Narrow-linewidth high-repetition-frequency three-wavelength laser

Abstract

The invention discloses a narrow-linewidth high-repetition-frequency three-wavelength laser which comprises a narrow-linewidth laser module, an annular cavity laser amplification module and a nonlinear frequency conversion module. Wherein the narrow linewidth laser module generates p polarization 1064nm laser, the p polarization 1064nm laser passes through the ring cavity laser amplification module to obtain amplified p polarization 1064nm laser, and the amplified p polarization 1064nm laser passes through the nonlinear frequency conversion module to obtain 1064nm laser, 532nm laser and 486nm laser. The near-infrared, green and blue three-wavelength laser can be output at the same time, and the laser has the advantages of being high in frequency stability, large in repetition frequency range and capable of outputting large laser energy.

Description

Technical Field

[0001] The invention belongs to the technical field of lasers, and in particular relates to a narrow-linewidth high-repetition-rate three-wavelength laser. Background Art

[0002] As the core light source of the new generation of space lidar, all-solid-state narrow-linewidth high-repetition-rate lasers have the characteristics of narrow linewidth, high beam quality, large energy, and high repetition rate. By modulating laser intensity information, phase information, and frequency information, high-repetition-rate lasers combined with single-photon accumulation can effectively improve the radar signal-to-noise ratio. They can be applied to global wind field detection, cloud / aerosol hyperspectral detection, ocean information detection, near-space atmospheric temperature and gravity wave detection, and other fields. Conventional narrow-linewidth high-repetition-rate lasers are realized by injection locking combined with master oscillator end-pump amplification technology.

[0003] Usually, pulsed single-frequency lasers use injection locking technology, that is, by continuously injecting seed light into the resonant cavity, combined with piezoelectric ceramics to control the cavity length or electro-optical phase modulation, the seed light pulls the adjacent longitudinal mode to start oscillation first, consumes the number of upper energy level particles, suppresses the oscillation of other modes, and achieves narrow linewidth laser output. The seed injection locking technologies that have been realized include Pound-Drever-Hall method, Ramp-Fire, Q time minimum establishment method and other methods. High repetition rate lasers generally use electro-optical Q-switching or acousto-optic Q-switching to achieve kHz high repetition rate main laser, and then combine traveling wave amplification technology to achieve pulse laser amplification.

[0004] Existing narrow linewidth pulse lasers use injection locking technology. Due to the limitations of piezoelectric ceramic resonant frequency or electro-optical phase modulation high voltage, the laser repetition rate is difficult to reach the kilohertz level, and the frequency stability is easily disturbed by the external environment, making it difficult to apply to platforms with high mechanical environment requirements such as airborne and satellite-borne. Conventional amplifiers also require additional isolators to prevent echoes from damaging the front stage, and the volume and size of the laser will increase. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a narrow-linewidth, high-repetition-rate three-wavelength laser, which can simultaneously output near-infrared, green and blue wavelength lasers, and also has the advantages of high frequency stability, a large repetition rate range and a large output laser energy.

[0006] The object of the present invention is achieved through the following technical scheme: a narrow-linewidth high-repetition-rate three-wavelength laser, comprising: a narrow-linewidth laser module, a ring-cavity laser amplification module and a nonlinear frequency conversion module; wherein the narrow-linewidth laser module generates a p-polarized 1064nm laser, the p-polarized 1064nm laser passes through the ring-cavity laser amplification module to obtain an amplified p-polarized 1064nm laser, and the amplified p-polarized 1064nm laser passes through the nonlinear frequency conversion module to obtain a 1064nm laser, a 532nm laser and a 486nm laser.

[0007] In the above-mentioned narrow-linewidth high-repetition-rate three-wavelength laser, the narrow-linewidth laser module includes a single-frequency seed laser and a first 1 / 2 wave plate; wherein the single-frequency seed laser generates a single-frequency linearly polarized 1064nm laser, and the single-frequency linearly polarized 1064nm laser passes through the first 1 / 2 wave plate to obtain a p-polarized 1064nm laser.

[0008] In the above narrow linewidth high repetition rate three-wavelength laser, the ring cavity laser amplification module includes a polarizer, a second / wave plate, a first reflector, a second reflector, a third reflector, a first Nd:YAG crystal, a second Nd:YAG crystal, a third Nd:YAG crystal, a first conversion lens, a second conversion lens, a first coupling lens group, a second coupling lens group, a third coupling lens group, a first semiconductor pump diode, a second semiconductor pump diode and a third semiconductor pump diode; wherein the p-polarized 1064nm laser generated by the narrow linewidth laser module is incident through the polarizer, and the polarization state is rotated 90° through the second 1 / 2 wave plate to become an s-polarized 1064nm laser, and the s-polarized 1064nm laser passes through The first reflector reflects and reaches the first Nd:YAG crystal. The first semiconductor pump diode generates a pump light of 800nm-900nm. The pump light of 800nm-900nm is coupled by the first coupling lens group to obtain coupled pump light. The coupled pump light is transmitted by the first reflector and reaches the first Nd:YAG crystal. The coupled pump light in the first Nd:YAG crystal amplifies the s-polarized 1064nm laser to obtain the first amplified s-polarized 1064nm laser. The first amplified s-polarized 1064nm laser passes through the first conversion lens and reaches the second reflector. After being reflected by the second reflector, it reaches the second Nd: The second semiconductor pump diode generates a second pump light of 800nm-900nm, the second pump light of 800nm-900nm is coupled by the second coupling lens group to obtain a coupled second pump light, the coupled second pump light is transmitted by the second reflector and reaches the second Nd:YAG crystal, the coupled second pump light in the second Nd:YAG crystal amplifies the s-polarized 1064nm laser after the first amplification to obtain a second amplified s-polarized 1064nm laser; the second amplified s-polarized 1064nm laser reaches the third reflector after passing through the second conversion lens, and reaches the third Nd:YAG crystal after being reflected by the third reflector. G crystal, the third semiconductor pump diode generates a third pump light of 800nm-900nm, the third pump light of 800nm-900nm is coupled by the third coupling lens group to obtain a coupled third pump light, the coupled third pump light is transmitted by the third reflector to reach the third Nd:YAG crystal, the coupled third pump light in the third Nd:YAG crystal amplifies the s-polarized 1064nm laser after the second amplification to obtain the s-polarized 1064nm laser after the third amplification; the s-polarized 1064nm laser after the third amplification is reflected by the polarizer and then passes through the second 1 / 2 wave plate to obtain the p-polarized 1064nm laser after the third amplification;The p-polarized 1064nm laser after the third amplification is reflected by the first reflector and reaches the first Nd:YAG crystal. The pump light coupled in the first Nd:YAG crystal amplifies the p-polarized 1064nm laser after the third amplification to obtain the p-polarized 1064nm laser after the fourth amplification. The p-polarized 1064nm laser after the fourth amplification passes through the first conversion lens and reaches the second reflector. After being reflected by the second reflector, it reaches the second Nd:YAG crystal. The second pump light coupled in the second Nd:YAG crystal amplifies the p-polarized 1064nm laser after the fourth amplification. After the 064nm laser is amplified, a p-polarized 1064nm laser after the fifth amplification is obtained; the p-polarized 1064nm laser after the fifth amplification reaches the third reflector after passing through the second conversion lens, and reaches the third Nd:YAG crystal after being reflected by the third reflector. The third pump light coupled in the third Nd:YAG crystal amplifies the p-polarized 1064nm laser after the fifth amplification to obtain the p-polarized 1064nm laser after the sixth amplification, i.e., the amplified p-polarized 1064nm laser; the amplified p-polarized 1064nm laser passes through the polarizer and reaches the nonlinear frequency conversion module. ;

[0009] In the above narrow linewidth high repetition rate three-wavelength laser, the nonlinear frequency conversion module includes an isolator, a third conversion lens, a frequency doubling crystal, a fourth reflector, a first plane mirror, a sum frequency crystal, an optical parametric oscillator crystal, a second plane mirror and a fifth reflector; wherein the amplified p-polarized 1064nm laser reaches the frequency doubling crystal through the isolator and the third conversion lens in sequence, and generates a 532nm laser after passing through the frequency doubling crystal; the 1064nm laser and the 532nm laser reach the fourth reflector, and part of the 1064nm laser and part of the 532nm laser are directly output after passing through the fourth reflector; the remaining part of the 1064nm laser and the remaining part of the 532nm laser are reflected by the fourth reflector and reach the first plane mirror, and the remaining part of the 1064nm laser reaches the sum frequency crystal through the first plane mirror, and generates a 355nm laser after passing through the sum frequency crystal, and the 355nm laser then passes through the optical parametric oscillator crystal to generate a 486nm laser, and the 486nm laser is emitted through the second plane mirror, and then output after being reflected by the fifth reflector.

[0010] In the above narrow-linewidth high-repetition-rate three-wavelength laser, the extinction ratio of the polarizer is 5000:1, and the material is ultraviolet fused quartz.

[0011] In the above narrow linewidth high repetition rate three-wavelength laser, the second 1 / 2 wave plate is an ultraviolet fused silica multi-stage wave plate.

[0012] In the above narrow linewidth high repetition rate three-wavelength laser, the first reflector, the second reflector and the third reflector are all plane reflectors, and are coated with a 45±3° 1064nm high reflective dielectric film and an 885nm pump light anti-reflective dielectric film.

[0013] In the above-mentioned narrow linewidth and high repetition rate three-wavelength laser, the side surfaces of the first Nd:YAG crystal, the second Nd:YAG crystal and the third Nd:YAG crystal are all roughened, and the end surfaces of the first Nd:YAG crystal, the second Nd:YAG crystal and the third Nd:YAG crystal are all polished and coated with 1064nm and 885nm 0° anti-reflection dielectric films.

[0014] In the above narrow linewidth high repetition rate three-wavelength laser, both the first conversion lens and the second conversion lens are plano-convex lenses, and both ends of the first conversion lens and the second conversion lens are coated with 1064nm high-transmittance dielectric films.

[0015] In the above narrow linewidth high repetition rate three-wavelength laser, the isolator adopts a 45° magneto-optical crystal made of TGG; the third conversion lens adopts a plano-concave mirror coated with a 0±10°1064nm high-transmittance dielectric film and a 532nm high-reflection dielectric film; the frequency doubling crystal adopts a type I critical phase-matched LBO crystal, and both ends of the frequency doubling crystal are coated with 1064nm and 532nm anti-reflection dielectric films; the fourth reflector adopts a plane mirror coated with a 45±3°1064nm, 532nm partial transmittance dielectric film; the first plane mirror is coated with a 0°1064nm, 53 2nm, 1317nm anti-reflection dielectric film and 355nm, 486nm high-reflection dielectric film; the sum frequency crystal adopts type II critical phase matching LBO crystal, and both ends of the sum frequency crystal are plated with 350-1350nm anti-reflection dielectric film; the optical parametric oscillator crystal adopts type II phase matching BBO crystal, and both ends of the optical parametric oscillator crystal are plated with 350-1350nm anti-reflection dielectric film; the second plane mirror is plated with 0±10°1064nm, 532nm, 355nm, 486nm high-reflection dielectric film and 1317nm anti-reflection dielectric film.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention solves the problems of poor frequency characteristics, low repetition rate, low integration and low optical parametric oscillation efficiency of existing narrow linewidth pulse lasers, and can simultaneously output three-wavelength lasers of near-infrared, green and blue light, and also has the advantages of high frequency stability (≤1MHz), large repetition rate range (1-10kHz) and large output laser energy (≥10mJ). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of a narrow-linewidth and high-repetition-rate three-wavelength laser provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] Figure 1 Schematic diagram of a narrow linewidth high repetition rate three-wavelength laser provided by an embodiment of the present invention. Figure 1 The narrow-linewidth high-repetition-rate three-wavelength laser includes: a narrow-linewidth laser module, a ring-cavity laser amplification module, and a nonlinear frequency conversion module; wherein the narrow-linewidth laser module generates p-polarized 1064nm laser, and the p-polarized 1064nm laser passes through the ring-cavity laser amplification module to obtain amplified p-polarized 1064nm laser, and the amplified p-polarized 1064nm laser passes through the nonlinear frequency conversion module to obtain 1064nm laser, 532nm laser, and 486nm laser. The ring-cavity laser amplification module generates 10mJ single-frequency linearly polarized laser of 1 to 5kHz; the nonlinear frequency conversion module realizes the simultaneous output of 1064nm, 532nm, and 486nm lasers.

[0022] The narrow linewidth laser module is composed of a single-frequency seed laser 1.1 and a 1 / 2 wave plate 1.2. The narrow linewidth main laser module generates a single-frequency linearly polarized laser of the order of hundreds of μJ at 1 to 5 kHz.

[0023] The narrow linewidth laser module includes a single-frequency seed laser 1.1 and a first 1 / 2 wave plate 1.2; wherein the single-frequency seed laser 1.1 generates a single-frequency linearly polarized 1064nm laser, and the single-frequency linearly polarized 1064nm laser passes through the first 1 / 2 wave plate to obtain a p-polarized 1064nm laser.

[0024] The single-frequency seed laser 1.1 generates a single-frequency linearly polarized laser of a specific frequency in the order of hundreds of μJ, and then strictly adjusts the polarization state through the 1 / 2 wave plate 1.2 to meet the p-light emission conditions; the single-frequency seed laser 1.1 adopts a semiconductor seed laser, and the modulation method adopts semiconductor direct modulation combined with an ytterbium-doped fiber amplifier (YDFA); the first 1 / 2 wave plate 1.2 is made of fused quartz, adopts a multi-level wave plate structure, and is coated with a main laser anti-reflection film.

[0025] The ring cavity laser amplification module includes a polarizer 2.1, a second 1 / 2 wave plate 2.2, a first reflector 2.3.1, a second reflector 2.3.2, a third reflector 2.3.3, a first Nd:YAG crystal 2.4.1, a second Nd:YAG crystal 2.4.2, a third Nd:YAG crystal 2.4.3, a first conversion lens 2.5.1, a second conversion lens 2.5.2, a first coupling lens group 2.6.1, a second coupling lens group 2.6.2, a third coupling lens group 2.6.3, a first semiconductor pump diode 2.7.1, a second semiconductor pump diode 2.7.2 and a third semiconductor pump diode 2.7.3; wherein,

[0026] The p-polarized 1064nm laser generated by the narrow linewidth laser module is incident through the polarizer 2.1, and the polarization state is rotated 90° through the second 1 / 2 wave plate 2.2 to become an s-polarized 1064nm laser. The s-polarized 1064nm laser is reflected by the first reflector 2.3.1 and reaches the first Nd:YAG crystal 2.4.1. The first semiconductor pump diode 2.7.1 generates 800nm-900nm pump light. The 800nm-900nm pump light is coupled by the first coupling lens group 2.6.1 to obtain coupled pump light. The coupled pump light is transmitted through the first reflector 2.3.1 and reaches the first Nd:YAG crystal 2.4.1. The coupled pump light in the first Nd:YAG crystal 2.4.1 amplifies the s-polarized 1064nm laser to obtain the first amplified s-polarized 1064nm laser.

[0027] The s-polarized 1064nm laser after the first amplification passes through the first conversion lens 2.5.1 and reaches the second reflector 2.3.2. After being reflected by the second reflector 2.3.2, it reaches the second Nd:YAG crystal 2.4.2. The second semiconductor pump diode 2.7.2 generates a second pump light of 800nm-900nm. The second pump light of 800nm-900nm is coupled by the second coupling lens group 2.6.2 to obtain a coupled second pump light. The coupled second pump light passes through the second reflector 2.3.2 and reaches the second Nd:YAG crystal 2.4.2. The second pump light coupled in the second Nd:YAG crystal 2.4.2 amplifies the s-polarized 1064nm laser after the first amplification to obtain a second amplified s-polarized 1064nm laser.

[0028] The s-polarized 1064nm laser after the second amplification passes through the second conversion lens 2.5.2 and reaches the third reflector 2.3.3. After being reflected by the third reflector 2.3.3, it reaches the third Nd:YAG crystal 2.4.3. The third semiconductor pump diode 2.7.3 generates a third pump light of 800nm-900nm. The third pump light of 800nm-900nm is coupled by the third coupling lens group 2.6.3 to obtain a coupled third pump light. The coupled third pump light is transmitted through the third reflector 2.3.3 and reaches the third Nd:YAG crystal 2.4.3. The coupled third pump light in the third Nd:YAG crystal 2.4.3 amplifies the s-polarized 1064nm laser after the second amplification to obtain a third amplified s-polarized 1064nm laser.

[0029] The s-polarized 1064nm laser after the third amplification is reflected by the polarizer 2.1 and then passes through the second 1 / 2 wave plate 2.2 to obtain the p-polarized 1064nm laser after the third amplification;

[0030] The p-polarized 1064nm laser after the third amplification is reflected by the first reflector 2.3.1 and reaches the first Nd:YAG crystal 2.4.1. The pump light coupled in the first Nd:YAG crystal 2.4.1 amplifies the p-polarized 1064nm laser after the third amplification to obtain the p-polarized 1064nm laser after the fourth amplification.

[0031] The p-polarized 1064nm laser after the fourth amplification passes through the first conversion lens 2.5.1 and reaches the second reflector 2.3.2. After being reflected by the second reflector 2.3.2, it reaches the second Nd:YAG crystal 2.4.2. The second pump light coupled in the second Nd:YAG crystal 2.4.2 amplifies the p-polarized 1064nm laser after the fourth amplification to obtain the p-polarized 1064nm laser after the fifth amplification.

[0032] The p-polarized 1064nm laser after the fifth amplification passes through the second transformation lens 2.5.2 and reaches the third reflector 2.3.3, and reaches the third Nd:YAG crystal 2.4.3 after reflection by the third reflector 2.3.3. The third pump light coupled in the third Nd:YAG crystal 2.4.3 amplifies the p-polarized 1064nm laser after the fifth amplification to obtain the p-polarized 1064nm laser after the sixth amplification, that is, the amplified p-polarized 1064nm laser; the amplified p-polarized 1064nm laser passes through the polarizer 2.1 and reaches the nonlinear frequency conversion module.

[0033] The p-polarized 1064nm laser (main laser) generated by the narrow linewidth laser module is incident through TFP 2.1, and the polarization state is rotated 90° to become s light after passing through 1 / 2 wave plate 2.2. Then, the 1064nm laser is reflected by three mirrors in turn through three-stage Nd:YAG crystals for laser amplification. The transformation lens is used to change the laser mode in the amplification optical path. When the 1064nm laser passes through the 45° reflector 2.3.3 and enters TFP 2.1, the polarization state of 1064nm is s polarization, and it is reflected by TFP 2.1. After passing through the second 1 / 2 wave plate 2.2 again, the polarization state changes back to p polarization. After that, the 1064nm laser is reflected by the 45° reflector 2.3.3 again and reaches TFP 2.1. At this time, the polarization state is p light, and the 1064nm laser transmission output completes laser double-pass amplification. The coupling lens group is used to transform the pump light mode, and the three semiconductor pump diodes provide pump energy to the Nd:YAG crystal respectively. TFP 2.1. 1 / 2 wave plate 2.2. Reflector forms a double-pass annular cavity.

[0034] TFP 2.1, incident angle of 45°, extinction ratio of 5000:1, made of UV fused quartz; 1 / 2 wave plate 2.2 is made of UV fused quartz multi-stage wave plate; 45° reflectors (first reflector 2.3.1, second reflector 2.3.2 and third reflector 2.3.3) are flat reflectors, coated with 45±3° 1064nm high reflective dielectric film and 885nm pump light anti-reflection dielectric film; Nd:YAG crystals (first Nd:YAG crystal 2.4.1, second Nd:YAG crystal 2.4.2, third Nd:YAG crystal 2.4.3) are roughened on the side, polished on the end, and coated with 1064nm and 885nm 0° anti-reflection dielectric film, one of the end faces is cut at 2°; the transformation lenses (the first transformation lens 2.5.1 and the second transformation lens (2.5.2) are plano-convex lenses made of fused quartz JGS1, and both ends are coated with 1064nm high-transmittance dielectric films; the semiconductor pump diodes (the first semiconductor pump diode 2.7.1, the second semiconductor pump diode 2.7.2 and the third semiconductor pump diode 2.7.3) use volume Bragg grating (VBG) wavelength-locked fiber-coupled semiconductor lasers, and the pumping modes are pulse pumping (1~5kHz) and continuous pumping, with a wavelength of 885nm.

[0035] The nonlinear frequency conversion module includes an isolator 3.1, a third conversion lens 3.2, a frequency doubling crystal 3.3, a fourth reflector 3.4, a first plane mirror 3.5, a sum frequency crystal 3.6, an optical parametric oscillator crystal 3.7, a second plane mirror 3.8 and a fifth reflector 3.9; wherein the amplified p-polarized 1064nm laser light passes through the isolator 3.1 and the third conversion lens 3.2 in sequence to reach the frequency doubling crystal 3.3, and generates a 532nm laser light after passing through the frequency doubling crystal 3.3; the 1064nm laser light and the 532nm laser light reach the fourth reflector 3.4, and part of the 1064nm laser light is The m laser and part of the 532nm laser are directly output after passing through the fourth reflector 3.4; the remaining part of the 1064nm laser and the remaining part of the 532nm laser are reflected by the fourth reflector 3.4 and reach the first plane mirror 3.5, and the remaining part of the 1064nm laser reaches the sum frequency crystal 3.6 through the first plane mirror 3.5, and generates a 355nm laser through the sum frequency crystal 3.6, and the 355nm laser is then passed through the optical parametric oscillator crystal 3.7 to generate a 486nm laser, and the 486nm laser is emitted through the second plane mirror 3.8, and then reflected by the fifth reflector 3.9 and output.

[0036] The 1064nm laser amplified by the ring cavity laser amplifier module 2 is passed through the isolator 3.1 to achieve unidirectional laser transmission, and is incident on the frequency doubling crystal 3.3 through the conversion lens 3.2 to generate a 532nm laser; then, after passing through the 45° reflector 3.4, part of the 1064nm and 532nm lasers are directly output, and part of the 1064nm and 532nm lasers are reflected through the plane mirror 3.5 and pass through the sum frequency crystal 3.6 to generate a 355nm laser, and the generated 355nm laser passes through the OPO crystal 3.7 to generate a 486nm laser, and the extra idle light generated by the OPO will be directly dissipated, and the 355nm laser that is not consumed in a single pass through the OPO crystal will be reflected back by the plane mirror 3.8, and reciprocate between the plane mirror 3.5 and the plane mirror 3.8 until it is completely converted into a 486nm laser; the generated 486nm laser is emitted through the plane mirror 3.8, and then reflected by the 45° reflector 3.9 and emitted in the same direction as the 1064nm and 532nm.

[0037] The extinction ratio of the polarizer 2.1 is 5000:1, and the material is ultraviolet fused quartz. The second 1 / 2 wave plate 2.2 is an ultraviolet fused quartz multi-stage wave plate. The first reflector 2.3.1, the second reflector 2.3.2 and the third reflector 2.3.3 are all plane reflectors, and are coated with 45±3°1064nm high-reflection dielectric film and 885nm pump light anti-reflection dielectric film. The side surfaces of the first Nd:YAG crystal 2.4.1, the second Nd:YAG crystal 2.4.2 and the third Nd:YAG crystal 2.4.3 are roughened, and the end surfaces of the first Nd:YAG crystal 2.4.1, the second Nd:YAG crystal 2.4.2 and the third Nd:YAG crystal 2.4.3 are polished and coated with 1064nm, 885nm 0° anti-reflection dielectric film. The first transform lens 2.5.1 and the second transform lens 2.5.2 are both plano-convex lenses, and both ends of the first transform lens 2.5.1 and the second transform lens 2.5.2 are coated with 1064nm high-transmittance dielectric films.

[0038] The isolator 3.1 adopts a 45° magneto-optical crystal made of TGG; the third conversion lens 3.2 adopts a plano-concave mirror coated with a 0±10° 1064nm high-transmittance dielectric film and a 532nm high-reflection dielectric film; the frequency doubling crystal 3.3 adopts a type I critical phase-matched LBO crystal, and both ends of the frequency doubling crystal 3.3 are coated with 1064nm and 532nm anti-reflection dielectric films; the fourth reflector 3.4 adopts a plane mirror coated with a 45±3° 1064nm and 532nm partial transmittance dielectric film (T=40%); the first plane mirror 3.5 is coated with a 0° 1064nm, 532nm, 1317nm anti-reflection dielectric film and 355nm, 486nm high-reflection dielectric film; the sum frequency crystal 3.6 adopts a type II critical phase-matched LBO crystal, and both ends of the sum frequency crystal 3.6 are plated with 350-1350nm anti-reflection dielectric film; the optical parametric oscillator crystal 3.7 adopts a type II phase-matched BBO crystal, and both ends of the optical parametric oscillator crystal 3.7 are plated with 350-1350nm anti-reflection dielectric film; the second plane mirror 3.8 is plated with 0±10°1064nm, 532nm, 355nm, 486nm high-reflection dielectric film and 1317nm anti-reflection dielectric film. The materials of the transformation lens 3.2, the 45° reflector 3.4, the plane mirror 3.5, the plane mirror 3.8, and the 45° reflector 3.9 are fused quartz JGS1.

[0039] This embodiment uses a ring double-pass three-stage amplifier to directly amplify low-energy single-frequency pulse light, and combines extracavity frequency doubling with external cavity resonance and frequency and optical parametric oscillation to achieve simultaneous output of kHz three-wavelength lasers.

[0040] This embodiment adopts ring cavity double-pass amplification combined with external cavity resonant nonlinear transformation to achieve near-infrared, green light, and blue light three-wavelength laser output with narrow linewidth, high repetition rate (kHz level), high beam quality, and relatively large energy (10mJ level), which meets the application requirements of airborne and satellite-borne wind field detection, cloud / aerosol detection, ocean detection, etc.

[0041] This embodiment solves the problems of poor frequency characteristics, low repetition rate, low integration and low optical parametric oscillation efficiency of existing narrow linewidth pulse lasers. It can simultaneously output three-wavelength lasers of near-infrared, green and blue light, and also has the advantages of high frequency stability (≤1MHz), large repetition rate range (1~10kHz) and large output laser energy (≥10mJ).

[0042] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A narrow linewidth high repetition rate three-wavelength laser, characterized in that include: Narrow linewidth laser module, ring cavity laser amplification module and nonlinear frequency conversion module; among which, The narrow linewidth laser module generates p-polarized 1064nm laser, which passes through the ring cavity laser amplification module to obtain amplified p-polarized 1064nm laser, and the amplified p-polarized 1064nm laser passes through the nonlinear frequency conversion module to obtain 1064nm laser, 532nm laser and 486nm laser.

2. The narrow linewidth high repetition rate three-wavelength laser according to claim 1, characterized in that: The narrow linewidth laser module comprises a single-frequency seed laser (1.1) and a first 1 / 2 wave plate (1.2); wherein, The single-frequency seed laser (1.1) generates single-frequency linearly polarized 1064nm laser light, and the single-frequency linearly polarized 1064nm laser light passes through the first 1 / 2 wave plate to obtain p-polarized 1064nm laser light.

3. The narrow linewidth and high repetition rate three-wavelength laser according to claim 1, characterized in that: The ring cavity laser amplification module comprises a polarizer (2.1), a second 1 / 2 wave plate (2.2), a first reflector (2.3.1), a second reflector (2.3.2), a third reflector (2.3.3), a first Nd:YAG crystal (2.4.1), a second Nd:YAG crystal (2.4.2), a third Nd:YAG crystal (2.4.3), a first conversion lens (2.5.1), a second conversion lens (2.5.2), a first coupling lens group (2.6.1), a second coupling lens group (2.6.2), a third coupling lens group (2.6.3), a first semiconductor pump diode (2.7.1), a second semiconductor pump diode (2.7.2) and a third semiconductor pump diode (2.7.3); wherein, The p-polarized 1064nm laser generated by the narrow linewidth laser module is incident through the polarizer (2.1), and the polarization state is rotated by 90° through the second 1 / 2 wave plate (2.2) to become an s-polarized 1064nm laser. The s-polarized 1064nm laser is reflected by the first reflector (2.3.1) and reaches the first Nd:YAG crystal (2.4.1). The first semiconductor pump diode (2.7.1) generates 800nm-900nm pump light. The 800nm-900nm pump light is coupled through the first coupling lens group (2.6.1) to obtain coupled pump light. The coupled pump light is transmitted through the first reflector (2.3.1) and reaches the first Nd:YAG crystal (2.4.1). The coupled pump light in the first Nd:YAG crystal (2.4.1) amplifies the s-polarized 1064nm laser to obtain the s-polarized 1064nm laser after the first amplification. The s-polarized 1064nm laser light after the first amplification passes through the first conversion lens (2.5.1) and reaches the second reflector (2.3.2), and reaches the second Nd:YAG crystal (2.4.2) after being reflected by the second reflector (2.3.2), the second semiconductor pump diode (2.7.2) generates a second pump light of 800nm-900nm, the second pump light of 800nm-900nm is coupled through the second coupling lens group (2.6.2) to obtain a coupled second pump light, the coupled second pump light is transmitted through the second reflector (2.3.2) and reaches the second Nd:YAG crystal (2.4.2), the second pump light coupled in the second Nd:YAG crystal (2.4.2) amplifies the s-polarized 1064nm laser light after the first amplification to obtain a second amplified s-polarized 1064nm laser light; The s-polarized 1064nm laser light after the second amplification passes through the second conversion lens (2.5.2) and reaches the third reflector (2.3.3), and reaches the third Nd:YAG crystal (2.4.3) after being reflected by the third reflector (2.3.3); the third semiconductor pump diode (2.7.3) generates a third pump light of 800nm-900nm, and the third pump light of 800nm-900nm is coupled through the third coupling lens group (2.6.3) to obtain a coupled third pump light, and the coupled third pump light passes through the third reflector (2.3.3) and reaches the third Nd:YAG crystal (2.4.3), and the coupled third pump light in the third Nd:YAG crystal (2.4.3) amplifies the s-polarized 1064nm laser light after the second amplification to obtain a third amplified s-polarized 1064nm laser light; The s-polarized 1064nm laser light after the third amplification is reflected by the polarizer (2.1) and then passes through the second 1 / 2 wave plate (2.2) to obtain the p-polarized 1064nm laser light after the third amplification; The p-polarized 1064nm laser after the third amplification is reflected by the first reflector (2.3.1) and reaches the first Nd:YAG crystal (2.4.1). The pump light coupled in the first Nd:YAG crystal (2.4.1) amplifies the p-polarized 1064nm laser after the third amplification to obtain the p-polarized 1064nm laser after the fourth amplification. The p-polarized 1064nm laser light after the fourth amplification passes through the first conversion lens (2.5.1) and reaches the second reflector (2.3.2), and reaches the second Nd:YAG crystal (2.4.2) after being reflected by the second reflector (2.3.2), and the second pump light coupled in the second Nd:YAG crystal (2.4.2) amplifies the p-polarized 1064nm laser light after the fourth amplification to obtain the p-polarized 1064nm laser light after the fifth amplification; The p-polarized 1064nm laser after the fifth amplification passes through the second conversion lens (2.5.2) and reaches the third reflector (2.3.3), and reaches the third Nd:YAG crystal (2.4.3) after being reflected by the third reflector (2.3.3). The third pump light coupled in the third Nd:YAG crystal (2.4.3) amplifies the p-polarized 1064nm laser after the fifth amplification to obtain the p-polarized 1064nm laser after the sixth amplification, i.e., the amplified p-polarized 1064nm laser. The amplified p-polarized 1064nm laser passes through the polarizer (2.1) and reaches the nonlinear frequency conversion module.

4. The narrow linewidth and high repetition rate three-wavelength laser according to claim 1, characterized in that: The nonlinear frequency conversion module comprises an isolator (3.1), a third conversion lens (3.2), a frequency doubling crystal (3.3), a fourth reflector (3.4), a first plane mirror (3.5), a sum frequency crystal (3.6), an optical parametric oscillator crystal (3.7), a second plane mirror (3.8) and a fifth reflector (3.9); wherein: The amplified p-polarized 1064nm laser light passes through the isolator (3.1) and the third conversion lens (3.2) in sequence to reach the frequency doubling crystal (3.3), and generates 532nm laser light after passing through the frequency doubling crystal (3.3); The 1064nm laser and the 532nm laser reach the fourth reflecting mirror (3.4), and part of the 1064nm laser and part of the 532nm laser are directly output after passing through the fourth reflecting mirror (3.4); the remaining part of the 1064nm laser and the remaining part of the 532nm laser are reflected by the fourth reflecting mirror (3.4) and reach the first plane mirror (3.5); the remaining part of the 1064nm laser reaches the sum frequency crystal (3.6) through the first plane mirror (3.5), and generates 355nm laser through the sum frequency crystal (3.6); the 355nm laser then passes through the optical parametric oscillator crystal (3.7) to generate 486nm laser; the 486nm laser is emitted through the second plane mirror (3.8), and then reflected by the fifth reflecting mirror (3.9) and output.

5. The narrow linewidth high repetition rate three-wavelength laser according to claim 3, characterized in that: The polarizer (2.1) has an extinction ratio of 5000:1 and is made of ultraviolet fused quartz.

6. The narrow linewidth and high repetition rate three-wavelength laser according to claim 3, characterized in that: The second 1 / 2 wave plate (2.2) is an ultraviolet fused silica multi-stage wave plate.

7. The narrow linewidth and high repetition rate three-wavelength laser according to claim 3, characterized in that: The first reflector (2.3.1), the second reflector (2.3.2) and the third reflector (2.3.3) are all plane reflectors, and are coated with a 45±3° 1064nm high-reflection dielectric film and an 885nm pump light anti-reflection dielectric film.

8. The narrow linewidth and high repetition rate three-wavelength laser according to claim 3, characterized in that: The side surfaces of the first Nd:YAG crystal (2.4.1), the second Nd:YAG crystal (2.4.2) and the third Nd:YAG crystal (2.4.3) are roughened, and the end surfaces of the first Nd:YAG crystal (2.4.1), the second Nd:YAG crystal (2.4.2) and the third Nd:YAG crystal (2.4.3) are polished and coated with 1064nm and 885nm 0° anti-reflection dielectric films.

9. The narrow linewidth and high repetition rate three-wavelength laser according to claim 3, characterized in that: The first transformation lens (2.5.1) and the second transformation lens (2.5.2) are both plano-convex lenses, and both ends of the first transformation lens (2.5.1) and the second transformation lens (2.5.2) are coated with 1064nm high-transmittance dielectric films.

10. The narrow linewidth high repetition rate three-wavelength laser according to claim 4, characterized in that: The isolator (3.1) adopts a 45° magneto-optical crystal made of TGG; The third transform lens (3.2) is a plano-concave mirror coated with a 0±10° 1064nm high-transmittance dielectric film and a 532nm high-reflection dielectric film; The frequency doubling crystal (3.3) adopts a type I critical phase-matched LBO crystal, and both ends of the frequency doubling crystal (3.3) are plated with 1064nm and 532nm anti-reflection dielectric films; The fourth reflector (3.4) is a plane mirror coated with a 45±3° 1064nm and 532nm partial transmittance dielectric film; The first plane mirror (3.5) is coated with 0° 1064nm, 532nm, 1317nm anti-reflection dielectric films and 355nm, 486nm high-reflection dielectric films; The sum frequency crystal (3.6) adopts a type II critical phase matching LBO crystal, and both ends of the sum frequency crystal (3.6) are plated with a 350-1350nm anti-reflection dielectric film; The optical parametric oscillator crystal (3.7) adopts a type II phase-matched BBO crystal, and both ends of the optical parametric oscillator crystal (3.7) are plated with a 350-1350nm anti-reflection dielectric film; The second plane mirror (3.8) is coated with 0±10° 1064nm, 532nm, 355nm, 486nm high reflective dielectric film and 1317nm anti-reflective dielectric film.

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