Laser oscillator

Abstract

A laser oscillator, comprising: a resonant cavity; a light source module (30), provided in the resonant cavity, the light source module (30) being configured to be able to output a first light beam, and the first light beam comprising elliptically polarized light; and a quarter-wave plate (40), provided in the resonant cavity and arranged on one side of the light source module (30) in the optical axis direction of the light source module (30), the quarter-wave plate (40) being perpendicular to the optical axis, and the quarter-wave plate (40) being configured to convert the elliptically polarized light in the first light beam into polarized light of a target type, so as to form a second light beam. The laser oscillator can achieve high-power pumping of a gain medium without being limited by the physicochemical properties of crystals, does not need selection of special crystal orientations of isotropic crystals, and improves the laser output efficiency.

Description

laser oscillator Technical Field

[0001] This solution relates to the field of laser technology, specifically to a laser oscillator. Background Technology

[0002] Currently, lasers have significant applications in all aspects of life, including material processing and information detection. A laser oscillator typically includes a resonant cavity, a gain medium, and a pump source. When linearly polarized laser output is required, an anisotropic crystal can be used as the gain medium to directly output linearly polarized laser light. However, when high-power linearly polarized laser light is needed, high-power pumping of the anisotropic crystal is required. Due to the limitations of the physicochemical properties of anisotropic crystals, this can lead to crystal breakage and damage.

[0003] To reduce the influence of the crystal's physicochemical properties on the output of high-power linearly polarized lasers, isotropic crystals with specific crystal orientations are chosen for outputting linearly polarized lasers. However, selecting a specific crystal orientation for the isotropic crystal is necessary to achieve linearly polarized laser output, and the process of selecting the crystal orientation is quite complicated.

[0004] In related technologies, to reduce the complexity of selecting the crystal orientation of isotropic crystals, isotropic crystals with ordinary crystal orientations are directly selected as the gain medium. An analyzer is placed within the resonant cavity, allowing the light output from the pumped isotropic crystal to pass through the analyzer. The analyzer filters out photons that do not conform to the desired polarization direction and outputs photons that do conform to the desired polarization direction, thus achieving direct output of linearly polarized laser light.

[0005] In the process of implementing the relevant technologies, at least the following problems were found:

[0006] When a polarizer is installed inside the resonant cavity, photons with polarization directions that do not conform to the required polarization direction will be output from the analyzer, causing photon leakage from the resonant cavity. On the one hand, photon leakage can easily cause resonant cavity saturation; on the other hand, it leads to a decrease in light conversion efficiency, resulting in low laser production efficiency. Summary of the Invention

[0007] The laser oscillator provided in this application can achieve high-power pumping of the gain medium without being limited by the physical and chemical properties of the crystal, and does not require special selection of the crystal orientation of the isotropic crystal, thereby improving the laser output efficiency.

[0008] In some embodiments, a laser oscillator is provided, comprising: a resonant cavity; a light source module disposed within the resonant cavity, the light source module being configured to output a first beam including elliptically polarized light; and a quarter-wave plate disposed within the resonant cavity and positioned on one side of the light source module along the optical axis direction, the quarter-wave plate being perpendicular to the optical axis, the quarter-wave plate being configured to convert the elliptically polarized light in the first beam into target-type polarized light to form a second beam.

[0009] This disclosure provides a laser oscillator that, by using a quarter-wave plate, adjusts the magnitudes of the S-component and P-component of light in a first beam, thereby converting elliptically polarized light in the first beam into target-type polarized light, and thus forming a second beam. Therefore, the quarter-wave plate can convert the first beam output from the light source module into a second beam, obtaining target-type polarized light, and ultimately, target-type polarized laser. This eliminates the need for an analyzer to generate target-type polarized light (e.g., linearly polarized light), reducing the need for an analyzer to filter out unsuitable light generated by the light source assembly, thus improving laser output efficiency.

[0010] Optionally, the light source module includes: a first side pump module, a rotator, and a second side pump module arranged sequentially along the optical axis; the first side pump module is configured to output a first sub-beam; the second side pump module is configured to output a second sub-beam; the rotator is configured to rotate the polarization state of the second sub-beam and output it to the first side pump module, so that the first sub-beam and the second sub-beam after polarization state rotation are coupled to form a first beam and output.

[0011] In this embodiment, the gain medium in the first side-pump module and the gain medium in the second side-pump module image each other. By setting a rotator between the first side-pump module and the second side-pump module, the radial (P-component direction) and tangential (S-component direction) components of the light field in the two gain media are interchanged. This introduces an opposite phase difference between the radial and tangential components in the two gain media, thereby compensating for the thermally induced birefringence effect.

[0012] Optionally, both the first side pump module and the second side pump module are isotropic gain medium side pump modules.

[0013] In this embodiment, by setting up an isotropic gain medium side pump module, the target type of polarized light can be output using an isotropic crystal with a common crystal orientation, reducing the complex process of selecting a special crystal orientation.

[0014] Optionally, the rotator includes a 90° rotator.

[0015] In this embodiment, by setting a 90° rotator, opposite phase differences are introduced between the radial and tangential components of the first sub-beam output by the first side pump module and the second sub-beam output by the second side pump module, thereby compensating for the thermally induced birefringence effect and reducing the impact of the thermally induced birefringence effect on the first beam.

[0016] Optionally, the target type of polarized light includes linearly polarized light; the laser oscillator also includes: a filter element, which is disposed on opposite sides of the light source module along the optical axis, so that the second beam passes through the light source module and then through the filter element; the filter element is configured to transmit linearly polarized light.

[0017] In this embodiment, by setting a filter, linearly polarized light can be transmitted through the filter, thereby enabling the resonant cavity to output linearly polarized light to obtain the target type of polarized light.

[0018] Optionally, the filter may include a Brewster polarizer.

[0019] In this embodiment, a Brewster polarizer is used to transmit linearly polarized light, specifically light from the second beam that conforms to the target polarization direction, to output linearly polarized laser light. It also filters out light from the second beam that does not conform to the target polarization direction, reducing the amount of non-target polarized light output from the resonant cavity and improving the quality of the laser beam output from the resonant cavity. Furthermore, by detecting the amount of non-target polarized light filtered out from the second beam by the filter, the conversion effect of the quarter-wave plate on the elliptically polarized light in the first beam can be determined, allowing for adjustment of the quarter-wave plate to improve the conversion effect on the elliptically polarized light in the first beam.

[0020] Optionally, the polarized light of the target type includes circularly polarized light; the laser oscillator also includes: a polarizing beam splitter prism, which is disposed at the light outlet of the resonant cavity along the optical axis, and is configured to decompose the second beam output from the resonant cavity into two orthogonal polarized light components.

[0021] In this embodiment, a polarizing beam splitter is used to decompose the second beam into two orthogonal polarized light components, namely, an S-component and a P-component. By comparing the magnitudes of the S-component and the P-component, it is verified whether the second beam is circularly polarized. This allows the angle of the quarter-wave plate to be adjusted based on the magnitudes of the S-component and the P-component, thereby changing the magnitudes of the S-component and the P-component to make the second beam circularly polarized.

[0022] Optionally, the laser oscillator further includes: a Q-switching assembly comprising a first Q-switch and a second Q-switch, wherein the first Q-switch and the second Q-switch are orthogonally arranged; the Q-switching assembly is configured to modulate a second beam.

[0023] In this embodiment, by setting a Q-switch assembly to modulate the second beam and form a pulsed laser, the practicality of the laser oscillator is improved. Specifically, by setting an orthogonally arranged first Q-switch and second Q-switch, the extinction ratio brought about by the Q-switch is increased, thereby increasing the optical loss in the resonant cavity and improving the output efficiency of the pulsed laser.

[0024] Optionally, the resonant cavity includes a reflector and an output mirror arranged sequentially along the optical axis. The reflector is configured to reflect the second beam. The output mirror is configured to partially transmit and partially reflect the second beam. The reflector, quarter-wave plate, light source module, and output mirror are arranged sequentially along the optical axis.

[0025] In this embodiment, a resonant cavity is formed by setting up a reflector and an output mirror, allowing the second beam to oscillate between the reflector and the output mirror to form a laser beam. Furthermore, a portion of the second beam is output through the output mirror to produce the laser beam.

[0026] Optionally, the laser oscillator further includes: a first transparent membrane disposed on the light-inlet side of the output mirror; a second transparent membrane disposed on both sides of the quarter-wave plate and at least one device in the light source module; the transmittance of the second transparent membrane is greater than that of the first transparent membrane.

[0027] In this embodiment, by providing a first transparent film on the light-inlet side of the output mirror and limiting the transmittance of the first transparent film, the output mirror can transmit a portion of the light in the second beam and reflect the remaining portion of the light in the second beam. By providing a second transparent film on both sides of the quarter-wave plate and at least one device in the light source module, the transmittance of the quarter-wave plate and at least one device in the light source module is improved, the light loss generated by the first and second beams when passing through the quarter-wave plate and the light source module is reduced, and the laser conversion efficiency is improved. Attached Figure Description

[0028] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 is a schematic diagram of the structure of a resonant cavity using anisotropic crystals or isotropic crystals with special crystal orientations as the gain medium, as provided in the embodiments of this disclosure.

[0030] Figure 2 is a schematic diagram of the structure of the related technology of setting an analyzer in the resonant cavity according to the embodiments of this disclosure;

[0031] Figure 3 is a schematic diagram of the structure of the laser oscillator provided in the embodiment of this disclosure;

[0032] Figure 4 is a schematic diagram of the structure of the laser oscillator with a filter element provided in an embodiment of this disclosure;

[0033] Figure 5 is a schematic diagram of the structure of a laser oscillator with a polarizing beam splitter provided in an embodiment of this disclosure;

[0034] Figure 6 is a schematic diagram of a laser oscillator Q-switch assembly provided in an embodiment of this disclosure;

[0035] Figure 7 is a schematic diagram of another laser oscillator Q-switch assembly provided in an embodiment of this disclosure;

[0036] Figure 8 is a schematic diagram of another laser oscillator Q-switch assembly provided in an embodiment of this disclosure;

[0037] Figure 9 is a schematic diagram of a nonlinear structure module for a laser oscillator provided in an embodiment of this disclosure;

[0038] Figure 10 is a power schematic diagram of the present application and related technologies provided in the embodiments of this disclosure;

[0039] Figure 11 is a power diagram of the fundamental frequency light and the frequency harmonic light of this application provided in an embodiment of this disclosure.

[0040] Reference numerals: 101, Reflector; 102, Light transmission mirror; 103, Gain medium; 104, Pump source; 105, Analyzer; 201, Reflector; 202, Output mirror; 30, Light source module; 301, First side pump module; 302, Optical rotator; 303, Second side pump module; 40, Quarter-wave plate; 50, Filter; 60, Polarizing beam splitter prism; 701, First Q switch; 702, Second Q switch; 801, First transparent film; 90, Nonlinear module; 901, Focusing lens; 902, Frequency conversion crystal; 903, Collimating lens; 904, Dichroic mirror. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the protection scope of this application.

[0042] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0043] Furthermore, in this application, directional terms such as "upper," "lower," "inner," and "outer" are defined relative to the indicated placement of the components in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the placement of the components in the accompanying drawings.

[0044] To facilitate understanding of the technical solution proposed in this application, the technical problem addressed by this application will be explained below.

[0045] Specifically, the laser oscillator in the relevant technology includes at least a resonant cavity, a gain medium, and a pump source. In the resonant cavity, after the gain medium is pumped by the pump source, atoms or molecules in the gain medium transition to a high-energy state and release photons upon returning to a low-energy state, thus forming laser light. The motion of the photons emitted by the gain medium within the resonant cavity is polarized motion. Polarized photons have two orthogonal optical components, which are classified as perpendicularly polarized light (hereinafter referred to as the S-component) and parallelly polarized light (hereinafter referred to as the P-component) based on the plane of incidence. When the S-component and P-component are equal, the photon motion is circularly polarized, thus forming circularly polarized light. When only the S-component or only the P-component exists, the photon motion is linearly polarized, thus forming linearly polarized light. When the S-component and P-component are unequal, the photon motion is elliptically polarized, thus forming elliptically polarized light.

[0046] To output linearly polarized light, there are generally three methods: using an anisotropic crystal as the gain medium, using an isotropic crystal with a specific crystal orientation as the gain medium, or placing a polarizer in the resonant cavity. The following is a detailed description of each of these three methods.

[0047] Referring to Figure 1, specifically, an anisotropic crystal is used as the gain medium 103 in the resonant cavity to generate and output linearly polarized laser. In Figure 1, the gain medium 103 is an anisotropic crystal. In this scheme, the laser oscillator includes a resonant cavity (including a reflector 101 and a transmission mirror 102), a gain medium 103, and a pump source 104. After being pumped, the anisotropic crystal can directly output linearly polarized laser. To output high-power linearly polarized laser, high-power pumping of the anisotropic crystal is required. However, due to the limitations of the physicochemical properties of the anisotropic crystal (including thermal conductivity and structural strength), the anisotropic crystal will experience crystal breakage under high-power pumping. Therefore, the resonant cavity using anisotropic crystal as the gain medium cannot output high-power linearly polarized laser.

[0048] For example, in a resonant cavity using an anisotropic crystal: neodymium-doped yttrium vanadate (Nd:YVO4) crystal as the gain medium 103, since Nd:YVO4 crystal is tetragonal and optically anisotropic, the polarization direction is related to the crystal axis. For example, after cutting along the a-axis or b-axis, the cut Nd:YVO4 crystal can be used to directly output linearly polarized light. Thus, outputting linearly polarized laser only requires a resonant cavity, gain medium 103, and pump source 104. However, due to the limitations of thermal conductivity and structural strength of yttrium vanadate (YVO4) crystal, high-power pumping will cause the YVO4 crystal to break, and therefore the resonant cavity using neodymium-doped yttrium vanadate (Nd:YVO4) crystal as the gain medium 103 cannot output high-power laser.

[0049] Referring to Figure 1, in the second related technology described in this application, the gain medium 103 is an isotropic crystal with a special crystal orientation. Specifically, an isotropic crystal with a special crystal orientation is used as the resonant cavity of the gain medium 103 to generate and output linearly polarized laser. In this scheme, the laser oscillator includes a resonant cavity (including a reflector 101 and a beam-transmitting mirror 102), a gain medium 103, and a pump source 104. Since isotropic crystals have the same physical properties in all directions, and linearly polarized laser can only be directly output under a special crystal orientation, it is necessary to select an isotropic crystal with a special crystal orientation to achieve linearly polarized laser output. However, the process of selecting a special crystal orientation is relatively complex.

[0050] For example, isotropic crystals with a specific crystal orientation include Nd:YAG crystals with the

[0100] crystal orientation.

[0051] Referring to Figure 2, the structure in Figure 2 represents the third related technology described in this application. Specifically, it uses a common isotropic crystal as the resonant cavity of the gain medium 103 to generate and output linearly polarized laser, requiring an analyzer 105 to be directly placed within the resonant cavity. In this scheme, the laser oscillator includes a resonant cavity (including a reflector 101 and a beam transfer mirror 102), a gain medium 103, a pump source 104, and an analyzer 105. The analyzer 105 filters out light that does not meet the polarization direction requirement, allowing light that does not meet the polarization direction requirement (exemplarily represented by arrow M in Figure 2) to be output directly from above the analyzer 105, while light that meets the polarization direction requirement (exemplarily represented by arrow N in Figure 2) is output from the right side of the beam transfer mirror 102, thereby achieving the output of linearly polarized laser. However, this method causes the resonant cavity to saturate due to the light being leaked and wasted, resulting in a decrease in light conversion efficiency and consequently, low production efficiency of the linearly polarized laser.

[0052] In summary, the technical challenges related to outputting linearly polarized lasers are as follows: When using anisotropic crystals as the gain medium, the crystal's physicochemical properties prevent high-power pumping and output of high-power linearly polarized lasers. When using isotropic crystals, a specific crystal orientation must be selected for outputting linearly polarized lasers, a complex process. Directly placing the analyzer within the resonant cavity results in some light leakage and waste, leading to cavity saturation and low laser conversion efficiency, ultimately resulting in low laser output efficiency.

[0053] The laser oscillator provided in this disclosure can achieve high-power pumping of the gain medium without being limited by the physicochemical properties of the crystal, and does not require special selection of the crystal orientation of the isotropic crystal, thereby improving the laser output efficiency. The following is a detailed description of the embodiments of this disclosure.

[0054] Referring to Figures 3 to 8, this disclosure provides a laser oscillator, including a resonant cavity, a light source module 30, and a quarter-wave plate 40. The light source module 30 is disposed within the resonant cavity and configured to output a first beam, which includes elliptically polarized light. The quarter-wave plate 40 is disposed within the resonant cavity and is positioned on one side of the light source module 30 along its optical axis. The quarter-wave plate 40 is perpendicular to the optical axis and is configured to convert the elliptically polarized light in the first beam into target-type polarized light, forming a second beam.

[0055] This disclosure provides a laser oscillator that, by setting a quarter-wave plate 40, adjusts the magnitudes of the S-component and P-component of the light in a first beam, thereby converting the elliptically polarized light in the first beam into target-type polarized light, and thus forming a second beam. Therefore, the quarter-wave plate 40 can convert the first beam output from the light source module 30 into a second beam, obtaining target-type polarized light, and ultimately, target-type polarized laser. This eliminates the need for an analyzer to generate target-type polarized light (e.g., linearly polarized light), reducing the need for an analyzer to filter out unsuitable light generated by the light source assembly, thus improving laser output efficiency.

[0056] Specifically, the magnitudes of the S-component and P-component of the second beam can be adjusted by rotating the quarter-wave plate 40, thereby changing the polarization type of the light in the second beam and forming polarized light of the target type.

[0057] For example, as shown in Figure 3, the first beam output from the light source module 30 is output along the optical axis to the quarter-wave plate 40. After being converted by the quarter-wave plate 40, the elliptically polarized light (illustratively shown in Figure 3 that the S-component is less than the P-component, but it could also be that the S-component is greater than the P-component) is converted into circularly polarized light (the S-component and P-component are equal, schematically shown in Figure 3) or linearly polarized light (only the S-component or only the P-component, not shown in Figure 3), etc., which are the target type of polarized light. Further, the second beam oscillates in the resonant cavity to form a laser, and then the target type of polarized laser is output from the resonant cavity.

[0058] Optionally, referring to Figures 3 to 8, the light source module 30 includes: a first side-pump module 301, a rotator 302, and a second side-pump module 303 arranged sequentially along the optical axis. The first side-pump module 301 is configured to output a first sub-beam. The second side-pump module 303 is configured to output a second sub-beam. The rotator 302 is configured to rotate the polarization state of the second sub-beam before outputting it to the first side-pump module 301, thereby coupling the first sub-beam with the polarization-rotated second sub-beam to form a first beam and output it.

[0059] In this embodiment, the gain medium in the first side pump module 301 and the gain medium in the second side pump module 303 image each other. By setting a rotator 302 between the first side pump module 301 and the second side pump module 303, the radial (P-component direction) and tangential (S-component direction) components of the light field in the two gain media are interchanged. This introduces an opposite phase difference between the radial and tangential components in the two gain media, thereby compensating for the thermally induced birefringence effect.

[0060] Specifically, thermally induced birefringence disrupts the linear polarization characteristics of the laser, thereby reducing the pulse energy of the output laser, compromising beam quality, and limiting the continuous operating time of the laser oscillator.

[0061] For example, as shown in Figures 3 to 8, after the polarization state of the second sub-beam output by the second side-pump module 303 is rotated by the optical rotator 302, the radial and tangential components of the second sub-beam are interchanged. After the polarization state of the second sub-beam is rotated, it enters the first side-pump module 301 and couples with the first sub-beam output by the first side-pump module 301. However, the radial and tangential components of the first sub-beam are not interchanged, so an opposite phase difference is introduced between the radial and tangential components of the first and second sub-beams, thereby compensating for the thermally induced birefringence effect and reducing the impact of the thermally induced birefringence effect on the first beam.

[0062] Optionally, both the first side pump module 301 and the second side pump module 303 are isotropic gain medium side pump modules.

[0063] In this embodiment, by setting up an isotropic gain medium side pump module, the target type of polarized light can be output using an isotropic crystal with a common crystal orientation, reducing the complex process of selecting a special crystal orientation.

[0064] Specifically, in this embodiment, the light source module 30 includes a gain medium and a pump source. The gain medium used in this solution is an isotropic crystal that does not require special crystal orientation selection, reducing the complexity of the crystal orientation selection process. Furthermore, the isotropic crystal can accept high-power pumping from the pump source to achieve high-power output of the target type of polarized laser.

[0065] For example, the isotropic gain medium side pump module is a YAG pump module, that is, the side pump module includes a gain medium and a pump source. The gain medium used in this solution is a YAG crystal.

[0066] Specifically, to obtain high-energy, low-repetition-rate nanosecond pulse output, the pump duration of the pump source is controlled to reach the fluorescence lifetime of the ions doped in the gain medium. At this time, the Q-switched pulse energy emitted by the laser oscillator reaches its maximum, thus realizing high-energy, low-repetition-rate nanosecond pulse output.

[0067] Specifically, to obtain high-repetition-rate nanosecond pulse output, the operating frequency of the laser oscillator is adjusted. However, different gain media require different operating frequencies.

[0068] For example, when the gain medium of the isotropic gain medium-side pump module is Nd:YAG, the operating frequency of the laser oscillator is adjusted to 5 to 70 kHz to obtain high repetition rate nanosecond pulse output. A preferred operating frequency range is 5 to 20 kHz to maintain a high output power for the laser oscillator.

[0069] For example, when the gain medium of the isotropic gain medium-side pump module is Nd:YVO4, the operating frequency of the laser oscillator is adjusted from 20 to 500 kHz to obtain high repetition rate nanosecond pulse output. A preferred operating frequency range is 20 to 250 kHz to maintain a high output power for the laser oscillator.

[0070] Optionally, the rotator 302 includes a 90° rotator.

[0071] In this embodiment, by setting a 90° rotator, opposite phase differences are introduced between the radial and tangential components of the first sub-beam output by the first side pump module 301 and the second sub-beam output by the second side pump module 303, thereby compensating for the thermal birefringence effect and reducing the impact of the thermal birefringence effect on the first beam.

[0072] Specifically, the 90° rotator is a 90° quartz rotator.

[0073] Specifically, along the optical axis, the first side pump module 301, the 90° optical rotator, and the second side pump module 303 are arranged sequentially.

[0074] Optionally, referring to Figures 4 and 7, the polarized light of the target type includes linearly polarized light. The laser oscillator also includes a filter 50. Along the optical axis, the filter 50 and the quarter-wave plate 40 are respectively disposed on opposite sides of the light source module 30, so that the second beam passes through the light source module 30 and then through the filter 50. The filter 50 is configured to transmit linearly polarized light.

[0075] In this embodiment, by setting a filter 50, linearly polarized light can be transmitted using the filter 50, thereby enabling the resonant cavity to output linearly polarized light to obtain the target type of polarized light.

[0076] Specifically, the filter 50 is also configured to filter out non-linearly polarized light, thereby removing any non-linearly polarized light that may exist in the second beam and reducing the presence of non-linearly polarized light in the laser output from the resonant cavity. Furthermore, by detecting the amount of non-linearly polarized light filtered out by the filter 50, the conversion effect of the quarter-wave plate 40 on the elliptically polarized light in the first beam can be determined, thus facilitating the adjustment of the quarter-wave plate 40 to reduce the amount of non-linearly polarized light in the second beam.

[0077] For example, referring to Figure 4, taking linearly polarized light with the P-component as the desired linearly polarized light as an example, the quarter-wave plate 40 converts the elliptically polarized light (schematically indicated in Figure 4 that the S-component is less than the P-component, but could also be greater than the P-component) in the first beam output by the light source module 30 into linearly polarized light (schematically indicated in Figure 4 that only the P-component exists, but could also be only the S-component). Furthermore, if the S-component still exists in the second beam, the filter 50 will filter it out. The arrow S marked on the left side of the filter 50 indicates the S-component in the second beam that has been filtered out by the filter 50. Therefore, by converting the polarization direction of the light using the quarter-wave plate 40, the amount of filtered light can be reduced, increasing the amount of light transmitted through the filter 50, thereby improving the laser output efficiency.

[0078] It is understandable that, taking the linearly polarized light required as the S-component as an example, it is only necessary to adjust the filter 50 so that it can transmit the linearly polarized light of the S-component while filtering out the linearly polarized light of the P-component. This application will not elaborate further here.

[0079] Specifically, the linearly polarized light includes linearly polarized light in the S-component direction and linearly polarized light in the P-component direction. The desired linearly polarized light can be obtained from the second beam of the transmission filter 50 by adjusting the filter element 50. For example, when the desired linearly polarized light is linearly polarized light in the P-component direction, the filter strip of the corresponding filter element 50 should be set vertically. When the desired linearly polarized light is linearly polarized light in the P-component direction, the filter strip of the corresponding filter element 50 should be set horizontally. If filtered light is detected by the filter element 50, the quarter-wave plate 40 is rotated to adjust the polarization type of the light in the first beam, reducing non-target polarized light in the second beam, so that the laser output from the resonant cavity is the desired linearly polarized laser.

[0080] For example, when the required linearly polarized light is linearly polarized in the S-component direction, after the first beam output from the light source module 30 is output to the quarter-wave plate 40, the elliptically polarized light in the first beam is converted into linearly polarized light in the S-component direction, forming a second beam. After being reflected by the resonant cavity, the second beam is output to the filter 50 along the optical axis. If all the light in the second beam is linearly polarized in the S-component direction, it can all pass through the filter 50. If there is light in the second beam that is not in the S-component direction (including light in the P-component direction of elliptically polarized light and / or light in the P-component direction of circularly polarized light), the light in the non-S-component direction is filtered out by the filter 50, thereby ensuring that the laser output from the resonant cavity is all linearly polarized laser in the S-component direction.

[0081] For example, when the required linearly polarized light is linearly polarized in the P-component direction, after the first beam output from the light source module 30 is output to the quarter-wave plate 40, the elliptically polarized light in the first beam is converted into linearly polarized light in the P-component direction, forming a second beam. After being reflected by the resonant cavity, the second beam is output to the filter 50 along the optical axis. If all the light in the second beam is linearly polarized in the P-component direction, it can all pass through the filter 50. If there is light in the second beam that is not in the P-component direction (including light in the S-component direction of elliptically polarized light and / or light in the S-component direction of circularly polarized light), the light in the non-P-component direction is filtered out by the filter 50, thereby ensuring that the laser output from the resonant cavity is all linearly polarized laser in the P-component direction.

[0082] Optionally, the filter 50 includes a Brewster polarizer.

[0083] In this embodiment, a Brewster polarizer is used to transmit linearly polarized light, specifically light from the second beam that conforms to the target polarization direction, to output linearly polarized laser light. It also filters out light from the second beam that does not conform to the target polarization direction, reducing the amount of non-target polarized light output from the resonant cavity and improving the quality of the laser beam output from the resonant cavity. Furthermore, by detecting the amount of non-target polarized light filtered out by the filter 50, the conversion effect of the quarter-wave plate 40 on the elliptically polarized light in the first beam can be determined, allowing for adjustment of the quarter-wave plate 40 to improve its conversion effect on the elliptically polarized light in the first beam.

[0084] Specifically, the Brewster polarizer can be adjusted so that the light transmitted through it corresponds to the linearly polarized light of the target.

[0085] Optionally, as shown in Figures 5 and 8, the polarized light of the target type includes circularly polarized light. The laser oscillator also includes a polarizing beam splitter 60. Along the optical axis, the polarizing beam splitter 60 is disposed at the light outlet of the resonant cavity, and the polarizing beam splitter 60 is configured to decompose the second beam output from the resonant cavity into two orthogonal polarized light components.

[0086] In this embodiment, a polarizing beam splitter 60 is used to decompose the second beam into two orthogonal polarized light components, namely, an S-component and a P-component. By comparing the magnitudes of the S-component and the P-component, it is verified whether the second beam is circularly polarized. This allows the angle of the quarter-wave plate 40 to be adjusted based on the magnitudes of the S-component and the P-component, thereby changing the magnitudes of the S-component and the P-component to make the second beam circularly polarized.

[0087] For example, referring to Figure 5, after the second beam is output from the resonant cavity, the circularly polarized light in the second beam is decomposed into two orthogonally polarized light components by the polarizing beam splitter 60, namely the S-component (represented by arrow S in Figure 5) and the P-component (represented by arrow P in Figure 5). When the power of the S-component is equal to the power of the P-component, the second beam is circularly polarized light. When the power of the S-component is not equal to the power of the P-component, the angle of the quarter-wave plate 40 can be adjusted to make the power of the S-component equal to the power of the P-component, thereby reducing the non-circularly polarized light in the second beam and improving the beam quality of the laser output from the resonant cavity.

[0088] Optionally, as shown in Figures 6, 7, and 8, the laser oscillator further includes a Q-switch assembly. The Q-switch assembly includes a first Q-switch 701 and a second Q-switch 702, with the first Q-switch 701 and the second Q-switch 702 orthogonally arranged. The Q-switch assembly is configured to modulate the second beam.

[0089] In this embodiment, by setting a Q-switch assembly to modulate the second beam and form a laser capable of pulsed output, the practicality of the laser oscillator is improved. Specifically, by setting an orthogonally arranged first Q-switch 701 and second Q-switch 702, the extinction ratio brought about by setting the Q-switches is increased, thereby increasing the optical loss in the resonant cavity and improving the output efficiency of the pulsed laser.

[0090] For example, the horizontal direction of the first Q switch 701 is parallel to the optical axis, and the horizontal direction of the second Q switch 702 is perpendicular to the optical axis.

[0091] Specifically, referring to Figure 7, the laser oscillator shown in Figure 7 can output pulsed linearly polarized laser light. For example, the second beam obtained after the first beam is converted by a quarter-wave plate 40 is linearly polarized light. The Q-switching component modulates the linearly polarized light within the resonant cavity, so that the output of the resonant cavity is pulsed linearly polarized laser light.

[0092] Specifically, referring to Figure 8, the laser oscillator shown in Figure 8 can output circularly polarized laser in pulses. For example, the second beam obtained after the first beam is converted by a quarter-wave plate 40 is circularly polarized light. The Q-switching component modulates the circularly polarized light in the resonant cavity so that the output of the resonant cavity is pulsed circularly polarized laser.

[0093] It is understandable that the magnitudes of the S-component and P-component of the beam between each device are schematically marked in Figures 7 and 8, respectively. The Q-switching component does not affect the magnitudes of the S-component and P-component of the first beam, nor does it affect the magnitudes of the S-component and P-component of the second beam.

[0094] Optionally, referring to Figures 3 to 8, the resonant cavity includes a reflector 201 and an output mirror 202 arranged sequentially along the optical axis. The reflector 201 is configured to reflect the second beam. The output mirror 202 is configured to partially transmit and partially reflect the second beam. The reflector 201, quarter-wave plate 40, light source module 30, and output mirror 202 are arranged sequentially along the optical axis.

[0095] In this embodiment, a resonant cavity is formed by setting a reflector 201 and an output mirror 202, with the output mirror 202 capable of partially reflecting the second beam. The second beam oscillates between the reflector 201 and the output mirror 202 to generate laser light. Furthermore, a portion of the second beam is output through the output mirror 202 to output laser light.

[0096] For example, as shown in Figures 3 to 8, after the second beam is output to the reflector 201, the S-ray component in the second beam is reflected through the optical axis of the light source module 30 and output to the output mirror 202.

[0097] Specifically, when the first beam output from the light source module 30 is sent to the quarter-wave plate 40, the first beam is converted into a second beam by the quarter-wave plate 40. When the second beam is sent to the reflector 201, it is reflected by the reflector 201 and then transmitted again through the quarter-wave plate 40 and the optical axis of the light source module 30, reaching the output mirror 202. Part of the second beam is output by the output mirror 202, while the remaining part of the second beam is reflected by the output mirror 202 and output to the optical axis of the light source module 30, continuing to oscillate within the resonant cavity.

[0098] Specifically, the output mirror 202 is configured to transmit a first power light in the second beam with a power greater than or equal to a preset power, and to reflect a second power light in the second beam with a power less than the preset power.

[0099] For example, after the second beam is output to the output mirror 202, the first power light in the second beam with a power greater than or equal to a preset power is output by the output mirror 202 to realize the laser oscillator outputting laser light. Meanwhile, the second power light in the second beam with a power less than the preset power is reflected by the output mirror 202 and output to the optical axis of the light source module 30, continuing to oscillate in the resonant cavity to realize the formation of laser light in the resonant cavity.

[0100] Specifically, the reflectivity of mirror 201 is greater than the preset reflectivity.

[0101] For example, the preset reflectance range includes [99.5%, 100%]. Specific values ​​for the preset reflectance include: 99.5%, 99.7%, or 100%.

[0102] Optionally, the laser oscillator further includes a first transparent membrane 801 and a second transparent membrane. The first transparent membrane 801 is disposed on the light-inlet side of the output mirror 202. The second transparent membrane is disposed on both sides of the quarter-wave plate 40 and at least one device in the light source module 30. The transmittance of the second transparent membrane is greater than that of the first transparent membrane 801.

[0103] In this embodiment, by providing a first transparent film 801 on the light-inlet side of the output mirror 202 and limiting the transmittance of the first transparent film 801, the output mirror 202 can transmit a portion of the light in the second beam and reflect the remaining portion of the light in the second beam. By providing a second transparent film on both sides of the quarter-wave plate 40 and at least one device in the light source module 30, the transmittance of the quarter-wave plate 40 and at least one device in the light source module 30 is improved, the light loss generated by the first beam and the second beam when passing through the quarter-wave plate 40 and the light source module 30 is reduced, and the laser conversion efficiency is improved.

[0104] Optionally, the transmittance of the first permeable membrane 801 is in the range of (0%, 40%), and the specific values ​​of the transmittance of the first permeable membrane 801 include 1%, 20% or 40%.

[0105] Optionally, the transmittance of the second membrane ranges from [99.5%, 100%], and the specific transmittance values ​​of the second membrane include 99.5%, 99.7%, or 100%.

[0106] Specifically, when the laser oscillator includes a filter element 50, a second transparent membrane is also disposed on both sides of the filter element 50.

[0107] Specifically, when the laser oscillator includes a polarizing beam splitter 60, a second transparent film is also disposed on the light-inlet side and the light-outlet side of the polarizing beam splitter 60.

[0108] Specifically, the wavelength range of the second permeable membrane includes 946nm, 1030nm, 1064nm, 1319nm, 2940nm, or 2790nm.

[0109] Optionally, as shown in Figure 9, the laser oscillator further includes a nonlinear module 90. Along the optical axis, the nonlinear module 90 is disposed at the light outlet of the resonant cavity. The nonlinear module 90 is configured to receive a second beam output from the resonant cavity and to adjust the frequency of the second beam to form a third beam.

[0110] In this embodiment, by adjusting the frequency of the second beam output from the resonant cavity, a third beam with the required frequency can be obtained, thereby improving the practicality of the laser oscillator.

[0111] Optionally, the nonlinear module includes: a focusing mirror 901, a frequency conversion crystal 902, a collimating mirror 903, and a dichroic mirror 904 arranged sequentially along the optical axis. The focusing mirror 901 is configured to transmit the second beam output from the resonant cavity. The frequency conversion crystal 902 is configured to adjust the frequency of the second beam. The collimating mirror 903 is configured to collimate the third beam. The dichroic mirror 904 is configured to output the third beam.

[0112] In this embodiment, a focusing mirror 901 and a dichroic mirror 904 are provided to provide space for the oscillation of the third beam to generate laser light. By incorporating a frequency-converting crystal 902, the frequency of the second beam can be changed to form the third beam, thereby improving the practicality of the laser oscillator.

[0113] Specifically, the dichroic mirror 904 is also configured to reflect the second beam. This reduces the amount of the second beam output by the nonlinear module, allowing the second beam to be reflected back to the frequency converter crystal 902 and converted into a third beam, thus improving the utilization rate of the second beam.

[0114] Specifically, the second beam includes a pump light, a signal light, and an idler light. After the second beam, which has passed through the focusing lens 901, further passes through the frequency conversion crystal 902, the pump light, signal light, and idler light overlap. Since the pump light, signal light, and idler light have different frequencies, the interaction between these three different frequency lights (pump light, signal light, and idler light) results in an amplitude gain in the signal light and idler light, and an amplitude attenuation in the pump light. This gain causes the resonant light wave (signal light and / or idler light) to oscillate in the resonant cavity, compensating for the losses caused by the resonant light wave oscillating back and forth between the focusing lens and the collimating lens.

[0115] Optionally, the frequency-converting crystal 902 includes a frequency-doubling crystal, a sum-frequency crystal, or a difference-frequency crystal. Thus, the frequency-doubling crystal enables the second beam to be frequency-doubled to form a third beam output. The sum-frequency crystal enables the second beam to be frequency-summed to form a third beam output. The difference-frequency crystal enables the second beam to be frequency-differentialized to form a third beam output. This allows for the generation of a third beam at the required frequency, improving the practicality of the laser oscillator.

[0116] For example, frequency doubling crystals include potassium titanium oxyphosphate (KTP) crystals, barium β-borate (BBO) crystals, lithium triborate (LBO) crystals, or periodically polarized lithium niobate (PPLN) crystals. Sum-frequency crystals include LBO crystals. Difference-frequency crystals include PPLN crystals.

[0117] Optionally, the laser oscillator further includes a fundamental frequency high-transmittance film. The fundamental frequency high-transmittance film is disposed on both sides of the focusing lens. This increases the transmittance of the focusing lens to the second beam, reduces the amount of reflected second beam, and improves the utilization rate of the second beam.

[0118] For example, the parameters of the fundamental frequency high-transmittance film are required to be AR@532nm, AR@946nm, AR@1064nm or AR@1319nm.

[0119] Optionally, the laser oscillator further includes a high-transmittance film and a partial-reflection film. The high-transmittance film is disposed on both ends of the frequency conversion crystal 902 and both sides of the collimating lens 903. The partial-reflection film is disposed on one side of the dichroic mirror 904. This increases the transmittance of the frequency conversion crystal 902 and the collimating lens 903 to the second and third beams, reducing the reflection of the second and third beams. Furthermore, the partial-reflection film enables the dichroic mirror 904 to reflect the second beam and output the third beam, increasing the content of the third beam in the output beam of the dichroic mirror 904.

[0120] Optionally, when the frequency-converting crystal 902 includes a frequency-doubling crystal, the high-transmittance film includes a fundamental frequency-doubling high-transmittance film. The partial reflection film includes a fundamental frequency high-reflectance, frequency-doubling high-transmittance film. This allows the third beam formed after frequency doubling by the frequency-doubling crystal to be output, while the undoubted second beam is reflected back to the frequency-doubling crystal to form the third beam, thereby improving the utilization rate of the second beam.

[0121] For example, when the frequency conversion crystal 902 includes a frequency doubling crystal, the parameters of the fundamental frequency light and frequency doubling high transmittance film are required to be AR@1064 & 532nm, AR@1319 & 659nm, AR@1319 & 660nm, or AR@946 & 488nm. Specifically, the parameters of the fundamental frequency light high reflectivity and frequency doubling high transmittance film are required to be AR@532nm, AR@660nm, or AR@488nm and HR@1064nm, HR@1319nm, or HR@946nm.

[0122] Optionally, when the frequency conversion crystal 902 includes a sum-frequency crystal, the high-transmittance film includes a fundamental frequency light and a sum-frequency light high-transmittance film. The partial reflection film includes a fundamental frequency light high-reflectance film and a sum-frequency light high-transmittance film. In this way, the third beam formed after being summed by the sum-frequency crystal is output, while the second beam that was not summed is reflected back to the sum-frequency crystal to form the third beam, thereby improving the utilization rate of the second beam.

[0123] For example, when the frequency conversion crystal 902 includes a sum-frequency crystal, the parameter requirements for the fundamental frequency light and frequency-doubled light high-transmittance film are AR@1064&532&355nm. Specifically, the parameter requirements for the fundamental frequency light high-reflection and frequency-doubled light high-transmittance film are AR@355nm and HR@1064nm or HR@532nm, etc.

[0124] Optionally, when the frequency conversion crystal 902 includes a difference frequency crystal, the high-transmittance film includes a fundamental frequency light difference frequency light high-transmittance film. The partial reflection film includes a fundamental frequency light high-reflectance light difference frequency light high-transmittance film. In this way, the third beam formed after being frequency-differentially frequencyd by the difference frequency crystal is output, while the second beam that has not been frequency-differentially frequencyd is reflected back to the difference frequency crystal to form the third beam, thereby improving the utilization rate of the second beam.

[0125] For example, when the frequency conversion crystal 902 includes a difference frequency crystal, the parameter requirements for the fundamental frequency light and frequency doubling light high transmittance film are AR@1064&1319&5.5μm. Specifically, the parameter requirements for the fundamental frequency light high reflectivity and frequency doubling light high transmittance film are AR@5.5μm and HR@1064nm or HR@1319nm.

[0126] Figure 10 is a power diagram of the present application and related technologies provided in the embodiments of this disclosure.

[0127] Specifically, referring to Figure 10, a comparison is made between the power of the laser oscillator provided in this application (indicated by line A in Figure 10) and the power of lasers in related technologies (indicated by line B in Figure 10). In Figure 10, the horizontal axis represents the pump current (unit: amperes), and the vertical axis represents the output power of the laser oscillator (unit: watts). As shown in the figure, the output power of the laser oscillator provided in this solution gradually increases with the increase of the pump current, and the increase is greater than that of lasers in related technologies. Under the same pump current, the output power of the laser oscillator provided in this solution increases more than that of lasers in related technologies. Therefore, the laser oscillator provided in this solution achieves high-power laser output.

[0128] Figure 11 is a power diagram of the fundamental frequency light and the frequency harmonic light of this application provided in an embodiment of this disclosure.

[0129] Specifically, referring to Figure 11, the output power of the fundamental frequency light (shown as line C in Figure 11) and the frequency-doubled light (shown as line D in Figure 11) output by the laser oscillator provided in this embodiment of the present disclosure varies with the pump current as shown in Figure 11. In Figure 11, the horizontal axis represents the pump current (unit: amperes), and the vertical axis represents the output power of the laser oscillator (unit: watts). Specifically, the wavelength of the fundamental frequency light is 1064 nm, and the wavelength of the frequency-doubled light is 532 nm.

[0130] It should be noted that those skilled in the art, upon considering the specification and practicing the application disclosed herein, will readily conceive of other embodiments of this application. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope of this application is indicated by the claims.

[0131] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A laser oscillator, characterized by, include: Resonant cavity; A light source module (30) is disposed in the resonant cavity, and the light source module (30) is configured to output a first beam, the first beam including elliptically polarized light; A quarter-wave plate (40) is disposed in the resonant cavity and disposed on one side of the light source module (30) along the optical axis direction of the light source module (30). The quarter-wave plate (40) is perpendicular to the optical axis. The quarter-wave plate (40) is configured to convert the elliptically polarized light in the first beam into target-type polarized light to form a second beam.

2. The laser oscillator of claim 1, wherein, The light source module (30) includes: A first side pump module (301), a gyroscope (302), and a second side pump module (303) are arranged sequentially along the optical axis. The first side pump module (301) is configured to output a first sub-beam; The second side pump module (303) is configured to output a second sub-beam; The rotator (302) is configured to rotate the polarization state of the second sub-beam and output it to the first side pump module (301), so that the first sub-beam and the second sub-beam after polarization state rotation are coupled to form the first beam and output.

3. The laser oscillator according to claim 2, characterized in that, Both the first side pump module (301) and the second side pump module (303) are isotropic gain medium side pump modules.

4. The laser oscillator according to claim 2, characterized in that, The rotator (302) includes a 90° rotator.

5. The laser oscillator according to any one of claims 1 to 4, characterized in that, The target type of polarized light includes linearly polarized light; The laser oscillator also includes: The filter (50) and the quarter-wave plate (40) are respectively disposed on opposite sides of the light source module (30) along the optical axis, so that the second beam passes through the light source module (30) and then passes through the filter (50). The filter (50) is configured to transmit the linearly polarized light.

6. The laser oscillator according to claim 5, characterized in that, The filter (50) includes a Brewster polarizer.

7. The laser oscillator according to any one of claims 1 to 4, characterized in that, The target type of polarized light includes circularly polarized light; The laser oscillator also includes: A polarizing beam splitter (60) is disposed at the light outlet of the resonant cavity along the optical axis. The polarizing beam splitter (60) is configured to decompose the second beam output from the resonant cavity into two orthogonal polarized light components.

8. The laser oscillator according to any one of claims 1 to 4, characterized by Also includes: The Q-switch assembly includes a first Q-switch (701) and a second Q-switch (702), wherein the first Q-switch (701) and the second Q-switch (702) are orthogonally arranged; the Q-switch assembly is configured to modulate the second beam.

9. The laser oscillator according to any one of claims 1 to 4, characterized in that, The resonant cavity includes: A reflecting mirror (201) and an output mirror (202) are arranged sequentially along the optical axis. The reflector (201) is configured to reflect a second beam of light; The output mirror (202) is configured to partially transmit and partially reflect the second beam; The reflector (201), the quarter-wave plate (40), the light source module (30) and the output mirror (202) are arranged sequentially along the optical axis.

10. The laser oscillator according to claim 9, characterized in that, Also includes: The first permeable membrane (801) is disposed on the light-inlet side of the output mirror (202); The second permeable membrane is disposed on both sides of the quarter-wave plate (40) and at least one device in the light source module (30); The transmittance of the second permeable membrane is greater than that of the first permeable membrane (801).

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