Self-frequency-doubling laser with soft-edge diaphragm

Abstract

The invention discloses a self-frequency-doubling laser with a soft-edge diaphragm, which belongs to the technical field of lasers and comprises a pumping source, a coupling system and a self-frequency-doubling crystal which are sequentially arranged along the advancing direction of a light path, the incident plane and the emergent plane of the self-frequency-doubling crystal are respectively plated with a corresponding filter film; a soft-edge diaphragm is engraved in the self-frequency-doubling crystal through laser; the coupling system focuses pump light emitted by the pump source into the self-frequency-doubling crystal, the self-frequency-doubling crystal converts the pump light into fundamental frequency light, the fundamental frequency light suppresses diffraction of a high-order mode after passing through the soft-edge diaphragm, and frequency-doubled light is output after passing through a nonlinear effect. According to the invention, the soft-edge diaphragm is engraved in the self-frequency-doubling crystal with the two ends plated with the filter films through laser, complex intra-cavity insertion elements and cavity length adjustment are abandoned, the self-frequency-doubling crystal with the soft-edge diaphragm engraved therein forms a resonant cavity, and the light beam quality is obviously improved only by using one crystal.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a self-frequency doubling laser with a soft-edge aperture. Background Technology

[0002] In recent years, self-frequency doubling lasers have found irreplaceable applications in fields requiring low-to-medium power, high-stability visible lasers due to their core advantages of integration, compactness, stability, and high efficiency.

[0003] The core material of a self-frequency-doubled laser is a self-frequency-doubled crystal, a multifunctional composite optical crystal whose fundamental characteristic lies in the atomic-level integration of "laser generation" and "frequency conversion" into a single crystal matrix. Furthermore, a complete resonant cavity can be formed by depositing filter films at both ends of the self-frequency-doubled crystal. However, the output beam quality of a self-frequency-doubled laser is limited by the quality of the self-frequency-doubled crystal itself. If the self-frequency-doubled crystal has problems such as crystal inhomogeneity or poor beam quality, the self-frequency-doubled laser will be unable to meet the requirements of higher-level technological fields such as biological detection applications and laser ranging radar.

[0004] Therefore, to improve beam quality, the method employed is to separate the filter from the self-frequency doubling crystal, and to add a hard stop between the input-side filter and the self-frequency doubling crystal. The final structure is as follows: Figure 1 As shown, along the optical path, the sequence is: pump source 1, coupling system 2, input mirror 5, hard aperture 6, self-frequency doubling crystal 3, and output mirror 7. Input mirror 5 is coated with a filter film from the original incident surface of the self-frequency doubling crystal, and output mirror 7 is coated with a filter film from the original exit surface of the self-frequency doubling crystal. That is, input mirror 5, hard aperture 6, self-frequency doubling crystal 3, and output mirror 7 form a new resonant cavity. This method results in an increased cavity length, leading to high loss, low efficiency, and reduced beam quality.

[0005] Based on the above problems, this application proposes a self-frequency doubling laser with a soft-edge aperture. By laser-engraving a soft-edge aperture on a self-frequency doubling crystal with filter films coated at both ends, the complex intracavity insertion elements and cavity length adjustment are eliminated. The self-frequency doubling crystal with the soft-edge aperture engraved inside constitutes the resonant cavity itself, and a significant improvement in beam quality is achieved with only one crystal. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a self-frequency doubling laser with a soft-edge aperture.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A self-frequency doubling laser with a soft-edge aperture includes a pump source, a coupling system, and a self-frequency doubling crystal arranged sequentially along the optical path. The incident and exit surfaces of the self-frequency doubling crystal are each coated with a corresponding filter film; The self-frequency doubling crystal has a soft-edge aperture engraved inside by laser. The coupling system focuses the pump light emitted by the pump source into a self-frequency doubling crystal. The self-frequency doubling crystal converts the pump light into fundamental frequency light. The fundamental frequency light is then filtered by a soft-edge aperture to suppress the diffraction of higher-order modes, and after passing through a nonlinear effect, it outputs frequency-doubled light.

[0008] Preferably, the distance between the incident surface and the exit surface in the self-frequency doubling crystal is b, and the distance between the soft-edge aperture and the incident surface in the self-frequency doubling crystal is a, then 0 ≤ a < b.

[0009] Preferably, the soft-edge aperture is a sawtooth aperture or a blind-spot glass aperture.

[0010] Preferably, the incident surface of the self-frequency doubling crystal is coated with a pump light high-transmittance film, a fundamental frequency light high-reflection film, and a frequency doubling light high-reflection film, and the exit surface of the self-frequency doubling crystal is coated with a pump light high-reflection film, a fundamental frequency light anti-reflection film, and a frequency doubling light high-transmittance film.

[0011] Preferably, the incident surface of the self-frequency doubling crystal is coated with a high-transmittance film for pump light (800-980nm), a high-reflectance film for fundamental frequency light (1000-1200nm), and a high-reflectance film for frequency doubling light (500-600nm); the exit surface of the self-frequency doubling crystal is coated with a high-reflectance film for pump light (800-980nm), an anti-reflection film for fundamental frequency light (1000-1200nm), and a high-transmittance film for frequency doubling light (500-600nm).

[0012] Preferably, the high-transmittance film for pump light (800-980nm) coated on the incident surface of the self-frequency doubling crystal has a transmittance of 95%. The high-reflectivity film for the fundamental frequency light (1000-1200nm) coated on the incident surface of the self-frequency doubling crystal has a reflectivity of 99.9%. The reflectivity of the high-reflectivity film (500-600nm) coated on the incident surface of the self-frequency doubling crystal is 99.9%.

[0013] Preferably, the matrix material of the self-frequency doubling crystal is GdCOB or YCOB.

[0014] Preferably, the doping ions in the self-frequency doubling crystal are Yb. 3+ or Nd 3+ .

[0015] Preferably, the pump source is a fiber laser module or a laser diode.

[0016] Preferably, the coupling system is a single coupling mirror or a dual coupling mirror.

[0017] The beneficial effects of this invention are: This invention eliminates the need for complex intracavity insertion elements and cavity length adjustment by laser-engraving a soft-edge aperture on a self-frequency doubling crystal with filter films coated at both ends. The self-frequency doubling crystal with the soft-edge aperture engraved inside constitutes the resonant cavity itself, and a significant improvement in beam quality is achieved using only one crystal. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0019] Figure 1 This is a schematic diagram of the structure of an existing self-frequency doubling laser in the background art; Figure 2 This is a schematic diagram of the self-frequency doubling laser with a soft-edge aperture in this invention; Figure 3 This is a schematic diagram of the optical path within the self-frequency doubling crystal in this invention; Figure 4 This is a schematic diagram of the soft-edge aperture being set on the incident surface of the self-frequency doubling crystal in this invention; Figure 5 This is a schematic diagram of the soft-edge aperture being disposed inside the self-frequency doubling crystal in this invention; in: 1. Pump source; 2. Coupling system; 3. Self-frequency doubling crystal; 31. Fundamental frequency light; 32. Frequency doubling light; 4. Soft-edge aperture; 5. Input mirror; 6. Hard aperture; 7. Output mirror. Detailed Implementation

[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0022] In this invention, terms such as "upper," "lower," "bottom," and "top" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are merely relational terms determined for the convenience of describing the structural relationship of the various components or elements of this invention, and do not specifically refer to any component or element in this invention, and should not be construed as limiting this invention.

[0023] In this invention, terms such as "connected" and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] like Figures 2-3 As shown, a self-frequency doubling laser with a soft-edge aperture includes a pump source 1, a coupling system 2, and a self-frequency doubling crystal 3 arranged sequentially along the optical path. The laser output wavelength of the pump source 1 matches the absorption peak of the self-frequency doubling crystal 3 material to ensure high-efficiency conversion of optical energy. The purpose of the coupling system 2 is to focus the pump light emitted by the pump source 1 into the self-frequency doubling crystal 3. The self-frequency doubling crystal 3 is cut at a certain frequency doubling angle, which is the direction with the highest nonlinear frequency doubling conversion efficiency. The incident and exit surfaces of the self-frequency doubling crystal 3 are each coated with a corresponding filter film; The self-frequency doubling crystal 3 has a soft-edge aperture 4 laser-engraved inside; the soft-edge aperture 4, as a diffraction suppression element, refers to an aperture with a periodic or non-periodic structure at its edge. The soft-edge aperture 4 modulates the beam through the structure at the edge of the aperture, thereby suppressing the diffraction phenomenon in the system and improving the beam uniformity in the system. The coupling system 2 focuses the pump light emitted by the pump source 1 into the self-frequency doubling crystal 3. The self-frequency doubling crystal 3 converts the pump light into fundamental frequency light 31 and frequency-doubled light 32. The self-frequency doubling crystal 3 converts the pump light into fundamental frequency light 31. After passing through the soft-edge aperture 4, the fundamental frequency light 31 suppresses the diffraction of higher-order modes and outputs frequency-doubled light 32 after nonlinear effects. The self-frequency doubling crystal 3 then outputs high-quality laser light.

[0026] Preferably, the distance between the incident surface and the exit surface of the self-frequency doubling crystal 3 is b, and the distance between the soft-edge aperture 4 and the incident surface of the self-frequency doubling crystal 3 is a, then 0 ≤ a < b.

[0027] That is, the soft-edge aperture 4 can be placed on the incident surface of the self-frequency doubling crystal 3, or it can be placed inside the self-frequency doubling crystal 3. When the soft-edge aperture 4 is placed on the incident surface of the self-frequency doubling crystal 3, as... Figure 4 As shown, when the soft-edge aperture 4 is placed inside the self-frequency doubling crystal 3, it is as follows: Figure 5 As shown.

[0028] Preferably, the soft-edge aperture 4 is a sawtooth aperture or a blind-spot glass aperture. The sawtooth aperture can be a triangular sawtooth aperture, a Gaussian sawtooth aperture, a sinusoidal sawtooth aperture, an amplitude-modulated sawtooth aperture, a radius-random sawtooth aperture, or a super-Gaussian sawtooth aperture.

[0029] Preferably, the incident surface of the self-frequency doubling crystal 3 is coated with a pump light high-transmittance film, a fundamental frequency light high-reflection film, and a frequency-doubled light high-reflection film, while the exit surface of the self-frequency doubling crystal 3 is coated with a pump light high-reflection film, a fundamental frequency light anti-reflection film, and a frequency-doubled light high-transmittance film. This configuration reduces the reflection of pump light at the incident surface, allowing most of the pump light to enter the self-frequency doubling crystal 3, thus improving the transmittance of the frequency-doubled light 32 at the exit surface and enhancing the conversion effect of the self-frequency doubling crystal 3.

[0030] Preferably, the incident surface of the self-frequency doubling crystal 3 is coated with a high-transmittance film for pump light (800-980nm), a high-reflectance film for fundamental frequency light (1000-1200nm), and a high-reflectance film for frequency doubling light (500-600nm). The exit surface of the self-frequency doubling crystal 3 is coated with a high-reflectance film for pump light (800-980nm), an anti-reflection film for fundamental frequency light (1000-1200nm), and a high-transmittance film for frequency doubling light (500-600nm).

[0031] Preferably, the high-transmittance film for pump light (800-980nm) coated on the incident surface of the self-frequency doubling crystal 3 has a transmittance of 95%; The reflectivity of the high-reflectivity film for the fundamental frequency light (1000-1200nm) coated on the incident surface of the self-doubling crystal 3 is 99.9%. The reflectivity of the high-reflectivity film (500-600nm) coated on the incident surface of the self-frequency doubling crystal 3 is 99.9%.

[0032] Preferably, the matrix material of the self-frequency doubling crystal 3 is GdCOB or YCOB.

[0033] Preferably, the doped ions in the self-frequency doubling crystal 3 are Yb. 3+ or Nd 3+ .

[0034] Preferably, the pump source 1 is a fiber laser module or a laser diode.

[0035] Preferably, the coupling system 2 is a single coupling mirror or a double coupling mirror, or it can be other forms of combined mirrors.

[0036] A self-frequency doubling laser with a soft-edge aperture is specifically implemented as follows: The pump light emitted from pump source 1 is focused onto self-frequency doubling crystal 3 by coupling system 2, exciting the doped ions in self-frequency doubling crystal 3. After energy level transition, it forms fundamental frequency light 31. A soft-edge aperture 4 is laser-engraved on the incident surface or inside of self-frequency doubling crystal 3. After passing through the soft-edge aperture 4, the diffraction of higher-order modes is suppressed. The fundamental frequency light 31 is then nonlinearly frequency-doubled by self-frequency doubling crystal 3 to form frequency-doubled light 32.

[0037] This invention eliminates the need for complex intracavity insertion elements and cavity length adjustment by laser-engraving a soft-edge aperture 4 on a self-frequency doubling crystal 3 with filter films coated at both ends. The self-frequency doubling crystal 3 with the soft-edge aperture 4 engraved on it constitutes a resonant cavity itself, and a significant improvement in beam quality is achieved using only one crystal.

[0038] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, they are not intended to limit the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A self-frequency doubling laser with a soft-edge aperture, characterized in that, It includes a pump source, a coupling system, and a self-frequency doubling crystal arranged sequentially along the optical path; The incident and exit surfaces of the self-frequency doubling crystal are each coated with a corresponding filter film; The self-frequency doubling crystal has a soft-edge aperture engraved inside by laser. The coupling system focuses the pump light emitted by the pump source into a self-frequency doubling crystal. The self-frequency doubling crystal converts the pump light into fundamental frequency light. The fundamental frequency light is then filtered by a soft-edge aperture to suppress the diffraction of higher-order modes, and after passing through a nonlinear effect, it outputs frequency-doubled light.

2. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, If the distance between the incident surface and the exit surface of the self-frequency doubling crystal is b, and the distance between the soft-edge aperture and the incident surface of the self-frequency doubling crystal is a, then 0 ≤ a < b.

3. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, The type of soft-edge aperture is a sawtooth aperture or a blind-spot glass aperture.

4. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, The incident surface of the self-frequency doubling crystal is coated with a pump light high-transmittance film, a fundamental frequency light high-reflection film, and a frequency doubling light high-reflection film, while the exit surface of the self-frequency doubling crystal is coated with a pump light high-reflection film, a fundamental frequency light anti-reflection film, and a frequency doubling light high-transmittance film.

5. The self-frequency doubling laser with a soft-edge aperture as described in claim 4, characterized in that, The incident surface of the self-frequency doubling crystal is coated with a high-transmittance film for pump light (800-980nm), a high-reflectance film for fundamental frequency light (1000-1200nm), and a high-reflectance film for frequency doubling light (500-600nm). The exit surface of the self-frequency doubling crystal is coated with a high-reflectance film for pump light (800-980nm), an anti-reflection film for fundamental frequency light (1000-1200nm), and a high-transmittance film for frequency doubling light (500-600nm).

6. The self-frequency doubling laser with a soft-edge aperture as described in claim 5, characterized in that, The high-transmittance film for pump light (800-980nm) coated on the incident surface of the self-frequency doubling crystal has a transmittance of 95%. The high-reflectivity film for the fundamental frequency light (1000-1200nm) coated on the incident surface of the self-frequency doubling crystal has a reflectivity of 99.9%. The reflectivity of the high-reflectivity film (500-600nm) coated on the incident surface of the self-frequency doubling crystal is 99.9%.

7. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, The matrix material of the self-frequency doubling crystal is GdCOB or YCOB.

8. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, The doped ion in the self-frequency doubling crystal is Yb. 3+ or Nd 3+ .

9. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, The pump source is a fiber laser module or a laser diode.

10. The self-frequency doubling laser with a soft-edge aperture as described in claim 1, characterized in that, The coupling system is a single coupling mirror or a double coupling mirror.

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