Short-wavelength laser

Abstract

The invention relates to the technical field of lasers, and discloses a short-wavelength laser which comprises a first pumping output unit, a second pumping output unit, a laser transmission unit, a cavity length adjusting unit and a resonant cavity. The resonant cavity comprises a first dichroic mirror, a first gain crystal, a second dichroic mirror, a first spectroscope, a third dichroic mirror, a second gain crystal, a fourth dichroic mirror and a second spectroscope, and the cavity length adjusting unit is used for adjusting the position of the first spectroscope. The position of the first spectroscope is adjusted through the cavity length adjusting unit so as to adjust the length of the resonant cavity, two paths of pump light are stable resonant cavities, and then stable high-power output of all-solid-state short-wavelength laser is achieved.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, in particular to a short-wavelength laser. Background Art

[0002] High-power green light, ultraviolet light and other short-wavelength lasers have demonstrated incomparable advantages in many industrial processing solutions, especially in the processing of high-reflective materials. With higher material absorption characteristics and smaller focused spots, they are deeply favored by industrial processing.

[0003] At present, there is only one gain crystal in the resonant cavity of a short-wavelength laser, and the pump light is focused inside a crystal. The power density inside the crystal is high, the thermal impact is high, and it is easy to reach the material damage threshold. Due to material limitations, it is difficult to stably output high-power lasers. In related technologies, two-way pumping is used to increase laser power, but it is more difficult for two-way pumping to form particle inversion than single-way pumping. If the cavity length is not appropriate, the two-way pump light or the generated base film light beam may produce coherent destructive interference, or other parts may be constructive and some may be destructive, resulting in reduced laser power.

[0004] Therefore, due to the limitation of gain medium material and cavity type, it is difficult for existing solid-state lasers to output stable high-power short-wavelength lasers. Therefore, there is an urgent need for a laser that can stably output high-power short-wavelength lasers. Summary of the invention

[0005] In view of this, the present invention provides a short-wavelength laser to solve or partially solve the technical problem that the existing laser cannot stably output high-power short-wavelength laser.

[0006] The technical solution proposed by the present invention is as follows:

[0007] The present invention provides a short-wavelength laser, comprising: a first pump output unit, a second pump output unit, a laser transmission unit, a cavity length adjustment unit and a resonant cavity, wherein the resonant cavity comprises a first dichroic mirror, a first gain crystal, a second dichroic mirror, a first beam splitter, a third dichroic mirror, a second gain crystal, a fourth dichroic mirror and a second beam splitter, and the cavity length adjustment unit is used to adjust the position of the first beam splitter; the first pump output unit is used to output a first pump light of a first wavelength to the first dichroic mirror, the first pump light is reflected by the first dichroic mirror and enters the first gain crystal along a first direction, the first gain crystal generates a base film beam of a second wavelength under the excitation of the first pump light, and the base film beam is transmitted through the first dichroic mirror. The dichroic mirror reflects to the first beam splitter, the second pump output unit is used to output the second pump light of the first wavelength to the third dichroic mirror, the second pump light is transmitted by the third dichroic mirror and enters the second gain crystal along the second direction, the second gain crystal generates a base film beam of the second wavelength under the stimulation of the second pump light, the base film beam is reflected to the second beam splitter through the fourth dichroic mirror; the second beam splitter is suitable for partially reflecting and partially transmitting the light beam of the second wavelength and the reflectivity is greater than the transmittance, so that the base film beam reciprocates in the resonant cavity and outputs the fundamental frequency light through the second beam splitter, the fundamental frequency light passes through the laser transmission unit, is converted into a short wavelength beam output after the frequency is converted by the laser transmission unit.

[0008] The short-wavelength laser of the present invention constructs a resonant cavity based on a first dichroic mirror, a first gain crystal, a second dichroic mirror, a first beam splitter, a third dichroic mirror, a second gain crystal, a fourth dichroic mirror and a second beam splitter. The first gain crystal and the second gain crystal are respectively in a first direction and a second direction. A first pump light and a second pump light enter the first gain crystal and the second gain crystal respectively to generate a base film beam. Double-path resonance is achieved in the same resonant cavity, and a higher laser power can be output. The structure is compact. At the same time, the position of the first beam splitter is adjusted by a cavity length adjustment unit to adjust the length of the resonant cavity, so that both pump lights are stable resonant cavities, laser particle number inversion and resonant amplification of the base film beam are formed, the base film beam reciprocates in the resonant cavity and outputs a fundamental frequency light through the second beam splitter. The fundamental frequency light is converted into a short-wavelength beam such as green light and ultraviolet light after frequency conversion by a laser transmission unit, so as to achieve stable high-power output of all-solid-state short-wavelength laser.

[0009] Optionally, the short-wavelength laser also includes a Q-switching device, and the third dichroic mirror, the first dichroic mirror, the first gain crystal, the Q-switching device and the second dichroic mirror are arranged in sequence along the first direction, and the third dichroic mirror, the second gain crystal and the fourth dichroic mirror are arranged in sequence along the second direction, and the third dichroic mirror is suitable for reflecting the base film light beam from the first direction to the second direction and reflecting the base film light beam from the second direction to the first direction, the wavelength ranges of the first wavelength and the second wavelength are different, the first dichroic mirror is suitable for transmitting the light beam of the second wavelength and reflecting the light beam of the first wavelength range, and the second dichroic mirror, the third dichroic mirror and the fourth dichroic mirror are all suitable for reflecting the light beam of the second wavelength and transmitting the light beam of the first wavelength range.

[0010] In this method, the arrangement order of the third dichroic mirror, the first dichroic mirror, the first gain crystal, the Q-switching device and the second dichroic mirror along the first direction, as well as the arrangement order of the third dichroic mirror, the second gain crystal and the fourth dichroic mirror along the second direction are clarified. This layout enables the pump light and the base film light beam to propagate and convert in the resonant cavity according to a predetermined path, thereby improving the efficiency and accuracy of the light beam transmission. At the same time, the transmission and reflection characteristics of each dichroic mirror for light beams of different wavelengths are specified, which can filter out the first pump light and the second pump light in the resonant cavity and improve the quality of the output laser.

[0011] Optionally, the first beam splitter is suitable for partially reflecting and partially transmitting the light beam of the second wavelength and the reflectivity is greater than the transmittance, so that the basement film light beam outputs a reference light through the first beam splitter; correspondingly, the cavity length adjustment unit includes an optical displacement platform and a detection device; the detection device is arranged on the side where the first beam splitter outputs the reference light, and is used to detect preset parameters of the reference light; the optical displacement platform is connected to the first beam splitter, and is used to adjust the position of the first beam splitter according to the preset parameters.

[0012] In this way, the preset parameters of the reference light are detected by the detection device, and the operating status of the laser and the quality of the output beam can be monitored in real time, providing a basis for the stable operation and parameter adjustment of the laser. The optical displacement platform accurately adjusts the position of the first beam splitter based on the preset parameters to adjust the length of the resonant cavity, thereby realizing the control and optimization of the reference light, and further improving the stability and consistency of the laser output beam.

[0013] Optionally, the laser transmission unit includes a reflector combination, a first nonlinear frequency conversion device and a fifth dichroic mirror, the reflector combination is used to reflect the fundamental frequency light into the first nonlinear frequency conversion device, the first nonlinear frequency conversion device is used to convert the fundamental frequency light into a short wavelength light beam of a third wavelength after frequency conversion, and the short wavelength light beam is reflected and output by the fifth dichroic mirror, wherein the fifth dichroic mirror is suitable for reflecting the light beam of the third wavelength and transmitting the light beam of the second wavelength.

[0014] In this way, effective conversion from fundamental frequency light to short wavelength is achieved, meeting the needs of short wavelength lasers in different application scenarios. The fifth dichroic mirror is suitable for reflecting the short wavelength light beam of the third wavelength and transmitting the light beam of the second wavelength, and can separate the converted short wavelength light beam from the unconverted light beam, ensuring the high purity of the output short wavelength light beam and improving the output quality of the laser.

[0015] Optionally, the first pump output unit includes a first pump group and a first coupling component, the first pump group includes a plurality of semiconductor lasers for outputting a first pump light by means of a spatial shaping coupling method, and the first coupling component is used to perform focus coupling on the first pump light; and / or, the second pump output unit includes a second pump group and a second coupling component, the second pump group includes a plurality of semiconductor lasers for outputting a second pump light by means of a spatial shaping coupling method, and the second coupling component is used to perform focus coupling on the second pump light.

[0016] In this method, the first pump output unit and the second pump output unit both include a pump group and a coupling component. The pump group is composed of a number of semiconductor lasers. The pump light is output through spatial shaping coupling, and then focused and coupled by the coupling component. This can improve the output power and quality of the pump light, provide more effective excitation for the gain crystal, and thus improve the overall performance of the laser.

[0017] Optionally, the first pump output unit further includes a sixth dichroic mirror, which is suitable for reflecting the light beam of the first wavelength and transmitting the light beam of the second wavelength, so as to reflect the first pump light after focus coupling to the first dichroic mirror; and / or, the second pump output unit further includes a seventh dichroic mirror, which is suitable for reflecting the light beam of the first wavelength and transmitting the light beam of the second wavelength, so as to reflect the second pump light after focus coupling to the fourth dichroic mirror.

[0018] In this manner, the quality of the input pump light can be improved by filtering the non-pump light through the sixth dichroic mirror and the seventh dichroic mirror.

[0019] Optionally, the short-wavelength laser also includes a first mode controller and a second mode controller, the first mode controller is arranged between the first gain crystal and the Q-switching device, and the second mode controller is arranged between the second gain crystal and the fourth dichroic mirror, and the first mode controller and the second mode controller are both used to filter out high-order modes generated in the resonant cavity.

[0020] In this way, the laser mode can be effectively controlled, the beam quality and monochromaticity of the output laser can be improved, and the short-wavelength beam output by the laser can be made purer and more stable, which is suitable for occasions with high requirements on beam quality.

[0021] Optionally, the short-wavelength laser further includes a heat management device, which is disposed between the Q-switching device and the second dichroic mirror and is used to filter out and consume stray light, idler light and high-order modes in the resonant cavity.

[0022] In this way, the interference and influence of these invalid light beams on the performance of the laser are reduced, and it also helps to reduce the temperature in the resonant cavity, improve the stability and reliability of the laser, and extend the service life of the laser.

[0023] Optionally, the short-wavelength laser also includes a first collector, a second collector and a third collector, the first collector is arranged on the transmission side of the second dichroic mirror, and is used to collect and consume the light beam of the first wavelength transmitted by the second dichroic mirror, the second collector is arranged on the transmission side of the fourth dichroic mirror, and is used to collect and consume the light beam of the first wavelength transmitted by the fourth dichroic mirror, and the third collector is arranged on the transmission side of the fifth dichroic mirror, and is used to collect and consume the light beam of the second wavelength transmitted by the fifth dichroic mirror.

[0024] In this manner, the light beams transmitted through the corresponding dichroic mirrors can be collected and consumed, thereby preventing these unused light beams from affecting the laser and further optimizing the performance of the laser.

[0025] Optionally, the short-wavelength laser further includes an eighth dichroic mirror, which is used to reflect the short-wavelength light beam reflected by the fifth dichroic mirror, wherein the eighth dichroic mirror is suitable for reflecting the light beam of the third wavelength and transmitting the light beam of the second wavelength.

[0026] In this method, the light beam reflected by the fifth dichroic mirror is further color-separated by the eighth dichroic mirror, thereby improving the monochromaticity of the output short-wavelength light beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly express the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 Schematic diagram of the structure of the first short-wavelength laser in an embodiment of the present invention;

[0029] Figure 2 is a schematic structural diagram of a second short-wavelength laser in an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram of a third short-wavelength laser in an embodiment of the present invention;

[0031] Figure 4 is a schematic structural diagram of a fourth short-wavelength laser in an embodiment of the present invention;

[0032] Figure 5 is a schematic structural diagram of a fifth short-wavelength laser in an embodiment of the present invention;

[0033] Figure 6 is a schematic structural diagram of a sixth short-wavelength laser in an embodiment of the present invention;

[0034] Figure 7 is a schematic structural diagram of a seventh short-wavelength laser in an embodiment of the present invention;

[0035] Figure numerals: 1-first pump group; 2-first coupling component; 3-sixth color dichroic mirror; 4-first color dichroic mirror; 5-first gain crystal; 6-first mode controller; 7-Q-switching device; 8-thermal management device; 9-second color dichroic mirror; 10-first collector; 11-first spectroscope; 12-optical displacement platform; 13-detection device; 14-second pump group; 15-second coupling component; 16-seventh color dichroic mirror; 17-third color dichroic mirror; 18-second gain crystal; 19-second mode controller; 20-fourth color dichroic mirror; 21-second collector; 22-second spectroscope; 23-first reflector; 24-second reflector; 25-first nonlinear frequency conversion device; 26-fifth color dichroic mirror; 27-third collector; 28-eighth color dichroic mirror. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In view of the technical problem that it is difficult to output high-power short-wavelength laser in the prior art, an embodiment of the present invention provides a short-wavelength laser, which adopts an all-solid-state solution and can accurately tune the laser resonant cavity to output high-power stable short-wavelength laser.

[0041] like Figure 1 As shown, the short-wavelength laser of the embodiment of the present invention includes: a first pump output unit, a second pump output unit, a laser transmission unit, a cavity length adjustment unit and a resonant cavity, the resonant cavity includes a first dichroic mirror 4, a first gain crystal 5, a Q-switched device 7, a second dichroic mirror 9, a first beam splitter 11, a third dichroic mirror 17, a second gain crystal 18, a fourth dichroic mirror 20 and a second beam splitter 22, and the cavity length adjustment unit is used to adjust the position of the first beam splitter 11.

[0042] The first pump output unit is used to output a first pump light of a first wavelength to the first dichroic mirror 4. After being reflected by the first dichroic mirror 4, the first pump light enters the first gain crystal 5 along the first direction. The first gain crystal 5 generates a base film beam of a second wavelength under the excitation of the first pump light. After passing through the Q-switching device 7, the base film beam is reflected by the second dichroic mirror 9 to the first beam splitter 11. The second pump output unit is used to output a second pump light of a first wavelength to the third dichroic mirror 17. After being transmitted by the third dichroic mirror 17, the second pump light enters the second gain crystal 18 along the second direction. The second gain crystal 18 generates a base film beam of a second wavelength under the excitation of the second pump light. The base film beam is reflected by the fourth dichroic mirror 20 to the second beam splitter 22.

[0043] The second beam splitter 22 is suitable for partially reflecting and partially transmitting the second wavelength light beam and the reflectivity is greater than the transmittance, so that the base film light beam reciprocates in the resonant cavity and outputs the fundamental frequency light through the second beam splitter 22. The fundamental frequency light passes through the laser transmission unit and is converted into a short wavelength light beam output after the frequency is converted by the laser transmission unit. Specifically, short wavelength lasers such as green light, near ultraviolet light, and deep ultraviolet light can be output.

[0044] Specifically, the first wavelength is 800nm-900nm, and the second wavelength is 1000nm-1100nm.

[0045] The first pump output unit uses a combination of multiple semiconductor lasers to output a first pump light, and the wavelength of the first pump light is 800nm-900nm.

[0046] The first dichroic mirror 4 mainly reflects the first pump light and inputs it into the resonant cavity to formally perform pumping. Generally, the first dichroic mirror 4 is coated with a 800nm-900nm high reflection film or a 1000nm-1100nm high transmission film.

[0047] The first gain crystal 5 is mainly used to provide activated particles, population inversion, etc. The first pump light reflected by the first dichroic mirror 4 undergoes stimulated radiation inside the first gain crystal 5 to generate 1000nm-1100nm photons and output them. Generally, in order to reduce loss, the first gain crystal 5 is double-end coated with 800nm ​​to 1100nm anti-reflection film.

[0048] The Q-switched device 7 is mainly used to generate pulsed light. More inversion particles are accumulated in the first gain crystal 5, thereby obtaining a higher output of excitation photons. At the same time, the Q-switched device 7 can output photons with higher peak power and peak energy, providing a basis for the subsequent nonlinear conversion. Generally, in order to reduce losses, the Q-switched device 7 is plated with a 800nm-1100nm high-transmittance film.

[0049] In other embodiments, the Q-switched device 7 may not be designed. In this case, a continuous wave laser rather than a pulsed laser is obtained, and the peak power will be lower than the pulsed laser mentioned above. However, it has a more stable laser processing effect when applied to laser processing fields such as laser welding and laser additive manufacturing.

[0050] The second dichroic mirror 9 is mainly used to reflect the base film light beam resonating in the resonant cavity, and filter out the first pump light and the second pump light participating in the pumping. Generally, in order to reduce the loss in the cavity, the second dichroic mirror 9 is coated with a 1000nm-1100nm high reflection film and a 800nm-900nm high transmission film.

[0051] The first beam splitter 11 is mainly used to reflect the base film infrared light resonating in the cavity, thus becoming one of the end mirrors of the resonant cavity. At the same time, this component will transmit a small part of the base film beam for mode detection, providing a prerequisite for automatic calibration and adjustment of cavity parameters. Generally, the first beam splitter 11 is coated with a high-transmittance 1000nm-1100nm film, and the coating parameters are designed to allow 0.01%-1% transmission. The specific parameters are adapted according to the detection accuracy.

[0052] The cavity length adjustment unit is mainly used to adjust the position of the first beam splitter 11 , and a high-precision stepping motor can be used to precisely adjust the position of the first beam splitter 11 according to calibration requirements to adjust the resonant cavity length.

[0053] The second pump output unit uses a combination of multiple semiconductor lasers to output the second pump light, and the wavelength of the second pump light is 800nm-900nm. The second pump light and the first pump light are collectively called pump light.

[0054] The third dichroic mirror 17 mainly transmits the second pump light and inputs it into the resonant cavity to formally perform pumping. Generally, the third dichroic mirror 17 is coated with a 800nm-900nm high-transmittance film or a 1000nm-1100nm high-reflection film.

[0055] The second gain crystal 18 is mainly used to provide activated particles, particle number inversion, etc. The second pump light transmitted by the third dichroic mirror 17 generates 1000nm-1100nm photons in the second gain crystal 18 through stimulated radiation and outputs them. Generally, in order to reduce the loss, the second gain crystal 18 is double-end-face coated with 800nm ​​to 1100nm anti-reflection film. The second gain crystal 18 plays a role of secondary stimulated radiation, providing more base film photons in the resonant cavity, and providing more base film beam output for outputting high-power green laser.

[0056] The fourth dichroic mirror 20 is mainly used to reflect the base film beam resonating in the cavity and filter out the pump light after pumping. Generally, in order to reduce the loss in the cavity, this component is coated with a 1000nm-1100nm high reflection film and a 800nm-900nm high transmission film.

[0057] The second beam splitter 22 is mainly used to split the basement membrane light beam resonating in the cavity. It is one of the end mirrors of the resonant cavity. The second beam splitter 22 is coated with a beam splitting film to ensure that a part of the basement membrane infrared light returns along the original optical path to form a resonant cavity, and the other part of the transmission output is used as the fundamental frequency light for nonlinear conversion output. Therefore, the wavelength of the fundamental frequency light and the basement membrane light beam is the same, both 1000nm-1100nm.

[0058] The laser transmission unit is mainly used to convert the fundamental frequency light into a short wavelength beam for output after frequency conversion. For example, the fundamental frequency light of 1000nm-1100nm can be doubled to a short wavelength beam of 500nm-550nm and output.

[0059] The short-wavelength laser of the present invention constructs a resonant cavity based on a first dichroic mirror 4, a first gain crystal 5, a Q-switching device 7, a second dichroic mirror 9, a first beam splitter 11, a third dichroic mirror 17, a second gain crystal 18, a fourth dichroic mirror 20 and a second beam splitter 22. The first gain crystal 5 and the second gain crystal 18 are respectively in a first direction and a second direction. The first pump light and the second pump light enter the first gain crystal 5 and the second gain crystal 18 respectively to generate a base film beam. Double-path resonance is realized in the same resonant cavity, and a higher laser power can be output. The structure is compact. At the same time, the position of the first beam splitter 11 is adjusted by a cavity length adjustment unit to adjust the length of the resonant cavity, so that both pump lights are stable resonant cavities, forming laser particle number inversion and resonant amplification of the base film beam. The base film beam reciprocates in the resonant cavity and outputs a fundamental frequency light through the second beam splitter 22. The fundamental frequency light is converted into a short-wavelength beam such as green light and ultraviolet light after frequency conversion by a laser transmission unit, so as to realize stable high-power output of short-wavelength laser.

[0060] In one embodiment, the first beam splitter 11 is suitable for partially reflecting and partially transmitting the light beam of the second wavelength and the reflectivity is greater than the transmittance, so that the base film light beam outputs a reference light through the first beam splitter 11; correspondingly, the cavity length adjustment unit includes an optical displacement platform 12 and a detection device 13; the detection device 13 is arranged on the side where the first beam splitter 11 outputs the reference light, and is used to detect preset parameters of the reference light; the optical displacement platform 12 is connected to the first beam splitter 11, and is used to adjust the position of the first beam splitter 11 according to the preset parameters.

[0061] The optical translation stage is composed of a high-precision stepper motor and an optical fixed platform. The optical fixed platform is provided with flexible heat dissipation treatment. The high-precision stepper motor can precisely adjust the position of the first beam splitter 11 to adjust the length of the resonant cavity according to calibration requirements.

[0062] The detection device 13 is mainly used to detect the reference light output by the first spectroscope 11. It can provide feedback based on the algorithm to compare the preset parameters such as mode, power, coordinates, number of longitudinal modes under normal conditions and perform self-feedback optimization through the optical displacement platform 12, so that the resonant cavity can automatically improve the requirements under different modes.

[0063] Specifically, since two pumps are in one resonant cavity, both pumps need to meet the following requirements: Only in this way can the two pump lights form a stable resonant cavity, form a laser particle number inversion and perform resonant amplification. Compared with a single pump, it is more difficult to form a particle number inversion, so it is necessary to detect the resonant state of the two pumps through the detection device 13, and to precisely adjust the resonant cavity length and calibration through the control of the optical displacement stage, so that both pumps meet the requirements of the above formula and form a good resonant cavity length state.

[0064] At the same time, in order to form a better beam quality, it is also required to adjust the waists of the two pump lights to the same position, that is, between the two gain crystals, so that the waists of the two pump lights overlap, so that the beam quality M2 can be relatively small and the beam quality is good.

[0065] In addition, it is also necessary to adjust the cavity length so that the two pump lights are in a coherent and constructive relationship when interfering, rather than a coherent destructive relationship or a relationship where some are constructive and some are destructive, in order to increase the beam power and reduce the appearance of high-order mode light. That is, the formula for the longitudinal mode spacing of the laser resonant cavity is: Δv = c / (2nL), where Δv is the longitudinal mode spacing when the periods of the longitudinal waves of the light overlap, where c is the speed of light, n is the refractive index of the medium in the cavity, and L is the cavity length of the resonant cavity.

[0066] Therefore, by comparing the preset parameters of the detected reference light with the set target value, when the detected value and the target value do not match, the resonant cavity length is adjusted through the optical displacement stage to improve the quality of the basement membrane beam.

[0067] In this manner, the preset parameters of the reference light are detected by the detection device 13, so that the operating status of the laser and the quality of the output light beam can be monitored in real time, providing a basis for the stable operation and parameter adjustment of the laser. The optical displacement platform 12 accurately adjusts the position of the first beam splitter 11 based on the preset parameters to adjust the length of the resonant cavity, thereby realizing the control and optimization of the reference light, and further improving the stability and consistency of the laser output light beam.

[0068] In some embodiments, the first pump output unit includes a first pump group 1 and a first coupling component 2. The first pump group 1 includes a plurality of semiconductor lasers for outputting a first pump light by spatial shaping coupling. A plurality of semiconductor lasers can output a higher power pump light by spatial shaping coupling. The wavelength of the first pump light is 800-900nm. The first coupling component 2 is used for focusing coupling the first pump light. The first coupling component 2 is mainly a combination of a plurality of lenses, which performs focusing coupling of the light beam at a certain ratio, adapts the resonant cavity design, and focuses the pump light to an optimal spot size.

[0069] And / or, the second pump output unit includes a second pump group 14 and a second coupling component 15, the second pump group 14 includes a plurality of semiconductor lasers, which are used to output the second pump light by spatial shaping coupling, and a plurality of semiconductor lasers can output higher power pump light by spatial shaping coupling, and the wavelength of the first pump light is 800-900nm. The second coupling component 15 is used to focus the second pump light. The second coupling component 15 is mainly a combination of multiple lenses, which performs focus coupling of the light beam in a certain ratio, adapts the resonant cavity design, and focuses the pump light to the optimal spot size.

[0070] In this method, the first pump output unit and the second pump output unit both include a pump group and a coupling component. The pump group is composed of a number of semiconductor lasers. The pump light is output through spatial shaping coupling, and then focused and coupled by the coupling component. This can improve the output power and quality of the pump light, provide more effective excitation for the gain crystal, and thus improve the overall performance of the laser.

[0071] Further, in some embodiments, the third dichroic mirror 17, the first dichroic mirror 4, the first gain crystal 5, the Q-switching device 7 and the second dichroic mirror 9 are arranged in sequence along the first direction, the third dichroic mirror 17, the second gain crystal 18 and the fourth dichroic mirror 20 are arranged in sequence along the second direction, the third dichroic mirror 17 is suitable for reflecting the base film light beam from the first direction to the second direction and reflecting the base film light beam from the second direction to the first direction, the wavelength ranges of the first wavelength and the second wavelength are different, the first dichroic mirror 4 is suitable for transmitting the light beam of the second wavelength and reflecting the light beam of the first wavelength range, and the second dichroic mirror 9, the third dichroic mirror 17 and the fourth dichroic mirror 20 are all suitable for reflecting the light beam of the second wavelength and transmitting the light beam of the first wavelength range.

[0072] In this method, the arrangement order of the third dichroic mirror 17, the first dichroic mirror 4, the first gain crystal 5, the Q-switching device 7 and the second dichroic mirror 9 along the first direction, and the arrangement order of the third dichroic mirror 17, the second gain crystal 18 and the fourth dichroic mirror 20 along the second direction are clearly defined. This layout enables the pump light and the base film light beam to propagate and convert in the resonant cavity according to a predetermined path, making the overall structure of the resonant cavity more compact. At the same time, the transmission and reflection characteristics of each dichroic mirror for light beams of different wavelengths are specified, which can filter out the first pump light and the second pump light in the resonant cavity and improve the quality of the output laser.

[0073] In some embodiments, the laser transmission unit includes a reflector combination, a first nonlinear frequency conversion device 25 and a fifth dichroic mirror 26. The reflector combination is used to reflect the fundamental frequency light into the first nonlinear frequency conversion device 25. The first nonlinear frequency conversion device 25 is used to convert the fundamental frequency light into a short wavelength light beam of a third wavelength after frequency conversion. The short wavelength light beam is reflected and output by the fifth dichroic mirror 26, wherein the fifth dichroic mirror 26 is suitable for reflecting the light beam of the third wavelength and transmitting the light beam of the second wavelength.

[0074] Specifically, the reflector assembly includes at least one reflector.

[0075] In one example, if Figure 1 As shown, the reflector assembly includes a first reflector 23, which is mainly used to fold the optical path of the fundamental frequency light transmitted and outputted by the second beam splitter 22, thereby improving the spatial integration of the product. Generally, in order to reduce loss, the first reflector 23 is coated with a 1000nm-1100nm high-reflection film.

[0076] In another example, if Figure 3 As shown, the reflector assembly includes a first reflector 23 and a second reflector 24. The second reflector 24 has the same parameters as the first reflector 23. The light path is turned and folded by the cooperation of the two reflectors, thereby further improving the spatial integration of the product.

[0077] The first nonlinear frequency converter is mainly used to perform frequency conversion on the fundamental frequency light output by the reflector combination. Generally, the first nonlinear frequency converter is used for double frequency, converting the fundamental frequency light (specifically, the infrared light beam of 1000nm-1100nm) into a short wavelength light beam of 500nm-550nm, and forming an infrared / short wavelength mixed light with the residual infrared light beam. Generally, in order to reduce loss, the first nonlinear frequency converter is coated with 500nm-550nm and 1000nm-1100nm anti-reflection films on both sides.

[0078] The fifth dichroic mirror 26 is mainly used for color separation of the mixed light beam output by the first nonlinear frequency converter. The fifth dichroic mirror 26 is coated with a dielectric dichroic film to reflect the short wavelength light beam, i.e., the third wavelength light beam, and transmit the second wavelength fundamental frequency light. Generally, in order to reduce the loss, the component is coated with a 500nm-550nm high reflection film and a 1000nm-1100nm high transmission film.

[0079] In this manner, effective conversion from fundamental frequency light to short wavelength is achieved, meeting the needs of different application scenarios for short wavelength lasers. The fifth dichroic mirror 26 is suitable for reflecting the short wavelength light beam of the third wavelength and transmitting the light beam of the second wavelength, and can separate the converted short wavelength light beam from the unconverted light beam, ensuring the high purity of the output short wavelength light beam and improving the output quality of the laser.

[0080] In some embodiments, Figure 2 As shown, the first pump output unit further includes a sixth dichroic mirror 3, which is suitable for reflecting a light beam of a first wavelength and transmitting a light beam of a second wavelength, so as to reflect the first pump light after focus coupling to the first dichroic mirror 4; and / or, the second pump output unit further includes a seventh dichroic mirror 16, which is suitable for reflecting a light beam of a first wavelength and transmitting a light beam of a second wavelength, so as to reflect the second pump light after focus coupling to the fourth dichroic mirror 20.

[0081] Specifically, the sixth dichroic mirror 3 is used to reflect and transmit the first pump light shaped by the first coupling component 2 into the resonant cavity, and at the same time, the sixth dichroic mirror 3 filters the base film light beam in the resonant cavity that is not completely transmitted by the first dichroic mirror 4, thereby playing the role of optical path stability and pump protection. Generally, the sixth dichroic mirror 3 is coated with a 800nm-900nm high reflection film and a 1000nm-1100nm high transmission film.

[0082] The seventh dichroic mirror 16 is used to reflect and transmit the second pump light shaped by the second coupling component 15 into the resonant cavity, and at the same time, the seventh dichroic mirror 16 filters the base film light beam incompletely reflected by the third dichroic mirror 17 in the resonant cavity, thereby playing the role of optical path stability and pump protection. Generally, the seventh dichroic mirror 16 is coated with a 800nm-900nm high reflection film and a 1000nm-1100nm high transmission film.

[0083] In this manner, the non-pump light is filtered by the sixth dichroic mirror 3 and the seventh dichroic mirror 16, so that the quality of the input pump light can be improved.

[0084] In some embodiments, Figure 4 As shown, the short-wavelength laser also includes a first mode controller 6 and a second mode controller 19. The first mode controller 6 is arranged between the first gain crystal 5 and the Q-switching device 7, and the second mode controller 19 is arranged between the second gain crystal 18 and the fourth dichroic mirror 20. The first mode controller 6 and the second mode controller 19 are both used to filter out high-order modes generated in the resonant cavity.

[0085] The first mode controller 6 and the second mode controller 19 are mainly used for intracavity mode selection, filtering out the generated high-order modes, and only allowing the basilar membrane to resonate and amplify, thereby outputting a basilar membrane light beam in the infrared band with a better M2, thereby having a high nonlinear conversion efficiency.

[0086] In this way, the laser mode can be effectively controlled, the beam quality and monochromaticity of the output laser can be improved, and the short-wavelength beam output by the laser can be made purer and more stable, which is suitable for occasions with high requirements on beam quality.

[0087] In some embodiments, Figure 5 As shown, the short-wavelength laser further includes a heat management device 8, which is disposed between the Q-switching device 7 and the second dichroic mirror 9 and is used to filter out and consume stray light, idler light and high-order modes in the resonant cavity.

[0088] The quality of thermal management of industrial lasers directly determines the power stability of the lasers. Thermal management device 8 is mainly used to filter out stray light, idle light and high-order modes in the resonant cavity and transmit them to the cold plate for consumption, thereby ensuring the thermal stability and safety of the lasers.

[0089] In some embodiments, Figure 6As shown, the short-wavelength laser further includes a first collector 10, a second collector 21 and a third collector 27. The first collector 10 is arranged on the transmission side of the second dichroic mirror 9, and is used to collect and consume the light beam of the first wavelength transmitted through the second dichroic mirror 9. The second collector 21 is arranged on the transmission side of the fourth dichroic mirror 20, and is used to collect and consume the light beam of the first wavelength transmitted through the fourth dichroic mirror 20. The third collector 27 is arranged on the transmission side of the fifth dichroic mirror 26, and is used to collect and consume the light beam of the second wavelength transmitted through the fifth dichroic mirror 26.

[0090] The first collector 10 , the second collector 21 and the third collector 27 are mainly used to collect and consume the residual pump light after pumping.

[0091] The first collector 10, the second collector 21 and the third collector 27 convert the idle photons into heat energy consumption by means of water cooling, air cooling and the like, thereby avoiding the influence of these unused light beams on the laser and further optimizing the performance of the laser.

[0092] In some embodiments, Figure 7 As shown, the short wavelength laser further includes an eighth dichroic mirror 28, which is used to reflect the short wavelength light beam reflected by the fifth dichroic mirror 26, wherein the eighth dichroic mirror 28 is suitable for reflecting the light beam of the third wavelength and transmitting the light beam of the second wavelength.

[0093] The eighth dichroic mirror 28 is mainly used to further separate the light beam reflected by the fifth dichroic mirror 26 to improve the monochromaticity of the output short-wavelength light beam. The eighth dichroic mirror 28 is coated with a dielectric dichroic film to reflect the short-wavelength light beam and transmit the fundamental frequency light beam.

[0094] In order to reduce the loss, the eighth dichroic mirror 28 is coated with a 500nm-550nm high reflection film and a 1000nm-1100nm high transmission film.

[0095] In this method, the light beam reflected by the fifth dichroic mirror 26 is further color-separated by the eighth dichroic mirror 28, thereby improving the monochromaticity of the output short-wavelength light beam.

[0096] Although example embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit and defined scope of the present invention, and such modifications and variations are all within the defined scope.

Claims

1. A short wavelength laser, characterized in that: include: A first pump output unit, a second pump output unit, a laser transmission unit, a cavity length adjustment unit and a resonant cavity, wherein the resonant cavity comprises a first dichroic mirror (4), a first gain crystal (5), a second dichroic mirror (9), a first beam splitter (11), a third dichroic mirror (17), a second gain crystal (18), a fourth dichroic mirror (20) and a second beam splitter (22), and the cavity length adjustment unit is used to adjust the position of the first beam splitter (11); The first pump output unit is used to output a first pump light of a first wavelength to the first dichroic mirror (4); the first pump light is reflected by the first dichroic mirror (4) and enters the first gain crystal (5) along a first direction; the first gain crystal (5) generates a base film light beam of a second wavelength under the stimulation of the first pump light; the base film light beam is reflected by the second dichroic mirror (9) to the first beam splitter (11); the second pump output unit is used to output a second pump light of a first wavelength to the third dichroic mirror (17); the second pump light is transmitted by the third dichroic mirror (17) and enters the second gain crystal (18) along a second direction; the second gain crystal (18) generates a base film light beam of a second wavelength under the stimulation of the second pump light; the base film light beam is reflected by the fourth dichroic mirror (20) to the second beam splitter (22); The second beam splitter (22) is suitable for partially reflecting and partially transmitting the light beam of the second wavelength, and the reflectivity is greater than the transmittance, so that the base film light beam reciprocates in the resonant cavity and outputs fundamental frequency light through the second beam splitter (22); the fundamental frequency light passes through the laser transmission unit, is converted into a short wavelength light beam after the frequency is converted by the laser transmission unit, and is output.

2. The short-wavelength laser according to claim 1, characterized in that: The invention also comprises a Q-switching device (7), wherein the third dichroic mirror (17), the first dichroic mirror (4), the first gain crystal (5), the Q-switching device (7) and the second dichroic mirror (9) are arranged in sequence along a first direction, and the third dichroic mirror (17), the second gain crystal (18) and the fourth dichroic mirror (20) are arranged in sequence along a second direction, and the third dichroic mirror (17) is adapted to reflect the base film light beam from the first direction to the second direction and reflect the base film light beam from the second direction to the first direction, and the wavelength ranges of the first wavelength and the second wavelength are different, the first dichroic mirror (4) is adapted to transmit the light beam of the second wavelength and reflect the light beam of the first wavelength range, and the second dichroic mirror (9), the third dichroic mirror (17) and the fourth dichroic mirror (20) are adapted to reflect the light beam of the second wavelength and transmit the light beam of the first wavelength range.

3. The short-wavelength laser according to claim 1, characterized in that: The first beam splitter (11) is adapted to partially reflect and partially transmit the light beam of the second wavelength, and the reflectivity is greater than the transmittance, so that the base film light beam passes through the first beam splitter (11) to output reference light; Correspondingly, the cavity length adjustment unit comprises an optical displacement platform (12) and a detection device (13); The detection device (13) is arranged on a side where the first beam splitter (11) outputs the reference light, and is used to detect preset parameters of the reference light; The optical displacement platform (12) is connected to the first beam splitter (11) and is used to adjust the position of the first beam splitter (11) according to the preset parameters.

4. The short-wavelength laser according to claim 1, characterized in that: The laser transmission unit comprises a reflector assembly, a first nonlinear frequency conversion device (25) and a fifth dichroic mirror (26); the reflector assembly is used to reflect the fundamental frequency light into the first nonlinear frequency conversion device (25); the first nonlinear frequency conversion device (25) is used to convert the fundamental frequency light into a short wavelength light beam of a third wavelength for output after frequency conversion; the short wavelength light beam is reflected and outputted through the fifth dichroic mirror (26); wherein the fifth dichroic mirror (26) is suitable for reflecting the light beam of the third wavelength and transmitting the light beam of the second wavelength.

5. The short-wavelength laser according to claim 1, characterized in that: The first pump output unit comprises a first pump group (1) and a first coupling component (2), wherein the first pump group (1) comprises a plurality of semiconductor lasers and is used to output a first pump light by means of spatial shaping coupling, and the first coupling component (2) is used to perform focusing coupling on the first pump light; And / or, the second pump output unit comprises a second pump group (14) and a second coupling component (15), the second pump group (14) comprises a plurality of semiconductor lasers for outputting a second pump light by means of spatial shaping coupling, and the second coupling component (15) is used for focusing coupling the second pump light.

6. The short-wavelength laser according to claim 5, characterized in that: The first pump output unit further comprises a sixth dichroic mirror (3), wherein the sixth dichroic mirror (3) is adapted to reflect the light beam of the first wavelength and transmit the light beam of the second wavelength, so as to reflect the first pump light after focus coupling to the first dichroic mirror (4); And / or, the second pump output unit further comprises a seventh dichroic mirror (16), wherein the seventh dichroic mirror (16) is adapted to reflect the light beam of the first wavelength and transmit the light beam of the second wavelength, so as to reflect the second pump light after focus coupling to the fourth dichroic mirror (20).

7. The short-wavelength laser according to claim 2, characterized in that: The short-wavelength laser further comprises a first mode controller (6) and a second mode controller (19), wherein the first mode controller (6) is arranged between the first gain crystal (5) and the Q-switching device (7), and the second mode controller (19) is arranged between the second gain crystal (18) and the fourth dichroic mirror (20), and the first mode controller (6) and the second mode controller (19) are both used to filter out high-order modes generated in the resonant cavity.

8. The short-wavelength laser according to claim 2, characterized in that: The short-wavelength laser also includes a heat management device (8), which is arranged between the Q-switching device (7) and the second dichroic mirror (9) and is used to filter out and consume stray light, idler light and high-order modes in the resonant cavity.

9. The short-wavelength laser according to claim 4, characterized in that: The short-wavelength laser further comprises a first collector (10), a second collector (21) and a third collector (27); the first collector (10) is arranged on the transmission side of the second dichroic mirror (9) for collecting and consuming the light beam of the first wavelength transmitted by the second dichroic mirror (9); the second collector (21) is arranged on the transmission side of the fourth dichroic mirror (20) for collecting and consuming the light beam of the first wavelength transmitted by the fourth dichroic mirror (20); the third collector (27) is arranged on the transmission side of the fifth dichroic mirror (26) for collecting and consuming the light beam of the second wavelength transmitted by the fifth dichroic mirror (26).

10. The short-wavelength laser according to claim 4, characterized in that: The short-wavelength laser further comprises an eighth dichroic mirror (28), which is used to reflect the short-wavelength light beam reflected by the fifth dichroic mirror (26), wherein the eighth dichroic mirror (28) is suitable for reflecting the light beam of the third wavelength and transmitting the light beam of the second wavelength.

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