10-12μm Tunable Diamond Raman Laser and Threshold Reduction Method

Abstract

This invention belongs to the field of laser technology. It proposes a 10-12 μm tunable diamond Raman laser and a threshold reduction method. A pulsed laser emission system emits a 2.1 μm pulsed laser, which is split into a reflection path and a transmission path by a first polarizer. The reflection path sequentially includes a second half-wave plate, a second polarizer, a first reflecting mirror, and a ring resonator, which outputs a 4.29-4.62 μm laser. The transmission path sequentially includes a third reflecting mirror and a parallel plane cavity, which outputs a 10-12 μm laser. Both types of lasers are injected into the diamond ring cavity via a second and a fourth reflecting mirror, respectively, generating a 10-12 μm tunable diamond Raman laser. This invention utilizes the first-order Raman effect of diamond crystal to obtain long-wave infrared laser in this band, solving the problems of high threshold and low conversion efficiency in existing diamond lasers outputting this laser.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a 10-12μm tunable diamond Raman laser and a threshold reduction method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Long-wave infrared lasers in the 10-12 μm band fall within the atmospheric transmission window, where the effects of atmospheric molecular absorption and aerosol scattering are significantly reduced, resulting in excellent long-distance transmission stability. This makes them a core light source in many key technological fields. In laser spectroscopy, they can be used to analyze the vibrational and rotational energy levels of molecules, enabling high-precision structural analysis. In atmospheric environmental monitoring, they can detect specific trace gas components, supporting environmental quality assessment. In optoelectronic countermeasures, they can meet the technical requirements for long-range target detection and jamming. Furthermore, this band of lasers is widely used in laser precision machining, laser medicine, and differential absorption radar, providing fundamental support for technological breakthroughs in these fields. As the performance requirements of various applications continue to increase, the demand for 10-12 μm lasers in terms of tunability, output stability, and energy utilization efficiency continues to grow. Developing more adaptable 10-12 μm tunable laser technology has become an important research direction in the field of laser technology.

[0004] Current technologies for obtaining 10-12 μm long-wavelength infrared lasers all have significant shortcomings: traditional CO2 gas lasers, while achieving a certain power output, suffer from limited wavelength adjustment and large overall size, making them unsuitable for miniaturized and integrated applications; quantum cascade lasers, despite their compact size, have low peak power, failing to meet the demands for high-power pulsed lasers; and while nonlinear frequency conversion technology is currently the mainstream approach, its limitations in thermal stability and nonlinear optical properties of long-wavelength infrared crystals make it difficult to simultaneously achieve high power output and long-term stable operation. Even research attempting to develop lasers in this band using the Raman effect of diamond crystals faces key technical bottlenecks: insufficient energy matching between pump and seed light prevents the formation of an efficient energy transfer path; the lack of effective control over the polarization state of the light leads to significant energy loss during laser conversion; and the mismatch between the resonant cavity's structural design and wavelength output requirements hinders stable generation of the target wavelength laser, ultimately resulting in a high overall pump threshold and low conversion efficiency, failing to meet the practical application requirements of 10-12 μm tunable lasers. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a 10-12μm tunable diamond Raman laser and a threshold reduction method. Leveraging the advantage of diamond crystal having the largest Raman frequency shift coefficient, a tunable output 4.29-4.62μm mid-wave laser is used to pump the diamond Raman resonator. A tunable output 10-12μm long-wave infrared laser is obtained in the diamond crystal through the first-order Raman effect, solving the problems of high threshold and low conversion efficiency faced by existing diamond lasers outputting 10-12μm long-wave infrared lasers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a 10-12μm tunable diamond Raman laser.

[0008] A 10-12μm tunable diamond Raman laser includes: a pulsed laser emitting system, a first half-wave plate, a first polarizer, a second half-wave plate, a second polarizer, a first mirror, a ring resonant cavity, a single-frequency continuous light laser, a second mirror, a plano-convex mirror, a third mirror, a parallel plane cavity, a fourth mirror, and a diamond ring cavity.

[0009] The pulsed laser emitting system is used to emit 2.1μm pulsed laser. A first half-wave plate and a first polarizer are arranged sequentially along the emission direction of the 2.1μm pulsed laser. The first polarizer is used to split the 2.1μm pulsed laser into reflected light and transmitted light.

[0010] The reflected light path is arranged with a second half-wave plate, a second polarizer, a first reflecting mirror and a ring resonant cavity in sequence. The ring resonant cavity is used to output 4.29-4.62μm laser light. The transmitted light path is arranged with a third reflecting mirror and a parallel plane cavity in sequence. The parallel plane cavity is used to output 10-12μm seed light.

[0011] A 4.29-4.62 μm laser and a 10-12 μm seed light are injected into the diamond ring cavity through the second and fourth mirrors, respectively, to generate a 10-12 μm tunable diamond Raman laser.

[0012] In one implementation of the first aspect of the present invention, the ring resonator is a ZGP-OPO ring resonator, and the parallel plane cavity is a ZGP-OPO parallel plane cavity. By adjusting the actual output laser wavelength of the ZGP-OPO ring resonator and the actual output laser wavelength of the ZGP-OPO parallel plane cavity, the output wavelength of the diamond ring cavity is tuned in the range of 10-12μm.

[0013] As a further limitation of the first aspect of the present invention, the pulsed laser emission system is a 2.1μm Ho:YAG MOPA pulsed laser system, wherein the first half-wave plate and the first polarizer are used to control the power of the reflected light and the transmitted light; the second half-wave plate and the second polarizer are used to ensure that the light input to the ZGP-OPO ring resonator by the 2.1μm Ho:YAG MOPA laser system is p-polarized light.

[0014] As a further limitation of the first aspect of the present invention, the ZGP-OPO ring resonator is a four-cavity mirror ring cavity, including: a first input mirror, a fifth reflecting mirror, a sixth reflecting mirror, a first output mirror, and a first ZGP crystal; the first ZGP crystal is arranged in the optical path between the first input mirror and the fifth reflecting mirror, and the cavity mirrors in the ZGP-OPO ring resonator are all plane mirrors; the 2.1μm pump light is incident from the first input mirror, and after multiple round trips between the first input mirror and the second output mirror via the fifth reflecting mirror and the sixth reflecting mirror, it is finally output at the first output mirror.

[0015] As a further limitation of the first aspect of the present invention, the first input mirror, the fifth reflecting mirror, and the sixth reflecting mirror in the ZGP-OPO ring resonant cavity have high transmittance for p-polarized light of 2.1μm and high reflectance for s-polarized light of 4.29-4.62μm.

[0016] The first output mirror has high transmittance for p-polarized light at 2.1 μm and partial transmittance for s-polarized light in the range of 4.29–4.62 μm.

[0017] As a further limitation of the first aspect of the present invention, the first output mirror receives the output light of the 4.29-4.62μm single-frequency continuous-wave laser and compresses the linewidth of the 4.29-4.62μm laser output from the ZGP-OPO ring resonator through the single-frequency continuous-wave seed.

[0018] In one implementation of the first aspect of the present invention, the cavity mirrors in the parallel planar cavity are all planar mirrors, including: a second input mirror, a second ZGP crystal, and a second output mirror, wherein the second ZGP crystal is located in the optical path between the second input mirror and the second output mirror;

[0019] The second input mirror has high transmittance at 2.1μm and high reflectance at 10-12μm; the second output mirror has high reflectance at 2.1μm and partial transmittance at 10-12μm.

[0020] In one implementation of the first aspect of the present invention, the diamond annular cavity is a three-cavity mirror annular cavity, and the diamond integrally follows... <111> Axial cutting, with the end face cut along Brewster's angle.

[0021] As a further definition of the first aspect of the present invention, the diamond annular cavity includes: a third input mirror, a diamond crystal, a seventh reflecting mirror, and a third output mirror; the third input mirror and the seventh reflecting mirror are plano-concave mirrors, and the third output mirror is a plane mirror;

[0022] The 4.29-4.62μm laser light reflected by the second mirror passes through a plano-convex mirror, is focused, and is incident on the third input mirror. The diamond crystal is located in the optical path between the third input mirror and the seventh mirror.

[0023] The third input mirror has high transmittance for 4.29-4.62μm and high reflectance for 10-12μm; the seventh reflecting mirror has high transmittance for 4.29-4.62μm and high reflectance for 10-12μm.

[0024] Secondly, the present invention provides a threshold reduction method.

[0025] A threshold reduction method, utilizing a 10-12 μm tunable diamond Raman laser of the first aspect of the present invention, includes the following steps:

[0026] The pulsed laser system is activated, outputting a 2.1μm pulsed laser.

[0027] The first half-wave plate adjusts the polarization state of the 2.1μm pulsed laser. The first polarizer splits the 2.1μm pulsed laser into reflected light and transmitted light and controls the power ratio of the two optical paths.

[0028] The reflected light is processed sequentially by the second half-wave plate and the second polarizer to become 2.1μm p-polarized light, and then guided into the ring resonant cavity through the first mirror. At the same time, the laser output from the 4.29-4.62μm single-frequency continuous light laser is injected into the ring resonant cavity as seed light, so that the 2.1μm p-polarized light interacts with the first ZGP crystal to output 4.29-4.62μm laser light.

[0029] The transmitted light is guided into the parallel plane cavity through the third reflecting mirror, and interacts with the second ZGP crystal in the parallel plane cavity to output a seed light of 10-12μm; the 4.29-4.62μm laser is focused by a plano-convex mirror and then guided into the diamond ring cavity along with the 10-12μm seed light.

[0030] The diamond ring cavity outputs 10-12μm laser light.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This invention innovatively develops a 10-12μm tunable diamond Raman laser. Leveraging the advantage of diamond crystal having the largest Raman frequency shift coefficient, a tunable 4.29-4.62μm mid-wave laser is used to pump the diamond Raman resonator. A tunable 10-12μm long-wave infrared laser is obtained in the diamond crystal through the first-order Raman effect. This solves the problems of high threshold and low conversion efficiency faced by existing diamond lasers outputting 10-12μm long-wave infrared lasers. It overcomes the limitations of traditional technologies that restrict laser wavelength tuning and rely on specific crystal properties, effectively improving laser conversion efficiency and avoiding problems such as output power attenuation and poor equipment stability caused by low crystal thermal conductivity and insufficient damage threshold. This provides a completely new technical solution for the practical application of 10-12μm band lasers.

[0033] This invention innovatively designs a ring resonator seed injection scheme. By precisely introducing seed light, it significantly reduces the pump threshold of 10-12μm diamond Raman laser output, overcoming the defect of traditional seedless injection schemes that require high-power pumping to initiate laser conversion. A co-source pumping scheme is adopted, using the same 2.1μm Ho:YAG MOPA pulsed laser system as the pump source to generate the required pump source and seed source for the diamond Raman resonator, effectively improving their temporal consistency and avoiding energy transfer losses and unstable laser output caused by asynchrony between the pump source and seed source. An optimized scheme of single-frequency continuous mid-wave laser injection is used for the pump source. The narrow linewidth characteristic of the single-frequency seed light significantly compresses the spectral linewidth of the pump light, reducing mode competition within the resonator and further improving the conversion efficiency of the diamond Raman laser. Simultaneously, it avoids the problems of poor monochromaticity and low application adaptability caused by wide-linewidth lasers, ultimately achieving high-power, high-stability, and wide-tuning-range output of 10-12μm long-wave infrared laser.

[0034] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 A schematic diagram of a 10-12μm tunable diamond Raman laser provided as an exemplary embodiment of the present invention;

[0037] Among them, 1-1, 2.1μm Ho: YAG MOPA pulsed laser system; 1-2, First half-wave plate; 1-3, First polarizer; 1-4, Second half-wave plate; 1-5, Second polarizer; 1-6, First mirror; 1-7, Third mirror; 2, ZGP-OPO ring resonator; 3-1, First input mirror; 3-2, Fifth mirror; 3-3, Sixth mirror; 3-4, First output mirror; 3-5, First ZGP crystal; 3-6, 4.29-4.62μm continuous light laser; 3-7, Second mirror; 3-8, Plano-convex mirror; 4, ZGP-OPO parallel planar cavity; 5-1, Second input mirror; 5-2, Second ZGP crystal; 5-3, Second output mirror; 5-4, Fourth mirror; 6, Diamond ring cavity; 7-1, Third input mirror; 7-2, Diamond crystal; 7-3, Seventh mirror; 7-4, Third output mirror; 8, Power meter. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] Diamond crystals exhibit high transmittance from the ultraviolet to long-wave infrared range. They can be pumped using mid-wave infrared lasers (4.29 μm–4.62 μm) to produce tunable long-wave infrared lasers (10 μm–12 μm) through the first-order Raman effect alone. Diamond also possesses extremely high thermal conductivity, a high damage threshold, and the largest Raman frequency shift coefficient among known crystal materials. Therefore, tunable long-wave infrared lasers (10–12 μm) can be output via first-order Raman spectroscopy. However, challenges such as high damage threshold and low conversion efficiency need to be overcome. To address these issues, this implementation proposes a tunable 10–12 μm diamond Raman laser, such as… Figure 1 As shown, it includes: a 2.1μm Ho:YAG MOPA pulsed laser system 1-1, a first half-wave plate 1-2 (used to adjust the polarization state of the 2.1μm light), a first polarizer 1-3, a second half-wave plate 1-4, a second polarizer 1-5, a first mirror 1-6, a ZGP-OPO ring resonator 2 (i.e., a zinc germanium phosphorus optical parametric oscillator ring resonator), a 4.29-4.62μm continuous light laser 3-6, a second mirror 3-7, a third mirror 1-7, a ZGP-OPO parallel plane cavity 4, a fourth mirror 5-4, and a diamond ring cavity 6.

[0041] In this implementation, the 2.1μm Ho:YAG MOPA pulsed laser system 1-1 is used to emit 2.1μm pulsed laser. The first half-wave plate 1-2 and the first polarizer 1-3 are arranged sequentially along the transmission direction of the 2.1μm pulsed laser. The first polarizer 1-3 splits the laser into two paths (a reflected light path and a refracted light path, respectively).

[0042] The reflected laser light in the optical path passes sequentially through the second half-wave plate 1-4, the second polarizer 1-5, the first reflecting mirror 1-6 (changing the direction of the optical path and introducing the 2.1μm p-polarized light into the ZGP-OPO ring resonator 2), and then outputs 4.29-4.62μm laser light from the ZGP-OPO ring resonator 2.

[0043] The transmitted laser in the refracted optical path passes through the third reflecting mirror 1-7 and the ZGP-OPO parallel planar cavity 4 to output a 10-12μm laser. The 4.29-4.62μm laser and the 10-12μm seed light are injected into the diamond ring cavity through the second reflecting mirror 3-7 and the fourth reflecting mirror 5-4, respectively, generating a 10-12μm tunable diamond Raman laser in the diamond ring cavity. The final output 10-12μm laser is measured by the power meter 8.

[0044] In this implementation, the output wavelength of the diamond ring cavity 6 is tuned in the 10-12 μm range by adjusting the actual output laser wavelength of the ZGP-OPO ring resonator 2 and the actual output laser wavelength of the ZGP-OPO parallel planar cavity. Specifically, the ZGP crystals 3-5 in the ZGP-OPO ring resonator 2 are axially adjusted using a pitching mount, and the second ZGP crystal 5-2 in the ZGP-OPO parallel planar cavity 4 is axially adjusted using a pitching mount, thereby achieving tuning of the output wavelength between 4.29-4.62 μm and 10-12 μm.

[0045] In the implementation of this invention, the 4.29-4.62μm and 10-12μm lasers injected into the diamond annular cavity 6 are output from the ZGP-OPO annular resonant cavity 2 and the ZGP-OPO parallel planar cavity 4, respectively. Both are generated by the same source pumping of the 2.1μm Ho:YAG MOPA pulsed laser system 1-1. The same source pumping scheme is used to obtain the pump source and seed source of the diamond Raman resonant cavity, which improves the consistency in the time domain.

[0046] In this invention, the 2.1μm Ho:YAG MOPA pulsed laser system 1-1 is a multi-stage amplified laser system composed of a Tm:YLF solid-state laser double-pumped Ho:YAG crystal. Specifically, the two-stage amplified 2.1μm Ho:YAGMOPA pulsed laser system 1-1 can output a maximum energy of 10kHz and 300W, providing pump for subsequent optical paths.

[0047] In this implementation, the first half-wave plate 1-2 and the first polarizer 1-3 are used to control the power of the reflected and transmitted light to ensure that the output is "2.1μm p-polarized light"; the second half-wave plate 1-4 and the second polarizer 1-5 are used to ensure that the light input to the ZGP-OPO ring resonator 2 by the 2.1μm Ho:YAG MOPA pulsed laser system 1-1 is p-polarized, and the ZGP crystal 3-5 is used for type I phase matching.

[0048] In this implementation, preferably, the ZGP-OPO ring resonator 2 includes: a first input mirror 3-1, a fifth reflector 3-2, a sixth reflector 3-3, a first output mirror 3-4, and a first ZGP crystal 3-5, wherein the first ZGP crystal 3-5 is arranged in the optical path between the first input mirror 3-1 and the fifth reflector 3-2.

[0049] In this implementation, the mirrors of the ZGP-OPO ring resonator 2 are all plane mirrors, all placed at 45° (the first input mirror 3-1, the fifth reflector 3-2, the sixth reflector 3-3, and the first output mirror 3-4 are arranged vertically adjacent to each other in sequence, forming a rectangular or square space); the 2.1μm pump light is incident from the first input mirror, and after passing through the fifth reflector 3-2 and the sixth reflector 3-3 multiple times between the first input mirror 3-1 and the first output mirror 3-4, it is finally output at the first output mirror 3-4.

[0050] In this implementation, preferably, the first input mirror 3-1, the fifth reflecting mirror 3-2, and the sixth reflecting mirror 3-3 have high transmittance for 2.1μm p-polarized light (allowing 2.1μm p-polarized light to smoothly enter the ZGP-OPO ring resonant cavity 2 and irradiate the first ZGP crystal 3-5), the first input mirror 3-1, the fifth reflecting mirror 3-2, and the sixth reflecting mirror 3-3 have high reflectance for 4.29-4.62μm s-polarized light (allowing this wavelength generated by the first ZGP crystal 3-5 to oscillate and amplify back and forth in the cavity); the first output mirror has high transmittance for 2.1μm p-polarized light (expelling excess 2.1μm p-polarized light), and a transmittance of 50% for 4.29-4.62μm s-polarized light (the amplified 4.29-4.62μm laser is output from here).

[0051] In this implementation, a 4.29-4.62μm continuous light laser 3-6 inputs 4.29-4.62μm single-frequency continuous light as a seed source at the first output mirror 3-4 of the ZGP-OPO ring resonator 2.

[0052] Specifically, an MgO:PPLN laser is used as a single-frequency continuous light seed source; the MgO:PPLN laser is injected from the first output mirror 3-4 of the ZGP-OPO ring resonator 2, which reduces the output threshold of the ZGP-OPO ring resonator and compresses the output laser linewidth of 4.29-4.62μm, thereby reducing the output threshold of the diamond ring cavity.

[0053] In this implementation, the ZGP-OPO parallel planar cavity 4 includes a second input mirror 5-1, a second ZGP crystal 5-2, and a second output mirror 5-3 arranged sequentially along the optical path. The second input mirror 5-1, the second ZGP crystal 5-2, and the second output mirror 5-3 are all planar mirrors. The second input mirror 5-1 has high transmittance at 2.1μm (allowing pump light to enter the cavity) and high reflectance at 10-12μm (allowing the wavelength generated by the second ZGP crystal 5-2 to oscillate and amplify). The second output mirror 5-3 has high reflectance at 2.1μm (preventing pump light from interfering with the output) and partial transmittance at 10-12μm (amplified 10-12μm seed light output), which can achieve seed light output with a lower threshold.

[0054] In this implementation, the diamond annular cavity 6 includes a third input mirror 7-1, a diamond crystal 7-2, a seventh reflecting mirror 7-3, and a third output mirror 7-4. The diamond crystal 7-2 is arranged in the optical path between the third input mirror 7-1 and the seventh reflecting mirror 7-3. The third input mirror 7-1 and the seventh reflecting mirror 7-3 in the diamond annular cavity 6 are plano-concave mirrors with a focal length of 50mm. The third output mirror 7-4 is a plane mirror. The 4.29-4.62μm pump light reflected by the second reflecting mirror 3-7 is focused and incident after passing through the plano-convex mirror 3-8.

[0055] Specifically, the third input mirror 7-1 has high transmittance for 4.29-4.62μm (allowing pump light to enter the diamond crystal) and high reflectance for 10-12μm (allowing seed light and newly generated target laser to oscillate and amplify in the cavity); the seventh reflecting mirror 7-3 has high transmittance for 4.29-4.62μm (allowing excess pump light to pass through) and high reflectance for 10-12μm (allowing seed light and newly generated target laser to oscillate and amplify in the cavity); the third output mirror has a transmittance of 10-12μm of up to 2%-5% (preferably 2%, for the final 10-12μm target laser output); the focal length of the plano-concave mirrors used in the annular cavity (third input mirror 7-1 and seventh reflecting mirror 7-3) is up to 50mm.

[0056] In this implementation, more specifically, a diamond annular cavity 6 three-cavity mirror annular cavity is used, and a seed injection method is employed to reduce the output threshold. Specifically, a diamond monolithic edge is used. <111> Axial cutting is performed, with the end face cut along Brewster's angle. Before the diamond annular cavity 6 is incident in the 4.29-4.62μm band, a plano-convex lens 3-8 with a focal length of 75mm is used. The lens is coated before and after, and has high transmission in the 4.29-4.62μm band. The diamond crystal is placed at the focal point to reduce the threshold. With the energy supply of the 4.29-4.62μm pump light, the 10-12μm seed light is amplified through the first-order Raman effect to generate a tunable 10-12μm laser.

[0057] In this implementation, the refracted light path generates 10-12μm seed light. After being reflected by the fourth reflecting mirror 5-4, the 10-12μm seed light enters the diamond ring cavity through the third output mirror 7-4. After entering the diamond ring cavity 6, the 10-12μm seed light will oscillate in the diamond ring cavity 6 and interact with the 4.29-4.62μm pump light to generate more 10-12μm laser light, which is finally output through the third output mirror 7-4.

[0058] In this implementation, the diamond annular cavity 6 preferably uses a three-cavity mirror, which can reduce the cavity length while using the seed injection method, thereby further reducing the output threshold. It is understood that in some other implementations, other numbers of cavities can also be used, such as four-cavity mirrors or five-cavity mirrors, which will not be elaborated here.

[0059] Based on the aforementioned 10-12μm tunable diamond Raman laser, this implementation proposes a threshold reduction method, including the following process:

[0060] The 2.1μm Ho:YAG MOPA pulsed laser system is activated, outputting 2.1μm pulsed laser light;

[0061] The first half-wave plate adjusts the polarization state of the 2.1μm pulsed laser. The first polarizer splits the 2.1μm pulsed laser into reflected light and transmitted light and controls the power ratio of the two optical paths.

[0062] The reflected light is processed sequentially by the second half-wave plate and the second polarizer to become 2.1μm p-polarized light, and then guided into the ZGP-OPO ring resonator through the first mirror. At the same time, the laser output from the 4.29-4.62μm single-frequency continuous light laser is injected into the ZGP-OPO ring resonator as seed light, so that the 2.1μm p-polarized light interacts with the first ZGP crystal to output 4.29-4.62μm laser light.

[0063] The transmitted light is introduced into the ZGP-OPO parallel plane cavity through the third reflecting mirror, and interacts with the second ZGP crystal in the ZGP-OPO parallel plane cavity to output a seed light of 10-12μm; the 4.29-4.62μm laser is focused by a plano-convex mirror and then introduced into the diamond ring cavity along with the 10-12μm seed light.

[0064] The diamond ring cavity outputs 10-12μm laser light.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A 10-12 μm tunable diamond Raman laser, comprising: a pulsed laser emitting system, a first half-wave plate, a first polarizer, a second half-wave plate, a second polarizer, a first mirror, a ring resonator, a single-frequency continuous wave laser, a second mirror, a plano-convex mirror, a third mirror, a parallel plane cavity, a fourth mirror and a diamond ring cavity; the pulsed laser emitting system is configured to emit 2.1 μm pulsed laser, the first half-wave plate and the first polarizer are arranged in sequence along the direction of the 2.1 μm pulsed laser, and the first polarizer is configured to split the 2.1 μm pulsed laser into reflected light and transmitted light; the second half-wave plate, the second polarizer, the first mirror and the ring resonator are arranged in sequence on the light path of the reflected light, the ring resonator is configured to output 4.29-4.62 μm laser, the third mirror and the parallel plane cavity are arranged in sequence on the light path of the transmitted light, and the parallel plane cavity is configured to output 10-12 μm seed light; the 4.29-4.62 μm laser and the 10-12 μm seed light are injected into the diamond ring cavity through the second mirror and the fourth mirror respectively, and the diamond ring cavity is configured to generate 10-12 μm tunable diamond Raman laser. 2.The 10-12 μm tunable diamond Raman laser of claim 1, wherein the ring resonator is a ZGP-OPO ring resonator, the parallel plane cavity is a ZGP-OPO parallel plane cavity, and the output wavelength of the diamond ring cavity is tuned to be in the range of 10-12 μm by adjusting the actual output laser wavelength of the ZGP-OPO ring resonator and the actual output laser wavelength of the ZGP-OPO parallel plane cavity. 3.The 10-12 μm tunable diamond Raman laser of claim 2, wherein the pulsed laser emitting system is a 2.1 μm Ho: YAG MOPA pulsed laser system, the first half-wave plate and the first polarizer are configured to control the power of the reflected light and the transmitted light, and the second half-wave plate and the second polarizer are configured to make the light input into the ZGP-OPO ring resonator by the 2.1 μm Ho: YAG MOPA laser system be p-polarized light. 4.The 10-12 μm tunable diamond Raman laser of claim 2, wherein the ZGP-OPO ring resonator adopts a four-cavity mirror ring resonator, comprising: a first input mirror, a fifth mirror, a sixth mirror, a first output mirror and a first ZGP crystal, the first ZGP crystal is arranged on the light path between the first input mirror and the fifth mirror, the cavity mirrors in the ZGP-OPO ring resonator are all plane mirrors, and 2.1 μm pump light is incident from the first input mirror, transmitted back and forth between the first input mirror and the second output mirror through the fifth mirror and the sixth mirror multiple times, and finally output at the first output mirror. 5.The 10-12 μm tunable diamond Raman laser of claim 4, wherein the first input mirror, the fifth mirror and the sixth mirror in the ZGP-OPO ring resonator have high transmission for 2.1 μm p-polarized light and high reflection for 4.29-4.62 μm s-polarized light. ​ ​ ​ ​ ​ ​ ​ ​ ​ The first output mirror is high-transmissive to p-polarized light of 2.1 μm and partially transmissive to s-polarized light of 4.29-4.62 μm.

6. The 10-12 μm tunable diamond Raman laser of claim 4, wherein, The first output mirror receives output light of the 4.29-4.62 μm single-frequency continuous light laser, and the line width of the 4.29-4.62 μm laser output by the ZGP-OPO ring resonant cavity is compressed by the single-frequency continuous seed.

7. The 10-12 μm tunable diamond Raman laser of claim 1, wherein, The cavity mirrors in the parallel plane cavity are all plane mirrors, including a second input mirror, a second ZGP crystal and a second output mirror, and the second ZGP crystal is located on the light path between the second input mirror and the second output mirror. The second input mirror is high-transmissive to 2.1 μm and high-reflective to 10-12 μm, and the second output mirror is high-reflective to 2.1 μm and partially transmissive to 10-12 μm.

8. The 10-12 μm tunable diamond Raman laser of claim 1, wherein, The diamond ring cavity is a three-cavity mirror ring cavity, and the diamond is cut along the <111> axis and the end face is cut along the Brewster angle.

9. The 10-12 μm tunable diamond Raman laser of claim 8, wherein, The diamond ring cavity includes a third input mirror, a diamond crystal, a seventh mirror and a third output mirror, the third input mirror and the seventh mirror are plano-concave mirrors, and the third output mirror is a plane mirror. The 4.29-4.62 μm laser reflected by the second mirror passes through the plano-convex mirror, is focused to the third input mirror, and the diamond crystal is located on the light path between the third input mirror and the seventh mirror. The third input mirror is high-transmissive to 4.29-4.62 μm and high-reflective to 10-12 μm, and the seventh mirror is high-transmissive to 4.29-4.62 μm and high-reflective to 10-12 μm.

10. A threshold reduction method, characterized by, The 10-12 μm tunable diamond Raman laser of any one of claims 1-9 includes the following processes: Start the pulse laser system to output 2.1 μm pulse laser; The first half-wave plate adjusts the polarization state of the 2.1 μm pulse laser, and the first polarizer divides the 2.1 μm pulse laser into reflected light and transmitted light and controls the power ratio of the two lights; The reflected light is processed into p-polarized light of 2.1 μm after passing through the second half-wave plate and the second polarizer in turn, and then is introduced into the ring resonant cavity through the first mirror, and the laser output by the 4.29-4.62 μm single-frequency continuous light laser is injected into the ring resonant cavity as seed light, so that the p-polarized light of 2.1 μm interacts with the first ZGP crystal to output 4.29-4.62 μm laser; The transmitted light is introduced into the parallel plane cavity through the third mirror, interacts with the second ZGP crystal in the parallel plane cavity to output 10-12 μm seed light, and the 4.29-4.62 μm laser is focused by the plano-convex mirror and introduced into the diamond ring cavity with the 10-12 μm seed light; The diamond ring cavity outputs 10-12 μm laser.

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