An optical parametric oscillator

Abstract

The application relates to an optical parametric oscillator and belongs to the technical field of optical parametric oscillators. The problems of low reliability of a laser, low quality of a laser beam, a large divergence angle and insufficient long-distance ranging in the prior art are solved. The oscillator comprises, in sequence along an optical axis, a total reflection mirror, a nonlinear crystal, a wedge-shaped mirror and an output mirror. Pump light is transmitted to the nonlinear crystal through the total reflection mirror. The nonlinear crystal is used for optical parametric conversion to convert the received pump light into signal light. The wedge-shaped mirror can rotate freely around the optical axis and is used for adjusting the output direction of the light beam. The output mirror is used for coupling 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-shaped mirror and the output mirror jointly form a complete resonant cavity. The signal light with high quality can be generated, the divergence angle of the emitted signal light is reduced, the long-distance ranging requirement is met, and the debugging process is greatly optimized by adjusting the wedge-shaped mirror.

Description

Technical Field

[0001] This invention relates to the field of optical parametric oscillator technology, and more particularly to an optical parametric oscillator. Background Technology

[0002] The optical parametric oscillator (OPO) of this invention is a nonlinear optical device that uses a nonlinear crystal as its working medium. In a typical OPO, three laser wavelengths are involved: generally, a short-wavelength laser beam is incident, generating two long-wavelength laser beams. The incident short-wavelength laser is called the pump light, and the two generated long-wavelength laser beams are called the signal light and the idler light, respectively. A typical OPO requires the working medium to be placed in a resonant cavity. Under the action of the pump light, a parametric conversion process occurs, and the oscillation of the resonant cavity forms a laser output with a wavelength different from the pump laser.

[0003] Optical parametric oscillators (OPOs) can be integrated into the pump resonant cavity to form an internal cavity OPO. This approach requires placing a nonlinear crystal within the pump resonant cavity and considering the oscillation requirements of the signal light in the coating of the resonant cavity mirrors to ensure stable oscillations of both the pump and signal lights. A typical example of this structure is described in patent CN 1123950C. Another type, external cavity OPO, offers greater structural flexibility compared to the internal cavity type. It allows the entire laser system to first generate a pump laser using an independent resonant cavity, and then couple the pump light into the OPO cavity to generate signal and idler light. A typical example of this structure is described in patent CN 1140024C.

[0004] Optical parametric oscillators (OPOs) are primarily used to generate new laser wavelengths. For example, in laser rangefinders, OPOs convert 1.06μm laser light into 1.57μm laser light. This wavelength of laser light can be absorbed by water molecules and, when it reaches the human eye, is converted into heat, thus preventing damage to the retina; this is known as an eye-safe laser. In current rangefinding applications, lasers suffer from low reliability, low beam quality, and large divergence angles, preventing the concentration of laser energy and hindering long-distance rangefinding. Summary of the Invention

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

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

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

[0008] The nonlinear crystal is used for optical parametric conversion, converting the received pump light into signal light;

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

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

[0011] The resonant cavity formed by 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 mirror includes one or two wedge lenses. When there are two wedge lenses, the wedge angles of the two wedge lenses are set to be the same.

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

[0014]

[0015] Where, θ max The maximum optical axis adjustment range is given by n, where n is the refractive index of the wedge mirror, and θ is the apex angle of the wedge mirror.

[0016] Furthermore, the oscillator also includes: a front lens barrel, a wedge-shaped lens rim, and a rear lens barrel;

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

[0018] The wedge-shaped mirror is mounted on the wedge-shaped mirror rim;

[0019] The wedge-shaped mirror is mounted on 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. The output mirror is installed at the rear end of the rear lens barrel.

[0020] Furthermore, the outer surface of the total reflection mirror cavity is coated with a film that reduces the transmittance of pump light and idler light, while the inner surface of the cavity is coated with a film that reduces the transmittance of pump light and idler light and reflects the total reflection of signal light.

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

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

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

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

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

[0027] The second lens mounting slot is located at the rear end of the second cylindrical lens barrel and is used to mount the output lens. Two adjacent bezel adjustment slots are provided at the rear position of the second cylindrical lens barrel. An installation limit is set inside the second cylindrical lens barrel and in the middle of the two bezel adjustment slots. Two wedge-shaped lens bezels are placed on both sides of the installation limit, and each wedge-shaped lens bezel corresponds to one bezel adjustment slot. By adjusting the wedge-shaped lens through the bezel adjustment slot, the beam direction is changed, thereby compensating for the installation tilt error of the total reflection mirror and the output lens.

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

[0029] 1. Using a wedge mirror as an optical path adjustment mechanism within the resonant cavity significantly optimizes the debugging process and enhances the overall stability of the resonant cavity. Without a wedge mirror, fine adjustment of the resonant cavity mirror is required, which necessitates consideration of how to intervene with the adjustment fixture and the tilting and movement during the lens fixing process. It is usually impossible to fix it using a mirror tube. In this application, the use of a wedge mirror allows for the adjustment of the beam direction, thereby enabling the fixed installation of the total reflection mirror, 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 mirror tubes, the reliability and stability of operation 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 beam, reduce the divergence angle of the emitted signal beam, and thus increase the ranging distance.

[0032] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0033] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0034] Figure 1 This is a schematic diagram of the optical path of an external cavity optical parametric oscillator.

[0035] Figure 2 This is an exploded view of an optical parametric oscillator device.

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

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

[0038] Figure 5 It is a rear-group lens tube structure.

[0039] Figure label:

[0040] 1-Total Reflection Mirror; 2-Nonlinear Crystal; 3-Wedge Mirror; 4-Output Mirror; 5-Front Group Tube; 6-Wedge Mirror Edge; 7-Rear Group Tube; 51-First Lens Injection Port; 52-First Lens Mounting Slot; 53-Crystal Mounting Slot; 54-Tube 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-Mounting Limit; 74-Edge Fitting Hole; 75-Edge Injection Port; 76-Edge Adjustment Slot; 77-Tube Fitting Hole; 78-Tube Injection Hole. Detailed Implementation

[0041] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form 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 intended to limit the scope of the present invention.

[0042] One specific embodiment of the present invention discloses an optical parametric oscillator, such as... Figure 1 As shown. The oscillator includes a total reflection mirror 1, a nonlinear crystal 2, a wedge mirror 3, and an output mirror 4 arranged sequentially 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 for optical parametric conversion, converting the received pump light into signal light;

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

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

[0047] The resonant cavity formed by 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 and amplifies repeatedly in the resonant cavity, gradually establishing a stable oscillation of the signal light. The idler light is directly output outside the cavity or is absorbed and lost by certain optical materials.

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

[0050]

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

[0052] Virtual confocal unstable cavities can suppress higher-order mode components in oscillations, generating high-quality signal light. Higher amplification in the unstable cavity leads to greater oscillation losses and a higher oscillation establishment threshold, thus requiring stronger pumping conditions. Furthermore, increasing the amplification can increase higher-order mode losses, making the modes within the cavity closer to the fundamental mode and improving the quality of the emitted laser beam.

[0053] The curvature of an unstable cavity endoscope is calculated as follows:

[0054]

[0055] 2L=R1+R2

[0056] Where 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 cavity length of the resonant cavity.

[0057] Furthermore, such as Figure 2 As shown, the oscillator also includes: a front lens barrel 5, a wedge-shaped lens rim 6, and a rear lens barrel 7;

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

[0059] The wedge-shaped mirror is mounted on the wedge-shaped mirror rim;

[0060] The wedge-shaped mirror is mounted on 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. The output mirror is installed at the rear end of the rear lens barrel.

[0061] Specifically, the wedge-shaped lens edging has several grooves for adjustment, and an edging adjustment groove is provided at the position corresponding to the rear lens barrel. After the wedge-shaped lens edging is installed into the rear lens barrel, the wedge-shaped lens edging can be rotated and adjusted from the outside through the edging adjustment groove.

[0062] Furthermore, the outer surface of the total reflection mirror cavity is coated with a film that reduces the transmittance of pump light and idler light, while the inner surface of the cavity is coated with a film that reduces the transmittance of pump light and idler light and reflects the total reflection of signal light.

[0063] Specifically, a 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 enhances the light transmission of pump light, signal light, and idler light.

[0065] Specifically, the nonlinear crystal can be PPLN, KTP, etc. The polarization direction of the incident pump light needs to be taken into account. The crystal is cut and placed according to a certain crystal axis direction and polarization direction to maximize the conversion efficiency.

[0066] Furthermore, the wedge mirror includes one or two wedge lenses. When there are two wedge lenses, the wedge angles of the two wedge lenses are set to be the same.

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

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

[0069]

[0070] Where, θ max The maximum optical axis adjustment range is given by n, where 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 direction of light transmission by rotating around the optical axis, allowing the central axis of its emitted beam to 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 reflection mirror and the output mirror.

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

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

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

[0075] Specifically, if the total reflection mirror, wedge mirror, and output mirror are made of lens materials that absorb idler frequency light, then the anti-reflection effect on idler frequency light can be ignored during lens coating.

[0076] The laser damage resistance threshold of the above-mentioned coating should be reasonably designed based on the actual laser power density.

[0077] Furthermore, such as Figure 3 and Figure 4 As shown, the front lens barrel includes: 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 slot is located at the front end of the first cylindrical lens barrel and is used to mount a total reflection mirror. The crystal mounting slot is located in the middle of the first cylindrical lens barrel and is used to place a nonlinear crystal. The rear end of the first cylindrical lens barrel has a connecting flange for connecting to the rear lens barrel.

[0079] Specifically, the front lens barrel also includes: a first lens glue injection port 51, a lens 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 slot has a first lens glue inlet, and the crystal mounting slot has eight crystal glue inlets for easy glue application, allowing the glue to flow between the contact surfaces of the lens and the lens barrel. These are used to fix the total reflection mirror and the nonlinear crystal, respectively. The lens barrel mounting feet are located on the bottom outer wall of the first cylindrical lens barrel for connection with other external devices. The lens barrel mounting feet are also provided with mounting holes and stress relief grooves. The mounting holes fix the optical parametric oscillator together with other devices, and the stress relief grooves are used to reduce the stress caused by insufficient flatness of the mounting surface and local protrusions hitting the lens barrel.

[0081] Specifically, the front and rear lens barrels can be an integral structure or designed as separate structures as needed. If designed as separate structures, a V-groove 58 and an injection hole should be provided at the root of the connecting flange. Initial fixing is achieved using set screws, and final fixing is achieved by adhesive bonding, which enhances the convenience and reliability of the assembly and adjustment process.

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

[0083] The second lens mounting slot is located at the rear end of the second cylindrical lens barrel and is used to mount the output lens. Two adjacent bezel adjustment slots are provided at the rear position of the second cylindrical lens barrel. An installation limit is set inside the second cylindrical lens barrel and in the middle of the two bezel adjustment slots. Two wedge-shaped lens bezels are placed on both sides of the installation limit, and each wedge-shaped lens bezel corresponds to one bezel adjustment slot. The wedge-shaped lens is adjusted by adjusting the bezel adjustment slot to change the beam direction, thereby compensating for the installation tilt error of the total reflection mirror and the output lens.

[0084] Specifically, the rear lens barrel also includes: a plurality of second lens glue injection ports 71, a plurality of edge binding and fastening holes 74, a plurality of edge binding glue injection ports 75, a plurality of lens barrel fastening holes 77, and a plurality of lens barrel glue injection ports 78.

[0085] The second lens mounting slot is provided with several second lens glue inlets, and several edge glue inlets are provided on both sides of the mounting limit. Several lens barrel glue inlets are provided at the front end of the rear lens barrel, which can facilitate glue application and allow the glue to flow into the contact surface between the lens and the lens barrel. These are used to fix the output lens, wedge lens, and the connection between the front and rear lens barrels, respectively. The edge fixing holes are located on both sides of the mounting limit, and the wedge lens edge is fixed with a set screw. The lens barrel fixing hole is located at the front end of the rear lens barrel, and is fixed with a set screw to the front lens barrel.

[0086] Specifically, the total reflection mirror, nonlinear crystal, and output mirror are directly fixed to the front and rear lens barrels by adhesive bonding. The lens barrels have corresponding surfaces and grooves for mechanical positioning of the lenses. After sequential installation, they are essentially coaxial thanks to machining precision. The adhesive bonding method ensures reliability under high and low temperature and vibration environments.

[0087] Specifically, the wedge-shaped lens is first glued to the wedge-shaped lens edging, and then installed inside the rear lens barrel. The wedge-shaped lens edging has a limiting surface, which can mechanically position the wedge-shaped lens. The rear lens barrel has an installation limiting structure, which allows the wedge-shaped lens with the edging to be mechanically positioned, ensuring correct positioning and preventing displacement within the rear lens barrel. The wedge-shaped lens edging has a V-groove, which can be engaged with a set screw to fix it inside the rear lens barrel, completing the initial fixation. A corresponding position on the lens barrel has an adhesive injection hole, which can be applied to glue the edging to the lens barrel, completing the final fixation and ensuring reliability.

[0088] For example, in this embodiment, two wedge mirrors are used, 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 a 1.57 μm signal light and a 3.29 μm idler light in the nonlinear crystal. This method is also applicable to other wavelengths, but requires modification of several design parameters, which will not be discussed in this embodiment.

[0089] Based on experience, the amplification factor M of the unstable cavity is selected as 1.4 times, the cavity length L = 30mm is selected, and the radius of curvature R1 of the inner surface of the total reflection mirror is calculated as 210mm based on the curvature of the cavity mirror, and the radius of curvature R2 of the inner surface of the output mirror is -150mm.

[0090] The total reflection mirror has a 1.06μm antireflection coating on the side away from the nonlinear crystal and a 1.06μm antireflection coating and a 1.57μm total reflection coating on the side closer to the nonlinear crystal. The lens material is H-K9L, which has a strong absorption effect on light with wavelengths above 2μm, that is, idler light of 3.29μm is absorbed.

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

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

[0093] The output mirror has 1.06μm and 1.57μm antireflective coatings on the side away from the nonlinear crystal, and a 1.57μm partial reflective coating and a 1.06μm antireflective coating on the side closer to the nonlinear crystal. The lens material is H-K9L. The partial reflectivity of the inner surface of the output mirror (the side closer to the nonlinear crystal) serves two purposes: first, it reflects a portion of the 1.57μm signal light to form feedback and maintain oscillation; second, it allows another portion of the 1.57μm signal light to pass through. The transmitted 1.57μm signal light passes through the output mirror material to the second side (the side away from the nonlinear crystal). At this point, it is only necessary to maximize the antireflection to allow the 1.57μm signal light to pass through.

[0094] All the coating requirements mentioned in this application include an antireflective coating for 1.06 μm because this wavelength of laser light needs to propagate unidirectionally to avoid reflection.

[0095] In this embodiment, the following steps should be followed when installing the entire component.

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

[0097] S2. Install the two wedge-shaped mirrors 3 into the wedge-shaped mirror edging 6 and inject glue from the edge to fix them. Then install the glued assembly into the rear mirror barrel 7, positioning it against the mounting limit 73, and then use set screws to lock and fix the wedge-shaped mirror edging 6 through the edging fixing hole 74;

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

[0099] S4. Connect the rear lens barrel 7 to the front lens barrel 5 with the connecting flange 59, and install the set screw in the lens barrel set hole 77 to lock and fix it, so that the front lens barrel 5 and the rear lens barrel 7 are connected as a whole.

[0100] S5. Couple 1.06μm linearly polarized pump light from one end of the total reflection mirror 1 into the nonlinear crystal 2 along the light transmission direction of the mirror tube. The polarization 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-locking hole 74 to allow the wedge-shaped mirror edge 6 to rotate normally. Insert a screwdriver or other object into the edge-locking adjustment slot 76 to move the wedge-shaped mirror edge 6, causing it to rotate the wedge-shaped mirror 3 around the optical axis. Repeatedly adjust the two wedge-shaped mirrors 3 to achieve the highest signal light energy and the best beam quality. Then tighten the set screw installed in the edge-locking hole 74.

[0101] S6. After the overall debugging and testing are completed, glue is injected and fixed through the edge glue injection port 75 and the lens barrel glue injection port 78 respectively, thus completing the debugging of the entire component.

[0102] Compared with existing technologies, the optical parametric oscillator provided in this embodiment uses a wedge mirror as an adjustment mechanism within the resonant cavity, which greatly optimizes the debugging process and enhances the overall stability of the resonant cavity. Without the wedge mirror, fine adjustment of the resonant cavity mirror is required, and consideration must be given to how to intervene with the adjustment fixture and the tilting and movement during the lens fixing process, which usually cannot be fixed by the mirror tube. By bonding and fixing the total reflection mirror, output mirror, nonlinear crystal, and wedge mirror to the front and rear mirror tubes, the reliability and stability of working in different environments are improved. Using an unstable cavity as the optical parametric oscillation cavity type can provide higher high-order mode loss, improve the beam quality of the optical parametric signal light, and reduce the divergence angle of the emitted signal light.

[0103] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0104] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical parametric oscillator, characterized in that, The oscillator includes a total reflection mirror, a nonlinear crystal, a wedge mirror, and an output mirror arranged sequentially along the optical axis; The pump light is transmitted to the nonlinear crystal through a total reflection mirror; The nonlinear crystal is used for optical parametric conversion, converting the received pump light into signal light; The wedge mirror, located between the nonlinear crystal and the output mirror, can rotate freely around the optical axis and is used to adjust the beam output direction; the wedge mirror includes one or two wedge mirrors, and when there are two wedge mirrors, the wedge angles of the two wedge mirrors are set to be the same; The output mirror is used to couple the signal light out. The resonant cavity formed by 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. The oscillator also includes: a front lens barrel, a wedge-shaped lens rim, and a rear lens barrel; The nonlinear crystal is mounted in the middle of the front lens barrel, and the total reflection mirror is mounted at the front end of the front lens barrel. The wedge-shaped mirror is mounted on the wedge-shaped mirror rim; The wedge-shaped lens is mounted on 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 lens is mounted on the rear end of the rear lens barrel. The rear lens barrel includes: a second cylindrical lens barrel, a second lens mounting groove, a mounting limit, and an edge adjustment groove; The second lens mounting slot is located at the rear end of the second cylindrical lens barrel and is used to mount the output lens. Two adjacent bezel adjustment slots are provided at the rear position of the second cylindrical lens barrel. An installation limit is provided inside the second cylindrical lens barrel and in the middle of the two bezel adjustment slots. Two wedge-shaped lens bezels are placed on both sides of the installation limit, and each wedge-shaped lens bezel corresponds to one bezel adjustment slot. By adjusting the wedge-shaped lens through the bezel adjustment slot, the beam direction is changed, thereby compensating for the installation tilt error of the total reflection mirror and the output lens. The rear lens barrel also includes: several second lens glue inlets, several edge binding and fastening holes, several edge glue inlets, several lens barrel fastening holes, and several lens barrel glue inlets.

2. The optical parametric oscillator according to claim 1, characterized in that, When two wedge lenses are selected, the maximum optical axis adjustment range of the double wedge lens should be calculated according to the parallelism error of the mounting surfaces of the total reflection mirror and the output mirror, using the following formula: in, Where n is the maximum optical axis adjustment range, and n is the refractive index of the wedge mirror. The apex angle of the wedge mirror.

3. The optical parametric oscillator according to claim 2, characterized in that, The outer side of the total reflection mirror cavity is coated with a film that reduces the transmittance of pump light and idler light, while the inner side of the cavity is coated with a film that reduces the transmittance of pump light and idler light and reflects the total reflection of signal light.

4. The optical parametric oscillator according to claim 3, characterized in that, The nonlinear crystal's light-transmitting surface is coated with a film that enhances the light transmission of pump light, signal light, and idler light.

5. An optical parametric oscillator according to claim 4, characterized in that, The light-transmitting surface of the wedge-shaped mirror is coated with a film that reduces the light transmission of pump light, signal light, and idler light.

6. An optical parametric oscillator according to claim 5, characterized in that, The inner 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, while the outer side of the cavity is coated with a film that increases the transmittance of pump light, signal light and idler light.

7. An optical parametric oscillator according to claim 2, characterized in that, The front lens barrel includes: a first cylindrical lens barrel, a first lens mounting slot, a crystal mounting slot, and a connecting flange; The lens mounting slot is located at the front end of the first cylindrical lens barrel and is used to mount a total reflection mirror. The crystal mounting slot is located in the middle of the first cylindrical lens barrel and is used to place a nonlinear crystal. The rear end of the first cylindrical lens barrel has a connecting flange for connecting to the rear lens barrel.

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