CN115954750A - A wavelength- and mode-controllable dual-wavelength solid-state vortex laser - Google Patents

Abstract

The invention discloses a dual-wavelength solid vortex laser with controllable wavelength and mode.A pumping source emits pumping light in a gain medium absorption band, the pumping light is output through an energy transmission optical fiber, collimated and focused through a coupling lens group, enters a gain medium through an input mirror, and generates reversed particle number to obtain laser; the input mirror and the output mirror form a resonant cavity with a first preset wavelength, an eigenmode in the resonant cavity is firstly focused by a first focusing lens in the cavity, the eigenmode is focused on the output mirror to form spherical aberration, and the controllable output of a fundamental transverse mode or an eddy optical rotation is realized by adjusting the position of the output mirror; vortex light output with selectable first preset wavelength and second preset wavelength dual-port wavelength and mode is realized by controlling the positions of the output mirror and the second focusing lens and combining the angle control of the quarter-wave plate; the first preset wavelength is generated in a resonant cavity formed by the input mirror and the output mirror in a resonant mode, and the second preset wavelength is generated in a resonant cavity formed by the input mirror, the total reflection mirror and the thin film polaroid in a resonant mode.

Description

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

technical field

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

Background technique

Vortex light has important applications in the fields of optical manipulation, imaging, and optical communication due to its characteristics of carrying orbital angular momentum information and spiral phase. At present, there are mainly two methods for obtaining vortex light, namely, extracavity modulation method and intracavity modulation method. The external cavity modulation is mainly based on devices such as helical phase plate, q plate and spatial light modulator to perform modulation outside the cavity, which can directly convert Gaussian mode 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, it is usually difficult to obtain high-power and high-energy vortex light output due to the damage threshold of the element. The intracavity modulation methods mainly include: off-axis pumping, point defect mirror method, ring pumping method, etc., which are favored by researchers because they can directly obtain vortex light output from the cavity, and have the advantages of compact structure, good beam quality and output High energy characteristics.

However, at present, most of the solid-state vortex lasers that can directly obtain vortex light from the cavity are single-wavelength output, or dual-wavelength or multi-wavelength output with weak controllability and non-adjustable power ratio.

With the development of vortex light technology, it is of great significance to realize a dual-wavelength vortex light with precise controllable wavelength and mode.

Contents of the invention

The invention provides a dual-wavelength solid-state vortex laser with controllable wavelength and mode. The invention can not only realize two kinds of single-wavelength optional or dual-wavelength simultaneous output, but also can realize vortex light output with controllable output mode, and the system is stable. , the operation is simple; the present invention controls the position of the output mirror and the second focusing lens in the cavity, and combines the quarter-wave plate to control the loss of the preset wavelength to realize the dual-port wavelength and mode selectable high-order vortex light output, which has a wide range of For the application prospect, please refer to the description below:

A dual-wavelength solid-state vortex laser with controllable wavelength and mode, the laser includes: a pump source,

The pump source emits the pump light in the absorption band of the gain medium, outputs it through the energy transmission fiber, collimates and focuses it through the coupling lens group, enters the gain medium through the input mirror, and generates a reversed particle number to obtain laser light;

The input mirror and the output mirror constitute a resonant cavity with the first preset wavelength. The eigenmodes in the resonant cavity are first focused by the first focusing lens in the cavity, and the eigenmodes are focused on the output mirror to form spherical aberration. By adjusting The position of the output mirror realizes the controllable output of the fundamental transverse mode or vortex light;

By controlling the position of the output mirror and the second focusing lens, combined with the angle control of the quarter-wave plate, the vortex light output with the first preset wavelength and the second preset wavelength dual-port wavelength and mode can be selected;

The first preset wavelength is resonantly generated in the resonant cavity formed by the input mirror and the output mirror, and the second preset wavelength is resonantly generated in the resonant cavity formed by the input mirror, the total reflection mirror and the film polarizer.

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

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

Wherein, the first focusing lens is a plano-convex lens coated with 1064nm and 1342nm high-transparency films. The output mirror is a flat mirror coated with 1342nm partial transmittance and 1064nm anti-reflection coating.

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

The third focusing lens is a plano-convex lens coated with 1064nm and 1342nm high-transparency films; the total reflection mirror is a plane mirror coated with 1342nm antireflection film and 1064nm high-reflection film.

The beneficial effects of the technical solution provided by the invention are:

(1) The present invention can effectively realize dual-port single-wavelength or dual-wavelength selectable, mode-switchable high order vortex light output;

(2) By inserting a focusing lens into the resonant cavity of a dual-wavelength laser, the present invention can respectively focus the eigenmodes of preset wavelengths in the cavity, form spherical aberration, and realize dual-wavelength vortex light output. The structure is simple, the operation is convenient, and it is suitable for application;

(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, has good structural stability, and can realize dual-wavelength vortex light output with any power ratio, and the wavelength and mode are controllable.

Description of drawings

Fig. 1 is a schematic structural diagram of a wavelength and mode controllable dual-wavelength solid-state vortex laser.

In the accompanying drawings, the parts list represented by each label is as follows:

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below.

Example 1

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

A dual-wavelength solid-state vortex laser with controllable wavelength and mode, comprising: a pump source 1, an energy transmission 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 .

Among them, the pump source 1 is a semiconductor laser with a central wavelength of 808nm and is coupled out by an optical fiber. The core size of the energy transmission fiber 2 is 105 μm and the numerical aperture is 0.22; the coupling lens group 3 with a coupling ratio of 1:3 is coated with 808nm high-transparency film; input mirror 4 is a plane mirror coated with 808nm high-transparency film, 1064nm and 1342nm high-reflection film; gain medium 5 is Nd:LuVO4 laser crystal, doping concentration 0.5at.%, crystal size 3×3×6mm3 , a-axis cutting, the crystal is wrapped with indium platinum and water-cooled, the cooling water temperature is 20°C; the first focusing lens 6 is a plano-convex lens coated with 1064nm and 1342nm high-transparency films; A flat mirror with a transmittance of 9%; the second focusing lens 8 is a plano-convex lens coated with 1064nm and 1342nm high-transmittance films; the film polarizer 9 is at the position of Brewster's angle; anti-reflection coating; the third focusing lens 11 is a plano-convex lens coated with 1064nm and 1342nm high-transparency coatings; the total reflection mirror 12 is a flat mirror coated with a 1064nm high-reflection coating and a 1342nm anti-reflection coating.

The 808nm semiconductor laser is used as the pump source 1 to emit the pump light in the absorption band of the gain medium, which is output through the energy transmission fiber 2, collimated and focused through the coupling lens group 3 with a coupling ratio of 1:3, and enters the gain medium 5 through the input mirror 4, That is, the Nd:LuVO4 laser crystal produces enough inversion particle numbers to obtain laser light. The input mirror 4 and the output mirror 7 constitute a resonant cavity with a first preset wavelength of 1342nm. The eigenmode in the 1342nm resonant cavity is firstly focused by the first focusing lens 6 in the cavity, and the eigenmode is focused on the output mirror 7 to form spherical aberration. By adjusting the position of the output mirror 7, the loss of the fundamental mode becomes larger , and the high-order mode in the cavity can oscillate in the cavity. Therefore, by changing the position of the output mirror 7, the controllable output of the 1342nm fundamental transverse mode or vortex light can be realized. When the distance between the output mirror 7 and the first focusing lens 6 is d1, the 1342nm vortex light output is realized, and at the position of the output mirror 7, the 1342nm vortex light is horizontally polarized light. Afterwards, after passing through the 1064nm thin-film polarizer 9 and the 1064nm quarter-wave plate 10, due to the different phase shifts of the S-polarized component and the P-polarized component, the output is transformed into elliptically polarized light.

The input mirror 4, the total reflection mirror 12 and the film polarizer 9 constitute a polarization-dependent 1064nm laser resonant cavity. And by changing the angle θ between the optical axis direction of the quarter-wave plate 10 and the polarization direction of the horizontal linear polarization, different output transmittances of the 1064nm resonant cavity can be realized. The 1064nm laser is excited from the gain medium 5, diverges after being focused by the first focusing lens 6, passes through the output mirror 7 coated with a 1064nm anti-reflection film, and focuses on the thin-film polarizer 9 through the second focusing lens 8, and passes through the thin-film polarizer 9 is converted into P light (horizontally polarized light), converted into circularly polarized light after rotating the quarter-wave plate 10, focused to the total reflection mirror 12 again through the third focusing lens 11, and reflected by the total reflection mirror 12 for the second time It is converted into S light (vertically polarized light) by the quarter-wave plate 10 and reflected from the film polarizer 9 to output. The 1064nm eigenmode is focused onto the thin-film polarizer 9 by passing through the third focusing lens 11 for the second time, and the output at this time 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 focal position of the fundamental mode has a certain offset due to the different spot size from the high-order mode, and its focus is far away from the thin film polarizer 9, resulting in a larger loss of the fundamental mode, so that the high-order mode in the cavity can oscillate in the cavity, In order to obtain 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 realized. In addition, since the 1064nm horizontally polarized light passes through the quarter-wave plate 10 twice, its polarization direction is rotated by 2θ with respect to the horizontal polarization direction (wherein, θ is the angle between the optical axis of the P-polarized light and the quarter-wave plate 10 ), 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 precisely controlling the rotation angle of the quarter-wave plate 10 , vortex light output with a single wavelength of 1342 nm or 1064 nm can be realized, and dual-wavelength vortex light output with different power ratios can also be realized. At the same time, the 1342nm laser transverse mode mode can realize the controllable output of the fundamental transverse mode or vortex light 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; and the 1064nm laser transverse mode mode can be The controllable output of the fundamental transverse mode or vortex light is realized 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 . In practical application, the gain medium 5 can be Nd:LuVO ₄ crystal, Nd:YVO ₄ crystal or the like.

Wherein, the pumping source 1 is a semiconductor laser with a central wavelength of 808nm. The input mirror 4 is a plane mirror coated with an anti-reflection coating for pump light, and high reflection coatings for 1064nm and 1342nm.

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 .

Wherein, the first preset wavelength is 1342nm, and the second preset wavelength is 1064nm.

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 high-permeability films of 1064nm and 1342nm.

The output mirror 7 is a plane mirror coated with a 1342nm partial transmittance and a 1064nm antireflection film.

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

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

It should be noted that, in the accompanying drawings or in the text of the specification, implementations that are not shown or described are forms known to those of ordinary skill in the art, and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them.

It should also be noted that the text may provide examples of parameters that include specific values, but these parameters need not be exactly equal to the corresponding values, but may approximate the corresponding values within acceptable error tolerances or design constraints.

In the embodiments of the present invention, unless otherwise specified, the models of the devices are not limited, as long as they can complete the above functions.

Those skilled in the art can understand that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the above-mentioned embodiments of the present invention are for description only, and do not represent the advantages and disadvantages of the embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

1. A dual-wavelength solid-state vortex laser with controllable wavelength and mode, said laser comprising: a pumping source, characterized in that, The pump source emits the pump light in the absorption band of the gain medium, outputs it through the energy transmission fiber, collimates and focuses it through the coupling lens group, enters the gain medium through the input mirror, and generates a reversed particle number to obtain laser light; The input mirror and the output mirror constitute a resonant cavity with the first preset wavelength. The eigenmodes in the resonant cavity are first focused by the first focusing lens in the cavity, and the eigenmodes are focused on the output mirror to form spherical aberration. By adjusting The position of the output mirror realizes the controllable output of the fundamental transverse mode or vortex light; By controlling the position of the output mirror and the second focusing lens, combined with the angle control of the quarter-wave plate, the vortex light output with the first preset wavelength and the second preset wavelength dual-port wavelength and mode can be selected; The first preset wavelength is resonantly generated in the resonant cavity formed by the input mirror and the output mirror, and the second preset wavelength is resonantly generated in the resonant cavity formed by the input mirror, the total reflection mirror and the film polarizer. 2. A dual-wavelength solid-state vortex laser with controllable wavelength and mode according to claim 1, wherein the pump source is a semiconductor laser with a central wavelength of 808nm; the input mirror is coated with a pump light amplifier Transparent film, plane mirror with 1064nm and 1342nm high reflection film. 3. a kind of wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, is characterized in that, described gain medium is Nd:LuVO4 laser crystal, doping concentration 0.5at.%, crystal size 3 ×3×6mm ³ . 4. A wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1, wherein the first preset wavelength is 1342nm, and the second preset wavelength is 1064nm. 5. A dual-wavelength solid-state vortex laser with controllable wavelength and mode according to claim 1, wherein the coupling lens group is a lens coated with a high-transparency film for pump light, and its coupling ratio is 1 :3. 6 . A wavelength and mode controllable dual-wavelength solid-state vortex laser according to claim 1 , wherein the first focusing lens is a plano-convex lens coated with high-transparency films of 1064 nm and 1342 nm. 7 . A dual-wavelength solid-state vortex laser with controllable wavelength and mode according to claim 1 , wherein the output mirror is a flat mirror coated with a 1342nm partial transmittance and a 1064nm anti-reflection coating. 8. A dual-wavelength solid-state vortex laser with controllable wavelength and mode according to claim 1, characterized in that, the second focusing lens is a plano-convex lens coated with 1064nm and 1342nm high-transparency films; One waveplate is coated with a 1064nm AR coating. 9. A dual-wavelength solid-state vortex laser with controllable wavelength and mode according to claim 1, characterized in that, the third focusing lens is a plano-convex lens coated with a high-transparency film of 1064nm and 1342nm; a total reflection mirror It is a flat mirror coated with 1342nm antireflection coating and 1064nm high reflection coating.

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