Ultraviolet laser

Abstract

The ultraviolet laser comprises a pump light source module, one side of the pump light source module is sequentially provided with a polarizer, a Q-switching module and a first reflecting mirror, the pump light source module and a reflecting light path are emitted into a green light oscillation cavity, and the green light oscillation cavity comprises a first dichroic mirror for receiving incident light. A second reflecting mirror is arranged on a reflecting light path of the first dichroic mirror, a sum frequency nonlinear crystal and a frequency doubling nonlinear crystal are arranged between the first dichroic mirror and the second reflecting mirror, a third reflecting mirror is arranged on a transmission light path of the first dichroic mirror, and a second dichroic mirror is arranged between the first dichroic mirror and the third reflecting mirror. And a reflection light path of the second dichroic mirror is an output light path of the laser. The unused green light is reflected back into the cavity through the third reflector to continue to participate in sum frequency, the green light oscillates between the second reflector and the third reflector, the green light utilization rate and the sum frequency efficiency are improved, and the purpose of improving the ultraviolet laser power is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of lasers, and particularly relates to an ultraviolet laser. Background Art

[0002] Ultraviolet lasers are very important in the field of industrial processing. Ultraviolet laser processing is a cold processing technology, called the "photoresist" effect, where photons with high load energy break the chemical bonds of materials or the surrounding medium. Therefore, the material is damaged by a non-thermal process, and no heating or thermal deformation occurs in the inner layer and nearby areas. The edges of the processed material are smooth, with a low degree of carbonization, and both fineness and thermal shock are reduced to very low levels. Therefore, the market demand for high-energy ultraviolet lasers is extremely large. However, in traditional intracavity frequency-doubled ultraviolet lasers, it is difficult to output high-energy ultraviolet lasers in the order of dozens of millijoules.

[0003] Currently, in traditional intracavity frequency-doubled ultraviolet lasers, the sum-frequency nonlinear crystal is closer to the laser crystal than the frequency-doubling nonlinear crystal. The reason is that generally, the larger the light spot and the lower the power density near the laser crystal in the resonant cavity, the lower the power density at the sum-frequency crystal, the lower the risk of damage to the sum-frequency crystal, and the longer the service life of the ultraviolet laser can be increased. The green light that is not utilized for sum-frequency in the optical path after the output of the ultraviolet light is directly absorbed by the absorber, resulting in the problems of wasted green light power and low sum-frequency efficiency. Summary of the Utility Model

[0004] Aiming at the deficiencies of the prior art, the utility model provides an ultraviolet laser to solve the problem that it is difficult for lasers in the prior art to output high-energy ultraviolet lasers.

[0005] The utility model realizes this purpose through the following technical solutions:

[0006] An ultraviolet laser includes a pump light source module. A first reflector is provided on one side of the pump light source module, and the pump light source module together with the reflection optical path is incident into a green light oscillation cavity. The green light oscillation cavity includes a first dichroic mirror for receiving incident light. A polarizer and a Q-switching module are provided on the optical path between the first dichroic mirror and the first reflector. A second reflector is provided on the reflection optical path of the first dichroic mirror. A sum-frequency nonlinear crystal and a frequency-doubling nonlinear crystal are provided on the optical path between the first dichroic mirror and the second reflector. A third reflector is provided on the transmission optical path of the first dichroic mirror. A second dichroic mirror is provided between the first dichroic mirror and the third reflector, and the reflection optical path of the second dichroic mirror is the output optical path of the laser.

[0007] Further, a diaphragm is provided on the optical path between the second reflector and the third reflector.

[0008] Further, the pump light source module includes a pump source and a laser crystal.

[0009] Further, the number of pump light source modules is set to two, and a rotator is provided between the two pump light source modules.

[0010] Further, the wavelength of the pump source is 808 nm, and it is a pulsed pump or a continuous pump.

[0011] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0012] 1. The second reflector and the third reflector form a green light oscillation cavity, which reflects the green light that was not used for sum frequency for the first time back into the cavity to form oscillation, increasing the sum frequency efficiency and improving the ultraviolet laser power.

[0013] 2. A diaphragm is added to the green light oscillation cavity to limit the spot size of the oscillating green light and protect the nonlinear crystal. Description of the Drawings

[0014] In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained based on the provided drawings.

[0015] Figure 1 It is a schematic structural diagram of the laser in the embodiment of the present utility model;

[0016] Reference numerals in the drawings: 1 - first reflector; 2 - Q-switching module; 3 - polarizer; 4 - fundamental frequency light oscillation optical path; 5 - pump source; 6 - laser crystal; 7 - rotator; 8 - first dichroic mirror; 9 - sum frequency nonlinear crystal; 10 - second harmonic generation nonlinear crystal; 11 - second reflector; 12 - second dichroic mirror; 13 - green light oscillation optical path; 14 - third reflector; 15 - diaphragm; 16 - ultraviolet light output optical path. Detailed Embodiments

[0017] The following will describe the exemplary embodiments of the present utility model in more detail with reference to the drawings. Although the exemplary embodiments of the present utility model are shown in the drawings, it should be understood that the present utility model can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present utility model and to fully convey the scope of the present utility model to those skilled in the art. It should be noted that, without conflict, the embodiments in the present utility model and the features in the embodiments can be combined with each other. The present utility model will be described in detail below with reference to the drawings and in combination with the embodiments.

[0018] The present utility model discloses an embodiment of an ultraviolet laser, and the structure and optical path of the laser are as Figure 1As shown in the figure, it includes a first pump light source module and a second pump light source module. Both the first pump light source module and the second pump light source module are composed of a pump source 5 and a laser crystal 6. A rotatory polarizer 7 is provided between the two pump light source modules. On the other side of the first pump light source module, a polarizer 3, a Q-switching module 2, and a first mirror 1 are sequentially provided. On the other side of the second pump light source module, a green light oscillation cavity is provided.

[0019] Figure 1 The right square area in the figure is the green light oscillation cavity, which includes a first dichroic mirror 8. A second mirror 11 is provided on the reflection optical path of the first dichroic mirror 8. A sum-frequency nonlinear crystal 9 and a second-harmonic generation nonlinear crystal 10 are provided on the optical path between the first dichroic mirror 8 and the second mirror 11. A diaphragm 15 is provided on the optical path between the first dichroic mirror 8 and the sum-frequency nonlinear crystal 9. A third mirror 14 is provided on the transmission optical path of the first dichroic mirror 8. A second dichroic mirror 12 is provided on the optical path between the first dichroic mirror 8 and the third mirror 14. The reflection optical path of the second dichroic mirror 12 is the laser output optical path.

[0020] The pump source 5 is used to inject pump energy into the laser crystal 6, and its pumping method can be end pumping or side pumping. The pump source 5 can be continuous pumping or pulsed pumping. When the pump source 5 is continuously pumped, continuously output fundamental frequency light can be obtained. When the pump source 5 is pulsed pumped, pulsed output fundamental frequency light can be obtained.

[0021] The laser crystal 6 can be neodymium-doped Nd:YAG, and yttrium aluminum garnet crystal is its active substance, which can excite pulsed laser or continuous laser, and the emitted laser is infrared wavelength 1064nm. The laser crystal can also be ytterbium-doped yttrium aluminum garnet crystal Yb:YAG, neodymium-doped glass Nd:Glass, neodymium-doped lithium fluoride crystal Nd:YLF, erbium-doped yttrium aluminum garnet crystal Er:YAG, etc.

[0022] The first mirror 1 and the second mirror 11 form two cavity mirrors of the resonator, enabling the fundamental frequency light to oscillate in the resonator. The second mirror 11 is coated with high reflectivity for 1064nm, 532nm, and 355nm, aiming to reflect the subsequent returned 532nm and 355nm lasers. The rotatory polarizer 7 is a 90° rotatory polarizer placed between the two pump light source modules, aiming to compensate for the thermal depolarization effect of the two laser crystals 6. The polarizer 3 is placed in the resonator and can be placed at any position between the first mirror 1 and the first dichroic mirror 8, aiming to change the randomly polarized fundamental frequency light in the resonator into linearly polarized light. The Q-switching module 2 is placed in the resonator and can be placed at any position between the first mirror 1 and the first dichroic mirror 8, aiming to change the fundamental frequency light into Q-switched laser.

[0023] The frequency-doubling nonlinear crystal 10 doubles the fundamental frequency light of 1064 nm in the cavity to generate green light of 532 nm. The sum-frequency nonlinear crystal 9 sums the frequencies of 1064 nm and 532 nm to generate ultraviolet light of 355 nm. The first dichroic mirror 8 is coated with high reflectivity for 1064 nm and high transmittance for 532 nm and 355 nm, and its purpose is to serve as the output mirror for 532 nm and 355 nm in the cavity. The second dichroic mirror 12 is coated with high reflectivity for 355 nm and high transmittance for 532 nm, and its purpose is to separate 532 nm and 355 nm to output the ultraviolet light.

[0024] The third reflector 14 is coated with high reflectivity for 532 nm. Its purpose is to form a green light oscillation cavity with the second reflector 11, enabling the green light to oscillate in the cavity, reflecting the unused green light back into the cavity to continue participating in sum-frequency. The 355 nm ultraviolet light generated by the re-sum-frequency will be reflected by the second reflector 11 and then pass through the second dichroic mirror 12 to output the ultraviolet light. The aperture stop 15 can be placed at any position between the second reflector 11 and the third reflector 14 in the green light oscillation cavity, not limited to one position. The aperture of the aperture stop is selected according to the cavity type design, and its purpose is to limit the spot size of the oscillating green light to protect the nonlinear crystal.

[0025] The triple-frequency resonant cavity of the present utility model is used to achieve high-energy ultraviolet output. Through the third reflector 14, the unused green light is reflected back into the cavity to continue participating in sum-frequency. The green light oscillates back and forth between the second reflector 11 and the third reflector 14, improving the utilization rate of green light and the sum-frequency efficiency, so as to achieve the purpose of increasing the power of ultraviolet laser. Among them, the aperture stop 15 is used to limit the spot size of the oscillating green light to protect the nonlinear crystal. The dichroic mirror 12 separates the green light and the ultraviolet light and outputs the ultraviolet light from the laser.

[0026] In the present utility model, the coatings and curvatures of the second reflector 11 and the third reflector 14 can be adjusted according to the specific optical path, not limited to one set of parameters.

[0027] In the present utility model, the green light oscillation cavity can be designed as a folded cavity according to requirements, not limited to a straight cavity, such as a Z-shaped cavity, an L-shaped cavity, etc.

[0028] It should be noted that in the description of the present utility model, the terms indicating directions or positional relationships such as "up", "down", "left", "right", "inside", "outside", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model.

[0029] In addition, it should be noted that in the description of the present utility model, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

Claims

1. An ultraviolet laser, characterized in that: It comprises a pump light source module, a first reflector is arranged at one side of the pump light source module, the pump light source module together with the reflected light path is incident into a green light oscillation cavity, the green light oscillation cavity comprises a first dichroic mirror for receiving incident light, a polarizer and a Q-switching module are arranged on the light path between the first dichroic mirror and the first reflector, a second reflector is arranged on the reflected light path of the first dichroic mirror, a sum frequency nonlinear crystal and a frequency doubling nonlinear crystal are arranged on the light path between the first dichroic mirror and the second reflector, a third reflector is arranged on the transmitted light path of the first dichroic mirror, a second dichroic mirror is arranged between the first dichroic mirror and the third reflector, and the reflected light path of the second dichroic mirror is the laser output light path.

2. The ultraviolet laser according to claim 1, characterized in that: An aperture is provided on the optical path between the second reflecting mirror and the third reflecting mirror.

3. The ultraviolet laser according to claim 1, characterized in that: The pump light source module includes a pump source and a laser crystal.

4. The ultraviolet laser according to any one of claims 1 to 3, characterized in that: The number of pump light source modules is set to two, and an optical rotator is arranged between the two pump light source modules.

5. The ultraviolet laser according to claim 3, characterized in that: The pump source wavelength is 808nm, which is pulse pumping or continuous pumping.

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