in the rear lens barrel 7 so that they are attached to the installation limit 73 for positioning, and then use the set screws to lock and fix the wedge mirror rim 6 through the rim fixing holes 74;

[0098] S3. Install the output mirror 4 in the lens mounting groove 72 of the rear lens barrel 7, and inject glue from the lens injection port 71 to fix it;

[0099] S4. The rear lens barrel 7 is connected to the connecting flange 59 of the front lens barrel 5, and the set screws are installed in the lens barrel fixing holes 77, and are locked and fixed so that the front lens barrel 5 and the rear lens barrel 7 are connected as a whole;

[0100] S5. Couple the 1.06μm linearly polarized pump light from one end of the total reflection mirror 1 along the light transmission direction of the lens barrel into the nonlinear crystal 2. The direction of the polarized electric field component of the pump light is parallel to the Y-axis of the nonlinear crystal 2. Slightly loosen the set screw in the edge fixing hole 74 so that the wedge mirror edge 6 can rotate normally. Insert a screwdriver or other object into the edge adjustment slot 76 to move the wedge mirror edge 6 so that it drives the wedge mirror 3 to rotate around the optical axis. Repeatedly adjust the two wedge mirrors 3 to maximize the signal light energy and achieve the best beam quality. Then tighten the set screw installed in the edge fixing hole 74;

[0101] S6. After the overall debugging test is completed, glue is injected from the edge glue injection port 75 and the lens barrel glue injection port 78 to fix the lens. At this point, the debugging of the entire assembly is completed.

[0102] Compared with the prior art, an optical parametric oscillator provided in this embodiment uses a wedge mirror as an adjustment mechanism in a resonant cavity, which greatly optimizes the debugging process and enhances the overall stability of the resonant cavity. If a wedge mirror is not used, it is necessary to finely adjust the resonant cavity reflector, and it is necessary to consider how to intervene in the adjustment tooling and the tilting and moving of the lens during the fixing process, which is usually impossible to fix in a barrel manner. By bonding and fixing the total reflector, output mirror, nonlinear crystal, and wedge mirror to the front and rear barrels, the reliability and stability of working in different environments are improved. Using an unstable cavity as the optical parametric oscillator cavity type can provide a higher high-order mode loss, improve the quality of the optical parametric signal light beam, and reduce the divergence angle of the output signal light.

[0103] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0104] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An optical parametric oscillator, characterized in that: The oscillator comprises a total reflection mirror, a nonlinear crystal, a wedge mirror and an output mirror arranged in sequence along the optical axis; The pump light is transmitted to the nonlinear crystal through a total reflection mirror; The nonlinear crystal is used to perform optical parametric conversion to convert the received pump light into signal light; The wedge-shaped mirror can rotate freely around the optical axis to adjust the output direction of the light beam; The output mirror is used to couple the signal light out; The resonant cavity composed of the total reflection mirror and the output mirror is a virtual confocal unstable cavity. The total reflection mirror, the nonlinear crystal, the wedge mirror and the output mirror together form a complete resonant cavity.

2. An optical parametric oscillator according to claim 1, characterized in that: The wedge-shaped mirror comprises one or two wedge-shaped lenses. When the number of the wedge-shaped lenses is two, the wedge angles of the two wedge-shaped lenses are set to be consistent.

3. An optical parametric oscillator according to claim 2, characterized in that: When two wedge-shaped lenses are used, the maximum optical axis adjustment range of the double wedge mirror should be calculated according to the parallelism error of the mounting surface of the total reflector and output mirror of the lens barrel according to the following formula: Among them, θ max is the maximum optical axis adjustment range, n is the refractive index of the wedge mirror, and θ is the apex angle of the wedge mirror.

4. An optical parametric oscillator according to claim 3, characterized in that: The oscillator further comprises: a front lens barrel, a wedge-shaped lens edging, and a rear lens barrel; The nonlinear crystal is installed in the middle of the front lens barrel, and the total reflection mirror is installed at the front end of the front lens barrel; The wedge mirror is mounted on the wedge mirror edging; The wedge-shaped mirror edge is installed in the middle of the rear lens barrel, the front end of the rear lens barrel is connected to the rear end of the front lens barrel, and the output mirror is installed at the rear end of the rear lens barrel.

5. An optical parametric oscillator according to claim 4, characterized in that: The outer side of the total reflection mirror cavity is coated with a film that increases the transmittance of pump light and idler light, and the inner side of the cavity is coated with a film that increases the transmittance of pump light and idler light and fully reflects signal light.

6. An optical parametric oscillator according to claim 5, characterized in that: The light-transmitting surface of the nonlinear crystal is coated with a film which increases the transmittance of pump light, signal light and idler light.

7. An optical parametric oscillator according to claim 6, characterized in that: The light-transmitting surface of the wedge-shaped mirror is coated with a film which can enhance the transmittance of pump light, signal light and idler light.

8. An optical parametric oscillator according to claim 7, characterized in that: The inner side of the output mirror cavity is coated with a film which increases the transmittance of pump light and idle light and partially reflects the signal light, and the outer side of the cavity is coated with a film which increases the transmittance of pump light, signal light and idle light.

9. An optical parametric oscillator according to claim 4, characterized in that: The front lens barrel comprises: a first cylindrical lens barrel, a first lens mounting groove, a crystal mounting groove and a connecting flange; The lens mounting groove is located at the front end of the first cylindrical lens barrel and is used to mount the total reflection mirror. The crystal mounting groove is located in the middle of the first cylindrical lens barrel and is used to place the nonlinear crystal. The rear end of the first cylindrical lens barrel has a connecting flange for connecting the rear lens barrel.

10. An optical parametric oscillator according to claim 4, characterized in that: The rear lens barrel comprises: a second cylindrical lens barrel, a second lens mounting groove, a mounting limiter, and an edge adjustment groove; The second lens mounting groove is located at the rear end of the second cylindrical lens barrel and is used to install the output mirror. Two adjacent edge-wrapping adjustment grooves are set at the middle and rear positions of the lens barrel of the second cylindrical lens barrel. An installation limit is set inside the lens barrel of the second cylindrical lens barrel and in the middle of the two edge-wrapping adjustment grooves. The edge-wrapping of two wedge-shaped mirrors is placed on both sides of the installation limit, and each edge-wrapping of the wedge-shaped mirror corresponds to an edge-wrapping adjustment groove. The wedge-shaped mirror is adjusted by the edge-wrapping adjustment groove to change the direction of the light beam, thereby compensating for the installation tilt error of the total reflection mirror and the output mirror.

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