Multi-wavelength frequency doubling laser device

Abstract

The invention discloses a multi-wavelength frequency doubling laser device, the multi-wavelength frequency doubling laser device comprises a fundamental frequency light generation assembly and a frequency doubling device, and the fundamental frequency light generation assembly is used for providing fundamental frequency light with at least two different wavelengths; the frequency multiplication device is used for carrying out frequency multiplication conversion on the fundamental frequency light to form frequency multiplication light, the frequency multiplication device comprises a plurality of fundamental frequency light incident planes and a plurality of frequency multiplication light emergent planes, the different fundamental frequency light incident planes are arranged in a crossed mode, and the frequency multiplication light emergent planes and the fundamental frequency light incident planes are in one-to-one correspondence and are parallel to each other; the fundamental frequency light with different wavelengths is incident to the fundamental frequency light incident plane along the first direction. The power and the frequency doubling conversion efficiency of the multi-wavelength frequency doubling laser device provided by the invention are improved.

Description

Technical Field

[0001] The present application belongs to the field of laser technology, and in particular relates to a multi-wavelength frequency-doubling laser device. Background Art

[0002] With the widespread application of laser devices, multi-wavelength frequency-doubling laser devices have developed rapidly. Currently, the main method for expanding the laser wavelength through the frequency-doubling process of multiple wavelengths of fundamental frequency light is to enter the frequency-doubling device along the phase-matching direction of one wavelength of the fundamental frequency light, thereby achieving simultaneous output of multiple wavelengths of frequency-doubling light. In this method, the same cut-angle crystal (frequency-doubling device) cannot simultaneously achieve phase matching for different wavelengths of fundamental frequency light, resulting in low frequency-doubling efficiency. Summary of the Invention

[0003] The purpose of this application is to solve the problem of low frequency doubling efficiency of multi-wavelength frequency doubling laser devices. This purpose is achieved through the following technical solutions:

[0004] This application proposes a multi-wavelength frequency-doubling laser device, comprising:

[0005] A fundamental frequency light generating component, used for providing fundamental frequency lights of at least two different wavelengths;

[0006] A frequency doubling device is used to perform frequency doubling conversion on the fundamental frequency light to form frequency doubling light. The frequency doubling device includes multiple fundamental frequency light incident surfaces and multiple frequency doubling light exit surfaces. Different fundamental frequency light incident surfaces are arranged to intersect. The frequency doubling light exit surfaces correspond to the fundamental frequency light incident surfaces one by one and are parallel to each other. The fundamental frequency lights of different wavelengths are all incident on the fundamental frequency light incident surfaces along a first direction.

[0007] The multi-wavelength frequency-doubling laser device provided in the present application is used to output frequency-doubling light of multiple wavelengths, and the multi-wavelength frequency-doubling laser device includes a fundamental frequency light generating component and a frequency-doubling device. The fundamental frequency light generating component is used to provide fundamental frequency lights of at least two different wavelengths. The frequency-doubling device is used to perform frequency-doubling conversion on the fundamental frequency light to form frequency-doubling light. The frequency-doubling device includes a plurality of fundamental frequency light incident surfaces and a plurality of frequency-doubling light exit surfaces, and the different fundamental frequency light incident surfaces are arranged to intersect, that is, the inclination angles of the different fundamental frequency light incident surfaces are different. Fundamental frequency lights of different wavelengths are all incident into the frequency-doubling device from a fundamental frequency light incident surface along a first direction, and fundamental frequency lights of different wavelengths can propagate in their corresponding phase-matching directions, respectively. After the fundamental frequency light is converted into frequency-doubled light by the frequency-doubling device, it is emitted from the frequency-doubled light exit surface. Since the frequency-doubled light exit surface corresponds to the fundamental frequency light incident surface one-to-one and is parallel to each other, each wavelength of frequency-doubled light is emitted from a frequency-doubled light exit surface with a tilt angle, and frequency-doubled light of different wavelengths is emitted from different frequency-doubled light exit surfaces, thereby achieving mutual non-interference between the different frequency-doubled lights. In this multi-wavelength frequency-doubling laser device, phase matching of fundamental frequency lights of different wavelengths is achieved through a single frequency-doubling crystal, thereby achieving frequency-doubled conversion of multiple wavelengths of fundamental frequency light through a single frequency-doubling crystal. The fundamental frequency lights of different wavelengths are all phase-matched within the frequency-doubling crystal, and the fundamental frequency lights of different wavelengths are independent of each other during the conversion and emission process and do not interfere with each other. This improves the power and frequency-doubled conversion efficiency of the multi-wavelength frequency-doubling laser device. In addition, the multi-wavelength frequency-doubling laser device is provided with only one frequency-doubling crystal, making the device simple and compact, and effectively reducing the size of the multi-wavelength frequency-doubling laser device. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0009] Figure 1 This is a schematic structural diagram of a first multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0010] Figure 2 This is a schematic diagram of internal light wave propagation in a multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0011] Figure 3 Schematic diagram of the structure of the second multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0012] Figure 4 Schematic diagram of the structure of the second multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0013] Figure 5Schematic diagram of the structure of the second multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0014] Figure 6 Schematic diagram of the structure of the second multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0015] Figure 7 Schematic diagram of the structure of the second multi-wavelength frequency-doubling laser device provided in an embodiment of the present application;

[0016] Figure 8 This is a schematic structural diagram of a second multi-wavelength frequency-doubling laser device provided in an embodiment of the present application.

[0017] The reference numerals are as follows:

[0018] 10. Multi-wavelength frequency-doubling laser device; 1. Fundamental frequency light generating assembly; 11. Pump source; 12. Resonant unit; 121. Resonant cavity mirror; 1211. First resonant cavity mirror; 1212. Second resonant cavity mirror; 122. Laser crystal; 1221. First laser crystal; 1222. Second laser crystal; 123. Spectroscopic component; 1231. First spectroscopic component; 1232. Second spectroscopic component; 13. Pulse modulation device; 2. Frequency doubling Device; 21, fundamental frequency light incident surface; 211, first fundamental frequency light incident surface; 212, second fundamental frequency light incident surface; 213, third fundamental frequency light incident surface; 22, doubled frequency light exit surface; 221, first doubled frequency light exit surface; 222, second doubled frequency light exit surface; 223, third doubled frequency light exit surface; k1, first direction; k2, second direction; k3, third direction; λ1, first doubled frequency light; λ2, second doubled frequency light; λ3, third doubled frequency light. DETAILED DESCRIPTION

[0019] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0020] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0021] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0022] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside," "outside," "inside," "outside," "below," "beneath," "above," and the like. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is flipped, an element described as "below" or "below" another element or feature would then be oriented as "above" or "above" another element or feature. Thus, the example term "below" can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly.

[0023] like Figure 1As shown, according to the embodiment of the present application, a multi-wavelength frequency doubling laser device 10 is proposed, and the multi-wavelength frequency doubling laser device 10 includes a fundamental frequency light generating component 1 and a frequency doubling device 2. The fundamental frequency light generating component 1 is used to provide at least two fundamental frequency lights of different wavelengths. The frequency doubling device 2 is used to perform frequency doubling conversion on the fundamental frequency light to form frequency doubling light. The frequency doubling device 2 includes a plurality of fundamental frequency light incident surfaces 21 and a plurality of frequency doubling light exit surfaces 22, and the different fundamental frequency light incident surfaces 21 are arranged to intersect with each other. The frequency doubling light exit surfaces 22 correspond to the fundamental frequency light incident surfaces 21 one by one and are parallel to each other, and the fundamental frequency lights of different wavelengths are all incident on the fundamental frequency light incident surface 21 along the first direction k1.

[0024] The multi-wavelength frequency doubling laser device 10 provided in the present application is used to output frequency doubling light of multiple wavelengths, and the multi-wavelength frequency doubling laser device 10 includes a fundamental frequency light generating component 1 and a frequency doubling device 2. The fundamental frequency light generating component 1 is used to provide fundamental frequency lights of at least two different wavelengths. The frequency doubling device 2 is used to perform frequency doubling conversion on the fundamental frequency light to form frequency doubling light. The frequency doubling device 2 includes a plurality of fundamental frequency light incident surfaces 21 and a plurality of frequency doubling light exit surfaces 22, and the different fundamental frequency light incident surfaces 21 are arranged to intersect, that is, the inclination angles of the different fundamental frequency light incident surfaces 21 are different. Fundamental frequency lights of different wavelengths are all incident into the frequency doubling device 2 from a fundamental frequency light incident surface 21 along the first direction k1, and the fundamental frequency lights of different wavelengths can propagate in their corresponding phase matching directions respectively. After the fundamental frequency light is converted into the doubled frequency light by the frequency doubling device 2, it is emitted from the doubled frequency light exit surface 22. Since the doubled frequency light exit surface 22 corresponds to the fundamental frequency light incident surface 21 one-to-one and is parallel to each other, each wavelength of the doubled frequency light is emitted from the doubled frequency light exit surface 22 at a different tilt angle. The doubled frequency light of different wavelengths is emitted from different doubled frequency light exit surfaces 22, thereby achieving mutual non-interference between the different doubled frequency lights. In this multi-wavelength frequency doubling laser device 10, phase matching of fundamental frequency lights of different wavelengths is achieved through a single frequency doubling device 2, thereby achieving frequency doubling conversion of multiple wavelengths of fundamental frequency light through a single frequency doubling device 2. The fundamental frequency lights of different wavelengths are all phase-matched within the frequency doubling device 2, and the fundamental frequency lights of different wavelengths are independent of each other during the conversion and emission process and do not interfere with each other. The power and frequency doubling conversion efficiency of the multi-wavelength frequency doubling laser device 10 are both improved. Furthermore, the multi-wavelength frequency doubling laser device 10 is provided with only one frequency doubling device 2 , thereby making the device simple and compact, and effectively reducing the volume of the multi-wavelength frequency doubling laser device 10 .

[0025] In order to obtain a relatively high frequency doubling efficiency, the fundamental frequency light needs to propagate along its phase matching direction. The phase matching directions of fundamental frequency lights of different wavelengths are different. In the multi-wavelength frequency doubling laser device 10 provided in the present application, by providing multiple fundamental frequency light incident surfaces 21 with different inclination angles on the frequency doubling device 2, and multiple frequency doubling light exit surfaces 22 that correspond one-to-one to the fundamental frequency light incident surface 21 and are parallel to each other, fundamental frequency lights of different wavelengths can be incident into the frequency doubling device 2 along the first direction k1 from different fundamental frequency light incident surfaces 21, so that each can propagate along its phase matching direction in the frequency doubling device 2, so that fundamental frequency lights of different wavelengths do not interfere with each other during frequency doubling conversion. In this embodiment, a frequency doubling device 2 can simultaneously achieve stable and efficient output of frequency doubling lights of multiple wavelengths. The fundamental frequency light will not propagate in the non-phase matching direction within the frequency doubling device 2, thereby avoiding the laser transmission loss caused by the fundamental frequency light passing through the non-phase matching frequency doubling device 2 and reducing the risk of damage to the frequency doubling device 2, thereby improving the service life and power of the multi-wavelength frequency doubling laser device 10.

[0026] Specifically, the region in the frequency doubling device 2 for performing frequency doubling conversion on fundamental frequency light of one wavelength is located between the corresponding fundamental frequency light incident surface 21 and the frequency doubling light exit surface 22 .

[0027] Specifically, since the number of frequency doubling devices 2 in the multi-wavelength frequency doubling laser device 10 is only one, the frequency doubling device 2 with the same cutting angle can be used to achieve frequency doubling conversion of fundamental frequency lights of different wavelengths. Therefore, by setting fundamental frequency light incident surfaces 21 with different inclination angles, fundamental frequency lights of different wavelengths are all incident on the frequency doubling device 2 along the first direction k1 from different fundamental frequency light incident surfaces 21, and the refracted light just meets the phase matching condition of the refracted light, so that fundamental frequency lights of different wavelengths propagate in their corresponding phase matching directions after being incident on the frequency doubling device 2.

[0028] In the multi-wavelength frequency-doubling laser device 10 provided in the present application, multiple fundamental frequency lights operate independently at different positions in the same frequency-doubling device 2, and can fully meet the phase matching conditions, with high frequency-doubling efficiency; the laser intensity in the frequency-doubling device 2 can be reduced, and the risk of damage to the frequency-doubling device 2 can be reduced; and the utilization rate of the frequency-doubling device 2 is high; the frequency-doubling lights of different wavelengths do not interfere with each other, which can greatly improve the output stability.

[0029] In one possible implementation, Figure 1 As shown, the fundamental frequency light generating component 1 includes a pump source 11 and a resonance unit 12. The resonance unit 12 includes at least two resonant cavity mirrors 121 and at least one laser crystal 122. The pump source 11 and the laser crystal 122 correspond to each other one by one and are arranged adjacent to each other. The pump source 11 is used to pump the laser crystal 122 to emit laser light. At least two resonant cavities are formed in the resonant unit 12, and the frequency doubling device 2 is located in the resonant cavity.

[0030] In the above embodiment, the fundamental frequency light generating assembly 1 includes a pump source 11 and a resonant unit 12. The resonant unit 12 includes at least two resonant cavity mirrors 121 and at least one laser crystal 122. The pump source 11 and the laser crystal 122 are arranged in a one-to-one correspondence and adjacent to each other. The pump source 11 is used to pump the laser crystal 122 to produce fundamental frequency light of multiple wavelengths. The resonant unit 12 forms at least two resonant cavities, which are used to select the multiple wavelengths of fundamental frequency light generated by the laser crystal 122. The selected at least two different wavelengths of fundamental frequency light are used for subsequent frequency doubling conversion.

[0031] Specifically, the wavelengths of the at least two fundamental frequency lights of different wavelengths are selected to be similar, so as to reduce the difficulty of designing the subsequent frequency doubling device 2 .

[0032] The frequency doubling device 2 is located in the resonant cavity and is used to perform frequency doubling on the fundamental frequency light of the selected wavelength. This method is called intracavity frequency doubling.

[0033] In the above embodiment, the pump source 11 can be a side-pumped laser crystal or an end-pumped laser crystal.

[0034] Specifically, one of the two resonant cavity mirrors 121 can be a fully reflective mirror, and the other can be a multi-wavelength coupling output mirror. The multi-wavelength coupling output mirror is used to reflect fundamental frequency light of multiple wavelengths, forming multiple fundamental frequency light oscillations within the resonant cavity. It is also used to output the multiple frequency-doubled light of multiple wavelengths generated by the frequency-doubling device 2. The multi-wavelength coupling output mirror is coated with a dielectric film with high reflectivity for the multiple wavelengths of fundamental frequency light and a dielectric film with high transmittance for the multiple wavelengths of frequency-doubled light.

[0035] Specifically, the frequency doubling device 2 can simultaneously span the oscillation optical paths of fundamental frequency lights of multiple different wavelengths, that is, span multiple resonant cavities, and is used to frequency-double fundamental frequency lights of multiple wavelengths to obtain frequency-doubled lights of multiple wavelengths.

[0036] In one possible implementation, Figure 1 As shown, the resonance unit 12 includes a first resonant cavity mirror 1211 and a second resonant cavity mirror 1212. The laser crystal 122 is located on a side of the first resonant cavity mirror 1211 close to the second resonant cavity mirror 1212. A first reflection film is provided on the surface of the first resonant cavity mirror 1211, and the first reflection film has a reflective effect on at least one wavelength of fundamental frequency light. A second reflection film and a first transmission film are provided on the surface of the second resonant cavity mirror 1212, and the second reflection film has a reflective effect on at least one wavelength of fundamental frequency light, and the first transmission film has a transmittive effect on frequency-doubled light.

[0037] In the above embodiment, the first resonant cavity mirror 1211 is a fully reflective mirror, which is used to reflect at least one of the multiple wavelengths of fundamental frequency light emitted by the laser crystal 122. The second resonant cavity mirror 1212 is a multi-wavelength coupling output mirror. The second resonant cavity mirror 1212 can not only reflect the at least one wavelength of fundamental frequency light, but also transmit multiple wavelengths of frequency-doubled light generated by doubled frequency conversion by the frequency-doubling device.

[0038] Specifically, when fundamental frequency light generating assembly 1 provides fundamental frequency light of multiple preset wavelengths, first resonant cavity mirror 1211 and second resonant cavity mirror 1212 can be used only to reflect the fundamental frequency light of the multiple preset wavelengths, thereby filtering the fundamental frequency light of different wavelengths. The fundamental frequency light of the multiple preset wavelengths is frequency-doubled to form frequency-doubled light of the multiple preset wavelengths, and second resonant cavity mirror 1212 can be used only to transmit the frequency-doubled light of the multiple preset wavelengths.

[0039] In one possible implementation, Figure 1 As shown, the fundamental frequency light generating assembly 1 is used to provide fundamental frequency light of a first wavelength and a second wavelength. The frequency doubling device 2 includes a first fundamental frequency light incident surface 211 and a second fundamental frequency light incident surface 212. The orthographic projections of the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212 on the plane of the first fundamental frequency light incident surface 211 are arranged along a second direction k2, which is perpendicular to the first direction k1.

[0040] In the above embodiment, since fundamental frequency lights of different wavelengths need to be incident on different fundamental frequency light incident surfaces 21 along the first direction k1, the positions of different fundamental frequency light incident surfaces 21 are different, while the incident directions of fundamental frequency lights of different wavelengths are the same. Therefore, it is necessary to adjust the positions of fundamental frequency lights of different wavelengths along the second direction k2 so that fundamental frequency lights of different wavelengths are incident on corresponding fundamental frequency light incident surfaces 21.

[0041] In the above embodiment, the frequency doubling device 2 includes a first frequency doubled light emitting surface 221 parallel to the first fundamental frequency light incident surface 211 , and also includes a second frequency doubled light emitting surface 222 parallel to the second fundamental frequency light incident surface 212 .

[0042] Specifically, the first wavelength fundamental frequency light is frequency-doubled to form the first frequency-doubled light λ1, which is emitted from the first frequency-doubled light exit surface 221, and the second wavelength fundamental frequency light is frequency-doubled to form the second frequency-doubled light λ2, which is emitted from the second frequency-doubled light exit surface 222.

[0043] In the above embodiment, after fundamental frequency lights of different wavelengths are incident on different fundamental frequency light incident surfaces 21 along the first direction k1, since the inclination angles of the different fundamental frequency light incident surfaces 21 are different, the light incident on the frequency doubling device 2 from each fundamental frequency light incident surface 21 can satisfy the phase matching condition in the frequency doubling device 2, so that fundamental frequency lights of different wavelengths propagate in their corresponding phase matching directions after being incident on the frequency doubling device 2, thereby improving the efficiency of frequency doubling conversion.

[0044] Specifically, if Figure 2 As shown, the first fundamental frequency light incident surface 211 is perpendicular to the first direction k1, and the angle α between the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212 satisfies:

[0045] α-β=θ1-θ2

[0046] sinα=n ω2 sinβ

[0047] Wherein, α is the angle between the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212, which is also the incident angle of the second wavelength fundamental frequency light on the second fundamental frequency light incident surface 212, β is the refraction angle of the second wavelength fundamental frequency light through the second fundamental frequency light incident surface 212, θ1 is the phase matching angle corresponding to the first wavelength fundamental frequency light inside the frequency doubling device 2, θ2 is the phase matching angle corresponding to the second wavelength fundamental frequency light inside the frequency doubling device 2, and n ω2 is the refractive index of the second wavelength fundamental frequency light in the frequency doubling device 2.

[0048] Specifically, the multi-wavelength frequency doubling laser device 10 is suitable for achieving phase matching of multiple fundamental frequency lights in the same main plane of the same frequency doubling device 2. The same main plane refers to the xoz plane, yoz plane, or xoy plane.

[0049] For example, at the same operating temperature, phase matching conditions can be met simultaneously in the xoz plane, yoz plane, or xoy plane. The xoz plane corresponds to φ = 0°, and the phase matching conditions for fundamental frequencies of different wavelengths differ only in the angle θ. The yoz plane corresponds to φ = 90°, and the phase matching conditions for fundamental frequencies of different wavelengths differ only in the angle θ. The xoy plane corresponds to θ = 90°, and the phase matching conditions for fundamental frequencies of different wavelengths differ only in the angle φ.

[0050] In one possible implementation, Figure 3 As shown, the resonance unit 12 further includes at least one spectroscopic component 123 , which is located on a side of the laser crystal 122 close to the second resonant cavity mirror 1212 , and is used to adjust the fundamental frequency light to be incident on the fundamental frequency light incident surface 21 along the first direction k1 .

[0051] In the above embodiment, the position of the fundamental frequency light of the preset wavelength along the second direction k2 can be adjusted by the light splitting component 123 , so that fundamental frequency lights of different wavelengths can be incident on different fundamental frequency light incident surfaces 21 along the first direction k1 .

[0052] The light splitting component 123 is located in the resonance unit 12 and includes a spectroscope. The spectroscope can be used to adjust the propagation direction of the fundamental frequency light, thereby adjusting the position of fundamental frequency lights of different wavelengths along the second direction k2.

[0053] In one possible implementation, Figure 4 As shown, the fundamental frequency light generating component 1 also includes a pulse modulation device 13, which is used to pulse modulate the fundamental frequency light. The pulse modulation device 13 is located between the laser crystal 122 and the spectroscopic component 123, or the pulse modulation device 13 is located between the spectroscopic component 123 and the frequency doubling device 2.

[0054] In the above embodiment, the pulse modulation device 13 can be at least one of any pulse modulation devices 13 such as acousto-optic Q-switching, electro-optic Q-switching, and mode-locking element to obtain short pulses of fundamental frequency light with high peak power.

[0055] The fundamental frequency light generating component 1 is used to provide fundamental frequency lights of at least two different wavelengths. Specifically, it can utilize the composite energy level structure of a single laser gain medium to simultaneously output fundamental frequency lights of multiple wavelengths, or utilize multiple laser gain media to output fundamental frequency lights of multiple wavelengths.

[0056] Specifically, the laser gain medium may be a laser crystal 122 .

[0057] In one possible implementation, Figure 1 and Figure 4 As shown, the resonant unit 12 includes a laser crystal 122 , a first resonant cavity mirror 1211 , the laser crystal 122 , a frequency doubling device 2 , and a second resonant cavity mirror 1212 , which are arranged in sequence along a first direction k1 .

[0058] The resonant unit 12 includes two beam splitting components 123, which are parallel to each other. The plane on which the beam splitting components 123 are located intersects with the first direction k1. The two beam splitting components 123 include a first beam splitting component 1231 and a second beam splitting component 1232. The first beam splitting component 1231 and the laser crystal 122 are arranged along the first direction k1. The first beam splitting component 1231 is located between the laser crystal 122 and the frequency doubling device 2. The orthographic projection of the first beam splitting component 1231 on the plane on which the first fundamental frequency light incident surface 211 is located and the orthographic projection of the second beam splitting component 1232 on the plane on which the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2.

[0059] The surface of the first light splitting component 1231 is provided with a first fundamental frequency light transmitting film, and the surface of the first light splitting component 1231 facing the second light splitting component 1232 is provided with a second fundamental frequency light reflecting film.

[0060] A second fundamental frequency light reflecting film is provided on the surface of the second light splitting component 1232 facing the first light splitting component 1231 .

[0061] In the above embodiment, the multi-wavelength fundamental frequency lights are simultaneously outputted through the composite energy level structure of a single laser gain medium, that is, fundamental frequency lights of multiple different wavelengths can be generated through one laser crystal 122 .

[0062] In the above embodiment, two resonant cavities are formed in the resonant unit 12, including a first resonant cavity and a second resonant cavity. The first resonant cavity is formed by the first resonant cavity mirror 1211, the laser crystal 122, and the second resonant cavity mirror 1212. The second resonant cavity is formed by the first resonant cavity mirror 1211, the laser crystal 122, the first spectroscopic component 1231, the second spectroscopic component 1232, and the second resonant cavity mirror 1212.

[0063] Specifically, a first fundamental frequency light is generated in the first resonant cavity, and a second fundamental frequency light is generated in the second resonant cavity.

[0064] The laser crystal 122 generates fundamental frequency light of multiple wavelengths. After cavity selection, the first and second wavelengths of fundamental frequency light are retained. The first wavelength of fundamental frequency light propagates along the first direction k1 and is the first fundamental frequency light. The first wavelength of fundamental frequency light passes through the first beam splitting component 1231 along the first direction k1. During the propagation process, the second wavelength of fundamental frequency light is incident on the surface of the first beam splitting component 1231 along the first direction k1, and is totally reflected by the first beam splitting component 1231 to the surface of the second beam splitting component 1232. Then, the second fundamental frequency light is obtained and is incident on the frequency doubling device 2 along the first direction k1. The orthographic projection of the first light-splitting component 1231 on the plane where the first fundamental frequency light incident surface 211 is located and the orthographic projection of the second light-splitting component 1232 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2. After being reflected by the first light-splitting component 1231 and the second light-splitting component 1232, the position of the second wavelength fundamental frequency light along the second direction k2 is adjusted, so that the second fundamental frequency light and the first fundamental frequency light are aligned along the second direction k2, thereby causing the second fundamental frequency light and the first fundamental frequency light to be incident on different fundamental frequency light incident surfaces 21. Specifically, the first fundamental frequency light-transmitting film has a high transmittance for the first wavelength fundamental frequency light, and the second fundamental frequency light-reflecting film has a high reflectance for the second wavelength fundamental frequency light.

[0065] By providing a first fundamental frequency light transmitting film on the surface of the first light splitting component 1231 , the first wavelength fundamental frequency light can be directly transmitted through the first light splitting component 1231 along the first direction k1 .

[0066] By arranging a second fundamental frequency light reflection film on the surface of the first light-splitting component 1231 facing the second light-splitting component 1232; and arranging a second fundamental frequency light reflection film on the surface of the second light-splitting component 1232 facing the first light-splitting component 1231, the second wavelength fundamental frequency light is first incident on the surface of the first light-splitting component 1231 along the first direction k1 by the laser crystal 122, and then incident on the surface of the second light-splitting component 1232 after being reflected by the first light-splitting component 1231, and then incident on the second fundamental frequency light incident surface 212 along the first direction k1 after being reflected by the surface of the second light-splitting component 1232.

[0067] In the above embodiment, the orthographic projection of the first light splitting component 1231 on the plane where the first fundamental frequency light incident surface 211 is located and the orthographic projection of the second light splitting component 1232 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2. The orthographic projections of the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 are arranged along the second direction k2. The orthographic projection of the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 is the first projection. The orthographic projection of the first light splitting component 1231 on the plane where the first fundamental frequency light incident surface 211 is the second projection. The orthographic projection of the second light splitting component 1232 on the plane where the first fundamental frequency light incident surface 211 is the third projection. The second projection and the third projection are arranged in a direction from the first fundamental frequency light incident surface 211 to the first projection, so that the first fundamental frequency light is incident on the first fundamental frequency light incident surface 211, and the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212.

[0068] Specifically, the first fundamental frequency light incident surface 211 is perpendicular to the first direction k1 , and the frequency doubling device 2 uses a frequency doubling crystal whose cutting angle meets the phase matching requirement when the first fundamental frequency light is perpendicularly incident on the first fundamental frequency light incident surface 211 .

[0069] The second fundamental frequency light incident surface 212 is at a preset angle to the first direction k1. The preset angle is the incident angle of the second fundamental frequency light on the second fundamental frequency light incident surface 212. The preset angle satisfies the following conditions: the refracted light formed after the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212 along the first direction k1 and refracted just meets the phase matching requirement for realizing the second frequency-doubled light output in the frequency-doubled crystal, so that the refracted light can realize efficient frequency-doubled conversion of the second fundamental frequency light in the frequency-doubled device 2.

[0070] In a specific embodiment, the phase matching adopts type I phase matching: Figure 1 As shown,

[0071] The laser crystal 122 may be made of praseodymium-doped yttrium lithium fluoride (Pr:YLF), and the pump source 11 may be a 444 nm semiconductor laser source.

[0072] The first wavelength fundamental frequency light is 640 nm, and the second wavelength fundamental frequency light is 604 nm.

[0073] The acute angle formed between the first light splitting component 1231 and the second light splitting component 1232 and the first direction k1 may be 45°.

[0074] The first fundamental frequency light transmitting film is a 45°, 640nm high transmittance film; the second fundamental frequency light reflecting film is a 45°, 604nm high reflective film.

[0075] The frequency doubling crystal can be a barium borate (BBO) crystal with a cutting angle of θ = 37.4° and φ = 0°, which corresponds to the phase matching condition of 320nm frequency doubling light by frequency doubling the 640nm fundamental frequency light (i.e., it meets the phase matching condition of the first wavelength fundamental frequency light), satisfying type I phase matching: 640nm(o)+640nm(o)→320nm(e).

[0076] The first fundamental frequency light incident surface 211 is perpendicular to the first direction k1, and the first fundamental frequency light incident surface 211 is provided with a first fundamental frequency light transmission film. The first wavelength fundamental frequency light is frequency-doubled by the frequency-doubling crystal to obtain the first frequency-doubled light. The first frequency-doubled light exit surface 221 is provided with a first frequency-doubled light transmission film. In this embodiment, the first frequency-doubled light transmission film is a 320nm high-transmittance film. The second fundamental frequency light incident surface 212 is tilted toward the side away from the light-splitting component 123, and the angle a1 between the second fundamental frequency light incident surface 212 and the first fundamental frequency light incident surface 211 is 6.9°, that is, the incident angle of the second wavelength fundamental frequency light on the second fundamental frequency light incident surface 212 is 6.9°. After being refracted into the frequency doubling crystal, the angle with the optical axis of the frequency doubling crystal is 40.2°, which just meets the phase matching condition for the frequency doubling conversion of the second wavelength fundamental frequency light (wavelength is 604nm), and meets Type I phase matching: 604nm(o)+604nm(o)→302nm(e). The second frequency doubling light exit surface 222 is provided with a second frequency doubling light transmission film. In this embodiment, the second frequency doubling light transmission film is a 302nm high-transmittance film.

[0077] In this embodiment, a first reflective film is provided on the surface of the first resonant cavity mirror 1211, and the first reflective film is a 640nm, 604nm high reflective film; a second reflective film and a first transmissive film are provided on the surface of the second resonant cavity mirror 1212, and the second reflective film is a 640nm, 604nm high reflective film, and the first transmissive film is a 320nm, 302nm high transmissive film.

[0078] In this embodiment, if Figure 4 As shown, a pulse modulation device 13 may also be included, specifically an electro-optical Q-switching device may be used to obtain fundamental frequency light of multiple wavelengths with several ns-level pulses.

[0079] Specifically, there may be only one pulse modulation device 13 , which is located between the laser crystal 122 and the light splitting component 123 .

[0080] In another specific embodiment, Figure 5 As shown, the phase matching adopts type II phase matching:

[0081] The laser crystal 122 may be made of neodymium-doped yttrium aluminum garnet (Nd:YAG), and the pump source 11 may be made of an 808 nm semiconductor laser source.

[0082] The first wavelength fundamental frequency light is 1338 nm, and the second wavelength fundamental frequency light is 1319 nm.

[0083] The acute angle formed between the first light splitting component 1231 and the second light splitting component 1232 and the first direction k1 may be 45°.

[0084] The first fundamental frequency light transmitting film is a 45°, 1338nm high transmittance film; the second fundamental frequency light reflecting film is a 45°, 1319nm high reflective film.

[0085] The frequency doubling crystal can be a lithium borate phosphate (LBO) crystal with a cutting angle of θ = 83.9° and φ = 0°, corresponding to the phase matching condition of 669nm frequency doubling light obtained by frequency doubling the 1338nm fundamental frequency light (i.e., meeting the phase matching condition of the first wavelength fundamental frequency light), satisfying type II phase matching: 1338nm(e)+1338nm(o)→669nm(o).

[0086] The first fundamental frequency light incident surface 211 is perpendicular to the first direction k1, and the first fundamental frequency light incident surface 211 is provided with a first fundamental frequency light transmission film. The first wavelength fundamental frequency light is frequency-doubled by the frequency-doubling crystal to obtain the first frequency-doubled light, and the first frequency-doubled light exit surface 221 is provided with a first frequency-doubled light transmission film. In this embodiment, the first frequency-doubled light transmission film is a 669nm high-transmittance film. The second fundamental frequency light incident surface 212 is tilted toward the side away from the light-splitting component 123, and the angle a2 between the second fundamental frequency light incident surface 212 and the first fundamental frequency light incident surface 211 is 0.17°, that is, the incident angle of the second wavelength fundamental frequency light on the second fundamental frequency light incident surface 212 is 0.17°. After being refracted into the frequency doubling crystal, the angle with the optical axis of the frequency doubling crystal is θ=83.8°, φ=0°, which just meets the phase matching conditions for the frequency doubling conversion of the second wavelength fundamental frequency light (wavelength is 1319nm), and meets the type II phase matching: 1319nm(e)+1319nm(o)→659.5nm(e). The second frequency doubling light exit surface 222 is provided with a second frequency doubling light transmission film. In this embodiment, the second frequency doubling light transmission film is a 659.5nm high-transmittance film.

[0087] In this embodiment, a first reflective film is provided on the surface of the first resonant cavity mirror 1211, and the first reflective film is a 1338nm, 1319nm high reflective film; a second reflective film and a first transmissive film are provided on the surface of the second resonant cavity mirror 1212, and the second reflective film is a 1338nm, 1319nm high reflective film, and the first transmissive film is a 669nm, 659.5nm high transmissive film.

[0088] In this embodiment, a pulse modulation device 13 may be further included. There may be only one pulse modulation device 13 , which is located between the laser crystal 122 and the light splitting component 123 .

[0089] In one possible implementation, Figure 3 As shown, the resonant unit 12 includes two laser crystals 122 , including a first laser crystal 1221 and a second laser crystal 1222 . The first laser crystal 1221 is used to provide a first wavelength fundamental frequency light, and the second laser crystal 1222 is used to provide a second wavelength fundamental frequency light.

[0090] The resonance unit 12 includes two first resonant cavity mirrors 1211, one of which is arranged in sequence along a first direction k1 with the first laser crystal 1221, the frequency doubling device 2, and the second resonant cavity mirror 1212, and the other first resonant cavity mirror 1211 is arranged along a third direction k3 with the second laser crystal 1222, and the third direction k3 intersects with the first direction k1.

[0091] The resonance unit 12 includes a splitter component 123 , which is arranged along a first direction k1 with the first laser crystal 1221 and located between the first laser crystal 1221 and the frequency doubling device 2 , and is arranged along a third direction k3 with the second laser crystal 1222 .

[0092] The surface of the light splitting component 123 is provided with a first fundamental frequency light transmitting film, and the surface of the light splitting component 123 facing the second laser crystal 1222 is provided with a second fundamental frequency light reflecting film.

[0093] In the above embodiment, fundamental frequency lights of multiple wavelengths are outputted through multiple laser gain media. Specifically, fundamental frequency lights of multiple different wavelengths can be generated through two laser crystals 122 .

[0094] In the above embodiment, two resonant cavities are formed in the resonant unit 12, including a first resonant cavity and a second resonant cavity. The first resonant cavity is formed by the first first resonant cavity mirror 1211, the first laser crystal 1221, and the second resonant cavity mirror 1212, and the second resonant cavity is formed by the second first resonant cavity mirror 1211, the second laser crystal 1222, the spectroscopic component 123 and the second resonant cavity mirror 1212.

[0095] Specifically, a first fundamental frequency light is generated in the first resonant cavity, and a second fundamental frequency light is generated in the second resonant cavity.

[0096] Each laser crystal 122 can generate fundamental frequency light of multiple wavelengths. The multiple wavelengths of fundamental frequency light generated by the first laser crystal 1221 are selected by the first resonant cavity to retain the first wavelength of fundamental frequency light. The first wavelength of fundamental frequency light propagates along the first direction k1 and is the first fundamental frequency light. The first wavelength of fundamental frequency light passes through the spectroscopic component 123 along the first direction k1. The multiple wavelengths of fundamental frequency light generated by the second laser crystal 1222 are selected by the second resonant cavity to retain the second wavelength of fundamental frequency light. During propagation, the second wavelength of fundamental frequency light is incident on the surface of the spectroscopic component 123 along the third direction k3 and is totally reflected by the spectroscopic component 123, resulting in the second fundamental frequency light. This light is then incident on the frequency doubling device 2 along the first direction k1. The second laser crystal 1222 and the second first resonant cavity mirror 1211 are located on one side of the first laser crystal 1221. The orthographic projections of the second laser crystal 1222 and the second first resonant cavity mirror 1211 on the plane of the first fundamental frequency light incident surface 211 and the orthographic projection of the first laser crystal 1221 on the plane of the first fundamental frequency light incident surface 211 are aligned along the second direction k2. After being reflected by the light-splitting component 123, the second wavelength fundamental frequency light is adjusted in position along the second direction k2, so that the second fundamental frequency light and the first fundamental frequency light are aligned along the second direction k2, thereby causing the second fundamental frequency light and the first fundamental frequency light to be incident on different fundamental frequency light incident surfaces 21. Specifically, the first fundamental frequency light-transmitting film has a high transmittance for the first wavelength fundamental frequency light, and the second fundamental frequency light-reflecting film has a high reflectance for the second wavelength fundamental frequency light.

[0097] By providing the first fundamental frequency light transmitting film on the surface of the light splitting component 123 , the first wavelength fundamental frequency light can be directly transmitted through the light splitting component 123 along the first direction k1 .

[0098] By setting a second fundamental frequency light reflection film on the surface of the splitter component 123 facing the second laser crystal 1222, the second wavelength fundamental frequency light can first be incident on the surface of the splitter component 123 along the third direction k3 from the laser crystal 122, and then be reflected by the splitter component 123 and incident on the second fundamental frequency light incident surface 212 along the first direction k1.

[0099] In the above embodiment, the orthographic projections of the second laser crystal 1222 and the second first resonant cavity mirror 1211 on the plane where the first fundamental frequency light incident surface 211 are located and the orthographic projection of the first laser crystal 1221 on the plane where the first fundamental frequency light incident surface 211 are located are arranged along the second direction k2, and the orthographic projections of the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 are located are arranged along the second direction k2, so that the first fundamental frequency light is incident on the first fundamental frequency light incident surface 211, and the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212.

[0100] Specifically, the first fundamental frequency light incident surface 211 is perpendicular to the first direction k1 , and the frequency doubling device 2 uses a frequency doubling crystal whose cutting angle meets the phase matching requirement when the first fundamental frequency light is perpendicularly incident on the first fundamental frequency light incident surface 211 .

[0101] The second fundamental frequency light incident surface 212 is at a preset angle to the first direction k1. The preset angle is the incident angle of the second fundamental frequency light on the second fundamental frequency light incident surface 212. The preset angle satisfies the following conditions: the refracted light formed after the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212 along the first direction k1 and refracted just meets the phase matching requirement for realizing the second frequency-doubled light output in the frequency-doubled crystal, so that the refracted light can realize efficient frequency-doubled conversion of the second fundamental frequency light in the frequency-doubled device 2.

[0102] In a specific embodiment: Figure 3 As shown,

[0103] The first laser crystal 1221 may be made of neodymium-doped lithium yttrium fluoride (Nd:YLF), and the pump source 11 corresponding to the first laser crystal 1221 may be an 808nm semiconductor laser source. The first wavelength fundamental frequency light is 1053nm.

[0104] The second laser crystal 1222 may be made of neodymium-doped yttrium vanadate (Nd:YVO), and the pump source 11 corresponding to the second laser crystal 1222 may be an 880nm semiconductor laser source. The second wavelength fundamental frequency light is 1064nm.

[0105] The acute angle formed between the light splitting component 123 and the first direction k1 may be 45°.

[0106] The first fundamental frequency light transmission film is a 45°, 1053nm high-transmission film; the second fundamental frequency light reflection film is a 45°, 1064nm high-reflection film.

[0107] The frequency doubling crystal can be a lithium triborate (LBO) crystal with a cutting angle of θ = 90.0°, φ = 10.7°, an operating temperature of 60°C, and a phase matching condition of 527nm frequency doubling light corresponding to the frequency doubling of 1053nm fundamental frequency light (i.e., meeting the phase matching condition of the first wavelength fundamental frequency light), satisfying type I phase matching: 1053nm(o)+1053nm(o)→527nm(e).

[0108] The first fundamental frequency light incident surface 211 is perpendicular to the first direction k1, and the first fundamental frequency light incident surface 211 is provided with a first fundamental frequency light transmission film. The first wavelength fundamental frequency light is frequency-doubled by the frequency-doubling crystal to obtain the first frequency-doubled light. The first frequency-doubled light exit surface 221 is provided with a first frequency-doubled light transmission film. In this embodiment, the first frequency-doubled light transmission film is a 527nm high-transmittance film. The second fundamental frequency light incident surface 212 is tilted toward the side away from the spectroscopic component 123, and the angle a3 between the second fundamental frequency light incident surface 212 and the first fundamental frequency light incident surface 211 is 2.1°, that is, the incident angle of the second wavelength fundamental frequency light on the second fundamental frequency light incident surface 212 is 2.1°. After being refracted into the frequency doubling crystal, the angle with the optical axis of the frequency doubling crystal is θ=90.0° and φ=10°, which just meets the phase matching conditions for the frequency doubling conversion of the second wavelength fundamental frequency light (wavelength is 1064nm) and satisfies type I phase matching: 1064nm(o)+1064nm(o)→532nm(e). The second frequency doubling light exit surface 222 is provided with a second frequency doubling light transmission film. In this embodiment, the second frequency doubling light transmission film is a 532nm high-transmittance film.

[0109] In this embodiment, a first reflective film is provided on the surface of the first resonant cavity mirror 1211, and the first reflective film is a 1053nm, 1064nm high reflective film; a second reflective film and a first transmissive film are provided on the surface of the second resonant cavity mirror 1212, and the second reflective film is a 1053nm, 1064nm high reflective film, and the first transmissive film is a 527nm, 532nm high transmissive film.

[0110] In this embodiment, if Figure 6 As shown, a pulse modulation device 13 may also be included, specifically an acousto-optic modulator may be used to obtain a plurality of fundamental frequency lights with pulses of the order of hundreds of nanoseconds.

[0111] Specifically, the number of the modulation device may be one, which is located between the light splitting component 123 and the frequency doubling crystal.

[0112] In one possible implementation, Figure 7 As shown, the fundamental frequency light generating assembly 1 is further configured to provide a third wavelength of fundamental frequency light. The frequency doubling device 2 further includes a third fundamental frequency light incident surface 213. The orthographic projections of the first fundamental frequency light incident surface 211, the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 lies, and the orthographic projections of the third fundamental frequency light incident surface 213 on the plane where the first fundamental frequency light incident surface 211 lies are arranged along a second direction k2.

[0113] Specifically, the third wavelength fundamental frequency light is frequency-doubled by the frequency-doubling device to form the third frequency-doubled light λ3 , and the third frequency-doubled light λ3 is emitted from the third frequency-doubled light emitting surface 223 .

[0114] In the above embodiment, since fundamental frequency lights of different wavelengths need to be incident on different fundamental frequency light incident surfaces 21 along the first direction k1, the positions of different fundamental frequency light incident surfaces 21 are different, while the incident directions of fundamental frequency lights of different wavelengths are the same. Therefore, it is necessary to adjust the positions of fundamental frequency lights of different wavelengths along the second direction k2 so that fundamental frequency lights of different wavelengths are incident on corresponding fundamental frequency light incident surfaces 21.

[0115] In the above embodiment, the frequency doubling device 2 includes a first frequency doubling light output surface 221 parallel to the first fundamental frequency light incident surface 211, a second frequency doubling light output surface 222 parallel to the second fundamental frequency light incident surface 212, and a third frequency doubling light output surface 223 parallel to the third fundamental frequency light incident surface 213.

[0116] In the above embodiment, after fundamental frequency lights of different wavelengths are incident on different fundamental frequency light incident surfaces 21 along the first direction k1, since the inclination angles of the different fundamental frequency light incident surfaces 21 are different, the light incident on the frequency doubling device 2 from each fundamental frequency light incident surface 21 can satisfy the phase matching condition in the frequency doubling device 2, so that fundamental frequency lights of different wavelengths propagate in their corresponding phase matching directions after being incident on the frequency doubling crystal, thereby improving the efficiency of frequency doubling conversion.

[0117] In one possible implementation, Figure 7 As shown, the resonance unit 12 includes two laser crystals 122 , and the two laser crystals 122 include a first laser crystal 1221 and a second laser crystal 1222 .

[0118] The resonance unit 12 includes two first resonant cavity mirrors 1211, one of which is arranged in sequence with the first laser crystal 1221, the frequency doubling device 2, and the second resonant cavity mirror 1212 along the first direction k1, and the other is arranged with the second laser crystal 1222 along the second direction k2.

[0119] The resonant unit 12 includes two spectroscopic components 123, which are parallel to each other. The plane where the spectroscopic components 123 are located intersects with the first direction k1. The two spectroscopic components 123 include a first spectroscopic component 1231 and a second spectroscopic component 1232. The first spectroscopic component 1231 and the first laser crystal 1221 are arranged along the first direction k1. The first spectroscopic component 1231 is located between the laser crystal 122 and the frequency doubling device 2. The orthographic projection of the second spectroscopic component 1232 on the plane where the first fundamental frequency light incident surface 211 is located and the orthographic projection of the first spectroscopic component 1231 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2.

[0120] Among them, the surface of the first light-splitting component 1231 is provided with a first fundamental frequency light transmitting film, the surface of the first light-splitting component 1231 facing the second light-splitting component 1232 is provided with a second fundamental frequency light reflecting film, the surface of the second light-splitting component 1232 facing the first light-splitting component 1231 is provided with a second fundamental frequency light reflecting film, and the surface of the first light-splitting component 1231 facing the second laser crystal 1222 is provided with a third fundamental frequency light reflecting film.

[0121] In the above embodiment, fundamental frequency lights of multiple wavelengths are outputted through multiple laser gain media. Specifically, fundamental frequency lights of three different wavelengths can be generated through two laser crystals 122 .

[0122] In the above embodiment, three resonant cavities are formed in the resonant unit 12, including a first resonant cavity, a second resonant cavity and a third resonant cavity. The first resonant cavity is formed by the first first resonant cavity mirror 1211, the first laser crystal 1221 and the second resonant cavity mirror 1212; the second resonant cavity is formed by the first first resonant cavity mirror 1211, the first laser crystal 1221, the first light-splitting component 1231, the second light-splitting component 1232 and the second resonant cavity mirror 1212; the third resonant cavity is formed by the second first resonant cavity mirror 1211, the second laser crystal 1222, the first light-splitting component 1231 and the second resonant cavity mirror 1212.

[0123] Specifically, a first fundamental frequency light is generated in the first resonant cavity, a second fundamental frequency light is generated in the second resonant cavity, and a third fundamental frequency light is generated in the third resonant cavity.

[0124] Each laser crystal 122 can generate fundamental frequency light of multiple wavelengths. The multiple wavelengths of fundamental frequency light generated by the first laser crystal 1221 are selected by the first and second resonant cavities to retain the first and second wavelengths of fundamental frequency light. The first wavelength of fundamental frequency light propagates along the first direction k1 and is the first fundamental frequency light. The first wavelength of fundamental frequency light passes through the first beam splitting component 1231 along the first direction k1. During propagation, the second wavelength of fundamental frequency light is incident on the surface of the first beam splitting component 1231 along the first direction k1 and is totally reflected by the first beam splitting component 1231 to the surface of the second beam splitting component 1232. The second fundamental frequency light is then obtained and incident on the frequency doubling device 2 along the first direction k1. The orthographic projection of the second beam splitter 1232 on the plane of the first fundamental frequency light incident surface 211 and the orthographic projection of the first beam splitter 1231 on the plane of the first fundamental frequency light incident surface 211 are aligned along the second direction k2. After being reflected by the first beam splitter 1231 and the second beam splitter 1232, the second wavelength fundamental frequency light is adjusted in position along the second direction k2, so that the second fundamental frequency light and the first fundamental frequency light are aligned along the second direction k2, thereby causing the second fundamental frequency light and the first fundamental frequency light to be incident on different fundamental frequency light incident surfaces 21. The multiple wavelengths of fundamental frequency light generated by the second laser crystal 1222 are selected by the third resonant cavity to retain the third wavelength fundamental frequency light. During propagation, the third wavelength fundamental frequency light is incident on the surface of the first beam splitter 1231 along the third direction k3 and is totally reflected by the first beam splitter 1231, obtaining the third fundamental frequency light. This light is then incident on the frequency doubling device 2 along the first direction k1. The second laser crystal 1222 and the second first resonant cavity mirror 1211 are located on one side of the first laser crystal 1221. The orthographic projections of the second laser crystal 1222 and the second first resonant cavity mirror 1211 on the plane of the first fundamental frequency light incident surface 211 and the orthographic projection of the first laser crystal 1221 on the plane of the first fundamental frequency light incident surface 211 are aligned along the second direction k2. After being reflected by the first beam splitting component 1231, the position of the third wavelength fundamental frequency light along the second direction k2 is adjusted, so that the third fundamental frequency light and the first fundamental frequency light are aligned along the second direction k2. This causes the third fundamental frequency light and the first fundamental frequency light to be incident on different fundamental frequency light incident surfaces 21, and consequently, the first fundamental frequency light, the second fundamental frequency light, and the third fundamental frequency light to be incident on different fundamental frequency light incident surfaces 21.

[0125] Specifically, the first fundamental frequency light transmitting film has high transmittance for the first wavelength fundamental frequency light, the second fundamental frequency light reflecting film has high reflectance for the second wavelength fundamental frequency light, and the third fundamental frequency light reflecting film has high reflectance for the third wavelength fundamental frequency light.

[0126] By providing a first fundamental frequency light transmitting film on the surface of the first light splitting component 1231 , the first wavelength fundamental frequency light can be directly transmitted through the first light splitting component 1231 along the first direction k1 .

[0127] By providing a second fundamental frequency light reflecting film on the surface of the first light-splitting component 1231 facing the second light-splitting component 1232, the second wavelength fundamental frequency light can first be incident on the surface of the first light-splitting component 1231 along the first direction k1 from the first laser crystal 1221, and then be incident on the surface of the second light-splitting component 1232 along the second direction k2 after being reflected by the first light-splitting component 1231, and then be incident on the second fundamental frequency light incident surface 212 along the first direction k1 after being reflected by the second light-splitting component 1232.

[0128] By setting a third fundamental frequency light reflection film on the surface of the first light-splitting component 1231 facing the second laser crystal 1222, the third wavelength fundamental frequency light can first be incident on the surface of the first light-splitting component 1231 along the third direction k3 from the second laser crystal 1222, and then be reflected by the first light-splitting component 1231 and incident on the third fundamental frequency light incident surface 213 along the first direction k1.

[0129] In the above embodiment, the orthographic projection of the first light-splitting component 1231 on the plane where the first fundamental frequency light incident surface 211 is located and the orthographic projection of the second light-splitting component 1232 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2. The orthographic projections of the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 are arranged along the second direction k2. The orthographic projection of the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 is a first projection, the orthographic projection of the first light-splitting component 1231 on the plane where the first fundamental frequency light incident surface 211 is a second projection, and the orthographic projection of the second light-splitting component 1232 on the plane where the first fundamental frequency light incident surface 211 is a third projection. The first fundamental frequency light incident surface 211 and the first projection are arranged in a direction where the second projection points to the third direction, so that the first fundamental frequency light is incident on the first fundamental frequency light incident surface 211 and the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212.

[0130] The orthographic projections of the second laser crystal 1222 and the second first resonant cavity mirror 1211 on the plane where the first fundamental frequency light incident surface 211 is located, and the orthographic projections of the first laser crystal 1221 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2, and the orthographic projections of the first fundamental frequency light incident surface 211 and the third fundamental frequency light incident surface 213 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2, so that the first fundamental frequency light is incident on the first fundamental frequency light incident surface 211, and the third fundamental frequency light is incident on the third fundamental frequency light incident surface 213.

[0131] That is, in the above embodiment, the orthographic projections of the first fundamental frequency light incident surface 211 and the second fundamental frequency light incident surface 212 on the plane where the first fundamental frequency light incident surface 211 are located, and the orthographic projections of the third fundamental frequency light incident surface 213 on the plane where the first fundamental frequency light incident surface 211 are located are arranged along the second direction k2, and the orthographic projections of the first light splitting component 1231, the second light splitting component 1232 and the second laser crystal 1222 on the plane where the first fundamental frequency light incident surface 211 are located are arranged along the second direction k2, so that the first fundamental frequency light is incident on the first fundamental frequency light incident surface 211 along the first direction k1, the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212 along the first direction k1, and the third fundamental frequency light is incident on the third fundamental frequency light incident surface 213 along the first direction k1.

[0132] Specifically, the first fundamental frequency light incident surface 211 is perpendicular to the first direction k1 , and the frequency doubling device 2 uses a frequency doubling crystal whose cutting angle meets the phase matching requirement when the first fundamental frequency light is perpendicularly incident on the first fundamental frequency light incident surface 211 .

[0133] The second fundamental frequency light incident surface 212 is at a first preset angle with the first direction k1. The first preset angle is the incident angle of the second fundamental frequency light on the second fundamental frequency light incident surface 212. The first preset angle satisfies the following conditions: the refracted light formed after the second fundamental frequency light is incident on the second fundamental frequency light incident surface 212 along the first direction k1 and refracted just meets the phase matching requirement for realizing the second frequency-doubled light output in the frequency-doubled crystal, so that the refracted light can realize efficient frequency-doubled conversion of the second fundamental frequency light in the frequency-doubled device 2.

[0134] The third fundamental frequency light incident surface 213 is at a second preset angle with the first direction k1. The second preset angle is the incident angle of the third fundamental frequency light on the third fundamental frequency light incident surface 213. The second preset angle satisfies the following conditions: the refracted light formed after the third fundamental frequency light is incident on the third fundamental frequency light incident surface 213 along the first direction k1 and refracted just meets the phase matching requirement for realizing the third frequency-doubled light output in the frequency-doubled crystal, thereby enabling the refracted light to realize efficient frequency-doubled conversion of the third fundamental frequency light in the frequency-doubled device 2.

[0135] In a specific embodiment: Figure 7 As shown,

[0136] The first laser crystal 1221 can be made of praseodymium-doped yttrium lithium fluoride (Pr:YLF), and the pump source 11 corresponding to the first laser crystal 1221 can be a 444nm semiconductor laser source. The first wavelength fundamental frequency light is 640nm, and the second wavelength fundamental frequency light is 604nm.

[0137] The second laser crystal 1222 may be made of yttrium aluminate doped with praseodymium (Pr:YAP), and the pump source 11 corresponding to the second laser crystal 1222 may be an argon ion laser. The third wavelength fundamental frequency light is 745 nm.

[0138] The orthographic projection of the first light splitting component 1231 on the plane where the first fundamental frequency light incident surface 211 is located and the orthographic projection of the second light splitting component 1232 on the plane where the first fundamental frequency light incident surface 211 is located are arranged along the second direction k2, and the degree of the acute angle among the angles formed by the first light splitting component 1231, the second light splitting component 1232 and the first direction k1 can be 45°.

[0139] The first fundamental frequency light transmission film is a 45°, 640nm high-transmittance film; the second fundamental frequency light reflection film is a 45°, 604nm high-reflection film; the third fundamental frequency light reflection film is a 45°, 745nm high-reflection film.

[0140] The frequency doubling crystal can be a potassium dihydrogen phosphate (KDP) crystal with a cutting angle of θ = 55.7° and φ = 0°, which corresponds to the phase matching condition of 320nm frequency doubling light by frequency doubling the 640nm fundamental frequency light (i.e., meeting the phase matching condition of the first wavelength fundamental frequency light), and satisfies the type I phase matching: 640nm(o)+640nm(o)→320nm(e).

[0141] The first fundamental frequency light incident surface 211 is perpendicular to the first direction k1, and the first fundamental frequency light incident surface 211 is provided with a first fundamental frequency light transmission film. The first wavelength fundamental frequency light is frequency-doubled by the frequency-doubling crystal to obtain the first frequency-doubled light. The first frequency-doubled light exit surface 221 is provided with a first frequency-doubled light transmission film. In this embodiment, the first frequency-doubled light transmission film is a 320nm high-transmittance film. The second fundamental frequency light incident surface 212 is tilted toward the side away from the spectroscopic component 123, and the angle between the second fundamental frequency light incident surface 212 and the first fundamental frequency light incident surface 211 is 13.5°, that is, the incident angle of the second wavelength fundamental frequency light on the second fundamental frequency light incident surface 212 is 13.5°. After being refracted into the frequency doubling crystal, the angle a4 with the optical axis of the frequency doubling crystal is θ=60.3°, φ=0°, which just meets the phase matching conditions for the frequency doubling conversion of the second wavelength fundamental frequency light (wavelength is 604nm), and meets Type I phase matching: 604nm(o)+604nm(o)→302nm(e). The second frequency doubling light exit surface 222 is provided with a second frequency doubling light transmission film. In this embodiment, the second frequency doubling light transmission film is a 302nm high-transmittance film. The third fundamental frequency light incident surface 213 is tilted toward the side away from the spectroscopic component 123, and the angle a5 between the third fundamental frequency light incident surface 213 and the first fundamental frequency light incident surface 211 is 23.3°, that is, the incident angle of the third wavelength fundamental frequency light on the third fundamental frequency light incident surface 213 is 23.3°. After being refracted into the frequency doubling crystal, the angle with the optical axis of the frequency doubling crystal is θ=47.6°, φ=0°, which just meets the phase matching conditions for the frequency doubling conversion of the third wavelength fundamental frequency light (wavelength is 745nm), and satisfies Type I phase matching: 745nm(o)+745nm(o)→372.5nm(e). The third frequency doubling light exit surface 223 is provided with a third frequency doubling light transmissive film. In this embodiment, the third frequency doubling light transmissive film is a 372.5nm high-transmittance film.

[0142] In this embodiment, a first reflection film is provided on the surface of the first first resonant cavity mirror 1211, and the first reflection film is a 640nm, 604nm high reflection film; a second reflection film and a first transmission film are provided on the surface of the second resonant cavity mirror 1212, and the second reflection film is a 640nm, 604nm, 745nm high reflection film, and the first transmission film is a 320nm, 302nm, 372.5 high transmission film; a third reflection film is provided on the surface of the second first resonant cavity mirror 1211, and the third reflection film is a 745nm high reflection film.

[0143] In this embodiment, if Figure 8As shown, a pulse modulation device 13 may also be included. There may be one pulse modulation device 13, located between the first laser crystal 1221 and the light-splitting component 123. There may also be two pulse modulation devices 13, one located between the first laser crystal 1221 and the light-splitting component 123, and the other located between the second laser crystal 1222 and the light-splitting component 123. Alternatively, there may be one pulse modulation device 13, located between the light-splitting component 123 and the frequency-doubling crystal.

[0144] In a feasible embodiment, the material of the laser crystal 122 includes praseodymium-doped lithium yttrium fluoride, neodymium-doped lithium yttrium fluoride, praseodymium-doped yttrium aluminate, or neodymium-doped yttrium vanadate.

[0145] In a feasible implementation, the material of the frequency doubling device 2 is a frequency doubling crystal that meets the birefringence phase matching condition.

[0146] Specifically, the material of the frequency multiplying device 2 includes barium borate (BBO), lithium borate phosphate (LBO), potassium titanyl phosphate (KTP) or potassium dihydrogen phosphate (KDP).

[0147] Among them, barium metaborate is suitable for the ultraviolet to near-infrared band, with high nonlinear coefficient and good optical properties.

[0148] Lithium borate phosphate is used in high-power laser systems and has high photodamage values.

[0149] Potassium titanyl phosphate is suitable for visible light and near-infrared bands and has high frequency doubling efficiency.

[0150] Potassium dihydrogen phosphate is suitable for the ultraviolet band and has a high frequency doubling coefficient.

[0151] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A multi-wavelength frequency-doubling laser device, characterized in that: include: A fundamental frequency light generating component, used for providing fundamental frequency lights of at least two different wavelengths; A frequency doubling device is used to perform frequency doubling conversion on the fundamental frequency light to form frequency doubling light. The frequency doubling device includes multiple fundamental frequency light incident surfaces and multiple frequency doubling light exit surfaces. Different fundamental frequency light incident surfaces are arranged to intersect. The frequency doubling light exit surfaces correspond to the fundamental frequency light incident surfaces one by one and are parallel to each other. The fundamental frequency lights of different wavelengths are all incident on the fundamental frequency light incident surfaces along a first direction.

2. The multi-wavelength frequency-doubling laser device according to claim 1, characterized in that: The fundamental frequency light generating component includes a pump source and a resonance unit. The resonance unit includes at least two resonant cavity mirrors and at least one laser crystal. The pump source corresponds to the laser crystal one-to-one and is arranged adjacent to the laser crystal. The pump source is used to pump the laser crystal to emit laser light. At least two resonant cavities are formed in the resonant unit, and the frequency doubling device is located in the resonant cavity.

3. The multi-wavelength frequency-doubling laser device according to claim 2, characterized in that: The resonance unit includes a first resonant cavity mirror and a second resonant cavity mirror. The laser crystal is located on a side of the first resonant cavity mirror close to the second resonant cavity mirror. A first reflection film is provided on the surface of the first resonant cavity mirror, and the first reflection film has a reflective effect on the fundamental frequency light of at least one wavelength. A second reflection film and a first transmission film are provided on the surface of the second resonant cavity mirror, and the second reflection film has a reflective effect on the fundamental frequency light of at least one wavelength, and the first transmission film has a transmittive effect on the frequency-doubled light.

4. The multi-wavelength frequency-doubling laser device according to claim 3, characterized in that: The resonance unit further includes at least one spectroscopic component, which is located on a side of the laser crystal close to the second resonant cavity mirror and is used to adjust the fundamental frequency light to be incident on the fundamental frequency light incident surface along the first direction.

5. The multi-wavelength frequency-doubling laser device according to claim 4, characterized in that: The fundamental frequency light generating component is used to provide a first wavelength fundamental frequency light and a second wavelength fundamental frequency light; The frequency doubling device includes a first fundamental frequency light incident surface and a second fundamental frequency light incident surface, wherein the orthographic projections of the first fundamental frequency light incident surface and the second fundamental frequency light incident surface on the plane where the first fundamental frequency light incident surface is located are arranged along a second direction, and the second direction is perpendicular to the first direction.

6. The multi-wavelength frequency-doubling laser device according to claim 5, characterized in that: The resonant unit includes a laser crystal, the first resonant cavity mirror, the laser crystal, the frequency doubling device, and the second resonant cavity mirror are arranged in sequence along the first direction; The resonant unit includes two beam splitting components, the two beam splitting components are parallel to each other, the plane where the beam splitting components are located intersects with the first direction, the two beam splitting components include a first beam splitting component and a second beam splitting component, the first beam splitting component and the laser crystal are arranged along the first direction, the first beam splitting component is located between the laser crystal and the frequency doubling device, and the orthographic projection of the first beam splitting component on the plane where the first fundamental frequency light incident surface is located and the orthographic projection of the second beam splitting component on the plane where the first fundamental frequency light incident surface is located are arranged along the second direction; Wherein, a first fundamental frequency light transmitting film is provided on the surface of the first light splitting component, and a second fundamental frequency light reflecting film is provided on the surface of the first light splitting component facing the second light splitting component; A second fundamental frequency light reflecting film is provided on a surface of the second light splitting component facing the first light splitting component.

7. The multi-wavelength frequency-doubling laser device according to claim 5, characterized in that: The resonant unit includes two laser crystals, the two laser crystals include a first laser crystal and a second laser crystal, the first laser crystal is used to provide the first wavelength fundamental frequency light, and the second laser crystal is used to provide the second wavelength fundamental frequency light; The resonant unit includes two first resonant cavity mirrors, wherein one of the first resonant cavity mirrors, the first laser crystal, the frequency doubling device, and the second resonant cavity mirror are arranged in sequence along the first direction, and the other of the first resonant cavity mirrors and the second laser crystal are arranged along a third direction, which intersects the first direction; The resonant unit includes a beam splitting component, the beam splitting component and the first laser crystal are arranged along the first direction, the beam splitting component is located between the first laser crystal and the frequency doubling device, and the beam splitting component and the second laser crystal are arranged along the third direction; The surface of the light splitting component is provided with a first fundamental frequency light transmitting film, and the surface of the light splitting component facing the second laser crystal is provided with a second fundamental frequency light reflecting film.

8. The multi-wavelength frequency-doubling laser device according to claim 5, characterized in that: The fundamental frequency light generating component is further used to provide a third wavelength fundamental frequency light; The frequency doubling device also includes a third fundamental frequency light incident surface, and the first fundamental frequency light incident surface, the orthographic projection of the second fundamental frequency light incident surface on the plane where the first fundamental frequency light incident surface is located, and the orthographic projection of the third fundamental frequency light incident surface on the plane where the first fundamental frequency light incident surface is located are arranged along the second direction.

9. The multi-wavelength frequency-doubling laser device according to claim 8, characterized in that: The resonance unit includes two laser crystals, and the two laser crystals include a first laser crystal and a second laser crystal; The resonant unit includes two first resonant cavity mirrors, wherein one of the first resonant cavity mirrors and the first laser crystal, the frequency doubling device, and the second resonant cavity mirror are arranged in sequence along the first direction, and the other first resonant cavity mirror and the second laser crystal are arranged along the second direction; The resonant unit includes two beam splitting components, the two beam splitting components are parallel to each other, the plane where the beam splitting components are located intersects with the first direction, the two beam splitting components include a first beam splitting component and a second beam splitting component, the first beam splitting component and the first laser crystal are arranged along the first direction, the first beam splitting component is located between the laser crystal and the frequency doubling device, and the orthographic projection of the first beam splitting component on the plane where the first fundamental frequency light incident surface is located and the orthographic projection of the second beam splitting part on the plane where the first fundamental frequency light incident surface is located are arranged along the second direction; Among them, the surface of the first light-splitting component is provided with a first fundamental frequency light transmitting film, the surface of the first light-splitting component facing the second light-splitting component is provided with a second fundamental frequency light reflecting film, the surface of the second light-splitting component facing the first light-splitting component is provided with a second fundamental frequency light reflecting film, and the surface of the first light-splitting component facing the second laser crystal is provided with a third fundamental frequency light reflecting film.

10. The multi-wavelength frequency-doubling laser device according to any one of claims 4 to 9, characterized in that: The fundamental frequency light generating component also includes a pulse modulation device, which is used to pulse modulate the fundamental frequency light. The pulse modulation device is located between the laser crystal and the spectroscopic component, or between the spectroscopic component and the frequency doubling device.

11. The multi-wavelength frequency-doubling laser device according to claim 2, characterized in that: The material of the laser crystal includes praseodymium-doped lithium yttrium fluoride, neodymium-doped lithium yttrium fluoride, praseodymium-doped yttrium aluminate or neodymium-doped yttrium vanadate; and / or, The material of the frequency doubling device includes barium metaborate, lithium borate phosphate, potassium titanyl phosphate or potassium dihydrogen phosphate.

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