CN103618206A - Full-solid-state single longitudinal mode yellow light laser - Google Patents

Abstract

The invention relates to a full-solid-state single longitudinal mode yellow light laser which is characterized in that an LD pump source, an optical coupling system and a Raman compound resonant cavity are included, and a torsion cavity film structure comprises a Brewster window and a lambda/4 wave plate combination; pump light emitted from the LD pump source is emitted to a laser crystal through the optical coupling system and then is absorbed, and the laser crystal generates base frequency light resonance after absorbing pump light energy; base frequency light is spread in a base frequency light resonant cavity in a reciprocating mode and forms linear polarized light through the Brewster window, and the lambda/4 combination on the two sides of the crystal guarantees that light spread in the crystal on the inner side of the lambda/4 wave plate combination is circular polarized light and light spread in the crystal on the outer side of the lambda/4 wave plate combination is linear polarized light; single longitudinal mode base frequency light is reflected by a beam splitter and is emitted to a Raman crystal to be converted to Stokes light which is spread in a Stokes light resonant cavity in a reciprocating mode, the Stokes light is reflected to the beam splitter through a first output mirror, and the Stokes light transmitted through the beam splitter is sent to a frequency doubling crystal which doubles the frequency of the single longitudinal mode Stokes light to generate single longitudinal mode yellow light; the single longitudinal mode yellow light is output after being reflected by the beam splitter.

Description

An all-solid-state single longitudinal mode yellow laser

technical field

The invention relates to an all-solid-state laser, in particular to an all-solid-state single longitudinal mode yellow laser.

Background technique

With the advantages of small size, high efficiency, stability and reliability, and easy operation, all-solid-state lasers have become irreplaceable ideal light sources in the laser industry. With the continuous improvement of crystal material growth technology and nonlinear optical technology, the output spectrum of all-solid-state lasers has been greatly expanded, covering multiple bands from infrared to visible light to ultraviolet. One of the highlights is the yellow laser in the 560nm-590nm band. get. According to the existing technology, the yellow-orange light in this band matches the absorption peaks of human hemoglobin and some specific fluorescent substances, so it is useful in the fields of blood cell counting, laser ophthalmology and dermatology treatment, biomedical testing, and deep space exploration. Wide application prospects.

The existing all-solid-state yellow laser implementation schemes are mainly divided into two categories: dual-wavelength sum frequency and Raman frequency doubling. Dual-wavelength means that two near-infrared wavelengths are simultaneously lased in the same laser system, and in a nonlinear crystal Carry out sum frequency to obtain yellow light, such as Lü, Y.F.et al., Laser Physics Letters 7(9), 634(2010), the prominent problem of this method is that the system is complex and difficult to operate, the pumping threshold is high, and generally complex film system design is required Or multiple pump light sources to provide the near-infrared wavelengths required by the sum frequency. In comparison, the combination of Raman frequency conversion and intracavity frequency doubling has proved to be a simpler and more effective way to achieve yellow light output, and is widely used in all-solid-state yellow light lasers. It can be used to obtain high-power pulsed The yellow laser output can also realize the effective operation of the continuous yellow solid-state laser.

However, in existing all-solid-state yellow lasers, due to the existence of spatial hole-burning effects and the simultaneous occurrence of multiple nonlinear processes in the same resonator, the laser works in a multi-mode mode, and the competition between the longitudinal modes will cause the laser The output power is unstable, and the yellow spectral line is not pure. In the traditional method, the linewidth of the laser is controlled by inserting frequency-selective components such as etalons. However, the problem it faces is that the production of frequency-selective components is demanding, sensitive to changes in pump power or cavity length, and single longitudinal mode operation Mechanisms are easily broken.

Contents of the invention

In view of the above problems, the purpose of the present invention is to provide an all-solid-state single longitudinal mode yellow laser that can effectively eliminate the spatial hole burning effect existing in the laser gain medium and realize stable output of single longitudinal mode yellow laser.

In order to achieve the above object, the present invention adopts the following technical solutions: an all-solid-state single longitudinal mode yellow laser, characterized in that: it includes an LD pump source, an optical coupling system and a Raman composite resonator, and the Raman composite resonator The cavity includes an input mirror, a first output mirror, a second output mirror, a twisted cavity structure, a laser crystal, a beam splitter, a Raman crystal and a nonlinear frequency doubling crystal, and the twisted cavity membrane structure includes a Brewster window and The λ/4 wave plate combination arranged in parallel on both sides of the laser crystal; the pump light emitted by the LD pump source is emitted into the Raman composite resonator through the optical coupling system and absorbed by the laser crystal, After the laser crystal absorbs the energy of the pump light, the fundamental frequency optical resonance is generated; the fundamental frequency light travels back and forth in the fundamental frequency optical resonator composed of the input mirror and the first output mirror and passes through the Brewster window to form a line Polarized light, the λ/4 wave plate combination on both sides of the laser crystal ensures that the light propagating in the laser crystal arranged inside the λ/4 wave plate combination is circularly polarized light, and the light propagating outside the λ/4 wave plate combination The light is linearly polarized light; the single longitudinal mode fundamental frequency light is reflected by the beam splitter and injected into the Raman crystal to be converted into Stokes light, and the Stokes light is in the Stokes light composed of the first output mirror and the second output mirror The resonant cavity propagates back and forth, and the Stokes light transmitted by the beam splitter is sent to the frequency doubling crystal, and the frequency doubling crystal doubles the frequency of the single longitudinal mode Stokes light according to the set frequency doubling conditions to generate a single longitudinal mode Yellow light; a part of the single longitudinal mode yellow light is directly emitted to the beam splitter and output through its reflection; another part of the single longitudinal mode yellow light is emitted to the second output mirror, and the second output mirror converts the single longitudinal mode The yellow light is reflected to the beam splitter and output through its reflection.

The λ/4 wave plate combination includes a first λ/4 wave plate and a second λ/4 wave plate, and the Brewster window is arranged between the input mirror and the first λ/4 wave plate or The Brewster window is disposed between the second λ/4 wave plate and the beam splitter.

The laser crystal adopts neodymium-doped isotropic crystals, ytterbium-doped isotropic crystals, neodymium-doped vanadate crystals cut along a specific axis, ytterbium-doped vanadate crystals cut along a specific axis, and bonded crystals. The light-transmitting surfaces at both ends of the laser crystal are coated with anti-reflection coatings for the pump light and the 1000nm-1200nm band.

The Raman crystal adopts one of yttrium vanadate, gadolinium vanadate, barium tungstate, potassium gadolinium tungstate, strontium tungstate, barium nitrate and lithium iodate, and the transparent surfaces at both ends of the Raman crystal are coated with There is an anti-reflection coating for the 1000nm ~ 1200nm band.

The frequency doubling crystal adopts one of lithium triborate, β-phase barium metaborate, potassium titanyl phosphate and bismuth borate. membrane.

The beam splitter is coated with a high-reflection film in the fundamental frequency band, a Stokes light high-transmission film, and a high-reflection film in the 500nm-600nm band.

An all-solid-state single longitudinal mode yellow laser is characterized in that: it includes an LD pump source, an optical coupling system and a Raman composite resonator, and the Raman composite resonator includes an input mirror, a first output mirror, a second an output mirror, a twisted cavity structure, a laser crystal, a beam splitter, a Raman crystal and a nonlinear frequency doubling crystal, the twisted cavity membrane structure includes a Brewster window and a λ parallel to both sides of the Raman crystal /4 wave plate combination; the pump light emitted by the LD pump source is emitted into the Raman composite resonant cavity by the fiber coupling system and absorbed by the laser crystal, and the laser crystal absorbs the energy of the pump light to generate The fundamental frequency optical resonance, the fundamental frequency light propagates back and forth in the fundamental frequency optical resonator composed of the input mirror and the first output mirror, and the fundamental frequency light is reflected by the beam splitter and injected into the Raman crystal to be converted into Stokes light , the Stokes light travels back and forth in the Stokes optical resonant cavity composed of the first output mirror and the second output mirror and forms linearly polarized light through the Brewster window, and the λ/4 on both sides of the Raman crystal The wave plate combination ensures that the light propagating in the Raman crystal arranged inside the λ/4 wave plate combination is circularly polarized light, and the light propagating outside the λ/4 wave plate combination is linearly polarized light; the single longitudinal mode Stokes light passes through the The first output mirror is reflected to the beam splitter, and the Stokes light transmitted by the beam splitter is sent to the frequency doubling crystal, and the frequency doubling crystal doubles the single longitudinal mode Stokes light according to the set frequency doubling condition A single longitudinal mode yellow light is generated at a high frequency; a part of the single longitudinal mode yellow light is directly emitted to the beam splitter and is reflected and output; the other part of the single longitudinal mode yellow light is emitted to the second output mirror, and the second output The mirror reflects the single longitudinal mode yellow light to the beam splitter and outputs it through reflection.

The λ/4 wave plate combination includes a first λ/4 wave plate and a second λ/4 wave plate, and the Brewster window is set between the first output mirror and the first λ/4 wave plate or the Brewster window is disposed between the second λ/4 wave plate and the beam splitter.

The beam splitter is coated with a high-reflection film in the fundamental frequency band, a Stokes light high-transmission film, and a high-reflection film in the 500nm-600nm band.

The laser crystal adopts neodymium-doped isotropic crystals, ytterbium-doped isotropic crystals, neodymium-doped vanadate crystals cut along a specific axis, ytterbium-doped vanadate crystals cut along a specific axis, and bonded crystals. The light-transmitting surfaces at both ends of the laser crystal are coated with anti-reflection coatings for the pump light and the 1000nm-1200nm band.

The Raman crystal adopts one of yttrium vanadate, gadolinium vanadate, barium tungstate, potassium gadolinium tungstate, strontium tungstate, barium nitrate and lithium iodate, and the transparent surfaces at both ends of the Raman crystal are coated with There is an anti-reflection coating for the 1000nm ~ 1200nm band.

The frequency doubling crystal adopts one of lithium triborate, β-phase barium metaborate, potassium titanyl phosphate and bismuth borate. membrane.

Due to the adoption of the above technical scheme, the present invention has the following advantages: 1. The present invention is provided with a twisted cavity structure, which includes a Brewster window and a λ/4 parallel arrangement on both sides of the laser crystal or Raman crystal. Wave plate combination, so the present invention combines Raman frequency conversion and nonlinear frequency doubling, and realizes the conversion from fundamental frequency light to Stokes light and then to yellow light in the Raman composite resonant cavity containing torsion cavity structure, fundamentally It eliminates the multi-longitudinal mode competition caused by the spatial hole-burning effect in traditional Raman lasers, realizes the single longitudinal mode yellow light output, improves the stability and spectral line purity of the all-solid-state single longitudinal mode yellow light laser output, and has the advantages of The advantages of small size, good beam quality and stable output. 2. The Raman composite resonator adopted in the present invention includes a fundamental frequency optical resonator composed of an input mirror and a first output mirror for converting pump light to fundamental frequency light, and a first output mirror and a second output mirror The composed stokes optical resonator is used for the conversion of fundamental frequency light to Raman light and the frequency doubling of Raman. Therefore, the laser resonator of the present invention adopts a composite structure design to ensure that multiple nonlinear processes occur simultaneously, and each conversion process Having its own relatively independent optical path is conducive to independent and flexible optimization of each optical field resonator, each process has a higher conversion efficiency, and effectively improves the conversion efficiency and output power of the laser. 3. The beam splitter of the present invention is used to separate the fundamental frequency light, Stokes light and yellow light, and the beam splitter is coated with a high reflection film in the fundamental frequency band, a Stokes light high transparency film and a 500nm-600nm band high reflection film, Therefore, it is ensured that each optical field can make full use of the high power density in the cavity, and at the same time, it is ensured that the light of different wavelengths has a relatively independent optical path, which is adjusted separately, and that the forward and reverse propagation of the yellow light emitted by the frequency doubling crystal is both Emitted from the same end of the laser, it not only improves the output power of the yellow light, but also avoids the heat load caused by the reabsorption of the yellow light by the laser crystal. The invention can be widely used in the production process of all solid-state single longitudinal mode yellow lasers.

Description of drawings

The present invention will be described in detail below in conjunction with the accompanying drawings. However, it should be understood that the accompanying drawings are provided only for better understanding of the present invention, and they should not be construed as limiting the present invention.

Fig. 1 is a schematic structural diagram of an all-solid-state single longitudinal mode yellow light laser system in which fundamental frequency light is torsional mode designed in the present invention, the black thick solid line represents the propagation of fundamental frequency light and stokes light, and the black thick dotted line represents the propagation of yellow light;

Fig. 2 is a schematic diagram of the structure of an all-solid-state single longitudinal mode yellow laser system in which Stokes light is torsional mode designed in the present invention, the thick black line represents the propagation of fundamental frequency light and Stokes light, and the thick black dashed line represents the propagation of yellow light.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, the all-solid-state single longitudinal mode yellow laser of the present invention includes an LD pump source 1, an optical coupling system 2 and a Raman composite resonator 3, and the Raman composite resonator 3 includes an input mirror 31, First output mirror 32, second output mirror 33, twisted cavity structure 34, laser crystal 35, beam splitter 36, Raman crystal 37 and nonlinear frequency doubling crystal 38; twisted cavity membrane structure 34 includes a Brewster window Combined with the λ/4 wave plate arranged in parallel on both sides of the laser crystal 35. The pump light emitted from the LD pump source 1 is emitted into the Raman composite resonant cavity 3 through the optical coupling system 2 and absorbed by the laser crystal 35. After the laser crystal 35 absorbs the energy of the pump light, the low-energy level particles transition to the high-energy level, forming The distribution of the number of particles is reversed. When the pump power reaches the laser threshold, the fundamental frequency optical resonance is generated in the Raman composite resonator 3, and the fundamental frequency light is in the fundamental frequency optical resonator composed of the input mirror 31 and the first output mirror 32. Back-and-forth propagation, linearly polarized light is formed through the Brewster window, and the λ/4 wave plate combination on both sides of the laser crystal 35 ensures that the light propagating in the laser crystal 35 arranged inside the λ/4 wave plate combination is circularly polarized light, The light propagating outside the λ/4 wave plate combination is linearly polarized light, ensuring that the fundamental frequency light works in a single longitudinal mode. The single longitudinal mode fundamental frequency light is reflected by the beam splitter 36 and injected into the Raman crystal 37. When the fundamental frequency light field When the intensity gradually increases and reaches the Raman threshold, the fundamental frequency light is converted into Stokes light with a longer wavelength by the stimulated Raman scattering of the Raman crystal 37 itself, and the Stokes light is transmitted by the first output mirror 32 and the second output mirror 33 The formed Stokes optical resonator propagates back and forth, the Stokes light is reflected to the beam splitter 36 through the first output mirror 32, and the Stokes light transmitted through the beam splitter 36 is sent to the frequency doubling crystal 38, and the frequency doubling crystal 38 is based on the set The frequency doubling condition doubles the frequency of the single longitudinal mode Stokes light to generate single longitudinal mode yellow light, wherein a part of the single longitudinal mode yellow light is directly transmitted to the beam splitter 36 and is reflected and output, and the other part of the single longitudinal mode yellow light is emitted To the second output mirror 33, the second output mirror 33 reflects the single longitudinal mode yellow light to the beam splitter mirror 36 and outputs it through reflection.

As shown in Figure 2, the twisted cavity film structure 34 can not only be arranged on both sides of the laser crystal 35, but also can be arranged on both sides of the Raman crystal 37. The specific optical path propagation is as follows: LD pump source 1 passes through the optical fiber coupling system 2 to pump The light is emitted into the Raman composite resonator cavity and absorbed by the laser crystal 35. After the laser crystal 35 absorbs the energy of the pump light, the fundamental frequency optical resonance is generated. The fundamental frequency light resonates in the fundamental frequency optical resonance composed of the input mirror 31 and the first output mirror 32. Back and forth in the cavity, the fundamental frequency light is reflected by the beam splitter 36 and injected into the Raman crystal 37 to be converted into Stokes light with a longer wavelength. Propagate, form linearly polarized light through the Brewster window, the λ/4 wave plate combination on both sides of the Raman crystal ensures that the light propagating in the Raman crystal 37 arranged inside the λ/4 wave plate combination is circularly polarized light, The light propagating outside the λ/4 wave plate combination is linearly polarized light, ensuring that the Stokes light works in a single longitudinal mode, and the single longitudinal mode Stokes light is reflected by the first output mirror 32 to the beam splitter 36, and the light transmitted by the beam splitter 36 The Stokes light is sent to the frequency doubling crystal 38 for frequency doubling to generate a single longitudinal mode yellow light, wherein a part of the single longitudinal mode yellow light is directly emitted to the beam splitter 36 and is reflected and output, and the other part of the single longitudinal mode yellow light is emitted to the second output mirror 33, the second output mirror 33 reflects the single longitudinal mode yellow light to the beam splitter 36 and outputs it through reflection.

In a preferred embodiment, the torsional cavity structure 34 is used to eliminate the multimode oscillation caused by the hole-burning effect of the laser crystal 35 or the Raman crystal 37 to ensure the single longitudinal mode output of the laser. The λ/4 wave plate combination includes two The same λ/4 wave plate, the first λ/4 wave plate 341 and the second λ/4 wave plate 342 (the two wave plates are distinguished for convenience of description), the central wavelength of the two λ/4 wave plates is the same as that of the base Corresponding to the wavelength of the fundamental frequency light or the Stokes light wavelength, while ensuring a high transmittance for the fundamental frequency light or the Stokes light wavelength, the existing λ with a high pass rate for the fundamental frequency light or the Stokes light wavelength can be used The /4 wave plate can also be coated with anti-reflection coating on the λ/4 wave plate, which is not limited. It can be either a zero-order wave plate or a multi-order wave plate. When the λ/4 wave plate wave plate combination is arranged on both sides of the laser crystal 35 in parallel, the Brewster window 343 is used to polarize the fundamental frequency light to form linearly polarized light, and to ensure that the linearly polarized light in a certain direction passes through the laser crystal 35. The Rust window blocks linearly polarized light in other directions, which can be placed between the first λ/4 wave plate 341 and the input mirror 31, or between the second λ/4 wave plate 342 and the beam splitter 36 . When the Brewster window 343 is arranged between the input mirror 31 and the first λ/4 wave plate 341, the Brewster window 343 should ensure high transmittance to the pump light, so as to ensure that the laser crystal 35 has a high transmittance to the pump light. Efficient absorption of Pu light. When the λ/4 wave plate combination is arranged on both sides of the Raman crystal 37 in parallel, the Brewster window 343 is used to polarize the Stokes light to form linearly polarized light, and ensure that the linearly polarized light in a certain direction passes through the Brewster A special window 343 blocks linearly polarized light in other directions, which can be placed between the first λ/4 wave plate 341 and the first output mirror 32, or between the second λ/4 wave plate 342 and the beam splitter 36 between.

Take the λ/4 wave plate combination placed on both sides of the laser crystal 35, and the Brewster window 343 placed between the second λ/4 wave plate 342 and the beam splitter 36 as an example to illustrate the optical path. The round-trip propagation will go through two λ/4 wave plates each twice, and the starting point is set at one end of the input mirror 31 as an example to illustrate the propagation process of the fundamental frequency light going back and forth once: the linearly polarized fundamental frequency light passes through the first λ/4 wave plate 341 Become circularly polarized light and inject it into the laser crystal 35, the circularly polarized light emitted from the laser crystal 35 passes through the second λ/4 wave plate 342 and becomes linearly polarized light, and the linearly polarized light in this direction passes through the Brewster window 343 smoothly Reflected by the beam splitter 36, the Raman crystal 37 emits to the first output mirror 32. Since the first output mirror 32 is coated with a high-reflection film of the wavelength of the fundamental frequency light, the fundamental frequency light is reflected back according to the original path, and passes through the Raman crystal in turn. 37. The beam splitter 36, the Brewster window 343, the second λ/4 wave plate 342 and the first λ/4 wave plate 341, during which the polarization returns to the initial state through the reverse polarization state conversion, and finally passes through the input mirror 31 Reflect back to the starting point.

In a preferred embodiment, the laser crystal 35 can be an isotropic crystal doped with neodymium (Nd) or doped with ytterbium (Yb), such as Nd doped with yttrium aluminum garnet Nd: YAG, doped with ytterbium yttrium aluminum garnet Yb: YAG ; It can also be neodymium-doped or ytterbium-doped vanadate crystals cut along a specific axis, such as yttrium vanadate (YVO ₄ ), gadolinium vanadate (GdVO ₄ ), lutetium vanadate (LuVO ₄ ); it can also be the following A type of bonded crystal: YAG/Nd:YAG, YVO ₄ /Nd:YVO ₄ , GdVO ₄ /Nd:GdVO ₄ , LuVO ₄ /Nd:LuVO ₄ . The doping concentration of the crystal should be selected according to different impurity ions and resonant cavity design; the light-transmitting surfaces at both ends of the laser crystal 35 are coated with anti-reflection coatings for the pump light and the 1000nm-1200nm band.

In a preferred embodiment, the Raman crystal 37 can be one of the following crystals with Raman activity: yttrium vanadate (YVO ₄ ), gadolinium vanadate (GdVO ₄ ), barium tungstate (BaWO ₄ ), tungstic acid Potassium gadolinium (KGW), strontium tungstate (SrWO ₄ ), barium nitrate (Ba(NO3)2), lithium iodate (LiIO3). The cutting direction and size of the crystal should be selected according to different resonant cavity types. The coating of the Raman crystal 37 needs to minimize the loss in the cavity in order to achieve low-threshold high-efficiency operation, so the light-transmitting surfaces at both ends of the Raman crystal are coated with anti-reflection coatings in the 1000nm-1200nm band.

In a preferred embodiment, the frequency doubling crystal 38 can use one of the following crystals: lithium triborate (LBO), β-phase barium metaborate (BBO), potassium titanyl phosphate (KTP) and bismuth borate (BIBO), select The frequency doubling crystal 38 is cut at a certain angle according to the phase matching condition corresponding to the frequency doubling process at the Stokes wavelength, and the two ends of the frequency doubling crystal 38 are coated with anti-reflection coatings in the 1000nm-1200nm band and 500nm-600nm band , so as to effectively improve the output power and conversion efficiency of the laser.

In a preferred embodiment, the input mirror 31 is coated with an anti-reflection coating for the wavelength of the pump light, and is coated with a high-reflection coating for the fundamental frequency and Stokes light bands (1000nm-1200nm), and the reflectivity is selected to be greater than 90%. The input mirror 31 can be a plane mirror or a curved mirror. When a curved mirror is used, the radius of curvature should be selected to meet the condition of a stable resonant cavity, which is not limited here.

In a preferred embodiment, the first output mirror 32 is coated with a high-reflection film for fundamental frequency light and Stokes light band (1000nm-1200nm), and the reflectivity is selected to be greater than 90%; the second output mirror 33 is coated with Stokes light band and 500 High reflective coating for ~600nm wavelength band, the reflectivity is selected to be greater than 90%. The first output mirror 32 and the second output mirror 33 can be flat mirrors or curved mirrors. When curved mirrors are used, the radius of curvature should be selected to meet the stable resonance condition of the laser, which is not limited here.

In a preferred embodiment, the beam splitter 36 is coated with a high-reflection film in the fundamental frequency band, a Stokes optical high-transparency film, and a high-reflection film in the 500nm-600nm band, and the intracavity loss should be reduced as much as possible when selecting the beam splitter , its size and angle will be determined according to the specific resonant cavity, which is not limited here.

In a preferred embodiment, the pumping source 1 can use an existing pumping source, and the pumping source 1 can use LD end pumping, which includes a laser diode, a driving power supply and a cooling device; the pumping source can also use an LD The side pump, which includes an LD side pump module, a driving power supply and a cooling device, is in the prior art and will not be repeated here.

In a preferred embodiment, the optical coupling system 2 includes a coupling fiber 21, a collimating lens 22 and a focusing lens 23, and the pumping source 1 sends the output pump light to the collimating lens 22 after being coupled by the coupling fiber Collimated into parallel light, the parallel light is sent to the focusing lens 23 to focus into the Raman composite resonant cavity 3 .

In a preferred embodiment, in order to suppress the thermal lens effect caused by the thermal load in each crystal, and control the temperature of the crystal to make the system in an optimal working state, the present invention can also include a crystal cooling device 4, which is the present crystal cooling device. There is a technology, which includes a metal block for clamping crystals and a water-cooling circulation system, and there are pipes in the metal block to communicate with the water-cooling circulation system of circulating flow. When in use, the laser crystal 35, the Raman crystal 37 and the frequency doubling crystal 38 are respectively wrapped with indium foil and placed in a metal block, and the laser crystal 35, the Raman crystal 37 and the Frequency doubling crystal 38 achieves the purpose of cooling. The crystal cooling device 4 of the present invention can also use a semiconductor cooling chip (TEC). When in use, the surroundings of the laser crystal 35, the Raman crystal 37 and the frequency doubling crystal 38 are respectively wrapped with indium foil and placed in a metal block. The block is connected with the semiconductor refrigeration plate to make the laser crystal 35, the Raman crystal 37 and the frequency doubling crystal 38 reach the purpose of cooling; the present invention can also include a crystal temperature control device, and the crystal temperature control device can adopt an intelligent temperature controller. Connect the intelligent temperature controller to the metal block and control its temperature in real time to stabilize at the user's set value.

The working process of the all-solid-state single longitudinal mode yellow laser of the present invention is described in detail below through specific embodiments:

Example 1:

，尺寸为4×4×5mm，两端通光面镀1000～1200nm和500～600nm波段增透膜，晶体的角度通过光学调节架进行精确控制以便实现最佳倍频效率。本实施例中各晶体的冷却可以采用循环水制冷装置或半导体制冷片TEC装置进行实现，各元件尽可能地紧密排练以便缩短腔长，减小损耗。As shown in Figure 1, the all-solid-state single longitudinal mode yellow laser of this embodiment is arranged in parallel with two λ/4 wave plates on both sides of the laser crystal 35, and the Brewster window 343 is arranged on the second λ/4 wave plate 342 and the beam splitter 36, wherein the Brewster window window ensures that the P-polarized 1064nm fundamental frequency light has zero reflection loss and prevents the S-polarized light from passing through; in addition, each optical element of the all-solid-state single longitudinal mode yellow laser in this embodiment The specific selection parameters are: the laser diode LD of the LD end pump source 1 provides 808nm pump light, the maximum output power is 20W, and it has a cooling device; the core diameter of the coupling fiber is Φ200um, the numerical aperture is 0.22, and the collimating and focusing lenses are coated There is an 808nm anti-reflection film; a Raman composite resonator composed of an input mirror 31, a first output mirror 32, a second output mirror 33 and a beam splitter 36, wherein the fundamental frequency optical resonator is composed of an input mirror 31 and a first output mirror The input mirror 31 is composed of a flat mirror, the coating requirement is 808nm transmittance greater than 90%, 1000nm-1200nm high reflection film, reflectivity greater than 99.5%, the first output mirror 32 adopts a concave mirror, the radius of curvature is 250mm, the mirror surface Coated with 1000nm～1200nm high reflection film, the reflectivity is greater than 99.5%. The first output mirror 32 and the second output mirror 33 form a Stokes optical resonant cavity. 600nm band high-reflection film with a reflectivity greater than 99.5%; the beam splitter 36 is a flat mirror for separating the 1064nm fundamental frequency light from the 1174nm Stokes light, and both sides of the mirror are coated with a 1064nm high-reflection film with a reflectivity greater than 99% and a transparent 1174nm anti-reflection coating with a pass rate greater than 99%, and the side of the beam splitter 36 facing the second output mirror 33 is also coated with a high-reflection film in the 500-600nm band, with a reflectivity greater than 95%; the laser crystal is made of neodymium-doped gadolinium vanadate (Nd:GdVO ₄ ), adopt c-cutting, doping concentration is 0.5at.%, size is 4×4×10mm, the two transparent surfaces of laser crystal 35 are coated with anti-reflection in 808nm and 1000nm～1200nm bands The temperature of the crystal is controlled at about 25°C; the Raman crystal 37 is made of gadolinium vanadate (GdVO ₄ ), cut in the c direction, and the size is 4×4×10mm. The temperature of the crystal is controlled at about 25°C; the frequency-doubling crystal 38 is made of β-phase barium metaborate (BBO), and the cutting angle meets the type I phase matching condition θ=21.5°,

, the size is 4×4×5mm, both ends are coated with 1000-1200nm and 500-600nm band anti-reflection coatings, the angle of the crystal is precisely controlled by the optical adjustment frame to achieve the best frequency doubling efficiency. The cooling of each crystal in this embodiment can be realized by a circulating water cooling device or a TEC device of a semiconductor cooling chip, and the components are arranged as closely as possible to shorten the cavity length and reduce loss.

The working process of the all-solid-state laser in this embodiment is as follows: LD end pump source 1 emits 808nm pump light, and after being collimated and focused by optical coupling system 2, it is injected into Nd:GdVO ₄ crystal 35 to generate 1064nm fundamental frequency light , the fundamental-frequency light travels back and forth in the fundamental-frequency optical resonant cavity formed by the input mirror 31, the beam splitter mirror 36 and the first output mirror 32, and the combination of the Brewster window 343 and the λ/4 wave plate together form a torsional cavity structure 34 , to ensure that the fundamental frequency light realizes single longitudinal mode operation, the 1064nm fundamental frequency light is Raman frequency shifted in the gadolinium vanadate GdVO ₄ 37 to output 1174nm single longitudinal mode Stokes light, and the Stokes light is injected into the BBO crystal 38 through the beam splitter 36 for further processing. The second frequency doubling produces yellow light, and finally the single longitudinal mode yellow light is reflected by the beam splitter 36 and output to the outside of the cavity.

Example 2:

As shown in Figure 2, this embodiment is basically the same as Embodiment 1, the difference is that the two λ/4 wave plates of the all-solid-state single longitudinal mode yellow laser of this embodiment are arranged in parallel on both sides of the Raman crystal 37, and the layout The Brewster window 343 is arranged between the second λ/4 wave plate 342 and the beam splitter 36, wherein the Brewster window 343 window ensures that the P-polarized Stokes light has zero reflection loss and prevents the S-polarized Stokes light from passing through, and the two λ The central wavelength of the /4 wave plate corresponds to the wavelength of the Stokes light, and the other optical path propagation processes are completely the same as those in Embodiment 1, and will not be repeated here.

In the above-mentioned embodiments, all optical components of the present invention can be positioned using corresponding external brackets during use. The specific position of each optical component is not limited in the present invention, and can be adjusted according to specific experimental requirements. The above-mentioned embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component can be changed to some extent, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not excluded from the protection scope of the present invention.

Claims (12)

1. a kind of all-solid-state single longitudinal mode yellow light laser, it is characterized in that: it comprises LD pumping source, optical coupling system and Raman composite resonant cavity, described Raman composite resonant cavity comprises input mirror, first output mirror, A second output mirror, a twisted cavity structure, a laser crystal, a beam splitter, a Raman crystal, and a nonlinear frequency-doubling crystal, the twisted cavity membrane structure includes a Brewster window and parallel devices arranged on both sides of the laser crystal λ/4 wave plate combination; The pump light emitted by the LD pump source is emitted into the Raman composite resonator cavity by the optical coupling system and absorbed by the laser crystal, and the laser crystal absorbs the energy of the pump light to generate a fundamental frequency optical resonance; The frequency light travels back and forth in the fundamental frequency optical resonator composed of the input mirror and the first output mirror and passes through the Brewster window to form linearly polarized light. The combination of λ/4 wave plates on both sides of the laser crystal ensures The light propagating in the laser crystal arranged inside the λ/4 wave plate combination is circularly polarized light, and the light propagating outside the λ/4 wave plate combination is linearly polarized light; the single longitudinal mode fundamental frequency light passes through the split The beam mirror is reflected and injected into the Raman crystal and converted into Stokes light, and the Stokes light propagates back and forth in the Stokes optical resonator composed of the first output mirror and the second output mirror, and the Stokes light transmitted through the beam splitter is sent In the frequency doubling crystal, the frequency doubling crystal doubles the frequency of the single longitudinal mode Stokes light according to the set frequency doubling conditions to generate single longitudinal mode yellow light; a part of the single longitudinal mode yellow light is directly emitted to the beam splitter The other part of the single longitudinal mode yellow light is emitted to the second output mirror, and the second output mirror reflects the single longitudinal mode yellow light to the beam splitter mirror and is reflected and output. 2. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 1, is characterized in that: described λ/4 wave plate combination comprises the first λ/4 wave plate and the second λ/4 wave plate, so The Brewster window is set between the input mirror and the first λ/4 wave plate or the Brewster window is set between the second λ/4 wave plate and the beam splitter . 3. A kind of all-solid-state single longitudinal mode yellow laser as claimed in claim 1, characterized in that: said laser crystal adopts neodymium-doped isotropic crystal, ytterbium-doped isotropic crystal, doped crystal cut along a specific axis One of neodymium vanadate crystals, ytterbium-doped vanadate crystals cut along a specific axis, and bonded crystals, the light-transmitting surfaces at both ends of the laser crystal are coated with lasers for pump light and 1000nm to 1200nm band AR coating. 4. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 1 or 2 or 3, characterized in that: said Raman crystal adopts yttrium vanadate, gadolinium vanadate, barium tungstate, potassium gadolinium tungstate , strontium tungstate, barium nitrate and lithium iodate, the light-transmitting surfaces at both ends of the Raman crystal are coated with anti-reflection coatings in the band of 1000nm to 1200nm. 5. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 1, 2 or 3, characterized in that: the frequency doubling crystal adopts lithium triborate, β-phase barium metaborate, potassium titanyl phosphate and boric acid One of bismuth, the two ends of the frequency doubling crystal are coated with anti-reflection coatings in the 1000nm-1200nm band and 500nm-600nm band. 6. A kind of all-solid-state single longitudinal mode yellow light laser device as claimed in claim 1 or 2 or 3, is characterized in that: described beam splitter mirror is coated with the highly reflective film of fundamental frequency band, Stokes light highly transparent film and 500nm ~ 600nm band high reflection film. 7. An all-solid-state single longitudinal mode yellow laser, characterized in that: it comprises an LD pump source, an optical coupling system and a Raman composite resonator, and the Raman composite resonator includes an input mirror, a first output mirror, A second output mirror, a twisted cavity structure, a laser crystal, a beam splitter, a Raman crystal and a nonlinear frequency doubling crystal, the twisted cavity membrane structure includes a Brewster window and is arranged in parallel on both sides of the Raman crystal λ/4 wave plate combination; The pump light emitted by the LD pump source is emitted into the Raman composite resonant cavity through the optical fiber coupling system and absorbed by the laser crystal. After the laser crystal absorbs the energy of the pump light, it generates a fundamental frequency optical resonance. The frequency light propagates back and forth in the base frequency optical resonator composed of the input mirror and the first output mirror, the base frequency light is reflected by the beam splitter and injected into the Raman crystal to be converted into Stokes light, and the Stokes light is converted into Stokes light by the The Stokes optical resonant cavity composed of the first output mirror and the second output mirror propagates back and forth and forms linearly polarized light through the Brewster window, and the combination of λ/4 wave plates on both sides of the Raman crystal ensures the setting The light propagating in the Raman crystal inside the λ/4 wave plate combination is circularly polarized light, and the light propagating outside the λ/4 wave plate combination is linearly polarized light; the single longitudinal mode Stokes light is reflected by the first output mirror to The beam splitter transmits the Stokes light transmitted by the beam splitter to the frequency doubling crystal, and the frequency doubling crystal doubles the frequency of the single longitudinal mode Stokes light according to the set frequency doubling conditions to generate a single longitudinal mode yellow Light; wherein a part of the single longitudinal mode yellow light is directly emitted to the beam splitter and output through its reflection; another part of the single longitudinal mode yellow light is emitted to the second output mirror, and the second output mirror converts the single longitudinal mode yellow The light is reflected to the beam splitter and output through reflection. 8. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 7, is characterized in that: described λ/4 wave plate combination comprises the first λ/4 wave plate and the second λ/4 wave plate, so The Brewster window is set between the first output mirror and the first λ/4 wave plate or the Brewster window is set between the second λ/4 wave plate and the beam splitter between. 9. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 7, characterized in that: the beam splitter is coated with a high reflection film in the fundamental frequency band, a Stokes light high transmittance film, and a 500nm-600nm band Highly reflective film. 10. A kind of all-solid-state single longitudinal mode yellow laser as claimed in claim 7 or 8 or 9, characterized in that: said laser crystal adopts neodymium-doped isotropic crystal, ytterbium-doped isotropic crystal, along a specific axis One of Nd-doped vanadate crystal cut along a specific axis, Yb-doped vanadate crystal cut along a specific axis and a bonded crystal, the light-transmitting surfaces at both ends of the laser crystal are coated with pump light and 1000nm Anti-reflection coating for ~1200nm band. 11. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 7 or 8 or 9, characterized in that: said Raman crystal adopts yttrium vanadate, gadolinium vanadate, barium tungstate, potassium gadolinium tungstate , strontium tungstate, barium nitrate and lithium iodate, the light-transmitting surfaces at both ends of the Raman crystal are coated with anti-reflection coatings in the band of 1000nm to 1200nm. 12. A kind of all-solid-state single longitudinal mode yellow light laser as claimed in claim 7 or 8 or 9, characterized in that: the frequency doubling crystal adopts lithium triborate, β-phase barium metaborate, potassium titanyl phosphate and boric acid One of bismuth, the two ends of the frequency doubling crystal are coated with anti-reflection coatings in the 1000nm-1200nm band and 500nm-600nm band.

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