A planar hollow vortex optical field laser

Abstract

The application discloses a kind of plane hollow vortex light field lasers, including fiber-coupled output semiconductor laser array (1), plano-convex lens (2), axicon lens (3), laser gain medium (4) and axicon lens (5). Fiber-coupled output semiconductor laser array (1) is the pump source of laser;Pump beam coupling system is composed of plano-convex lens (2) and axicon lens (3), generates focusing annular beam for exciting vortex phase laser to run in resonant cavity;Axicon lens (3) conical surface and axicon lens (5) cylindrical surface constitute the resonant cavity of laser, for obtaining the center as circular hollow plane vortex light field laser. Plane hollow vortex light field laser can be used for the inside processing and cutting of cylindrical material, high-precision plane scanning or plane polishing and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser, and particularly relates to a planar hollow vortex light field laser. BACKGROUND

[0002] In recent years, people have designed and implemented different forms of hollow lasers, such as anti-Gaussian hollow laser (patent 201811357253.9), double half anti-Gaussian hollow laser (patent 201811357117.X), double Gaussian hollow laser, double half Gaussian hollow laser (patent 201811208397.8), non-uniform polarization hollow laser (patent 201910065979.3), and multi-wavelength hollow laser (patent 201910066066.3), etc. These hollow laser beams have large dark spot size, high light intensity contrast, and can maintain high stability when the central dark spot area is transmitted to the far field. Hollow laser beams have important application prospects in the fields of scanning imaging, laser ranging, neutral atom laser cooling, and laser collimation of cold atom beams. If the hollow beam has a spiral structure of the wavefront phase, each photon carries orbital angular momentum, which can make it have important application prospects in the fields of super-resolution microscopic imaging, nonlinear optics, quantum optics, high-capacity optical communication, bio-photonics, nano-photonics, micro-nano processing, and optical manipulation of micro-particles and biological cells. Recently, people have developed different kinds of vortex phase hollow lasers, such as hollow laser with vortex phase multiple modes (patent 202111665250.3) and cylindrical vector laser with adjustable vortex phase topological charge number (patent 202111663417.2).

[0003] The common point of the above-mentioned vortex phase hollow lasers is that the beam intensity is distributed in a cylindrical shape, which is helpless for the actual needs of inside machining and cutting of cylindrical materials, high-precision planar scanning, and planar polishing, which limits the application of vortex hollow beams. However, planar light field lasers can meet the above-mentioned needs, and the vortex phase carried by the laser can improve the cutting efficiency of the material, the polishing quality, and the precision of planar scanning. SUMMARY

[0004] The application aims to provide a planar hollow vortex light field laser to solve the technical problems in the background art.

[0005] In order to solve the technical problems, the technical scheme of the application is as follows:

[0006] A planar hollow vortex light field laser comprises a fiber-coupled semiconductor laser array, and further comprises a plano-convex lens, an axicon lens, a laser gain medium, and an axicon lens arranged along the optical axis of the emitted light beam.

[0007] The semiconductor laser array coupled by the fiber serves as the pump source for the laser. The beam emitted from the pump source is collimated by a plano-convex lens and then formed into an axisymmetric parallel diverging beam by the conical surface of an axial-cone lens. After being focused by the convex surface of the axial-cone lens, the parallel beams from different directions converge to a point, forming a circular focusing ring on the focal plane of the axial-cone lens when viewed from the 2π direction. The focusing ring beam pumps the laser gain medium and excites a vortex phase light field laser to operate within the resonant cavity.

[0008] Furthermore, the conical surface of the axial-cone lens and the cylindrical surface of the axial-cone lens constitute the resonant cavity of the laser, which is used to obtain a hollow planar laser with a circular center.

[0009] Furthermore, the pump beam coupling system of the laser consists of a plano-convex lens and an axono-cone lens, which generates a focused circular beam to excite the vortex phase laser to operate within the cavity.

[0010] Furthermore, the conical surface of the axial-conical lens serves as the input mirror of the resonant cavity, with an anti-reflection coating deposited on the pump light and a high-reflection coating deposited on the laser, while the convex surface of the axial-conical lens is coated with an anti-reflection coating on the pump light; the cylindrical surface of the axial-conical lens serves as the output coupling mirror of the resonant cavity, with an anti-reflection coating deposited on the laser on the convex surface, a reflective coating deposited on the laser on the conical surface, and a dielectric film with a transmittance of 5-10% deposited on the cylindrical surface of the laser.

[0011] Furthermore, the laser gain medium is placed on the common focal plane of the two convex surfaces of the axial conical lens and the axial conical lens, and its light transmission surface is the pump light and the laser-coated antireflection film.

[0012] Furthermore, the cone angle α of the cone surface of the axial-cone lens, the focal length f1 of the convex surface, the refractive index n, and the pump focal ring radius r satisfy cos(α / 2)=nsin[α-tan -1 [(r / f1)] relation.

[0013] Furthermore, the cone angle β of the cone surface of the axial cone lens, the focal length f2 of the convex surface, and the pump focal ring radius r satisfy the relationship r = f2 / tanβ.

[0014] Furthermore, the cone angle α of the axial-cone lens cone surface, the focal length f1 of the convex surface, the refractive index n, and the cone angle β of the axial-cone lens cone surface and the focal length f2 of the convex surface satisfy the following:

[0015] cos(α / 2)=nsin[α-tan -1 The relationship is (f2 / f1tanβ).

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] The laser of the plane hollow vortex light field can overcome the defects of the prior art, that is, the laser can realize the machining and cutting of the inner side of the cylindrical material and the high-precision plane polishing and plane scanning, and the vortex phase carried by the plane hollow laser improves the machining and cutting efficiency of the material, the plane polishing quality and the plane scanning precision. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a schematic diagram of the laser structure of the present application.

[0019] Figure 2 The figure is a schematic diagram of the plane hollow vortex light field laser distribution (the arrow is the propagation direction of the laser). DETAILED DESCRIPTION

[0020] The specific embodiment of the present application will be described below in combination with the examples:

[0021] It should be noted that the structures, proportions, sizes, etc. shown in the present application are only used to cooperate with the content disclosed in the present application, so as to be understood and read by those skilled in the art, and are not used to limit the conditions that can be implemented by the present application. Any modification of the structure, change of the proportional relationship or adjustment of the size, which does not affect the effects and purposes that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0022] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" in the present application are only used for the convenience of clear description, and are not used to limit the scope of the present application. The change or adjustment of the relative relationship, without substantial change of the technical content, is also regarded as the scope of the present application.

[0023] Example 1:

[0024] The present application provides a plane hollow vortex light field laser, and the output beam of the laser is a circular hollow plane vortex light field. The present application is realized by the following technical scheme: a plane hollow vortex light field laser, as shown in Figure 1As shown, from left to right, the semiconductor laser array 1 with fiber-coupled output, plano-convex lens 2, axicon lens 3, laser gain medium 4 and axicon lens 5 are arranged in sequence. The semiconductor laser array 1 with fiber-coupled output is the pump source of the laser; the pump beam coupling system is composed of plano-convex lens 2 and axicon lens 3, the light beam emitted by the pump source is collimated by plano-convex lens 2 and then forms an axisymmetric parallel divergent light beam by the conical surface of axicon lens 3, and then the light beam is focused by the convex surface of axicon lens 3, and different parallel light beams converge at a point, and a circular focusing ring is formed on the focal plane of axicon lens 3 from the 2π direction, and the focusing ring light beam pumps the laser gain medium 4 to excite vortex phase light field laser to run in the resonant cavity; the conical surface of axicon lens 3 and the cylindrical surface of axicon lens 5 constitute the resonant cavity of the laser, which is used to obtain the center circular hollow plane laser, Figure 2 The conical surface of axicon lens 3 is the input mirror of the resonant cavity, and the conical surface is coated with an antireflection film for the pump light and a high-reflection film for the laser, and the convex surface is coated with an antireflection film for the pump light; the cylindrical surface of axicon lens 5 is the output coupling mirror of the resonant cavity, and the convex surface is coated with an antireflection film for the laser, the conical surface is coated with a high-reflection film for the laser, and the cylindrical surface is coated with a dielectric film with a transmittance of 5-10% for the laser; in order to obtain the best power density and mode matching of the pump light and the laser, the laser gain medium 4 is placed on the common focal plane of the two convex surfaces of axicon lens 3 and axicon lens 5, and the light transmission surface is coated with an antireflection film for the pump light and the laser.

[0025] Suppose the radius of the pump focal ring of the laser is r, the refractive index of axicon lens 3 is n, the focal length of the convex surface is f1, the cone angle of the conical surface is α, the refraction angle of the pump light beam passing through the conical surface of axicon lens 3 is ρ, and the angle between the refracted light and the horizontal axis of the laser system is ω1, in order to satisfy the condition that the laser in the resonant cavity is perpendicular to the conical surface of axicon lens 3, then

[0026] sin[(π-α) / 2]=nsinρ (1)

[0027] ω1=α-ρ (2)

[0028] r=f1tanω1 (3)

[0029] Solving equations 1-3 simultaneously gives

[0030] cos(α / 2)=nsin[α-tan -1 (r / f1)] (4)

[0031] Suppose the focal length of the convex surface of axicon lens 5 is f2, the cone angle of the conical surface is β, the deflection angle of the cavity laser passing through the convex surface of axicon lens 5 is ω2, and the incident angle of the cavity laser on the conical surface of axicon lens 5 is θ, in order to satisfy the condition that the laser in the resonant cavity is perpendicular to the cylindrical surface of axicon lens 5, then

[0032] r = f2tan ω2 (5)

[0033] ω2+ 2θ = π / 2 (6)

[0034] θ = β / 2 (7)

[0035] Solving equations 5-7, we have

[0036] r = f2 / tan β (8)

[0037] In order to obtain the plane hollow vortex light field laser running in the resonator and make the laser output from the cylindrical surface of the axicon 5, solving equations 4 and 8, we have:

[0038] cos(α / 2) = n sin [α - tan -1 (f2 / f1tan β)] (9)

[0039] Example 2:

[0040] The following unit devices can be used to realize the plane hollow vortex light field laser: the output wavelength of the fiber-coupled semiconductor laser array 1 is 808 nm, the fiber core diameter is 400 μm, and the numerical aperture is 0.22; the focal length of the plano-convex lens 2 is 200 mm, and the light transmission surface thereof is coated with 808 nm antireflection film; the axicon 3 is made of K9 glass with n = 1.52, the cone angle α = 70°, the focal length of the convex surface is 58 mm, and the cone surface and the convex surface are coated with 808 nm antireflection film, and the cone surface is coated with 1064 nm high reflection film; the laser gain medium 4 is made of Nd:YAG crystal, the Nd 3+ doping concentration, the light transmission surface thereof is coated with 808 nm and 1064 nm antireflection film; the pump source and the Nd:YAG crystal are cooled by TEC, and the temperature is controlled in the range of 15°±0.5°; the axicon 5 is made of K9 glass, the cone angle β = 60°, the focal length of the convex surface is 50 mm, the convex surface is coated with 1064 nm antireflection film, the cone surface is coated with 1064 nm high reflection film, and the cylindrical surface is coated with 10% medium film for 1064 nm transmittance.

[0041] Example 3:

[0042] The following unit devices can be used to realize the plane hollow vortex light field laser: the output wavelength of the fiber-coupled semiconductor laser array 1 is 940 nm, the fiber core diameter is 400 μm, and the numerical aperture is 0.22; the focal length of the plano-convex lens 2 is 200 mm, and the light transmission surface thereof is coated with 808 nm antireflection film; the axicon 3 is made of quartz glass with n = 1.46, the cone angle α = 80°, the focal length of the convex surface is 11 mm, and the cone surface and the convex surface are coated with 940 nm antireflection film, and the cone surface is coated with 1030 nm high reflection film; the laser gain medium 4 is made of Yb:YAG crystal, the Yb 3+The doping concentration is 940 nm and 1030 nm antireflection film is coated on the light-incident surface; the pump source and Yb:YAG crystal are cooled by TEC and the temperature is controlled in the range of 15°±0.5°; the axicon lens 5 is made of quartz glass, the cone angle β=50°, the focal length of the convex surface is 15 mm, the convex surface is coated with 1030 nm antireflection film, the cone surface is coated with 1030 nm high reflection film, and the cylindrical surface is coated with 5% dielectric film for 1030 nm.

[0043] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

[0044] Many other changes and modifications can be made to the application without departing from the spirit and scope of the application. It is to be understood that the application is not limited to the specific embodiments described herein, but only by the claims made and their equivalents.

Claims

1. A planar hollow vortex laser, characterized in that, include: The fiber-coupled semiconductor laser array (1) also includes a plano-convex lens (2), an axono-cone lens (3), a laser gain medium (4), and an axono-cone lens (5) arranged along the optical axis of the emitted beam; The semiconductor laser array (1) output by the fiber coupling is the pump source of the laser. The beam emitted by the pump source is collimated by the plano-convex lens (2) and then formed into an axisymmetric parallel diverging beam by the conical surface of the axial conical lens (3). After being focused by the convex surface of the axial conical lens (3), the parallel beams in different directions converge to a point. From the 2π direction, a circular focusing ring is formed on the focal plane of the axial conical lens (3). The focusing ring beam pumps the laser gain medium (4) to excite the vortex phase light field laser to run in the resonant cavity.

2. The planar hollow vortex laser according to claim 1, characterized in that, The conical surface of the axial conical lens (3) and the cylindrical surface of the axial conical lens (5) constitute the resonant cavity of the laser, which is used to obtain a hollow planar laser with a circular center.

3. A planar hollow vortex laser according to claim 1, characterized in that, The pump beam coupling system of the laser consists of a plano-convex lens (2) and an axono-cone lens (3), which generates a focused circular beam to excite the vortex phase laser to run in the cavity.

4. A planar hollow vortex laser according to claim 1, characterized in that, The conical surface of the axial-conical lens (3) is the input mirror of the resonant cavity. Its conical surface is coated with an anti-reflection film for the pump light, and at the same time, the conical surface is coated with a high-reflection film for the laser, while the convex surface is coated with an anti-reflection film for the pump light. The cylindrical surface of the axial-conical lens (5) is the output coupling mirror of the resonant cavity. The convex surface is coated with a laser anti-reflection film, the conical surface is coated with a laser reflection film, and the cylindrical surface is coated with a dielectric film with a transmittance of 5-10% for the laser.

5. A planar hollow vortex laser according to claim 1, characterized in that, The laser gain medium (4) is placed on the common focal plane of the two convex surfaces of the axial conical lens (3) and the axial conical lens (5), and its light transmission surface is the pump light and the laser coating antireflection film.

6. A planar hollow vortex laser according to claim 1, characterized in that, The cone angle α of the cone surface of the axial-cone lens (3), the focal length f1 of the convex surface, the refractive index n, and the pump focal ring radius r satisfy cos(α / 2)=nsin[α-tan -1 [(r / f1)] relation.

7. A planar hollow vortex laser according to claim 1, characterized in that, The cone angle β of the cone surface of the axial cone lens (5), the focal length f2 of the convex surface, and the pump focal ring radius r satisfy the relationship r=f2 / tanβ.

8. A planar hollow vortex laser according to claim 1, characterized in that, The cone angle α of the cone surface of the axial conical lens (3), the focal length f1 of the convex surface, and the refractive index n satisfy the same conditions as the cone angle β of the cone surface of the axial conical lens (5) and the focal length f2 of the convex surface: cos(α / 2)=nsin[α-tan -1 The relationship is (f2 / f1tanβ).

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