A dual-wavelength solid-state vortex laser with controllable wavelength and mode

Abstract

The invention discloses a dual-wavelength solid-state vortex laser with controllable wavelength and mode. A pump source emits pump light in the absorption band of a gain medium, which is output through an energy transfer optical fiber, collimated and focused by a coupling lens group, and enters the gain medium through an input mirror to generate an inverted population to obtain laser light. The input mirror and the output mirror form a resonant cavity with a first preset wavelength. The eigenmode in the resonant cavity is first focused by a first focusing lens in the cavity. The eigenmode is focused on the output mirror to form spherical aberration. The controllable output of a fundamental transverse mode or vortex light is achieved by adjusting the position of the output mirror. By controlling the positions of the output mirror and the second focusing lens and combining the angle control of a quarter-wave plate, vortex light output with selectable wavelengths and modes at dual ports of the first preset wavelength and the second preset wavelength is achieved. The first preset wavelength is generated by resonance in the resonant cavity formed by the input mirror and the output mirror, and the second preset wavelength is generated by resonance in the resonant cavity formed by the input mirror, the total reflection mirror, and the thin-film polarizer.

Description

Technical Field

[0001] The present invention relates to the field of vortex lasers, in particular to a dual-wavelength solid-state vortex laser with controllable wavelength and mode. Background Art

[0002] Vortex light has important applications in optical manipulation, imaging, and optical communications due to its characteristics such as carrying orbital angular momentum information and having spiral phase. At present, there are two main methods for obtaining vortex light, namely extracavity modulation and intracavity modulation. Extracavity modulation is mainly based on modulation outside the cavity using devices such as spiral phase plates, q-plates, and spatial light modulators, which can directly convert Gaussian modes into vortex light. Although the extracavity modulation method has the advantage of simple operation, this type of conversion element is often designed and processed for a specific wavelength band. At the same time, due to the damage threshold of the element, it is usually difficult to obtain high-power and high-energy vortex light output. The intracavity modulation method mainly includes: off-axis pumping, point defect mirror method, ring pumping method, etc., which are favored by researchers because they can obtain vortex light output directly from the cavity. They have the characteristics of compact structure, good beam quality and high output energy.

[0003] However, most of the solid-state vortex lasers that can currently obtain vortex light directly from the cavity have single-wavelength output, or dual-wavelength or multi-wavelength output with poor controllability and unadjustable power ratio.

[0004] With the development of vortex light technology, it is of great significance to realize dual-wavelength vortex light with precisely controllable wavelength and mode. Summary of the Invention

[0005] The present invention provides a dual-wavelength solid-state vortex laser with controllable wavelength and mode. This invention not only enables two single wavelengths to be selected or dual wavelengths to be output simultaneously, but also enables vortex light output with controllable output mode. The system is stable and easy to operate. By controlling the positions of the intracavity output mirror and the second focusing lens, combined with a quarter-wave plate to control the loss of a preset wavelength, the present invention achieves high-order vortex light output with selectable dual-port wavelength and mode. This device has broad application prospects, as described below:

[0006] A dual-wavelength solid-state vortex laser with controllable wavelength and mode, the laser comprising: a pump source,

[0007] The pump source emits pump light within the absorption band of the gain medium, which is output through the energy transmission fiber, collimated and focused by the coupling lens group, and enters the gain medium through the input mirror to generate inverse particle number to obtain laser light;

[0008] The input mirror and the output mirror form a resonant cavity with a first preset wavelength. The eigenmode in the resonant cavity is first focused by the first focusing lens in the cavity. The eigenmode is focused on the output mirror, forming spherical aberration. By adjusting the position of the output mirror, the controllable output of the fundamental transverse mode or vortex light can be achieved.

[0009] By controlling the positions of the output mirror and the second focusing lens and combining the angle control of the quarter-wave plate, a vortex light output with selectable wavelength and mode at the dual-port of the first preset wavelength and the second preset wavelength is achieved;

[0010] The first preset wavelength is generated by resonance in the resonant cavity formed by the input mirror and the output mirror, and the second preset wavelength is generated by resonance in the resonant cavity formed by the input mirror, the total reflection mirror and the thin film polarizer.

[0011] The pump source is a semiconductor laser with a central wavelength of 808 nm. The input mirror is a plane mirror coated with a pump light anti-reflection coating and a 1064 nm and 1342 nm high-reflection coating. The gain medium is a Nd:LuVO4 laser crystal with a doping concentration of 0.5 at.%, and a crystal size of 3 × 3 × 6 mm. 3 .

[0012] Furthermore, the first preset wavelength is 1342 nm, and the second preset wavelength is 1064 nm. The coupling lens group is a lens coated with a high-transmittance film for pump light, and its coupling ratio is 1:3.

[0013] The first focusing lens is a plano-convex lens coated with a 1064nm and 1342nm high-transmittance film, and the output mirror is a plane mirror coated with a 1342nm partial transmittance and a 1064nm anti-reflection film.

[0014] The second focusing lens is a plano-convex lens coated with a 1064nm and 1342nm high-transmittance film; the quarter-wave plate is coated with a 1064nm anti-reflection film.

[0015] The third focusing lens is a plano-convex lens coated with 1064nm and 1342nm high-transmittance films; the total reflection mirror is a plane mirror coated with 1342nm anti-reflection film and 1064nm high-reflection film.

[0016] The beneficial effects of the technical solution provided by the present invention are:

[0017] (1) The present invention can effectively achieve dual-port single wavelength or dual wavelength selectable and mode-switchable high-order vortex light output by inserting a focusing lens into the resonant cavity and adjusting the positions of the quarter-wave plate, the output mirror, and the second focusing lens;

[0018] (2) The present invention inserts a focusing lens into the dual-wavelength laser resonant cavity, thereby focusing the eigenmodes of preset wavelengths in the cavity separately, forming spherical aberration and realizing dual-wavelength vortex light output. The structure is simple, the operation is convenient, and it is suitable for application.

[0019] (3) The present invention realizes the output of vortex light with selectable wavelength by inserting a lens into the resonant cavity of the dual-wavelength laser. The structure has good stability and can realize the output of dual-wavelength vortex light with arbitrary power ratio. The wavelength and mode are controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of a dual-wavelength solid-state vortex laser with controllable wavelength and mode.

[0021] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0022]

[0023] DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are described in further detail below.

[0025] Example 1

[0026] The embodiment of the present invention provides a dual-wavelength solid-state vortex laser with controllable wavelength and mode, see Figure 1 , see the following description for details:

[0027] A wavelength- and mode-controllable dual-wavelength solid-state vortex laser comprises: a pump source 1, an energy transmission optical fiber 2, a coupling lens group 3, an input mirror 4, a gain medium 5, a first focusing lens 6, an output mirror 7, a second focusing lens 8, a thin-film polarizer 9, a quarter-wave plate 10, a third focusing lens 11, and a total reflection mirror 12.

[0028] Among them, the pump source 1 is a semiconductor laser with a central wavelength of 808nm and fiber-coupled output. The core size of the energy transmission fiber 2 is 105μm and the numerical aperture is 0.22. The coupling lens group 3 has a coupling ratio of 1:3 and its surface is coated with an 808nm high-transmittance film. The input mirror 4 is a plane mirror coated with an 808nm high-transmittance film and a 1064nm and 1342nm high-reflection film. The gain medium 5 is a Nd:LuVO4 laser crystal with a doping concentration of 0.5at.%, a crystal size of 3×3×6mm3, a-axis cut, the crystal is coated with indium platinum and water-cooled, and the cooling water temperature is 20°C. The focusing lens 6 is a plano-convex lens coated with a high-transmittance film for 1064nm and 1342nm; the output mirror 7 is a plane mirror coated with a high transmittance for 1064nm and a transmittance of 9% for 1342nm; the second focusing lens 8 is a plano-convex lens coated with a high-transmittance film for 1064nm and 1342nm; the thin-film polarizer 9 is at the Brewster angle; the quarter-wave plate 10 is coated with a 1064nm anti-reflection film; the third focusing lens 11 is a plano-convex lens coated with a high-transmittance film for 1064nm and 1342nm; the total reflection mirror 12 is a plane mirror coated with a high-reflection film for 1064nm and an anti-reflection film for 1342nm.

[0029] An 808nm semiconductor laser, serving as pump source 1, emits pump light within the gain medium's absorption band. This light is then output through a power transmission fiber 2, collimated and focused by a coupling lens assembly 3 with a 1:3 coupling ratio, and then enters a gain medium 5, a Nd:LuVO4 laser crystal, via an input mirror 4, generating sufficient population inversion to produce laser light. The input mirror 4 and the output mirror 7 form a resonant cavity with a first preset wavelength of 1342nm. The eigenmode within the 1342nm resonant cavity is first focused by a first focusing lens 6. This eigenmode is then focused onto the output mirror 7, causing spherical aberration. Adjusting the position of the output mirror 7 increases the fundamental mode loss, allowing higher-order modes within the cavity to oscillate. Consequently, by varying the position of the output mirror 7, controllable output of the 1342nm fundamental transverse mode or vortex light can be achieved. When the distance between the output mirror 7 and the first focusing lens 6 is d1, 1342nm vortex light output is achieved. At this point, at the position of the output mirror 7, the 1342nm vortex light is horizontally polarized. After that, after passing through the 1064nm thin-film polarizer 9 and the 1064nm quarter-wave plate 10, the S-polarization component and the P-polarization component experience different phase shifts and are converted into elliptically polarized light output.

[0030] The input mirror 4, the total reflection mirror 12, and the thin-film polarizer 9 form a polarization-dependent 1064nm laser resonant cavity. By varying the angle θ between the optical axis of the quarter-wave plate 10 and the polarization direction of the horizontal linear polarization, different 1064nm resonant cavity output transmittances can be achieved. The 1064nm laser is excited from the gain medium 5, focused by the first focusing lens 6, and then diverged. It passes through the output mirror 7 coated with a 1064nm antireflection film, and is focused by the second focusing lens 8 onto the thin-film polarizer 9. There, it is converted into P light (horizontally polarized light). After rotating the quarter-wave plate 10, it is converted into circularly polarized light. It is refocused by the third focusing lens 11 onto the total reflection mirror 12. Reflected by the total reflection mirror 12, it passes through the quarter-wave plate 10 a second time and is converted into S light (vertically polarized light). It is then reflected from the thin-film polarizer 9 for output. The 1064nm eigenmode is focused onto the thin-film polarizer 9 due to its second passage through the third focusing lens 11, and the output is a Gaussian mode. Since the high-order mode and the low-order mode have different spot sizes, adjusting the position of the second focusing lens 8, that is, changing the distance d2 between the second focusing lens 8 and the output mirror 7, can introduce 1064nm spherical aberration, so that the focus of the high-order mode falls on the thin-film polarizer 9, and the fundamental mode has a certain offset in its focusing position due to its different spot size from the high-order mode, and its focus is far away from the thin-film polarizer 9, resulting in a larger fundamental mode loss, so that the high-order mode in the cavity can oscillate in the cavity, thereby obtaining 1064nm vortex light output. Therefore, by changing the position of the second focusing lens 8, the controllable output of the 1064nm fundamental transverse mode or vortex light can be achieved. In addition, since the 1064nm horizontally polarized light passes through the quarter-wave plate 10 twice, its polarization direction rotates by 2θ relative to the horizontal polarization direction (where θ is the angle between the P-polarized light and the optical axis of the quarter-wave plate 10), and the 1064nm laser coupling output transmittance is T=sin 2 (2θ). Therefore, by changing the rotation angle of the quarter wave plate 10, different output transmittances of 1064nm can be obtained, thereby further adjusting the power ratio of 1064nm and 1342nm. Therefore, by accurately controlling the rotation angle of the quarter wave plate 10, vortex light output of a single wavelength of 1342nm or 1064nm can be achieved, and dual-wavelength vortex light output of different power ratios can also be achieved. At the same time, the 1342nm laser transverse mode mode can be achieved by adjusting the position of the output mirror 7, that is, changing the distance d1 between the output mirror 7 and the first focusing lens 6 to realize the controllable output of the fundamental transverse mode or vortex light; and the 1064nm laser transverse mode mode can be achieved by adjusting the position of the second focusing lens 8, that is, changing the distance d2 between the second focusing lens 8 and the output mirror 7 to realize the controllable output of the fundamental transverse mode or vortex light. In actual application, the gain medium 5 can be Nd:LuVO4 crystal, Nd:YVO4 crystal, etc.

[0031] The pump source 1 is a semiconductor laser with a central wavelength of 808 nm, and the input mirror 4 is a plane mirror coated with a pump light anti-reflection film and a 1064 nm and 1342 nm high-reflection film.

[0032] Preferably, the gain medium 5 is a Nd:LuVO4 laser crystal with a doping concentration of 0.5 at.%, and a crystal size of 3×3×6 mm. 3 .

[0033] The first preset wavelength is 1342 nm, and the second preset wavelength is 1064 nm.

[0034] Preferably, the coupling lens group 3 is a lens coated with a high transmittance film for pump light, and its coupling ratio is 1:3. The first focusing lens 6 is a plano-convex lens coated with a high transmittance film for 1064nm and 1342nm.

[0035] The output mirror 7 is a plane mirror coated with a 1342nm partial transmittance and a 1064nm anti-reflection film.

[0036] The second focusing lens 8 is a plano-convex lens coated with a 1064nm and 1342nm high-transmittance film, and the quarter-wave plate 10 is coated with a 1064nm anti-reflection film.

[0037] The third focusing lens 11 is a plano-convex lens coated with 1064nm and 1342nm high-transmittance films. The total reflection mirror 12 is a plane mirror coated with 1342nm anti-reflection film and 1064nm high-reflection film.

[0038] It should be noted that any implementations not shown or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods described in the embodiments; those skilled in the art may easily modify or replace them.

[0039] It should also be noted that examples of parameters including specific values ​​may be provided herein, but these parameters do not need to be exactly equal to the corresponding values, but may be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint.

[0040] Unless otherwise specified, the embodiments of the present invention do not limit the models of the components. Any component that can perform the above functions may be used.

[0041] Those skilled in the art will understand that the accompanying drawings are only a schematic diagram of a preferred embodiment, and the serial numbers of the embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-wavelength solid-state vortex laser with controllable wavelength and mode, the laser comprising: A pump source, characterized in that The pump source emits pump light within the absorption band of the gain medium, which is output through the energy transmission fiber, collimated and focused by the coupling lens group, and enters the gain medium through the input mirror to generate inverse particle number to obtain laser light; The input mirror and the output mirror form a resonant cavity with a first preset wavelength. The eigenmode in the resonant cavity is first focused by the first focusing lens in the cavity. The eigenmode is focused on the output mirror, forming spherical aberration. By adjusting the position of the output mirror, the controllable output of the fundamental transverse mode or vortex light can be achieved. By controlling the positions of the output mirror and the second focusing lens and combining the angle control of the quarter-wave plate, a vortex light output with selectable wavelength and mode at the dual-port of the first preset wavelength and the second preset wavelength is achieved; The first preset wavelength is generated by resonance in the resonant cavity formed by the input mirror and the output mirror, and the second preset wavelength is generated by resonance in the resonant cavity formed by the input mirror, the total reflection mirror and the thin film polarizer.

2. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The pump source is a semiconductor laser with a central wavelength of 808 nm; the input mirror is a plane mirror coated with a pump light anti-reflection film and 1064 nm and 1342 nm high-reflection films.

3. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The gain medium is Nd:LuVO4 laser crystal with a doping concentration of 0.5 at.%, and a crystal size of 3×3×6 mm. 3 .

4. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The first preset wavelength is 1342 nm, and the second preset wavelength is 1064 nm.

5. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The coupling lens group is a lens coated with a high-transmittance film for pump light, and its coupling ratio is 1:

3.

6. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The first focusing lens is a plano-convex lens coated with a 1064 nm and 1342 nm high-transmittance film.

7. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The output mirror is a plane mirror coated with a 1342 nm partial transmittance and a 1064 nm anti-reflection film.

8. The wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, characterized in that: The second focusing lens is a plano-convex lens coated with a 1064 nm and 1342 nm high-transmittance film; the quarter-wave plate is coated with a 1064 nm anti-reflection film.

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