Double-resonant-cavity Q-switched laser and laser Q-switched output method

Abstract

The invention discloses a double-resonant-cavity Q-switched laser, two resonant cavities which share a laser crystal and a Q-switched switch but have different cavity lengths are formed through a rotatable half-wave plate, and the polarization state of light is changed by rotating the half-wave plate, so that the light is converted between the two resonant cavities; under the condition that a gain medium or a device structure is not changed, half-wave plate rotation is provided, and pulse width conversion can be simply achieved.

Description

Technical Field

[0001] The present application belongs to the field of optical devices, and specifically relates to a dual-resonance cavity Q-switched laser and a laser Q-switched output method. Background Art

[0002] Laser technology is an advanced technology widely used in industrial manufacturing, medical treatment, scientific research and other fields. Among them, Q-switched nanosecond lasers are widely used in precision processing of metal and non-metal materials because of their high peak power and short pulse width. However, the output wavelength and output pulse width of the laser have an important influence on the processing efficiency and effect. Different materials and processing requirements require different wavelengths and pulse widths. Therefore, lasers that can achieve wavelength and pulse width switching have a wider application prospect. The wavelength and pulse width can be switched by replacing the working medium of the laser or adjusting the parameters of the laser. For example, the output wavelength of the laser can be changed by replacing different types of laser crystals, or the output pulse width of the laser can be changed by adjusting the pump power of the laser and the repetition frequency of the output pulse. In addition, some lasers achieve wavelength and pulse width switching by setting multiple resonant cavities, each of which corresponds to a different wavelength or pulse width. However, the process of replacing the working medium of the laser or adjusting the parameters of the laser is relatively cumbersome, which is not conducive to the rapid switching of wavelength and pulse width; although the method of setting multiple resonant cavities can achieve wavelength switching, it will increase the complexity and cost of the laser. Existing lasers usually can only operate at a fixed pulse width or wavelength, which cannot meet a variety of processing requirements and limits their scope of application. Summary of the invention

[0003] In order to improve the defects of the prior art, the present application provides a dual-resonance cavity Q-switched laser, which can realize the switching of different pulse widths, and further provides a laser Q-switched output method.

[0004] The present application provides a dual-resonance cavity Q-switched laser with adjustable pulse width, comprising a pump light source, a first reflector, a laser crystal, a Q switch, a half-wave plate, a first thin-film polarizer, a first dichroic mirror, a first output mirror, a first frequency conversion module, a second reflector, a second thin-film polarizer, a second dichroic mirror, a second frequency conversion module, a third reflector, and a third dichroic mirror;

[0005] Wherein, the pump light source is used to emit pump laser;

[0006] A first resonant cavity is formed between the first reflector and the second reflector;

[0007] A second resonant cavity is formed between the first reflecting mirror and the third reflecting mirror.

[0008] In one embodiment, the first resonant cavity includes a first reflector, a laser crystal, a Q switch, a half-wave plate, a first thin-film polarizer, a first dichroic mirror, a first frequency conversion module, and a second reflector, which are arranged in sequence;

[0009] The first output mirror reflects the reflected output light of the first dichroic mirror and outputs a first laser beam.

[0010] In one embodiment, the second resonant cavity includes the first reflector, a laser crystal, a Q switch, a half-wave plate, a first thin-film polarizer, and a second thin-film polarizer, a second dichroic mirror, a second frequency conversion module, and a third reflector, which are sequentially arranged;

[0011] The second thin-film polarizer is arranged at the polarized light output end of the first thin-film polarizer.

[0012] In one embodiment, the third dichroic mirror is disposed at the reflected light output end of the second dichroic mirror.

[0013] In one embodiment, the third dichroic mirror serves as a second output mirror to output a second laser beam; or, the third dichroic mirror reflects light to the first output mirror, and after being transmitted through the first output mirror, outputs a third laser beam along the direction of the first laser beam.

[0014] In one embodiment, the first frequency conversion module and the second frequency conversion module are the same or different and are independently selected from a double frequency crystal or a combination of a double frequency crystal and a triple frequency crystal.

[0015] In one embodiment, the half-wave plate is angularly rotatable;

[0016] And / or the laser crystal is selected from any one of Nd:YVO4 laser crystal, Nd:YAG crystal, Nd:YLF crystal, Nd:KGW crystal, Yb:YVO4 crystal, Yb:YAG crystal, Yb:YLF crystal, Yb:KGW crystal, Pr:YLF crystal, Pr:YAP crystal, Pr:LiLuF4 crystal, Pr:LaF3 crystal, and Ti:Sapphire crystal;

[0017] and / or the Q switch is selected from any one of an acousto-optic modulator and an electro-optic modulator;

[0018] And / or the first output mirror is a thin film polarizer or a dichroic mirror.

[0019] The present application also provides a laser Q-switched output method, comprising:

[0020] A laser is provided, comprising a pump light source, a first resonant cavity and a second resonant cavity, wherein the first resonant cavity and the second resonant cavity comprise the same half-wave plate;

[0021] The pump light source provides pump laser as incident light, which is injected into the half-wave plate;

[0022] The half-wave plate is placed at a first polarization angle, the incident light is placed at a first polarization state, propagates in a first resonant cavity, and outputs a first laser beam;

[0023] The half-wave plate is rotated to a second polarization angle, the incident light is in a second polarization state, propagates in a second resonant cavity, and outputs a second laser beam;

[0024] The first polarization angle is different from the second polarization angle, and the first polarization state is different from the second polarization state.

[0025] In one embodiment, the first resonant cavity and the second resonant cavity have different cavity lengths; and / or the first resonant cavity and the second resonant cavity include the same or different frequency doubling crystals; and / or the first laser beam and the second laser beam are output from different output directions, or the first laser beam and the second laser beam are output from the same output direction to form a third laser beam.

[0026] In one embodiment, the method is implemented via the aforementioned laser.

[0027] Beneficial effects of this application:

[0028] The laser provided in the present application forms two resonant cavities with different cavity lengths but a common laser crystal and a Q switch through a rotatable half-wave plate. The polarization state of the light is changed by rotating the half-wave plate, so that the light is transformed between the two resonant cavities to achieve the conversion of the light pulse width; further, the conversion of the light wavelength is achieved by respectively arranging different frequency conversion modules in the two resonant cavities. The laser of the present application can simply realize the conversion of the light wavelength and pulse width by providing half-wave plate rotation without changing the gain medium or device structure. The wavelength and pulse width can be quickly switched according to different materials and processing requirements, greatly improving the processing efficiency and effect, meeting a variety of processing requirements, and expanding the scope of application of the laser. At the same time, since the laser of the present application only needs a set of laser crystals and Q switches, the structure of the laser is simplified, the cost is reduced, and it has high practical value and broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0030] Figure 1 A schematic diagram of the structure of a laser with dual-path laser output provided in one embodiment of the present application;

[0031] Figure 2 A schematic diagram of the structure of a laser for laser beam combining output provided in another embodiment of the present application. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0033] See also Figure 1 and Figure 2 The embodiment of the present application provides an actively Q-switched laser, including a pump light source (not shown in the figure), a first reflector 1, a laser crystal 2, a Q switch 3, a half-wave plate 4, a first thin-film polarizer 5, a first dichroic mirror 13, a first output mirror 14, a first frequency conversion module 11, a second reflector 12, a second thin-film polarizer 6, a second dichroic mirror 9, a second frequency conversion module 7, a third reflector 8, and a third dichroic mirror 10;

[0034] Wherein, the pump light source is used to emit pump laser;

[0035] A first resonant cavity is formed between the first reflector 1 and the second reflector 12 ; a second resonant cavity is formed between the first reflector 1 and the third reflector 8 .

[0036] The laser provided in the embodiment of the present application is configured with two resonant cavities of different lengths, and changes the polarization state of light through a rotatable half-wave plate, selects resonant cavities with different cavity lengths, and realizes the switching of laser pulse widths. The switching of different pulse widths can be conveniently realized without changing the pump light source or the laser crystal medium or other parameters of the laser.

[0037] like Figure 1 and Figure 2 As shown, in some embodiments, the first resonant cavity includes a first reflector 1, a laser crystal 2, a Q switch 3, a half-wave plate 4, a first thin-film polarizer 5, a first dichroic mirror 13, a first frequency conversion module 11, a second reflector 12 and a first output mirror 14, which are arranged in sequence; the second resonant cavity includes a first reflector 1, a laser crystal 2, a Q switch 3, a half-wave plate 4, a first thin-film polarizer 5, a second thin-film polarizer 6, a second dichroic mirror 9, a second frequency conversion module 7, and a third reflector 8, which are arranged in sequence.

[0038] The half-wave plate 4 is a rotatable half-wave plate. A first resonant cavity is formed between the first reflector 1 and the second reflector 12; a second resonant cavity is formed between the first reflector 1 and the third reflector 8. The half-wave plate is rotated to change the polarization state of light, thereby realizing the switching of the resonant cavity. Different resonant cavity lengths realize the change of pulse width.

[0039] In the first resonant cavity, the half-wave plate 4 is at the first polarization angle. When the light passes through the half-wave plate 4, the light is in the first polarization state, for example, the original polarization state is kept unchanged. The light propagates to the first thin-film polarizer 5, and then transmits through the first thin-film polarizer 5, and then passes through the first dichroic mirror 13 and the first frequency conversion module 11 in sequence. A part of the light forms a continuous oscillation of light between the first reflector 1 and the second reflector 12 after being reflected by the second reflector 12, and a part of the light is reflected by the first dichroic mirror 13 to the surface of the first output mirror 14 to output the first laser beam. The two surfaces of the first dichroic mirror 13 are coated with film layers with different light transmittances, so that the first surface of the first dichroic mirror 13 can transmit the transmitted light of the first thin-film polarizer 5, and the second surface can reflect the light after the frequency conversion by the first frequency conversion module 11, and output the light out of the first resonant cavity.

[0040] In the second resonant cavity, the half-wave plate 4 rotates from the first polarization angle to the second deflection angle, for example, by 45°. The polarization direction of the light changes after passing through the half-wave plate 4 and is in the second polarization state. When propagating to the first thin-film polarizer 5, it is reflected. The second thin-film polarizer 6 is arranged at the polarized light output end of the first thin-film polarizer 5. The reflected light of the first thin-film polarizer 5 is reflected by the second thin-film polarizer 6 in turn, and then transmitted through the second dichroic mirror 9, enters the second frequency conversion module 7, and forms a continuous oscillation of light between the first reflector 1 and the third reflector 8 after being reflected by the third reflector 8. A part of the light is reflected by the third reflector 8 to the second dichroic mirror 9, and then output. The two surfaces of the second dichroic mirror 9 are coated with film layers with different light transmittances, so that the first surface of the second dichroic mirror 9 can transmit the reflected light of the second thin-film polarizer 6, and the second surface can reflect the light after the frequency conversion of the second frequency conversion module 7, and guide the light out of the second resonant cavity.

[0041] In some embodiments, Figure 1 As shown, a third dichroic mirror 10 is provided at the reflected light output end of the second dichroic mirror 9. The third dichroic mirror 10 serves as a second output mirror to output the second laser beam. At this time, the light of the first resonant cavity is output by the first output mirror 14, and the light of the second resonant cavity is output by the third dichroic mirror 10, that is, the light of the first resonant cavity and the light of the second resonant cavity are output in two different output directions.

[0042] In some embodiments, Figure 2As shown, a third dichroic mirror 10 is provided at the reflected light output end of the second dichroic mirror 9. The third dichroic mirror 10 reflects the light to the first output mirror 14, and after being transmitted through the first output mirror 14, it is combined with the first laser beam to output a third laser beam. As an example, the light output by the first dichroic mirror 13 in the first resonant cavity has the same wavelength as the light output by the second dichroic mirror 9 in the second resonant cavity. In this case, the first output mirror 14 can be a thin film polarizer to achieve coupling of light of the same wavelength; or the light output by the first dichroic mirror 13 in the first resonant cavity has a different wavelength from the light output by the second dichroic mirror 9 in the second resonant cavity. In this case, the first output mirror 14 can be a dichroic mirror that transmits the light output by the second resonant cavity and reflects the light output by the first resonant cavity.

[0043] The output lasers of the first resonant cavity and the second resonant cavity can be output in two ways in different output directions, or can be output in a combined beam in the same output direction. Accordingly, two light outlets or one light outlet can be set on the laser according to the needs of laser application.

[0044] In some embodiments, the angle of the half-wave plate 4 is 0° to 45°. When the half-wave plate 4 does not change the original polarization direction of the light, the angle of the half-wave plate 4 is defined as 0°, and the light propagates in the first resonant cavity; when the half-wave plate 4 completely changes the light to a direction perpendicular to the original polarization direction, the angle of the half-wave plate 4 is 45°, and the light propagates in the second resonant cavity. When the angle of the half-wave plate 4 is greater than 0° and less than 45°, part of the light propagates in the first resonant cavity, and part of the light propagates in the second resonant cavity. The angle of the half-wave plate 4 can be adjusted according to the actual required frequency of the output laser.

[0045] In some embodiments, the first frequency conversion module 11 and the second frequency conversion module 7 are respectively selected from a double frequency crystal or a combination of a double frequency crystal and a triple frequency crystal. The double frequency crystals of the first frequency conversion module 11 and the second frequency conversion module 7 can be the same or different. When the double frequency crystals are the same, the two resonant cavities output the same wavelength. When the double frequency crystals are different, the two resonant cavities output different wavelengths. In some specific embodiments, the first frequency conversion module 11 includes a double frequency crystal and a triple frequency crystal; the second frequency conversion module 7 includes a double frequency crystal. At this time, the first resonant cavity can output triple frequency laser, and the second resonant cavity can output double frequency laser. When the half-wave plate is rotated to achieve the conversion of the resonant cavity, the conversion of different wavelengths and laser output are achieved.

[0046] In some embodiments, the laser crystal 2 can be selected from any one of Nd:YVO4 laser crystal, Nd:YAG crystal, Nd:YLF crystal, Nd:KGW crystal, Yb:YVO4 crystal, Yb:YAG crystal, Yb:YLF crystal, Yb:KGW crystal, Pr:YLF crystal, Pr:YAP crystal, Pr:LiLuF4 crystal, Pr:LaF3 crystal, and Ti:Sapphire crystal.

[0047] The Q switch 3 is selected from any one of an acousto-optic modulator and an electro-optic modulator. Preferably, the Q switch 3 is an acousto-optic modulator with an operating frequency of 24 to 110 MHz.

[0048] In the present application, there are no special restrictions on the pump light source, Q switch and each device, and the technical parameters of each device can be adjusted according to the application requirements to achieve the output of the laser beam with the required technical parameters. For example, the pump laser emitted by the pump light source can be 808nm, 878nm, 880nm or other wavelengths, and the pump light source can be side pumped or end pumped. It can be understood in the art that when the pump light source is end pumped, the first reflector 1 can transmit the pump laser.

[0049] In some embodiments, the half-wave plate 4 , namely a half-wave plate, is made of quartz.

[0050] In some embodiments, the surface coating of the first thin-film polarizer is a 1064nm polarizing film layer, the incident angle is 45 degrees to 80 degrees, the transmittance for p-polarized laser is ≥99%, the reflectivity for s-polarized laser is ≥99.8%, and the wavelength range is 900 to 1300nm; the surface coating of the second thin-film polarizer is a 1064nm polarizing film layer, the incident angle is 45 degrees to 80 degrees, the transmittance for p-polarized light is ≥99%, the reflectivity for s-polarized light is ≥99.8%, and the wavelength range is 900 to 1300nm.

[0051] In some embodiments, the first reflector 1 is a total reflector, and the second reflector 12 is a total reflector; one side of the first dichroic mirror 13 is coated with a 1064nm anti-reflection film with a transmittance ≥ 99.5%; the other side is coated with a 532nm / 355nm total reflection film with a reflectivity of 99.5% for light with a wavelength of 532nm / 355nm.

[0052] One side of the first output mirror 14 is coated with a 355nm total reflection film and a 532nm anti-reflection film, with a reflectivity of ≥99.5% for a wavelength of 355nm and a transmittance of ≥99.5% for a wavelength of 532nm; the other side is coated with a 532nm anti-reflection film, with a transmittance of ≥99.5% for a wavelength of 532nm.

[0053] One side of the second dichroic mirror 9 is coated with a 1064nm anti-reflection film with a transmittance of ≥99.5%; the other side is coated with a 532nm / 355nm total reflection film with a reflectivity of 99.5% for light with a wavelength of 532nm / 355nm.

[0054] One side of the third dichroic mirror 10 is coated with a 355nm total reflection film and a 532nm anti-reflection film, with a reflectivity of 355nm wavelength ≥99.5% and a light transmittance of 532nm wavelength ≥99.5%; the other side is coated with a 532nm anti-reflection film, with a light transmittance of 532nm wavelength ≥99.5%.

[0055] In some embodiments, the wavelength of the pump light source is 808 nm, 878.6 nm, or 880 nm.

[0056] In some embodiments, the frequency doubling crystal is an LBO crystal, and the frequency tripling crystal is an LBO crystal.

[0057] In some embodiments, the ratio of the cavity length of the first resonant cavity to the cavity length of the second resonant cavity is 1:2.

[0058] Another embodiment of the present application provides a laser Q-switched output method, comprising:

[0059] A laser is provided, comprising a pump light source, a first resonant cavity and a second resonant cavity, wherein the first resonant cavity and the second resonant cavity comprise the same half-wave plate;

[0060] A pump light source provides a pump laser as incident light, which is injected into the half-wave plate;

[0061] The half-wave plate 4 is placed at a first polarization angle, the incident light is placed at a first polarization state, propagates in a first resonant cavity, and outputs a first laser beam;

[0062] The rotating half-wave plate 4 is at a second polarization angle, the incident light is in a second polarization state, propagates in the second resonant cavity, and outputs a second laser beam;

[0063] The first polarization angle is different from the second polarization angle, and the first polarization state is different from the second polarization state.

[0064] In some embodiments, the first resonant cavity and the second resonant cavity have different cavity lengths;

[0065] In some embodiments, the first resonant cavity and the second resonant cavity include the same or different frequency doubling crystals;

[0066] In some embodiments, the first laser beam and the second laser beam are output from different output directions, or the first laser beam and the second laser beam are output from the same output direction.

[0067] The laser Q-switched output method can be implemented by the laser mentioned above. The working principle and working method of the aforementioned laser are applicable to the laser Q-switched output method and will not be described in detail.

[0068] The following specific examples are provided to further illustrate the technical solution of the present application. The examples are only used as examples to explain the technical solution of the present application and should not be regarded as limiting the scope of protection of the present application.

[0069] Example 1 Dual-cavity laser with dual output paths

[0070] Pump light source: output wavelength is 808nm, output power is 80w;

[0071] Laser crystal: Nd:YVO4 laser crystal, size 4mm×4mm×20mm;

[0072] Acousto-optic modulator: operating frequency is 41MHz;

[0073] First reflector 1: The surface coating is a 1064nm total reflection film, the reflectivity of the light with a wavelength of 1064nm is 99.9%, the diameter is 12.7mm, and the thickness is 6mm;

[0074] Half-wave plate 4: quartz material, diameter 12.7mm, thickness 1mm;

[0075] First thin film polarizer 5: surface coating is a polarizing film layer of 1064nm, incident angle is 56.5 degrees, transmittance for p-polarized laser is 99.5%, reflectivity for s-polarized laser is 99.9%, size is 25mm×15mm×2mm;

[0076] First dichroic mirror 13: The first surface coating is a 1064nm antireflection film, and the transmittance of light at a wavelength of 1064nm is 99.5%. The second surface coating is a 532nm / 355nm total reflection film, and the reflectivity of light at a wavelength of 532nm / 355nm is 99.5%. The diameter is 12.7mm and the thickness is 3mm.

[0077] First output mirror 14: the first surface coating is a 355nm total reflection film and a 532nm anti-reflection film, the transmittance of light at a wavelength of 532nm is 99.5%, the reflectance of light at a wavelength of 355nm is 99.5%, the second surface coating is a 532nm anti-reflection film, the transmittance of light at a wavelength of 532nm is 99.5%, the diameter is 12.7mm, and the thickness is 6mm;

[0078] First frequency conversion module 11: double frequency crystal: LBO crystal, size 4mm×4mm×10mm triple frequency crystal: LBO crystal, size 4mm×4mm×20mm;

[0079] Second reflector 12: surface coating is 1064nm / 532nm total reflection film, reflectivity of light with wavelength of 1064nm / 532nm is 99.5%, diameter is 12.7mm, thickness is 6mm;

[0080] Second thin film polarizer 6: surface coating is a polarizing film layer of 1064nm, incident angle is 56.5 degrees, transmittance for p-polarized laser is 99.5%, reflectivity for s-polarized laser is 99.9%, size is 25mm×15mm×2mm;

[0081] Second dichroic mirror 9: the first surface coating is a 1064nm anti-reflection film, and the second surface coating is a 532nm total reflection film;

[0082] The third dichroic mirror 10: the first surface coating is a 1064nm anti-reflection film and a 532nm total reflection film, the transmittance of light at a wavelength of 1064nm is 99.5%, and the reflectance of light at a wavelength of 532nm is 99.5%, the second surface coating is a 1064nm anti-reflection film, the transmittance of light at a wavelength of 1064nm is 99.5%, the diameter is 12.7mm, and the thickness is 6mm;

[0083] Second frequency conversion module 7: double frequency crystal: LBO crystal, size 4mm×4mm×15mm;

[0084] The third reflector 8: the surface coating is a 1064nm / 532nm total reflection film, the reflectivity of the light with a wavelength of 1064nm / 532nm is 99.5%, the diameter is 12.7mm, and the thickness is 6mm;

[0085] The length of the first resonant cavity: 200mm;

[0086] The length of the second resonant cavity: 400mm;

[0087] like Figure 1 As shown, when the laser is working, the pump light source is turned on, and the light is propagated from the pump light source to the laser crystal, and modulated by the acousto-optic modulator. At this time, the half-wave plate is 0°, and the polarization state of the light is not changed. The light is transmitted through the half-wave plate 4, the first thin-film polarizer 5, and the first dichroic mirror 13 in sequence, and then the frequency is converted by the first frequency conversion module 11 (the first frequency conversion module 11 includes a double frequency crystal and a triple frequency crystal), and then reflected by the second reflector 12 to form a continuous oscillation of the light. After passing through the first frequency conversion module 11, the frequency of the light is converted, and a part of the light is reflected by the second reflector 12 and reaches a side surface of the first dichroic mirror 13, and then reflects to the first output mirror 14, forming a first laser beam, and the pulse width of the output light is 15ns, and the wavelength is 355nm;

[0088] The half-wave plate 4 is rotated to change the polarization direction of the light. The polarized light passing through the half-wave plate 4 is reflected by the first thin-film polarizer 5 and the second thin-film polarizer 6 in sequence, and then passes through the second dichroic mirror 9 and the second frequency conversion module 7 to be reflected by the third reflecting mirror 8, forming a continuous oscillation of the light. After passing through the second frequency conversion module 7 (the second frequency conversion module 7 is a double frequency crystal), the frequency of the light is changed. A part of the light is reflected by the third reflecting mirror 8 and reaches one side surface of the second dichroic mirror 9 and is reflected to the third dichroic mirror 10. The third dichroic mirror 10 serves as a second output mirror to output a second laser beam. The pulse width of the output light is 30ns and the wavelength is 532nm.

[0089] In this embodiment, the first frequency conversion module 11 and the second frequency conversion module 7 may also use the same doubled frequency crystal or a combination of the same doubled frequency crystal and tripled frequency crystal to output two laser beams with different pulse widths and the same wavelength.

[0090] In this embodiment, the operator can select different light outlet positions according to the shape and position of the laser processing parts, and select different resonant cavities by rotating the half-wave plate 4 according to the processing method, and select the output light with the required pulse width, wavelength and light outlet position.

[0091] For example, as one of the examples, rotate the half-wave plate 4 to 0°, select the first resonant cavity, set the first frequency conversion module 11 to a doubled frequency crystal, obtain a first laser beam, and output it from the first light output port 15 corresponding to the light output end of the first output mirror 14 to obtain an output light with a first pulse width and a first wavelength.

[0092] As a second example, the half-wave plate is rotated 4 to 45°, the second resonant cavity is selected, and the second frequency conversion module 7 is set to a combination of a doubled frequency crystal and a tripled frequency crystal to obtain a second laser beam, which is output from the second light outlet 16 corresponding to the light output end of the third dichroic mirror 10 to obtain output light of a second pulse width and a second wavelength.

[0093] As a third example, the half-wave plate is rotated 4 to 30°, part of the light enters the first resonant cavity, and part of the light enters the second resonant cavity, the first frequency conversion module 11 is set to be a combination of a doubled frequency crystal and a tripled frequency crystal, the second frequency conversion module 7 is a doubled frequency crystal, and the first light output port 15 corresponding to the light output end of the first output mirror 14 outputs a first laser beam with a third pulse width and a third wavelength, and the second light output port 16 corresponding to the light output end of the third dichroic mirror 10 outputs a second laser beam with a fourth pulse width and a fourth wavelength.

[0094] Example 2 Dual-cavity laser beam combining output laser

[0095] The difference from Example 1 is that the first output mirror 14 is arranged on one side of the light output end of the third dichroic mirror 10, the light output by the third dichroic mirror 10 is transmitted through the first output mirror 14, the light output by the first dichroic mirror 13 is reflected by the first output mirror 14, the transmitted light is coupled with the reflected light, and is output from the light output surface of the first output mirror 14.

[0096] like Figure 2 As shown, when the laser is working, the pump light source is turned on, and the light is propagated from the pump light source to the laser crystal, and modulated by the acousto-optic modulator. At this time, the half-wave plate is 0°, and the polarization state of the light is not changed. The light is transmitted through the half-wave plate 4, the first thin-film polarizer 5, and the first dichroic mirror 13 in sequence, and then the frequency is converted by the first frequency conversion module 11 (the first frequency conversion module 11 includes a double frequency crystal and a triple frequency crystal), and then reflected by the second reflector 12 to form a continuous oscillation of the light. After passing through the first frequency conversion module 11, the frequency of the light is converted, and a part of the light is reflected by the second reflector 12 and reaches a side surface of the first dichroic mirror 13, and then reflects to the first output mirror 14, forming a first laser beam, and the pulse width of the output light is 15ns, and the wavelength is 355nm;

[0097] The half-wave plate 4 is rotated to change the polarization direction of the light. The polarized light passing through the half-wave plate 4 is reflected by the first thin-film polarizer 5 and the second thin-film polarizer 6 in sequence, and then passes through the second dichroic mirror 9 and the second frequency conversion module 7 to be reflected by the third reflecting mirror 8 to form a continuous oscillation of the light. After the frequency is converted by the second frequency conversion module 7 (the second frequency conversion module 7 is a double frequency crystal), the frequency of the light is converted. A part of the light is reflected by the third reflecting mirror 8 and reaches a side surface of the second dichroic mirror 9 and is reflected to the third dichroic mirror 10. The third dichroic mirror 10 reflects the light to the first output mirror 14. The first output mirror 14 is a dichroic mirror that can transmit the light output by the third dichroic mirror 10. After being transmitted by the first output mirror 14, the light is coupled with the optical path of the first laser beam and outputs the third laser beam. The pulse width of the output light is 15ns and 30ns, and the wavelength is 355nm and 532nm.

[0098] In this embodiment, the first frequency conversion module 11 and the second frequency conversion module 7 can also use the same doubled frequency crystal or the same combination of doubled frequency crystal and tripled frequency crystal. The first output mirror 14 is a thin film polarizer, which couples two laser beams of the same wavelength and outputs them.

[0099] In this embodiment, only one light outlet 15 position may be set, and different resonant cavities may be selected by rotating the half-wave plate 4, so that the switching of output lights with different pulse widths and wavelengths can be achieved at the same light outlet position.

[0100] For example, as one of the examples, rotate the half-wave plate 4 to 0°, select the first resonant cavity, set the first frequency conversion module 11 to a doubled frequency crystal, obtain a first laser beam, and output it from the first light output port corresponding to the light output end of the first output mirror 14 to obtain an output light with a first pulse width and a first wavelength.

[0101] As a second example, the half-wave plate 4 is rotated to 45°, the second resonant cavity is selected, and the second frequency conversion module 7 is set to a frequency tripling crystal to obtain a second laser beam. The third dichroic mirror 10 propagates the light to the first output mirror 14, and after being transmitted through the first output mirror 14, the light is output from the first light outlet corresponding to the light output end of the first output mirror 14 to obtain output light of a second pulse width and a second wavelength.

[0102] As a third example, the half-wave plate 4 is rotated to 30°, a part of the light enters the first resonant cavity, and a part of the light enters the second resonant cavity, the first frequency conversion module 11 is set to be a combination of a double frequency crystal and a triple frequency crystal, the second frequency conversion module 7 is a double frequency crystal, and the first output mirror 14 is a dichroic mirror, and after coupling two laser beams of different wavelengths, they are output from the first light outlet 15 corresponding to the light output end of the first output mirror 14. In the third example, the half-wave plate 4 can also be rotated to other angles greater than 0° and less than 45°, and the first frequency conversion module 11 and the second frequency conversion module 7 can also select other combinations, as long as the first frequency conversion module 11 and the second frequency conversion module 7 adjust the light to different frequencies, the coupled output of laser beams of different wavelengths can be achieved.

[0103] In the fourth example, the half-wave plate 4 is rotated to 30°, part of the light enters the first resonant cavity, and part of the light enters the second resonant cavity. The first frequency conversion module 11 is set to be a combination of a double frequency crystal and a triple frequency crystal. The second frequency conversion module 7 is the same as the first frequency conversion module 11. The first output mirror 14 is a thin-film polarizer. After coupling two laser beams of the same wavelength, they are output from the first light outlet 15 corresponding to the light output end of the first output mirror 14. In the third example, the half-wave plate 4 can also be rotated to other angles greater than 0° and less than 45°. The first frequency conversion module 11 and the second frequency conversion module 7 can also select other combinations. As long as the first frequency conversion module 11 and the second frequency conversion module 7 adjust the light to the same frequency, the coupled output of laser beams of the same wavelength can be achieved.

[0104] As can be seen from the above embodiments, the laser provided by the present application forms two resonant cavities with a common laser crystal and a Q-switched switch but different cavity lengths through a rotatable half-wave plate, and changes the polarization state of the light by rotating the half-wave plate, so that the light is converted between the two resonant cavities to achieve the conversion of the light pulse width; further, the conversion of the light wavelength is achieved by respectively setting different frequency conversion modules in the two resonant cavities. The laser of the present application can simply realize the conversion of the light wavelength and pulse width by providing half-wave plate rotation without changing the gain medium or device structure. Moreover, the laser provided by the present application can realize dual-path output or combined beam output by setting the direction of the dichroic mirror, and can realize setting one or more light outlets as needed. When only one light outlet is set, the switching and selection of lasers with different pulse widths and different wavelengths output at the same light outlet can also be realized through the conversion of the resonant cavity. The laser provided by the present application has a simple structure and is easy to operate. It can be applied to different application scenarios and actual needs, and has a wide range of application prospects.

[0105] The dual-cavity Q-switched laser and laser Q-switched output method provided by the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A dual-resonance Q-switched laser, characterized in that: It includes a pump light source, a first reflector, a laser crystal, a Q switch, a half-wave plate, a first thin-film polarizer, a first dichroic mirror, a first output mirror, a first frequency conversion module, a second reflector, a second thin-film polarizer, a second dichroic mirror, a second frequency conversion module, a third reflector, and a third dichroic mirror; Wherein, the pump light source is used to emit pump laser; A first resonant cavity is formed between the first reflector and the second reflector; A second resonant cavity is formed between the first reflecting mirror and the third reflecting mirror.

2. The laser according to claim 1, characterized in that The first resonant cavity includes the first reflector, a laser crystal, a Q switch, a half-wave plate, a first thin-film polarizer, a first dichroic mirror, a first frequency conversion module, and a second reflector, which are arranged in sequence; The first output mirror reflects the reflected output light of the first dichroic mirror and outputs a first laser beam.

3. The laser according to claim 2, characterized in that The second resonant cavity comprises the first reflector, a laser crystal, a Q switch, a half-wave plate, a first thin-film polarizer, a second thin-film polarizer, a second dichroic mirror, a second frequency conversion module, and a third reflector, which are sequentially arranged; The second thin-film polarizer is arranged at the polarized light output end of the first thin-film polarizer.

4. The laser according to claim 3, characterized in that The third dichroic mirror is arranged at the reflected light output end of the second dichroic mirror.

5. The laser according to claim 4, characterized in that The third dichroic mirror serves as a second output mirror to output a second laser beam; or, the third dichroic mirror reflects light to the first output mirror, and after being transmitted through the first output mirror, outputs a third laser beam along the direction of the first laser beam.

6. The laser according to any one of claims 1 to 5, characterized in that: The first frequency conversion module and the second frequency conversion module are the same or different and are independently selected from a double frequency crystal or a combination of a double frequency crystal and a triple frequency crystal.

7. The laser according to claim 1, characterized in that The half-wave plate is angularly rotatable; and / or the laser crystal is selected from any one of Nd:YVO4 laser crystal, Nd:YAG crystal, Nd:YLF crystal, Nd:KGW crystal, Yb:YVO4 crystal, Yb:YAG crystal, Yb:YLF crystal, Yb:KGW crystal, Pr:YLF crystal, Pr:YAP crystal, Pr:LiLuF4 crystal, Pr:LaF3 crystal, and Ti:Sapphire crystal; and / or the Q switch is selected from any one of an acousto-optic modulator and an electro-optic modulator; And / or the first output mirror is a thin film polarizer or a dichroic mirror.

8. A laser Q-switched output method, characterized in that: include: A laser is provided, comprising a pump light source, a first resonant cavity and a second resonant cavity, wherein the first resonant cavity and the second resonant cavity comprise the same half-wave plate; The pump light source provides pump laser as incident light, which is injected into the half-wave plate; The half-wave plate is placed at a first polarization angle, the incident light is placed at a first polarization state, propagates in a first resonant cavity, and outputs a first laser beam; The half-wave plate is rotated to a second polarization angle, the incident light is in a second polarization state, propagates in a second resonant cavity, and outputs a second laser beam; The first polarization angle is different from the second polarization angle, and the first polarization state is different from the second polarization state.

9. The laser Q-switched output method according to claim 8, characterized in that: The first resonant cavity and the second resonant cavity have different cavity lengths; and / or the first resonant cavity and the second resonant cavity include the same or different frequency doubling crystals; and / or the first laser beam and the second laser beam are output from different output directions, or the first laser beam and the second laser beam are output from the same output direction to form a third laser beam.

10. The laser Q-switched output method according to claim 8 or 9, characterized in that: The method is implemented via the laser according to any one of claims 1-7.

Images