A short-wavelength laser

Abstract

This invention relates to the field of laser technology and discloses 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. The resonant cavity includes 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 cavity length adjustment unit is used to adjust the position of the first beam splitter. This invention adjusts the position of the first beam splitter by the cavity length adjustment unit to adjust the length of the resonant cavity, achieving stable resonant cavities for both pump beams, thereby realizing stable high-power output of an all-solid-state short-wavelength laser.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more particularly to a short-wavelength laser. Background Technology

[0002] High-power green and ultraviolet short-wavelength lasers have shown unparalleled advantages in many industrial processing solutions, especially in the processing of highly reflective materials, where they are favored by industrial processing due to their higher material absorption characteristics and smaller focused spot size.

[0003] Currently, short-wavelength laser resonators contain only one gain crystal, with the pump light focused within this single crystal. The crystal's internal power density is high, leading to significant thermal impact and a tendency to reach the material damage threshold. This material limitation makes it difficult to stably output high-power lasers. Related technologies utilize dual-pumping to increase laser power; however, dual-pumping presents greater challenges in achieving particle inversion compared to single-pumping. If the cavity length is inappropriate, interference between the two pump beams or the resulting base film beam may result in coherent destructive interference, or other constructive or destructive phenomena, thus reducing laser power.

[0004] Therefore, existing solid-state lasers are limited by the gain medium material and cavity shape, making it difficult to output stable high-power short-wavelength lasers. Thus, 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 existing lasers cannot stably output high-power short-wavelength lasers.

[0006] The technical solution proposed in this invention is as follows:

[0007] This 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. The resonant cavity includes 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 cavity length adjustment unit is used to adjust the position of the first beam splitter. The first pump output unit outputs a first pump light of a first wavelength to the first dichroic mirror. After being reflected by the first dichroic mirror, the first pump light enters the first gain crystal along a first direction. Under the excitation of the first pump light, the first gain crystal generates a base film beam of a second wavelength. The base film beam passes through the first dichroic mirror and then the second gain crystal. The dichroic mirror reflects the light to the first beam splitter. The second pump output unit outputs the second pump light of the first wavelength to the third beam splitter. After being transmitted by the third beam splitter, the second pump light enters the second gain crystal along the second direction. Under the excitation of the second pump light, the second gain crystal generates a base film beam of the second wavelength. The base film beam is reflected by the fourth beam splitter back to the second beam splitter. The second beam splitter is suitable for partially reflecting and partially transmitting the second wavelength beam, with a reflectivity greater than the transmittance, so that the base film beam reciprocates in the resonant cavity and outputs the fundamental frequency light after passing through the second beam splitter. The fundamental frequency light passes through the laser transmission unit and is converted into a short wavelength beam output after frequency conversion by the laser transmission unit.

[0008] The short-wavelength laser of this invention is based on a resonant cavity constructed from 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 and second gain crystals, respectively, are fed by a first pump light in a first direction and a second pump light in a second direction to generate a base film beam. Dual-path resonance is achieved within the same resonant cavity, enabling higher laser power output and a compact structure. Simultaneously, the position of the first beam splitter is adjusted by a cavity length adjustment unit to adjust the length of the resonant cavity, ensuring that both pump light paths are stable resonant cavities. This results in population inversion of laser particles and resonant amplification of the base film beam. The base film beam reciprocates within the resonant cavity and outputs fundamental frequency light through the second beam splitter. After frequency conversion by a laser transmission unit, the fundamental frequency light is converted into short-wavelength beams such as green light and ultraviolet light for output, achieving stable high-power output of all-solid-state short-wavelength laser.

[0009] Optionally, the short-wavelength laser further includes a Q-switching device. A third dichroic mirror, a first dichroic mirror, a first gain crystal, a Q-switching device, and a second dichroic mirror are arranged sequentially along a first direction. A third dichroic mirror, a second gain crystal, and a fourth dichroic mirror are arranged sequentially along a second direction. The third dichroic mirror is suitable for reflecting a base film beam from the first direction to the second direction and reflecting a base film beam from the second direction to the first direction. The first wavelength and the second wavelength have different wavelength ranges. The first dichroic mirror is suitable for transmitting a beam of the second wavelength and reflecting a beam of the first wavelength range. The second, third, and fourth dichroic mirrors are all suitable for reflecting a beam of the second wavelength and transmitting a 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 is clearly defined, as well as the arrangement order of the third dichroic mirror, the second gain crystal, and the fourth dichroic mirror along the second direction. This arrangement allows the pump light and the base film beam to propagate and convert within the resonant cavity along a predetermined path, improving the efficiency and accuracy of beam transmission. At the same time, the transmission and reflection characteristics of each dichroic mirror for beams of different wavelengths are specified, which can filter out the first pump light and the second pump light in the resonant cavity, thereby improving the quality of the output laser.

[0011] Optionally, the first beam splitter is suitable for partially reflecting and partially transmitting a beam of the second wavelength, with a reflectivity greater than a transmittance, so that the base film beam outputs 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 located on the side where the reference light is output by the first beam splitter 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 method, the laser's operating status and output beam quality can be monitored in real time by detecting the preset parameters of the reference light through a detection device. This provides a basis for the stable operation and parameter adjustment of the laser. The optical displacement platform precisely adjusts the position of the first beam splitter based on the preset parameters to adjust the resonant cavity length, thereby achieving control and optimization of the reference light and further improving the stability and consistency of the laser's output beam.

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

[0014] In this method, the 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 is suitable for reflecting the third wavelength short wavelength beam and transmitting the second wavelength beam, which can separate the converted short wavelength beam from the unconverted beam, ensuring high purity of the output short wavelength 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 several semiconductor lasers for outputting first pump light through spatial shaping coupling. The first coupling component is used to focus and couple 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 several semiconductor lasers for outputting second pump light through spatial shaping coupling. The second coupling component is used to focus and couple the second pump light.

[0016] In this approach, both the first pump output unit and the second pump output unit include a pump group and a coupling component. The pump group consists of several semiconductor lasers and outputs pump light through spatial shaping coupling. The pump light is then focused and coupled by the coupling component, which 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 adapted to reflect a beam of light of the first wavelength and transmit a beam of light of the second wavelength, so as to reflect the focused and coupled first pump light to the first dichroic mirror; and / or, the second pump output unit further includes a seventh dichroic mirror, which is adapted to reflect a beam of light of the first wavelength and transmit a beam of light of the second wavelength, so as to reflect the focused and coupled second pump light to the third dichroic mirror.

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

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

[0020] This method can effectively control the laser mode, improve the beam quality and monochromaticity of the output laser, and make the short-wavelength beam output by the laser cleaner and more stable, which is suitable for occasions with high beam quality requirements.

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

[0022] This approach reduces the interference and impact of these invalid beams on laser performance, while also helping to lower the temperature inside the resonant cavity, improve the stability and reliability of the laser, and extend its lifespan.

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

[0024] In this method, the light beams transmitted through the corresponding dichroic mirrors can be collected and consumed, avoiding the impact of these unused light beams on the laser and further optimizing the laser's performance.

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

[0026] In this method, the beam reflected by the fifth dichroic mirror is further dichroically separated by the eighth dichroic mirror, thereby improving the monochromaticity of the output short-wavelength beam. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

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

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

[0031] Figure 4 This is a schematic diagram of the structure of the fourth short-wavelength laser in this embodiment of the invention;

[0032] Figure 5 This is a schematic diagram of the structure of the fifth short-wavelength laser in this embodiment of the invention;

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

[0034] Figure 7 This is a schematic diagram of the structure of the seventh short-wavelength laser in this embodiment of the invention;

[0035] Reference numerals: 1-First pump group; 2-First coupling component; 3-Sixth dichroic mirror; 4-First dichroic mirror; 5-First gain crystal; 6-First mode controller; 7-Q-switching device; 8-Thermal management device; 9-Second dichroic mirror; 10-First collector; 11-First beam splitter; 12-Optical displacement platform; 13-Detection device; 14-Second pump group; 15-Second coupling component; 16-Seventh dichroic mirror; 17-Third dichroic mirror; 18-Second gain crystal; 19-Second mode controller; 20-Fourth dichroic mirror; 21-Second collector; 22-Second beam splitter; 23-First reflecting mirror; 24-Second reflecting mirror; 25-First nonlinear frequency conversion device; 26-Fifth dichroic mirror; 27-Third collector; 28-Eighth dichroic mirror. Detailed Implementation

[0036] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Furthermore, 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 lasers with existing technology, the present invention provides a short-wavelength laser that adopts an all-solid-state solution and can precisely tune the laser resonant cavity, thereby outputting high-power and stable short-wavelength lasers.

[0041] like Figure 1 As shown, the short-wavelength laser of this embodiment 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-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 cavity length adjustment unit is used to adjust the position of the first beam splitter 11.

[0042] The first pump output unit outputs 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. Under the excitation of the first pump light, the first gain crystal 5 generates a base film beam of a second wavelength. 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 outputs 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. Under the excitation of the second pump light, the second gain crystal 18 generates a base film beam of a second wavelength. 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 a beam of the second wavelength, with a reflectivity greater than a transmittance, so that the base film 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 and is converted into a short-wavelength beam output after frequency conversion by the laser transmission unit. Specifically, it can output short-wavelength lasers such as green light, near-ultraviolet light, and deep ultraviolet light.

[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 the first pump light, the wavelength of which is between 800nm ​​and 900nm.

[0046] The first dichroic mirror 4 primarily reflects the first pump light and inputs it into the resonant cavity to perform the pumping function. Generally, the first dichroic mirror 4 is coated with an 800nm-900nm high-reflectivity film and a 1000nm-1100nm high-transmittance film.

[0047] The first gain crystal 5 is mainly used to provide activation particles, population inversion, etc. The first pump light, after being reflected by the first dichroic mirror 4, undergoes stimulated emission inside the first gain crystal 5 to generate 1000nm-1100nm photons and is then output. Generally, in order to reduce losses, the first gain crystal 5 is coated with a double-end coating, with an anti-reflection coating of 800nm ​​to 1100nm.

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

[0049] In other embodiments, the Q-switching device 7 may not be designed. In this case, a continuous wave laser will be obtained instead of a pulsed laser. The peak power will be lower than that of the pulsed laser mentioned above, but it will have 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 beam resonating in the resonant cavity, and to filter out the first pump light and the second pump light that participate after pumping. Generally, in order to reduce cavity loss, the second dichroic mirror 9 is coated with a 1000nm-1100nm high reflectivity film and an 800nm-900nm high transmittance film.

[0051] The first beam splitter 11 is mainly used to reflect the infrared light from the base film resonating within the cavity, thus becoming one of the end mirrors of the resonant cavity. Simultaneously, this component transmits a small portion 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, with the coating parameters designed to allow for 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. It can use a high-precision stepper motor 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 multiple semiconductor lasers to output a second pump light with a wavelength of 800nm-900nm. The second pump light and the first pump light are collectively referred to as the pump light.

[0054] The third dichroic mirror 17 primarily transmits the second pump light into the resonant cavity, where it performs its pumping function. Generally, the third dichroic mirror 17 is coated with an 800nm-900nm high-transmittance film and a 1000nm-1100nm high-reflection film.

[0055] The second gain crystal 18 is mainly used to provide activation particles and population inversion. The second pump light transmitted through the third dichroic mirror 17 undergoes stimulated emission inside the second gain crystal 18 to generate 1000nm-1100nm photons, which are then output. Generally, to reduce losses, the second gain crystal 18 is coated with a double-end coating of 800nm ​​to 1100nm antireflection coating. The second gain crystal 18 acts as a secondary stimulated emission, providing more base film photons to the resonant cavity and more base film beam output for the high-power green laser.

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

[0057] The second beam splitter 22 is mainly used to split the base film 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 part of the base film infrared light returns along the original optical path to form the resonant cavity, and the other part is transmitted and output as the fundamental frequency light for nonlinear conversion. Therefore, the wavelengths of the fundamental frequency light and the base film beam are the same, both being 1000nm-1100nm.

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

[0059] The short-wavelength laser of this invention is based on a resonant cavity constructed from 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, respectively, are fed by a first pump light in a first direction and a second pump light in a second direction, generating a base film beam. Dual-path resonance is achieved within the same resonant cavity, enabling higher laser power output and a compact structure. Simultaneously, the position of the first beam splitter 11 is adjusted by a cavity length adjustment unit to regulate the length of the resonant cavity, ensuring that both pump light paths are stable resonant cavities. This results in population inversion of the laser particles and resonant amplification of the base film beam. The base film beam reciprocates within the resonant cavity and outputs fundamental frequency light via the second beam splitter 22. After frequency conversion by a laser transmission unit, the fundamental frequency light is converted into short-wavelength beams such as green light and ultraviolet light, achieving stable high-power output of the short-wavelength laser.

[0060] In one embodiment, the first beam splitter 11 is adapted to partially reflect and partially transmit a beam of the second wavelength, with a reflectivity greater than a transmittance, so that the base film beam outputs 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 disposed on the side of the first beam splitter 11 where the reference light is output, 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 displacement stage consists of a high-precision stepper motor and an optical fixing platform. The optical fixing platform is equipped 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 beam splitter 11. It can compare the preset parameters such as mode, power, coordinates, and number of longitudinal modes under normal conditions according to the algorithm and perform self-feedback optimization through the optical displacement platform 12, so that the resonant cavity can automatically meet the requirements of different modes.

[0063] Specifically, since the two pumps are located within a single resonant cavity, both pumps must satisfy the following conditions: Only in this way can both pump beams be made into stable resonant cavities, forming laser population inversion and resonant amplification. Compared with single-pump, it is more difficult to form population inversion. Therefore, it is necessary to detect the resonant state of the two pumps through the detection device 13, and to precisely adjust and calibrate the resonant cavity length by adjusting the optical displacement stage, so that both pumps meet the requirements of the above formula and form a good resonant cavity length state.

[0064] Simultaneously, to achieve better beam quality, the beam waists of the two pump beams must be aligned at the same position, specifically between the two gain crystals. This overlap of the beam waists ensures a smaller beam quality M2 and thus better beam quality.

[0065] Furthermore, it is necessary to adjust the cavity length to ensure that the two pump beams are in a coherent and constructive relationship during interference, rather than a coherent and destructive relationship or a relationship where some parts are constructive and others are destructive. This is to improve beam power and reduce the occurrence of higher-order modes. Specifically, the formula for the longitudinal mode spacing of a laser resonator is: Δv = c / (2nL), where Δv is the overlap of the periods of the longitudinal waves when the longitudinal modes are interleaved, where c is the speed of light, n is the refractive index of the cavity medium, and L is the cavity length.

[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 length of the resonant cavity is adjusted by the optical displacement stage to improve the quality of the base film beam.

[0067] In this method, the preset parameters of the reference light are detected by the detection device 13, which can monitor the operating status of the laser and the quality of the output beam in real time, providing a basis for the stable operation and parameter adjustment of the laser. The optical displacement platform 12 precisely adjusts the position of the first beam splitter 11 based on the preset parameters to adjust the resonant cavity length, thereby realizing the control and optimization of the reference light and further improving the stability and consistency of the laser output 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 several semiconductor lasers for outputting first pump light through spatial shaping coupling. Multiple semiconductor lasers using spatial shaping coupling can output pump light with higher power. The wavelength of the first pump light is in the range of 800-900 nm. The first coupling component 2 is used for focusing and coupling the first pump light. The first coupling component 2 is mainly a combination of multiple lenses to focus and couple the beam at a certain ratio, adapting to the resonant cavity design to focus the pump light to the 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 several semiconductor lasers for outputting second pump light through spatial shaping coupling. Multiple semiconductor lasers using spatial shaping coupling can output pump light with higher power. The wavelength of the first pump light is 800-900 nm. The second coupling component 15 is used for focusing and coupling the second pump light. The second coupling component 15 is mainly a combination of multiple lenses to focus and couple the beam at a certain ratio, adapting to the resonant cavity design to focus the pump light to the optimal spot size.

[0070] In this approach, both the first pump output unit and the second pump output unit include a pump group and a coupling component. The pump group consists of several semiconductor lasers and outputs pump light through spatial shaping coupling. The pump light is then focused and coupled by the coupling component, which 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] Furthermore, 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 sequentially along the first direction, and the third dichroic mirror 17, the second gain crystal 18, and the fourth dichroic mirror 20 are arranged sequentially along the second direction. The third dichroic mirror 17 is suitable for reflecting the base film beam from the first direction to the second direction and reflecting the base film 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 beam of the second wavelength and reflecting the beam of the first wavelength range. The second dichroic mirror 9, the third dichroic mirror 17, and the fourth dichroic mirror 20 are all suitable for reflecting the beam of the second wavelength and transmitting the 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 is clearly defined, as well as the arrangement order of the third dichroic mirror 17, the second gain crystal 18, and the fourth dichroic mirror 20 along the second direction. This arrangement allows the pump light and the base film beam to propagate and convert within the resonant cavity along 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 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 mirror assembly and a first nonlinear frequency conversion device.

[0074] The combination of the fifth dichroic mirror 25 and the fifth dichroic mirror 26 is used to reflect the fundamental frequency light into the first nonlinear frequency converter 25. The first nonlinear frequency converter 25 is used to convert the fundamental frequency light into a short-wavelength beam of the third wavelength after frequency conversion. The short-wavelength beam is reflected by the fifth dichroic mirror 26 and output. The fifth dichroic mirror 26 is suitable for reflecting the beam of the third wavelength and transmitting the beam of the second wavelength.

[0075] Specifically, the mirror assembly includes at least one mirror.

[0076] In one example, such as Figure 1As shown, the reflector assembly includes a first reflector 23, which is mainly used to deflect and fold the fundamental frequency light transmitted through the second beam splitter 22, thereby improving the spatial integration of the product. Generally, to reduce losses, the first reflector 23 is coated with a 1000nm-1100nm high-reflectivity film.

[0077] In another example, such as Figure 3 As shown, the reflector assembly includes a first reflector 23 and a second reflector 24. The second reflector 24 and the first reflector 23 have the same parameters. The two reflectors work together to achieve optical path bending and folding, thereby further improving the product's spatial integration.

[0078] The first nonlinear frequency converter is mainly used to convert the fundamental frequency light output by the reflector combination. Generally, the first nonlinear frequency converter is used as a second harmonic converter, converting the fundamental frequency light (specifically, an infrared beam of 1000nm-1100nm) into a short wavelength beam of 500nm-550nm, while simultaneously forming an infrared / short wavelength mixed light with the residual infrared beam. Generally, to reduce losses, the first nonlinear frequency converter is coated with anti-reflection films of 500nm-550nm and 1000nm-1100nm on both sides.

[0079] The fifth dichroic mirror 26 is mainly used to separate the mixed beam output by the first nonlinear frequency converter. The fifth dichroic mirror 26 is coated with a dielectric beam splitter to reflect the short-wavelength beam, i.e. the third wavelength beam, and transmit the fundamental frequency light of the second wavelength. Generally, in order to reduce losses, this component is coated with a 500nm-550nm high-reflectivity film and a 1000nm-1100nm high-transmittance film.

[0080] In this method, the 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 third wavelength short wavelength beam and transmitting the second wavelength beam, which can separate the converted short wavelength beam from the unconverted beam, ensuring high purity of the output short wavelength beam and improving the output quality of the laser.

[0081] In some embodiments, such as Figure 2 As shown, the first pump output unit further includes a sixth dichroic mirror 3, which is adapted to reflect a beam of light of the first wavelength and transmit a beam of light of the second wavelength, so as to reflect the focused and coupled first pump light to the first dichroic mirror 4; and / or, the second pump output unit further includes a seventh dichroic mirror 16, which is adapted to reflect a beam of light of the first wavelength and transmit a beam of light of the second wavelength, so as to reflect the focused and coupled second pump light to the third dichroic mirror 17.

[0082] 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. Simultaneously, the sixth dichroic mirror 3 filters out the base film beam that is not completely transmitted through the first dichroic mirror 4 within the resonant cavity, thus stabilizing the optical path and protecting the pump. Generally, the sixth dichroic mirror 3 is coated with an 800nm-900nm high-reflectivity film and a 1000nm-1100nm high-transmittance film.

[0083] The seventh dichroic mirror 16 is used to reflect the second pump light, shaped by the second coupling component 15, into the resonant cavity. Simultaneously, the seventh dichroic mirror 16 filters out the base film beam that is incompletely reflected by the third dichroic mirror 17 within the resonant cavity, thus stabilizing the optical path and protecting the pump. Generally, the seventh dichroic mirror 16 is coated with an 800nm-900nm high-reflectivity film and a 1000nm-1100nm high-transmittance film.

[0084] In this method, the quality of the input pump light can be improved by filtering the non-pump light through the sixth dichroic mirror 3 and the seventh dichroic mirror 16.

[0085] In some embodiments, such as 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 disposed between the first gain crystal 5 and the Q-switching device 7, and the second mode controller 19 is disposed between the second gain crystal 18 and the fourth dichroic mirror 20. Both the first mode controller 6 and the second mode controller 19 are used to filter out higher-order modes generated in the resonant cavity.

[0086] The first mode controller 6 and the second mode controller 19 are mainly used for intracavity mode selection, filtering out the generated higher-order modes and only allowing the base film to resonate and amplify, thereby outputting a base film beam with better infrared band M2, thus having high nonlinear conversion efficiency.

[0087] This method can effectively control the laser mode, improve the beam quality and monochromaticity of the output laser, and make the short-wavelength beam output by the laser cleaner and more stable, which is suitable for occasions with high beam quality requirements.

[0088] In some embodiments, such as Figure 5 As shown, the short-wavelength laser also includes a thermal 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 higher-order modes in the resonant cavity.

[0089] The quality of thermal management of industrial lasers directly determines the power stability of the laser. Thermal management devices are mainly used to filter out stray light, idler light and higher-order modes in the resonant cavity and conduct them to the cold plate for consumption, so as to ensure the thermal stability and safety of the laser.

[0090] In some embodiments, such as Figure 6 As shown, the short-wavelength laser also includes a first collector 10, a second collector 21, and a third collector 27. The first collector 10 is disposed on the transmission side of the second dichroic mirror 9 and is used to collect and consume the first wavelength beam transmitted through the second dichroic mirror 9. The second collector 21 is disposed on the transmission side of the fourth dichroic mirror 20 and is used to collect and consume the first wavelength beam transmitted through the fourth dichroic mirror 20. The third collector 27 is disposed on the transmission side of the fifth dichroic mirror 26 and is used to collect and consume the second wavelength beam transmitted through the fifth dichroic mirror 26.

[0091] 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.

[0092] The first collector 10, the second collector 21, and the third collector 27 convert idle frequency photons into heat energy through water cooling, air cooling, and other methods, thereby avoiding the impact of these unused beams on the laser and further optimizing the laser's performance.

[0093] In some embodiments, such as Figure 7 As shown, the short-wavelength laser also includes an eighth dichroic mirror 28, which is used to reflect the short-wavelength beam reflected by the fifth dichroic mirror 26. The eighth dichroic mirror 28 is suitable for reflecting a beam of the third wavelength and transmitting a beam of the second wavelength.

[0094] The eighth dichroic mirror 28 is mainly used to further separate the light beam reflected by the fifth dichroic mirror 26, thereby improving the monochromaticity of the output short-wavelength light beam. The eighth dichroic mirror 28 is coated with a dielectric beam-splitting film to reflect the short-wavelength light beam and transmit the fundamental frequency light beam.

[0095] To reduce losses, the eighth dichroic mirror 28 is coated with a 500nm-550nm high-reflectivity film and a 1000nm-1100nm high-transmittance film.

[0096] In this method, the beam reflected by the fifth dichroic mirror 26 is further dichroically separated by the eighth dichroic mirror 28, thereby improving the monochromaticity of the output short-wavelength beam.

[0097] While exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions and modifications to these embodiments without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined herein.

Claims

1. A short-wavelength laser, characterized in that, include: The system comprises 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 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 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). After being reflected by the first dichroic mirror (4), the first pump light enters the first gain crystal (5) along the first direction. Under the excitation of the first pump light, the first gain crystal (5) generates a base film beam of a second wavelength. 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. Under the excitation of the second pump light, the second gain crystal (18) generates a base film beam of a second wavelength. The base film 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 beam of the second wavelength and the reflectivity is greater than the transmittance, so that the base film beam moves back and forth 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 beam output after frequency conversion by the laser transmission unit. The first beam splitter (11) is suitable for partially reflecting and partially transmitting the beam of the second wavelength, and the reflectivity is greater than the transmittance, so that the base film beam outputs 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 set on the side where the reference light is output from the first beam splitter (11) and is used to detect the 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.

2. The short-wavelength laser according to claim 1, characterized in that, It also includes a Q-switching device (7). 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 sequentially along the first direction. The third dichroic mirror (17), the second gain crystal (18), and the fourth dichroic mirror (20) are arranged sequentially along the second direction. The third dichroic mirror (17) is adapted to reflect the base film beam from the first direction to the second direction and reflect the base film 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 adapted to transmit the beam of the second wavelength and reflect the beam of the first wavelength range. The second dichroic mirror (9), the third dichroic mirror (17), and the fourth dichroic mirror (20) are all adapted to reflect the beam of the second wavelength and transmit the beam of the first wavelength range.

3. The short-wavelength laser according to claim 1, characterized in that, The laser transmission unit includes a mirror assembly, a first nonlinear frequency converter (25), and a fifth dichroic mirror (26). The mirror assembly is used to reflect the fundamental frequency light into the first nonlinear frequency converter (25). The first nonlinear frequency converter (25) is used to convert the fundamental frequency light into a short-wavelength beam of the third wavelength after frequency conversion. The short-wavelength beam is reflected and output by the fifth dichroic mirror (26). The fifth dichroic mirror (26) is suitable for reflecting the beam of the third wavelength and transmitting the beam of the second wavelength.

4. The short-wavelength laser according to claim 1, characterized in that, The first pump output unit includes a first pump group (1) and a first coupling component (2). The first pump group (1) includes several semiconductor lasers for outputting first pump light through spatial shaping coupling. The first coupling component (2) is used to focus and couple the first pump light. 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 for outputting a second pump light through spatial shaping coupling, and the second coupling component (15) is used for focusing and coupling the second pump light.

5. The short-wavelength laser according to claim 4, characterized in that, The first pump output unit further includes a sixth dichroic mirror (3), which is adapted to reflect the first wavelength beam and transmit the second wavelength beam, so as to reflect the focused and coupled first pump light to the first dichroic mirror (4). And / or, the second pump output unit further includes a seventh dichroic mirror (16) adapted to reflect the first wavelength beam and transmit the second wavelength beam, so as to reflect the focused and coupled second pump light to the third dichroic mirror (17).

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

7. The short-wavelength laser according to claim 2, characterized in that, The short-wavelength laser also includes a thermal management device (8), which is disposed between the Q-switching device (7) and the second dichroic mirror (9) for filtering and consuming stray light, idler light and higher-order modes in the resonant cavity.

8. The short-wavelength laser according to claim 3, characterized in that, The short-wavelength laser also includes a first collector (10), a second collector (21), and a third collector (27). The first collector (10) is disposed on the transmission side of the second dichroic mirror (9) and is used to collect and consume the first wavelength beam transmitted through the second dichroic mirror (9). The second collector (21) is disposed on the transmission side of the fourth dichroic mirror (20) and is used to collect and consume the first wavelength beam transmitted through the fourth dichroic mirror (20). The third collector (27) is disposed on the transmission side of the fifth dichroic mirror (26) and is used to collect and consume the second wavelength beam transmitted through the fifth dichroic mirror (26).

9. The short-wavelength laser according to claim 3, characterized in that, The short-wavelength laser also includes an eighth dichroic mirror (28) for reflecting the short-wavelength beam reflected by the fifth dichroic mirror (26), wherein the eighth dichroic mirror (28) is adapted to reflect the beam of the third wavelength and transmit the beam of the second wavelength.

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