Narrow-linewidth tunable raman laser and emission method

Abstract

The application discloses a narrow linewidth tunable Raman laser and an emission method, relates to the field of Raman lasers, and comprises a half-wave plate, a pump source and a focusing lens which are arranged on the two sides of the half-wave plate, a laser resonant cavity is arranged on the other side of the focusing lens, a cavity locking frequency doubler is arranged on the other side of the laser resonant cavity, a shaping lens group is arranged between the laser resonant cavity and the cavity locking frequency doubler, a dichroic mirror is arranged on the other side of the cavity locking frequency doubler, the laser resonant cavity is arranged in a V-shaped cavity structure which is composed of an input mirror, an output mirror and a reflective blazed grating, a diamond crystal is arranged between the input mirror and the output mirror, and the reflective blazed grating is arranged below the diamond crystal. The stability of the laser resonant cavity is improved through the design of the cavity mirror, the wavelength adjustment is accurate to 0.01 nm, and the loss in the transmission process is reduced through the cavity locking frequency doubler of the ring-shaped cavity structure.

Description

[0001] Method Domain

[0002] This invention relates to the field of Raman lasers, and in particular to a narrow-linewidth tunable Raman laser and its emission method.

[0003] Background Method

[0004] Visible lasers with narrow linewidths and tunable wavelengths have broad application prospects in fields such as lidar, metrology, and quantum physics. Currently, methods for obtaining tunable visible light wavelengths include optical parametric oscillation (OPO) and rare-earth ion radiation. However, OPO methods often result in linewidth broadening and beam degradation, while rare-earth ion radiation's wavelength output is limited by the fluorescence spectrum of the rare-earth ions themselves, making it difficult to achieve a large wavelength extension. With the development of nonlinear techniques, stimulated Raman scattering (SRS) induced by molecular vibrations in Raman media has become an important method for achieving large laser frequency conversions. Raman lasers based on SRS have many advantages: Raman frequency shifting can achieve laser output at wavelengths with vacant emission cross-sections of rare-earth ions; currently, Raman conversion has been used to achieve output from deep ultraviolet to mid-infrared; Raman frequency shifting is only related to the lattice vibration of the medium and is independent of the pump light frequency, so tuning the pump light frequency can obtain Raman light with the same frequency tuning range; Raman gain is proportional to the pump light intensity, without saturation effect or spatial hole burning effect, and the Raman laser output power directly depends on the pump light power, enabling energy conversion close to the quantum efficiency limit and narrow linewidth output.

[0005] Researchers have achieved Raman laser output through straight cavity and ring cavity lasers. However, at high power operation, the Raman medium in the resonant cavity absorbs residual pump light, generating a thermal effect that greatly interferes with the stability of the resonant cavity. At the same time, the Stokes return light cannot be separated from the pump light, causing it to return directly to the pump source position, which can easily damage it and affect its stability. Therefore, this greatly limits the improvement of Raman laser power and its application. In addition, there is an important demand for visible light Raman lasers with narrow linewidth and tunable wavelength range for space environment detection. However, it is difficult to achieve both narrow linewidth and visible light wavelength tunability simultaneously based on the nonlinear frequency conversion of traditional solid-state lasers.

[0006] Therefore, a narrow-linewidth tunable Raman laser and its emission method are provided to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a narrow-linewidth tunable Raman laser and its emission method, which reduces the need for optical isolators, improves the stability of the laser resonator, reduces losses during transmission, enables precise adjustment of the wavelength of the optical signal, reduces the linewidth of the output optical signal, and ultimately achieves narrow-linewidth tunable wavelength output.

[0008] To achieve the above objectives, the present invention provides a narrow-linewidth tunable Raman laser and an emission method thereof, comprising a half-wave plate and a pump source and a focusing lens respectively disposed on both sides of the half-wave plate. A laser resonant cavity is disposed on the other side of the focusing lens, and a cavity-locked frequency multiplier is disposed on the other side of the laser resonant cavity. A shaping lens group is disposed between the laser resonant cavity and the cavity-locked frequency multiplier. A dichroic mirror is disposed on the other side of the cavity-locked frequency multiplier. The laser resonant cavity is configured as a V-shaped cavity structure consisting of an input mirror, an output mirror, and a reflective blazed grating. A diamond crystal is disposed between the input mirror and the output mirror, and the reflective blazed grating is disposed below the diamond crystal.

[0009] Preferably, the cavity multiplier includes a frequency multiplier crystal and a second cavity reflector and a cavity output mirror symmetrically arranged on both sides of the frequency multiplier crystal. A cavity input mirror is arranged above the second cavity reflector, and a first cavity reflector is arranged above the cavity output mirror. The cavity input mirror and the first cavity reflector are symmetrically arranged according to the frequency multiplier crystal.

[0010] Preferably, the shaping lens group includes two convex lenses, the surfaces of which are coated with a broadband dielectric film that highly transmits Stokes light, and the wavelength range of the Stokes light is set to 1.18-1.26 μm.

[0011] Preferably, the surface of the focusing lens is coated with a broadband dielectric film that enhances the transmission of pump light, and the wavelength range of the pump light is set to 1.02-1.08 μm. The surface of the dichroic mirror is coated with a broadband dielectric film that highly reflects Stokes light and highly transmits second-order harmonic light, and the wavelength range of Stokes light is set to 1.18-1.26 μm, and the wavelength range of second-order harmonic light is set to 0.59-0.63 μm.

[0012] Preferably, the reflectivity of the input mirror, the reflectivity of the output mirror, and the reflectivity of the reflective blazed grating are all different. The input mirror is a plano-concave mirror with a radius of curvature of 50 mm. The flat surface of the input mirror is coated with a broadband dielectric film that enhances the transmission of pump light, and the concave surface of the input mirror is coated with a broadband dielectric film that has a Stokes light reflectivity greater than 99.9%. The wavelength range of the Stokes light is set to 1.18-1.26 μm. The output mirror is a plano-concave mirror with a radius of curvature of 100 mm. The output mirror has a concave surface coated with a broadband dielectric film that has a pump light reflectivity greater than 99.9% and a Stokes light transmittance of 0.1%-0.5%. The flat surface of the output mirror is coated with a broadband dielectric film that transmits Stokes light. The wavelength range of the Stokes light is set to 1.18-1.26 μm. The reflective blazed grating has a reflectivity greater than 99.9% and a reflection band set to 1.18-1.26 μm. The reflective blazed grating has a plurality of grating lines.

[0013] Preferably, the diamond crystal is a synthetic diamond crystal cut along the diagonal axis of the face, and the dimensions of the diamond crystal are 7×4×1.2mm. 3 The diamond crystal has a wide-bandgap dielectric film with a transmittance of more than 99.5% for pump light and Stokes light on both sides. The wavelength range of the pump light is set to 1.02-1.08 μm and the wavelength range of the Stokes light is set to 1.18-1.26 μm.

[0014] Preferably, the input mirror of the lock cavity is a plane mirror. The left side of the input mirror is coated with a broadband dielectric film that enhances the transmittance of Stokes light, with the wavelength range of Stokes light set to 1.18-1.26 μm. The right side of the input mirror is coated with a broadband dielectric film that has a transmittance of 2-4% for Stokes light, with the wavelength range of Stokes light set to 1.18-1.26 μm. The output mirror of the lock cavity is a plano-concave mirror with a radius of curvature of 100 mm. The concave surface of the output mirror is coated with a broadband dielectric film that has a reflectance of greater than 99.9% for Stokes light and a broadband dielectric film that has a transmittance of greater than 90% for frequency-doubled light, with the wavelength range of Stokes light set to 1.18-1.26 μm. The wavelength range is set to 0.59-0.63 μm. The plane of the lock cavity output mirror is coated with a broadband dielectric film with a transmittance of greater than 99.5% for frequency-doubled light, and the wavelength range of the frequency-doubled light is set to 0.59-0.63 μm. The first lock cavity reflector is a plane reflector, and its surface is coated with a broadband dielectric film with a reflectance of greater than 99.9% for Stokes light, and the wavelength range of Stokes light is set to 1.18-1.26 μm. The second lock cavity reflector is a plano-concave reflector with a radius of curvature of 100 mm, and its concave surface is coated with a broadband dielectric film with a reflectance of greater than 99.9% for Stokes light, and the wavelength range of Stokes light is set to 1.18-1.26 μm.

[0015] Preferably, the frequency doubling crystal is an LBO crystal, the LBO crystal has a cut angle of 90°, a temperature phase of 0°, and a size of 4×4×10mm. 3 The LBO crystal has a broadband dielectric film on both sides to enhance the transmission of Stokes light and frequency doubling light. The wavelength range of the Stokes light is set to 1.18-1.26μm, and the wavelength range of the frequency doubling light is set to 0.59-0.63μm.

[0016] Preferably, the emission method of a narrow-linewidth tunable Raman laser includes the following steps:

[0017] S1: The pump source emits pump light, which is coupled to the focusing lens after passing through a half-wave plate;

[0018] S2: The coupled pump light passes through the input mirror and enters the diamond crystal. The diamond crystal uses the SRS effect to convert the pump light into a Stokes light signal, adjusts the angle of the reflective blazed grating, and performs precise wavelength adjustment. The precision adjustment range is set to [0.01-0.1] nm.

[0019] S3: The Stokes optical signal passes through the output mirror and enters the shaping lens group, which couples the Stokes optical signal.

[0020] S4: The cavity-locked frequency multiplier multiplies the frequency of the coupled Stokes optical signal and outputs frequency-doubled light;

[0021] S5: The dichroic mirror separates the frequency-doubled light from the leaked Stokes light signal and outputs a narrow-linewidth visible laser.

[0022] Preferably, in step S1, both the first preset power and the first preset wavelength of the pump light can be tuned.

[0023] Therefore, the present invention, employing the above-described structure, provides a narrow-linewidth tunable Raman laser and its emission method, which offers the following advantages:

[0024] (1) By designing an intracavity reflector, the remaining pump light and Stokes light are separated at the reflector, reducing the coating requirements of the dichroic mirror and the requirements for the optical isolator, thereby improving the stability of the laser resonator.

[0025] (2) A reflective blazed grating is used as one of the cavity mirrors of the laser resonator to achieve wavelength adjustment accurate to 0.01 nm, enabling it to be applied in fields that require precision down to the relevant atomic energy level spectral lines;

[0026] (3) A cavity-locked frequency multiplier with a ring cavity structure is used to reduce the loss during transmission and effectively increase the length of the cavity-locked frequency multiplier, thereby reducing the linewidth of the output optical signal and achieving a narrow linewidth of 0.59-0.63μm tuned wavelength output.

[0027] The method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a structural diagram of a narrow-linewidth tunable Raman laser according to the present invention;

[0029] Figure 2 This is a structural diagram of a cavity-locked frequency multiplier for a narrow-linewidth tunable Raman laser according to the present invention;

[0030] Figure 3 This is a structural diagram of a reflective blazed grating for a narrow-linewidth tunable Raman laser according to the present invention.

[0031] The components are: 1. Pump source; 2. Half-wave plate; 3. Focusing lens; 4. Input mirror; 5. Diamond crystal; 6. Reflective blazed grating; 7. Output mirror; 8. Shaping lens group; 9. Cavity frequency multiplier; 91. Cavity input mirror; 92. First cavity reflector; 93. Second cavity reflector; 94. Frequency doubling crystal; 95. Cavity output mirror; 10. Dichroic mirror. Detailed Implementation

[0032] The method of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Unless otherwise defined, the methodological or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0034] The terms "comprising" or "including" as used in this invention mean that the element preceding the term encompasses the element listed after the term, and do not exclude the possibility of encompassing other elements. Terms such as "inner," "outer," "upper," and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. In this invention, unless otherwise explicitly specified and limited, the term "attached" and similar terms should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two elements or the interaction relationship between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] Example

[0036] like Figure 1 As shown, this invention provides a narrow-linewidth tunable Raman laser and its emission method, comprising a half-wave plate 2 and a pump source 1 and a focusing lens 3 respectively disposed on both sides of the half-wave plate 2. The pump source 1 is used to output a frequency of ω. P The pump light is linearly polarized and has a spectral linewidth of less than 0.1 nm. A half-wave plate 2 is used to adjust the polarization state of the pump light. A focusing lens 3 is used to focus the pump light signal into the crystal of the Raman laser. The surface of the focusing lens 3 is coated with a broadband dielectric film that prevents the pump light from passing through. The wavelength range of the pump light is set to 1.02-1.08 μm.

[0037] A laser resonant cavity is provided on the other side of the focusing lens 3, a cavity-locking frequency multiplier 9 is provided on the other side of the laser resonant cavity, a shaping lens group 8 is provided between the laser resonant cavity and the cavity-locking frequency multiplier 9, and a dichroic mirror 10 is provided on the other side of the cavity-locking frequency multiplier 9.

[0038] The shaping lens group 8 includes two convex lenses, both of which are coated with a broadband dielectric film that transmits Stokes light highly. The wavelength range of the Stokes light is set to 1.18-1.26 μm.

[0039] The surface of the dichroic mirror 10 is coated with a broadband dielectric film that has high reflectivity to Stokes light and high transmittance to frequency-doubled light. The wavelength range of the Stokes light is set to 1.18-1.26 μm, and the wavelength range of the frequency-doubled light is set to 0.59-0.63 μm.

[0040] The laser resonant cavity is configured as a V-shaped cavity structure consisting of an input mirror 4, an output mirror 7, and a reflective blazed grating 6. A diamond crystal 5 is disposed between the input mirror 4 and the output mirror 7, and the reflective blazed grating 6 is disposed below the diamond crystal 5.

[0041] The distance L1 between the input mirror 4 and the left side of the diamond crystal 5 is set to 25mm, the distance L2 between the right side of the diamond crystal 5 and the output mirror 7 is set to 98mm, and the distance L3 between the input mirror 4 and the reflective blazed grating 6 is set to 150mm. The distance L3 between the input mirror 4 and the reflective blazed grating 6 is adjustable, and the adjustment range is set to 40-400mm.

[0042] The reflectivity of the input mirror 4, the reflectivity of the output mirror 7, and the reflectivity of the reflective blazed grating 6 are all different. The input mirror 4 is a plano-concave mirror with a radius of curvature of 50 mm. The flat surface of the input mirror 4 is coated with a broadband dielectric film that enhances the transmission of pump light, and the concave surface of the input mirror 4 is coated with a broadband dielectric film that enhances the transmission of pump light. The concave surface of the input mirror 4 is coated with a broadband dielectric film with a reflectivity of greater than 99.9% for Stokes light. The wavelength range of Stokes light is set to 1.18-1.26 μm.

[0043] The output mirror 7 is a plano-concave reflector with a radius of curvature of 100 mm. The concave surface of the output mirror 7 is coated with a broadband dielectric film with a pump light reflectivity greater than 99.9% and a Stokes light transmittance of 0.1%-0.5%. The flat surface of the output mirror 7 is coated with a broadband dielectric film that transmits to the 1.18-1.26 μm band, so as to realize the dual-pass utilization of the pump light.

[0044] Diamond crystal 5 is a synthetic diamond crystal cut along the diagonal axis of the face. The dimensions of diamond crystal 5 are 7×4×1.2mm. 3Both sides of the diamond crystal 5 are coated with a broadband dielectric film with a transmittance of more than 99.5% for pump light and Stokes light. The wavelength range of the pump light is set to 1.02-1.08μm, and the wavelength range of the Stokes light is set to 1.18-1.26μm.

[0045] like Figure 2 As shown, the cavity multiplier 9 includes a frequency multiplier crystal 94 and a second cavity reflector 93 and a cavity output mirror 95 symmetrically arranged on both sides of the frequency multiplier crystal 94. A cavity input mirror 91 is arranged above the second cavity reflector 93, and a first cavity reflector 92 is arranged above the cavity output mirror 95. The cavity input mirror 91 and the first cavity reflector 92 are symmetrically arranged according to the frequency multiplier crystal 94.

[0046] The distance L4 between the lock cavity input mirror 91 and the first lock cavity reflector 92 is set to 150mm, the distance L5 between the lock cavity input mirror 91 and the lock cavity output mirror 95 is set to 100mm, the distance L6 between the first lock cavity reflector 92 and the second lock cavity reflector 93 is set to 100mm, the distance L7 between the second lock cavity reflector 93 and the left side of the frequency doubling crystal 94 is set to 51.5mm, and the distance L8 between the right side of the frequency doubling crystal 94 and the lock cavity output mirror 95 is set to 51.5mm.

[0047] The lock cavity input mirror 91 is a plane mirror. Its left side is coated with a broadband dielectric film that enhances the transmittance of Stokes light, with the wavelength range of Stokes light set to 1.18-1.26 μm. Its right side is coated with a broadband dielectric film that has a transmittance of 2-4% for Stokes light, with the wavelength range of Stokes light also set to 1.18-1.26 μm. The lock cavity output mirror 95 is a plano-concave mirror with a radius of curvature of 100 mm. Its concave surface is coated with a broadband dielectric film that has a reflectance of greater than 99.9% for Stokes light and a broadband dielectric film that has a transmittance of greater than 90% for frequency-doubled light, with the wavelength range of Stokes light set to 1.18-1.26 μm. The wavelength range of the frequency-doubled light is set to 0.59-0.63 μm. The plane of the lock cavity output mirror 95 is coated with a broadband dielectric film with a transmittance of greater than 99.5% for frequency-doubled light, and the wavelength range of the frequency-doubled light is set to 0.59-0.63 μm. The first lock cavity reflector 92 is a plane reflector, and its surface is coated with a broadband dielectric film with a reflectance of greater than 99.9% for Stokes light, and the wavelength range of Stokes light is set to 1.18-1.26 μm. The second lock cavity reflector 93 is a plano-concave reflector with a radius of curvature of 100 mm, and its concave surface is coated with a broadband dielectric film with a reflectance of greater than 99.9% for Stokes light, and the wavelength range of Stokes light is set to 1.18-1.26 μm.

[0048] The frequency doubling crystal 94 uses an LBO crystal with a 90° cut angle, a 0° temperature phase, and dimensions of 4×4×10mm. 3 The LBO crystal has a broadband dielectric film on both sides to enhance the transmission of Stokes light and frequency doubling light. The wavelength range of the Stokes light is set to 1.18-1.26μm, and the wavelength range of the frequency doubling light is set to 0.59-0.63μm.

[0049] like Figure 3 As shown, the reflective blazed grating 6 has a reflectivity and diffraction rate greater than 99.9%, and the reflection wavelength is set to 1.18-1.26 μm. The reflective blazed grating 6 has several grating lines. The angle between the grating normal a and the grating normal b of the reflective blazed grating 6 is equal to the blaze angle γ of the reflective blazed grating 6. The angle between the incident ray and the grating normal b of the reflective blazed grating 6 is the incident angle θ. i The incident angle θ of the light is changed by rotating the displacement platform. i It can achieve wavelength change output. The grating constant d of the reflective blazed grating 6 is the distance between two adjacent grating lines. In this embodiment, the grating constant d of the reflective blazed grating 6 is set to 2000nm.

[0050] The emission method of a narrow-linewidth tunable Raman laser includes the following steps:

[0051] S1: The pump source emits pump light, which is coupled to the focusing lens after passing through a half-wave plate;

[0052] S2: The coupled pump light passes through the input mirror and enters the diamond crystal. The diamond crystal uses the SRS effect to convert the pump light into a Stokes light signal, adjusts the angle of the reflective blazed grating, and performs precise wavelength adjustment. The precision adjustment range is set to [0.01-0.1] nm.

[0053] S3: The Stokes optical signal passes through the output mirror and enters the shaping lens group, which couples the Stokes optical signal.

[0054] S4: The cavity-locked frequency multiplier multiplies the frequency of the coupled Stokes optical signal and outputs frequency-doubled light;

[0055] S5: The dichroic mirror separates the frequency-doubled light from the leaked Stokes light signal and outputs a narrow-linewidth visible laser.

[0056] In step S1, both the first preset power and the first preset wavelength of the pump light can be tuned;

[0057] In step S2, the coupled pump light passes through the input mirror 4 and enters the diamond crystal 5, where it is focused at the center. The waist radius of the pump beam is 42 μm. The efficiency of the focused pump light is improved, and it is easier to filter out non-target wavelength light. The frequency is ω. P The pump light excites the ground-state atoms of diamond crystal 5 to a virtual Raman upper level, simultaneously generating a frequency of ω. S Raman photons and a frequency of ω R The optical phonon, and satisfying ω P =ω S +ω R The Raman frequency shift of diamond crystal 5 was set to 1332 cm⁻¹. -1 When the pump light wavelength is 1.02-1.08 μm, the excited Stokes light wavelength is 1.18-1.26 μm;

[0058] In step S2, the Stokes light oscillates in a Raman oscillator composed of an input mirror 4, a reflective blazed grating 6, and an output mirror 7. By adjusting the angle of the reflective blazed grating 6, the Raman wavelength is precisely adjusted. When the reflective blazed grating 6 rotates by 0.00635 mrad and the Stokes center wavelength is 1240 nm, its wavelength range changes by 0.01 nm; when the reflective blazed grating 6 rotates by 0.0319 mrad, the wavelength range changes by 0.05 nm; and when the reflective blazed grating 6 rotates by 0.0638 mrad, the wavelength range changes by 0.1 nm.

[0059] In step S3, after the Stokes light is output through the output mirror 7, the beam size is matched with the beam size in the cavity doubler 9 under the action of the shaping lens group 8, which greatly improves the conversion efficiency.

[0060] Therefore, the present invention employs the above-mentioned narrow linewidth tunable Raman laser and emission method, which reduces the need for optical isolators, improves the stability of the laser resonator, reduces losses during transmission, achieves wavelength adjustment accurate to 0.01nm while reducing the linewidth of the output optical signal, and realizes narrow linewidth 0.59-0.63μm tunable wavelength output.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the method of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the method of the present invention, and these modifications or equivalent substitutions should not cause the modified method to deviate from the spirit and scope of the method of the present invention.

Claims

1. A narrow-linewidth tunable Raman laser, characterized in that: The system includes a half-wave plate and pump sources and focusing lenses respectively disposed on both sides of the half-wave plate. A laser resonant cavity is disposed on the other side of the focusing lens, and a cavity-locked frequency multiplier is disposed on the other side of the laser resonant cavity. A shaping lens group is disposed between the laser resonant cavity and the cavity-locked frequency multiplier. A dichroic mirror is disposed on the other side of the cavity-locked frequency multiplier. The laser resonant cavity is configured as a V-shaped cavity structure consisting of an input mirror, an output mirror, and a reflective blazed grating. A diamond crystal is disposed between the input mirror and the output mirror, and the reflective blazed grating is disposed below the diamond crystal. The reflectivity of the input mirror, the reflectivity of the output mirror, and the reflective blazed grating are all different. The input mirror is a plano-concave mirror with a radius of curvature of 50 mm. The flat surface of the input mirror is coated with a broadband dielectric film that enhances the reflection of pump light, and the concave surface of the input mirror is coated with a broadband dielectric film that has a reflectivity greater than 99.9% for Stokes light in the 1.18-1.26 μm band. The output mirror is a plano-concave mirror with a radius of curvature of 100 mm. The concave surface of the output mirror... The output mirror is coated with a broadband dielectric film that has a pump light reflectivity greater than 99.9% and a Stokes light transmittance of 0.1%-0.5% in the 1.18-1.26μm wavelength range. The plane of the output mirror is coated with a broadband dielectric film that transmits Stokes light in the 1.18-1.26μm wavelength range. The reflective blazed grating has a reflectivity greater than 99.9% in the Stokes light wavelength range of 1.18-1.26μm. The reflective blazed grating is provided with a plurality of grating lines.

2. The narrow linewidth tunable Raman laser according to claim 1, characterized in that: The cavity multiplier includes a frequency multiplier crystal and a second cavity reflector and a cavity output mirror symmetrically arranged on both sides of the frequency multiplier crystal. A cavity input mirror is arranged above the second cavity reflector, and a first cavity reflector is arranged above the cavity output mirror. The cavity input mirror and the first cavity reflector are symmetrically arranged according to the frequency multiplier crystal.

3. A narrow-linewidth tunable Raman laser according to claim 1, characterized in that: The shaping lens group includes two convex lenses, and the surfaces of the two convex lenses are coated with a broadband dielectric film that is highly transmissive to Stokes light with a wavelength of 1.18-1.26 μm.

4. A narrow-linewidth tunable Raman laser according to claim 1, characterized in that: The surface of the focusing lens is coated with a broadband dielectric film that enhances the transmission of pump light with a wavelength of 1.02-1.08μm, and the surface of the dichroic mirror is coated with a broadband dielectric film that has high reflectivity to Stokes light with a wavelength of 1.18-1.26μm and high transmission to frequency-doubled light in the 0.59-0.63μm band.

5. A narrow-linewidth tunable Raman laser according to claim 1, characterized in that: The diamond crystal is a synthetic diamond crystal cut along the diagonal axis, and the dimensions of the diamond crystal are 7×4×1.2mm. 3 The diamond crystal has a wide-band dielectric film with a wavelength of 1.18-1.26 μm and a Stokes transmittance greater than 99.5% on both sides, which is used to pump light in the wavelength range of 1.02-1.08 μm.

6. A narrow-linewidth tunable Raman laser according to claim 2, characterized in that: The input mirror of the lock cavity is a plane mirror. Its left end face is coated with a broadband dielectric film that enhances the transmittance of Stokes light with a wavelength of 1.18-1.26 μm, and its right end face is coated with a broadband dielectric film with a transmittance of 2-4% for Stokes light with a wavelength of 1.18-1.26 μm. The output mirror of the lock cavity is a plano-concave mirror with a radius of curvature of 100 mm. Its concave surface is coated with a broadband dielectric film with a reflectance greater than 99.9% for Stokes light with a wavelength of 1.18-1.26 μm and a transmittance greater than 99.9% for second-harmonic light with a wavelength of 0.59-0.63 μm. The lock cavity output mirror has a 90% broadband dielectric film. The plane of the lock cavity output mirror is coated with a broadband dielectric film with a transmittance greater than 99.5% for octave light with a wavelength of 0.59-0.63μm. The first lock cavity reflector is a plane reflector, and its surface is coated with a broadband dielectric film with a reflectance greater than 99.9% for Stokes light with a wavelength of 1.18-1.26μm. The second lock cavity reflector is a plano-concave reflector with a radius of curvature of 100mm, and its concave surface is coated with a broadband dielectric film with a reflectance greater than 99.9% for Stokes light with a wavelength of 1.18-1.26μm.

7. A narrow-linewidth tunable Raman laser according to claim 2, characterized in that: The frequency doubling crystal is an LBO crystal with a cut angle of 90° and a temperature phase of 0°. The LBO crystal is designed to have dimensions of 4×4×10mm. 3 The LBO crystal has a broadband dielectric film on both sides to enhance the transmission of Stokes light with a wavelength of 1.18-1.26μm and frequency-doubled light with a wavelength of 0.59-0.63μm.

8. A method for emitting a narrow-linewidth tunable Raman laser as described in any one of claims 1-7, characterized in that: Includes the following steps: S1: The pump source emits pump light, which is coupled to the focusing lens after passing through a half-wave plate; S2: The coupled pump light passes through the input mirror and enters the diamond crystal. The diamond crystal uses the SRS effect to convert the pump light into a Stokes light signal, adjusts the angle of the reflective blazed grating, and performs precise wavelength adjustment. The precision adjustment range is set to [0.01-0.1] nm. S3: The Stokes optical signal passes through the output mirror and enters the shaping lens group, which couples the Stokes optical signal. S4: The cavity-locked frequency multiplier multiplies the frequency of the coupled Stokes optical signal and outputs frequency-doubled light; S5: The dichroic mirror separates the frequency-doubled light from the leaked Stokes light signal and outputs a narrow-linewidth visible laser.

9. The emission method of a narrow-linewidth tunable Raman laser according to claim 8, characterized in that: In step S1, both the first preset power and the first preset wavelength of the pump light can be tuned.

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