CN218549065U - Ultraviolet fiber laser - Google Patents

Abstract

The application provides an ultraviolet fiber laser, includes high repetition frequency polarization maintaining fiber laser, first Brewster's window piece, second half-wave plate, first plano-convex lens, first frequency conversion crystal, first speculum, second frequency conversion crystal, fourth speculum, second plano-convex lens in proper order. The high repetition frequency polarization-maintaining fiber laser can output high repetition frequency polarization-maintaining fundamental frequency signal light. And the 1000-1100nm fundamental frequency signal light which passes through the first Brewster window sheet has a specific polarization state. The rotation angle of the polarization state is adjusted to a proper polarization state by using the second half-wave plate and the first Brewster window plate, and the high-power incident light entering the first frequency conversion crystal and the second frequency conversion crystal can meet the polarization state and energy requirements of crystal frequency doubling by setting the placing angles of the first reflector and the second frequency conversion crystal. The arrangement improves the light-light conversion efficiency of the system, and can obtain ultraviolet light output with high repetition frequency, high energy conversion efficiency, high power and stability.

Description

Ultraviolet fiber laser

Technical Field

The invention relates to the technical field of laser, in particular to an ultraviolet fiber laser with high repetition frequency and high stability.

Background

With the increasing demand of new energy industry in recent years, higher requirements are put forward on the front-end laser processing technology. The absorption rate of the traditional infrared laser to high-reflectivity materials is very low due to the material absorption factor, and welding and cutting of the high-reflectivity materials such as copper materials in the lithium battery industry cannot be met. Ultraviolet laser light is popular in society because it can be precisely processed in a finer field due to its short wavelength.

The current main mode for generating ultraviolet laser is to generate the ultraviolet laser by a pure solid-state laser in a resonant cavity plus frequency conversion mode, so that the formed ultraviolet laser has high peak power and single pulse energy, but is limited by the characteristics of solid materials, the repetition frequency of the laser is low, the energy conversion efficiency is low, and the output ultraviolet beam power cannot be too high. The fiber laser has the characteristics of high integration degree, high stability and the like, and the output of high-power laser can be easily realized by changing the length of the gain fiber.

At present for the stability that improves laser output, can adopt the polaroid to change laser transmission's polarization state usually to satisfy the stable output of laser, nevertheless the polaroid is big to the absorption of light, and the light loss through the polaroid is big, and polaroid material itself is difficult to tolerate high power laser, and easy material damage loses efficacy, is difficult to realize the laser output of high power, stability.

Therefore, an ultraviolet laser is needed to be invented, and ultraviolet output with high repetition frequency, high energy conversion efficiency, high power and stability can be obtained.

SUMMERY OF THE UTILITY MODEL

The present application is directed to an ultraviolet fiber laser, so as to solve the problems mentioned in the background art.

In order to achieve the above purpose, the present application provides the following technical solutions: an ultraviolet fiber laser sequentially comprises a high repetition frequency polarization maintaining fiber laser, a first Brewster window plate, a second half wave plate, a first plano-convex lens, a first frequency conversion crystal, a first reflector, a second frequency conversion crystal, a fourth reflector and a second plano-convex lens.

The specific working principle and process of the application are as follows:

the high-repetition-frequency polarization-maintaining fiber laser can output linear polarization fundamental frequency signal light with high repetition frequency polarization maintaining of 1000-1100nm, and when input laser light is linearly polarized light, the polarization-maintaining fiber laser still outputs linearly polarized light after the input laser light is transmitted by the polarization-maintaining fiber laser.

The first Brewster window sheet is an optical lens placed at a Brewster angle, and 1000-1100nm fundamental frequency signal light passing through the first Brewster window sheet has a specific polarization state.

When the light beam passes through the second half-wave plate, the second half-wave plate adjusts the direction of the polarization state of the linearly polarized light so as to meet the requirement of the first frequency conversion crystal on the direction of the polarization state of the high-power input laser entering the first frequency conversion crystal, and the ideal frequency doubling laser is obtained. The first plano-convex lens focuses the light beam to achieve high energy density and high power density of the light beam incident on the first frequency conversion crystal 8.

The first frequency conversion crystal uses LBO/BBO or other frequency doubling crystals, when 1000-1100nm fundamental frequency signal light passes through the first frequency conversion crystal and the power density reaches a nonlinear threshold value, corresponding second harmonic, namely frequency doubling light, can be generated, the light frequency of the generated frequency doubling light is half of the fundamental frequency light, and the generated light is ultraviolet. Because the frequency doubling light and the fundamental frequency signal light which are emitted from the first frequency conversion crystal are divergent light.

The light receiving surface of the first reflector is a concave mirror with a reflection function, the first reflector is adopted to focus and correct frequency doubling light and fundamental frequency signal light emitted from the first frequency conversion crystal, and the high-power incident light entering the second frequency conversion crystal can meet the angle requirement of the polarization state of the second frequency conversion crystal by setting the placing angles of the first reflector and the second frequency conversion crystal. When the 1000-1100nm and 500-550nm mixed light after being reflected and focused by the first reflecting mirror passes through the second frequency conversion crystal and the power density reaches a nonlinear threshold value, corresponding third harmonic light, namely sum frequency light, is generated, the light frequency of the generated sum frequency light is three times of that of fundamental frequency light, and ultraviolet light beams (330-370 nm) are generated at the moment.

And the fourth reflector screens the light beam passing through the second frequency conversion crystal, and separates the required 330-370nm ultraviolet light beam from the residual 1000-1100nm and 500-550nm light beams after frequency tripling. And finally, the second plano-convex lens collimates the ultraviolet light emitted from the second variable frequency crystal so as to meet the subsequent production requirement.

The laser is realized by carrying out twice external cavity frequency multiplication on a high repetition frequency polarization-maintaining fiber laser, after the high repetition frequency polarization-maintaining fiber laser outputs high repetition frequency polarization-maintaining 1000-1100nm infrared light to reach a first Brewster window piece, because a certain included angle is formed between the first Brewster window piece and a light path, the return light generated by the light beam due to incomplete transmission or other reasons is very little, and the first Brewster window piece can enable linear polarization to have better transmittance. Secondly, a light beam passing through the first brewster window sheet, namely, a 1000-1100nm fundamental frequency signal light has a specific polarization state, but a three-dimensional coordinate relationship is formed between the light path direction and the polarization direction, and the independent adjustment and control of the first brewster window sheet is difficult to completely meet the requirement of the first frequency conversion crystal on the polarization state of the incident laser, or the independent adjustment and control of the first brewster window sheet is generally only capable of adjusting and controlling the directions of 1-2 dimensions, and is difficult to stably output the laser required by the first frequency conversion crystal.

The second half-wave plate is arranged behind the first Brewster window plate, and the half-wave plate is mainly used for adjusting the polarization direction of the light beam behind the lens to rotate with the polarization direction in front of the light beam in the other dimension, so that the laser meeting the requirement of the first frequency conversion crystal is further improved, the return light is reduced, and the overall stability of the device is improved.

The first reflector focuses and corrects frequency doubling light and fundamental frequency signal light emitted from the first frequency conversion crystal, and the angle requirements of power, energy and polarization state required by the third harmonic of the second frequency conversion crystal are met by setting the placement angles of the first reflector and the second frequency conversion crystal.

This application can protect the high repetition frequency polarization maintaining fiber laser of front end on the one hand (high repetition frequency polarization maintaining fiber laser is very sensitive to the returning light, easily takes place during the returning light intensity that optic fibre is got a little or the device damage), and on the other hand this design can greatly improve the power stability of system, because the light that the former light path route returned and forward transmission have same phase place, frequency, cycle isoparametric, easily takes place to interfere, disturbs former light path transmission.

The utility model provides an ultraviolet fiber laser can improve ultraviolet fiber laser system stability by a wide margin, this ultraviolet fiber laser includes first Brewster window piece at least, the second half wave plate, first speculum, because Brewster window piece, the half wave plate, the absorption of first speculum to light is less than the absorption of conventional polaroid to light far away, and the material has stronger tolerance to high power laser, then can realize the stable output of high power, and simultaneously, based on the characteristic of Brewster's angle, the ingenious half wave plate that utilizes is adjusted the polarization state, and then can realize laser light path stability, output power stability, and greatly reduced the device damage rate to ultraviolet fiber laser.

Drawings

In order to clearly illustrate the embodiments or technical solutions of the present application, the drawings used in the embodiments or technical solutions of the present application will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a first structure of an ultraviolet fiber laser provided by the present application;

fig. 2 is a schematic diagram of a second structure of the ultraviolet fiber laser provided by the present application;

fig. 3 is a schematic diagram of a third structure of the ultraviolet fiber laser provided by the present application;

fig. 4 is a schematic diagram of a fourth structure of the ultraviolet fiber laser provided by the present application;

fig. 5 is a schematic diagram of a fifth structure of the ultraviolet fiber laser provided by the present application;

fig. 6 is a schematic diagram of a sixth structure of the ultraviolet fiber laser provided by the present application.

Reference numerals: 1. the high-repetition-frequency polarization-maintaining fiber laser comprises a high-repetition-frequency polarization-maintaining fiber laser, 2, a first half-wave plate, 3, a first Brewster window plate, 4, a second half-wave plate, 5, a first aperture diaphragm, 6, a first plano-convex lens, 7, a first temperature control system, 8, a first frequency conversion crystal, 9, a first reflector, 10, a second reflector, 11, a first collector, 13, a second temperature control system, 14, a third reflector, 15, a second collector, 16, a fourth reflector, 17, a second frequency conversion crystal, 18, a second aperture diaphragm, 19, a second plano-convex lens, 12, a third half-wave plate, 20 and a second Brewster window plate.

Detailed Description

In order that those skilled in the art will better understand the disclosure, the following detailed description will be given with reference to the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and do not limit the scope of the claims of the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

Referring to fig. 1, fig. 1 is a schematic diagram of a first structure of an ultraviolet fiber laser provided in the present application, which includes a high repetition frequency polarization maintaining fiber laser 1, a first brewster window plate 3, a second half-wave plate 4, a first plano-convex lens 6, a first frequency conversion crystal 8, a first reflector 9, a second frequency conversion crystal 17, a fourth reflector 16, and a second plano-convex lens 19 in sequence.

The high repetition frequency polarization-maintaining fiber laser 1 can output the linear polarization type fundamental frequency signal light with the high repetition frequency polarization-maintaining wavelength of 1000-1100 nm.

The first Brewster window piece 3 is an optical lens placed at a Brewster angle, and 1000-1100nm fundamental frequency signal light passing through the first Brewster window piece 3 has a specific polarization state.

The first Brewster window sheet 3 can greatly reduce the influence of light returned along the original path on the stability and safety of the front end frequency optical path caused by incomplete transmission of all lens end faces after passing through the lens, the design can greatly protect the high repetition frequency polarization maintaining optical fiber laser 1 at the front end, and meanwhile, the existence of the lens can greatly improve the stability of the output optical path of the whole system.

The second half-wave plate 4 can be used to adjust the polarization state rotation angle of the linearly polarized infrared light after passing through the first brewster window plate 3 by rotating the placement angle of the second half-wave plate 4. Because the first frequency conversion crystal 8 has strict requirements on the polarization state of incident light entering the first frequency conversion crystal 8, when input laser is high-power laser, the first frequency conversion crystal 8 has strict requirements on the polarization state of the incident light entering the first frequency conversion crystal 8, the polarization state of the incident light meets the working requirement with high difficulty and has an unsatisfactory effect by adjusting the setting of the first frequency conversion crystal 8, the direction requirement of the first frequency conversion crystal 8 on the direction polarization state of the incident light cannot be met by independently setting the first brewster window plate 3, and when the polarization state rotation angle is adjusted to a proper polarization state by using the second half-wave plate 4 and the first brewster window plate 3, the light-light conversion efficiency of the whole system is greatly improved, the cost is greatly saved, and the power consumption is reduced.

When the light beam passes through the first plano-convex lens 6, the light beam is focused, so that the energy density and the power density of the light beam are improved.

The first frequency conversion crystal 8 uses LBO/BBO or other frequency doubling crystals, when 1000-1100nm fundamental frequency signal light passes through the crystal and the power density reaches a nonlinear threshold value, corresponding second harmonic, namely frequency doubling light, can be generated, the light frequency of the generated frequency doubling light is half of the fundamental frequency light, and at the moment, the generated green light is 500-550 nm.

Since the light beam output from the first frequency conversion crystal 8 contains the generated second harmonic 500-550nm and the 1000-1100nm fundamental frequency light which does not participate in the nonlinear conversion in the first frequency conversion crystal, the light beams of the two frequencies output at this time have the same phase and transmission direction, and the output mixed light beam has a larger divergence. The light receiving surface of the first reflecting mirror 9 is a concave mirror with a reflecting function, the mixed light beams are reflected in the same direction after passing through the first reflecting mirror 9, and the first reflecting mirror 9 performs divergence focusing correction on the mixed light beams in the same ratio. Since the energy density and power density of the light beam determine the efficiency of the third harmonic generation, the light intensity of the third harmonic in the second frequency conversion crystal 17 is more easily generated when the light beam is focused. That is, the presence of the first mirror 9, in addition to the divergence correction of the light beam output by the first frequency-converting crystal 8, simultaneously maximizes the power density and energy density required when the mixed light beam after passing through the first mirror 9 generates the third harmonic inside the second frequency-converting crystal 17. To increase the power density and energy density of the beam required for third harmonic generation, the concave curvature of the first mirror 9 is dimensioned to the laser parameters.

Because the light beam entering the second frequency conversion crystal 17 comprises the mixed light of 1000-1100nm and 500-550nm, and the half-wave plate is used to make it difficult to adjust and control the light beams with two wavelengths to reach the ideal polarization state angle, the high-power incident light entering the second frequency conversion crystal 17 can meet the angle requirement of the polarization state of the second frequency conversion crystal 17 by setting the placing angles of the first reflector 9 and the second frequency conversion crystal 17.

The second frequency conversion crystal 17 uses LBO/BBO or other nonlinear optical crystal suitable for generating third harmonic, when 1000-1100nm and 500-550nm mixed light after being reflected and focused by the first reflector 9 passes through the crystal and the power density reaches a nonlinear threshold, corresponding third harmonic, i.e. sum frequency light, is generated, the light frequency of the generated sum frequency light is three times of that of the fundamental frequency light, so the process of generating the light is also called triple frequency, and the generated light is ultraviolet light beam (330-370 nm).

The fourth reflector 16 can screen the light beam passing through the second frequency conversion crystal 17, reflect a required 330-370nm ultraviolet light beam, transmit the residual 1000-1100nm and 500-550nm light beams after frequency tripling, strip the light beams from the main optical path, and further separate residual fundamental frequency signal light and frequency doubled light.

The second plano-convex lens 19 collimates the ultraviolet light emitted from the second frequency conversion crystal 17.

Further, in order to substantially eliminate the problem that the reflected light on the end face of the optical element returns along the original path and further influences the stability of the system light beam, when the polarization state of the light beam is adjusted by using the second half-wave plate 4, the polarization direction of the adjusted light beam is perpendicular to that before the adjustment.

Furthermore, in order to reduce the loss of the fundamental frequency light, the front and back light receiving surfaces of the second half-wave plate 4 are plated with 1000-1100nm antireflection films, so that the transmittance of the fundamental frequency light passing through the component is improved.

Further, the first brewster window piece 3 can be placed at the most appropriate angle according to the refractive index of the material corresponding to the wavelength of 1000-1100nm, so that the loss of the first brewster window piece 3 to the fundamental frequency light in the system is reduced, and further, the transmittance of the fundamental frequency light when the fundamental frequency light passes through the first brewster window piece 3 is greatly improved.

Further, in order to improve the transmittance of fundamental frequency light when passing through the member, the light-receiving end face of the first brewster window sheet 3 is subjected to high polishing treatment.

Further, in order to improve the damage threshold of the first brewster window piece 3, the two end faces of the first brewster window piece 3 are not coated with a film.

Furthermore, in order to reduce the loss of light transmitted by the first brewster window sheet 3, the front and back light-receiving end faces of the first plano-convex lens 6 are plated with 1000-1100nm antireflection films. More specifically, the first plano-convex lens 6 will eventually focus the light beam into the first frequency translating crystal 8. Meanwhile, the first plano-convex lens 6 is arranged in a manner that the convex end receives light and the plane end faces one side of the first frequency conversion crystal 8, so that the influence of aberration on the system can be reduced.

Further, in order to increase the power of the fundamental frequency light that is subjected to nonlinear conversion in the first frequency conversion crystal 8 and further increase the frequency doubling efficiency, the light-receiving end face of the first frequency conversion crystal 8 is plated with a 1000-1100nm antireflection film.

Further, after the nonlinear conversion, in order to reduce the influence of the residual signal light on the first frequency conversion crystal 8 and to increase the power of the emitted frequency-doubled light, the light-emitting surface of the first frequency conversion crystal 8 is simultaneously plated with a 1000-1100nm antireflection film and a 500-550n antireflection film.

Further, in order to greatly increase the reflection power of the mixing light (1000-1100 nm and 500-550 nm) for the third harmonic and further increase the frequency tripling efficiency, the concave surface of the first reflecting mirror 9 is plated with 1000-1100nm and 500-550nm high reflection films.

Further, the first reflecting mirror 9 can strip the 330-370nm light beam reflected by the fourth reflecting mirror 16 and the second frequency conversion crystal 17 from the light path, so as to improve the stripping efficiency of the first reflecting mirror 9 on the ultraviolet light beam, prevent the ultraviolet light beam returning along the light path from influencing the light path stability of the whole system, prevent the returning ultraviolet light beam from returning to the front device and damaging the fiber laser, and both end faces of the first reflecting mirror 9 are plated with 330-370nm antireflection films.

Further, in order to improve the power of the mixed light subjected to nonlinear conversion in the second frequency conversion crystal 17 and improve the sum frequency conversion efficiency, the light receiving end face and the light emitting end face of the second frequency conversion crystal 17 are both plated with anti-reflection films of 1000-1100nm and 500-550 nm.

Further, after the nonlinear conversion, in order to increase the power of the outgoing light and the frequency light and greatly reduce the end reflection, a 330-370nm antireflection film is simultaneously plated on the light-emitting surface of the second frequency conversion crystal 17.

Further, in order to increase the output power of the required ultraviolet light beam, the first surface of the fourth reflecting mirror 16 is plated with a 330-370nm high reflection film, and simultaneously, both the first surface and the second surface are plated with 1000-1100nm and 500-550nm antireflection films, and the residual fundamental frequency signal light and the frequency doubled light of 1000-1100nm and 500-550nm are stripped from the main optical path through the antireflection films.

Further, to reduce the influence of the aberration on the system, also when the second plano-convex lens 19 is placed, the flat end receives light toward the fourth mirror 16, and the convex end emits light.

Further, in order to improve the power value of the ultraviolet light output of the whole system and the power stability of the system, and reduce the proportion that the violet light emitted from the second frequency conversion crystal 17 is reflected back to the front device through the second plano-convex lens 19, and further reduce the damage to the front device, the light receiving surface and the light emitting surface of the second plano-convex lens 19 are both plated with anti-reflection films of 330-370 nm.

Referring to fig. 2, fig. 2 is a schematic diagram of a second structure of an ultraviolet fiber laser provided in the present application, where the ultraviolet fiber laser further includes a first half-wave plate 2 on the basis of the ultraviolet fiber laser shown in fig. 1, and the first half-wave plate 2 is located between the high repetition frequency polarization maintaining fiber laser 1 and a first brewster window plate 3. Similarly, a three-dimensional coordinate relation is formed between the light path direction and the polarization direction, and the polarization state direction of the signal light penetrating through the component can be adjusted by rotating the placing angle of the first half-wave plate 2, so that the polarization state requirement of the incident light of the first brewster window plate 3 is met, the fundamental frequency light penetrating through the first brewster window plate 3 is greatly improved, the output is stable, and even the light output by the high-repetition-frequency polarization-preserving fiber laser can completely penetrate through the first brewster window plate.

Referring to fig. 3, fig. 3 is a schematic diagram of a third structure of the ultraviolet fiber laser provided in the present application, and the ultraviolet fiber laser may further include a second reflecting mirror 10, a first collector 11, a third reflecting mirror 14, and a second collector 15 on the basis of the ultraviolet fiber laser shown in fig. 2, where the second reflecting mirror 10 and the first collector 11 are both located outside a transmission end surface of the first reflecting mirror 9, the first collector 11 surrounds the second reflecting mirror 10, the third reflecting mirror 14 and the second collector 15 are both located outside a transmission end surface of the fourth reflecting mirror 16, and the second collector 15 surrounds the third reflecting mirror 14.

The second reflector 10 can deflect the ultraviolet light beams stripped by the first reflector 9 to annihilate the ultraviolet light beams in the first collector 11, so that the ultraviolet light beams are prevented from returning along the original optical path to influence the stability of the system or being reflected to the cavity to damage optical devices. The third reflector 14 can fold the idler frequency light transmitted by the fourth reflector 16 back and annihilate the idler frequency light in the second collector 15, so as to prevent the idler frequency light from returning along an original optical path and affecting the stability of the whole machine. In order to improve the reflection efficiency, the second reflector 10 is coated with a 330-370nm high reflection film. In order to improve the folding back effect, the third reflector 14 is coated with high reflective films of 1000-1100nm and 500-550 nm.

Further, since the first reflecting mirror 9 reflects the mixed light (1000-1100 nm and 500-550 nm) outputted from the first inverter crystal 8 with a high reflection film, even if it is coated with a high reflection film, it cannot reflect 100%, and the second reflecting mirror 10 is coated with a high reflection film of 500-550nm and 1000-1100nm at the same time, reflects the mixed light incompletely reflected by the first reflecting mirror 9 into the first collector 11 and annihilates it, so as to improve the reflectance of the mixed light.

The first collector 11 is mainly used for annihilating photons of mixed light (500-550 nm and 1000-1100 nm) incompletely reflected by the first reflector 9 and ultraviolet light (330-370 nm) stripped by the first reflector 9 after being reflected by the second reflector 10, the second collector 15 is mainly used for absorbing and dissipating 1000-1100nm and 500-550nm fundamental frequency signal light and frequency doubling light which are incompletely transmitted or returned from a rear end light path, and the mixed light and the incompletely reflected frequency doubling light which are incompletely reflected by the second frequency conversion crystal 17 are annihilated in the second collector 15 to convert light energy into heat energy.

Further, in order to reduce the influence of thermal energy caused by idler-frequency annihilation on the system stability, the first collector 11 and the second collector 15 are subjected to strong heat dissipation treatment.

Further, in order to reduce the influence of the specular reflection of the wall materials of the first collector 11 and the second collector 15 on the stability of the light path, the light receiving areas of the first collector 11 and the second collector 15 are roughened.

Referring to fig. 4, fig. 4 is a schematic diagram of a fourth structure of the uv fiber laser provided in the present application, and the uv fiber laser may further include a first crystal temperature control system 7 and a second crystal temperature control system 13 on the basis of the uv fiber laser shown in fig. 3, where the first crystal temperature control system surrounds the first frequency conversion crystal 8, the system is configured to provide a constant temperature working environment for the first frequency conversion crystal 8 and provide a fixed setting condition for the first frequency conversion crystal 8, and the second crystal temperature control system 13 surrounds the second frequency conversion crystal 17, and the system is configured to provide a constant temperature working environment for the second frequency conversion crystal 17 and provide a fixed setting condition for the second frequency conversion crystal 17.

Furthermore, the temperature rising/lowering component and the temperature feedback adjusting system are arranged in the first crystal temperature control system 7 and the second crystal temperature control system 13, and the automatic adjustment can be carried out according to the real-time temperature feedback under the influence of the ambient temperature or other factors, so that the first frequency conversion crystal always works at a specific temperature, and the power stability of the system is greatly improved.

Referring to fig. 5, fig. 5 is a schematic diagram of a fifth structure of the uv fiber laser provided by the present application, and the uv fiber laser may further include a first aperture stop 5 and a second aperture stop 18 on the basis of the uv fiber laser shown in fig. 4, where the first aperture stop 5 is located between the second half-wave plate 4 and the first plano-convex lens 6, and the second aperture stop 18 is located between the fourth mirror 16 and the second plano-convex lens 19.

The first aperture stop 5 and the second aperture stop 18 can both largely block the influence of non-axial light beams reflected by other devices behind the first aperture stop on the light path stability of the whole system, and simultaneously can also block stray light possibly generated in front of the first aperture stop from exiting from the system, and in addition, the first aperture stop 5 and the second aperture stop 18 also have the effect of a finite mode.

Further, the first aperture stop 5 and the second aperture stop 18 can limit the emergent light of the ultraviolet system to be consistent with the design when the emergent light is transmitted on an outer light path, namely, the debugging deviation is reduced.

Further, in order to improve the stability of the light path, the bottoms of the first small aperture stop 5 and the second small aperture stop 18 should be subjected to corresponding heat dissipation treatment.

Referring to fig. 6, fig. 6 is a schematic diagram of a sixth structure of the uv fiber laser provided in the present application, which may further include a third half-wave plate 12 and a second brewster window plate 20 on the basis of the uv fiber laser shown in fig. 5.

The third half-wave plate 12 and the second brewster window plate 20 are sequentially located behind the second plano-convex lens 19. Also, the third half wave plate 12 adjusts the polarization state of the light beam passing through the member to be transmitted in a certain direction. The second brewster window 20 is also an optical lens disposed at a brewster angle, and is used to divide the laser optical path from the outside air and protect the internal components of the laser. The third half-wave plate 12 also adjusts the polarization direction of the beam that the component passes through component 10, greatly increasing the transmittance of the second brewster window plate 20.

Further, in order to improve the output power and the stability of the system power and improve the transmittance of the ultraviolet beam, both end faces of the third half-wave plate 12 are coated with 330-370 antireflection films.

Furthermore, in order to improve the output power of the system ultraviolet light beam, the component calculates the most appropriate placing angle according to the refractive index of the material corresponding to the wavelength of 330-370nm so as to greatly improve the transmissivity of the frequency doubled light when the frequency doubled light passes through the lens.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include elements inherent in the list. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or device that comprises the element. In addition, parts of the above technical solutions provided in the embodiments of the present application, which are consistent with the implementation principles of corresponding technical solutions in the prior art, are not described in detail so as to avoid redundant description.

The principles and embodiments of the present application are described herein using specific examples, which are only used to help understand the method and its core idea of the present application. It should be noted that, for those skilled in the art, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and various embodiments in the present application can be combined, and those improvements, modifications and combinations also fall within the protection scope of the claims of the present application.

Claims (10)

1. An ultraviolet fiber laser is characterized by sequentially comprising a high repetition frequency polarization maintaining fiber laser (1), a first Brewster window plate (3), a second half wave plate (4), a first plano-convex lens (6), a first frequency conversion crystal (8), a first reflector (9), a second frequency conversion crystal (17), a fourth reflector (16) and a second plano-convex lens (19);

the high repetition frequency polarization-maintaining optical fiber laser (1) outputs linear polarization type fundamental frequency signal light with high repetition frequency polarization-maintaining wavelength of 1000-1100 nm;

the first Brewster window sheet (3) is an optical lens placed at a Brewster angle;

when the light beam passes through the first plano-convex lens (6), the light beam is focused;

the first frequency conversion crystal (8) and the second frequency conversion crystal (17) are frequency doubling crystals;

the light receiving surface of the first reflector (9) is a concave mirror with a reflecting function, and the mixed light beams can be reflected in the same direction after passing through the first reflector (9);

the fourth reflector (16) can screen the light beams passing through the second frequency conversion crystal (17), reflect the needed 330-370nm ultraviolet light beams, transmit the residual 1000-1100nm and 500-550nm light beams after frequency tripling, and strip the light beams from the main light path;

and the second plano-convex lens (19) collimates the ultraviolet light emitted from the second frequency conversion crystal (17).

2. The uv fiber laser according to claim 1, further comprising a first half-wave plate (2), the first half-wave plate (2) being located between the high repetition frequency polarization maintaining fiber laser (1) and the first brewster window plate (3).

3. The UV fiber laser according to claim 2, further comprising a second mirror (10), a first collector (11), a third mirror (14), and a second collector (15), wherein the second mirror (10) and the first collector (11) are located outside the transmissive end surface of the first mirror (9), the first collector (11) surrounds the second mirror (10), the third mirror (14) and the second collector (15) are located outside the transmissive end surface of the fourth mirror (16), and the second collector (15) surrounds the third mirror (14).

4. The uv fiber laser according to claim 3, further comprising a first crystal temperature control system (7) and a second crystal temperature control system (13), wherein the first crystal temperature control system (7) surrounds the first frequency conversion crystal (8) and is configured to provide a constant temperature working environment for the first frequency conversion crystal (8) and to provide fixed conditions for the first frequency conversion crystal (8), and wherein the second crystal temperature control system (13) surrounds the second frequency conversion crystal (17) and is configured to provide a constant temperature working environment for the second frequency conversion crystal (17) and to provide fixed conditions for the second frequency conversion crystal (17).

5. The uv fiber laser according to claim 4, further comprising a first aperture stop (5) and a second aperture stop (18), the first aperture stop (5) being located between the second half-wave plate (4) and the first plano-convex lens (6), the second aperture stop (18) being located between the fourth mirror (16) and the second plano-convex lens (19).

6. The UV fiber laser according to claim 5, further comprising a third half-wave plate (12), a second Brewster window plate (20), said third half-wave plate (12), said second Brewster window plate (20) being located in sequence after said second plano-convex lens (19).

7. The uv fiber laser according to claim 1, wherein the second half-wave plate (4) adjusts the polarization state of the beam such that the adjusted polarization direction of the beam is perpendicular to the direction before adjustment.

8. The uv fiber laser according to claim 1, characterized in that the first brewster window plate (3) is placed at the most suitable angle calculated from the refractive index of the material corresponding to a wavelength of 1000-1100 nm.

9. The ultra-violet fiber laser of claim 1, wherein both end faces of the first mirror (9) are coated with a 330-370nm anti-reflection coating.

10. The ultra-violet fiber laser of claim 4, wherein the fourth mirror (16) is coated with a high reflection coating of 330-370nm on the first side and with anti-reflection coatings of 1000-1100nm and 500-550nm on both the first and second sides.

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