Controllable vortex dual-ring laser based on fixed-intercept zooming ring pump orthogonal polarization

Abstract

The application discloses a fixed-intercept zooming ring pumping orthogonal polarization controllable vortex double-ring laser, which comprises a fiber-coupled output semiconductor laser array (1), a plano-convex lens (2), a fixed-intercept zooming ring pumping beam generating system (3), a first conical mirror (4), a laser gain medium (5), a V-shaped crystal conical mirror (6), a plane mirror (7) and a second conical mirror (8). The laser can realize orthogonal polarization controllable vortex double-ring laser output, and the topological charge number of the laser vortex phase can be continuously adjusted. The fixed-intercept zooming ring pumping system can make the laser maintain high mode matching degree during the adjustment process. The spin angular momentum and the orbital angular momentum carried by the laser beam can improve the particle trapping efficiency and reduce the thermal damage of the biological cells caused by the laser beam. The double polarization characteristics of the inner ring tangential and the outer ring radial can be fully utilized, the particle can be captured, and high-resolution imaging can be performed at the same time, so that the application of the vector vortex light field in the biomedical field can be greatly expanded.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more specifically to a tunable vortex dual-ring laser based on a fixed-intercept variable-focus ring pumped by an orthogonal polarization. Background Technology

[0002] Hollow light fields play a crucial role in optical imaging, optical trapping, optical information processing, electron acceleration, and optical manipulation of microscopic particles. In recent years, various types of hollow light field lasers have been designed and implemented, such as anti-Gaussian hollow lasers (patent 201811357253.9), double-and-a-half anti-Gaussian hollow lasers (patent 201811357117.X), double-Gaussian hollow lasers, double-and-a-half Gaussian hollow lasers (patent 201811208397.8), non-uniformly polarized hollow lasers (patent 201910065979.3), and multi-wavelength hollow lasers (patent 201910066066.3). These hollow lasers possess large dark spot sizes, and under certain conditions, their beam width-to-radius ratio can produce high light intensity contrast, enabling effective intensity gradient cooling. Recently, various types of vortex-phase hollow lasers have been developed, such as hollow lasers with vortex-phase multiple modes (patent 202111665250.3) and cylindrical vector lasers with tunable vortex phase topological charge (patent 202111663417.2). However, these vortex-phase hollow lasers share the common feature of having a single polarization and a single-ring intensity distribution, meaning that when used as "optical tweezers," they can only capture a specific type of particle with similar properties.

[0003] This invention realizes an orthogonally polarized tunable vortex dual-ring laser. The radially polarized hollow vortex light field in the dual rings, after being focused by a high numerical aperture lens, forms a super-diffraction-limited, ultra-long subwavelength optical needle. Scanning with this subwavelength optical needle allows for the acquisition of vertical information of three-dimensional objects while maintaining subwavelength lateral resolution. Using this subwavelength optical needle as a machining "knife," structures with large aspect ratios and subwavelength lateral dimensions can be fabricated. Simultaneously, the tangentially polarized hollow vortex light field in the dual rings, after being focused by a high numerical aperture lens, forms an ultra-long high-potential-well optical tube, enabling more efficient particle trapping. This invention fully utilizes the dual polarization characteristics of the inner ring (tangential) and the outer ring (radial), achieving both particle trapping and high-resolution imaging, greatly expanding the application of vector vortex light fields in the biomedical field. Furthermore, this invention, through a fixed-intercept variable-focus ring pumping system, can adjust the topological charge of the laser vortex phase, and the position of the pump focus ring in the laser gain medium remains constant during the adjustment of the pump focus ring's focal length, ensuring high mode matching of the laser during adjustment. Summary of the Invention

[0004] In order to solve the technical problems existing in the background art, the present invention aims to provide a tunable vortex double-ring laser based on a fixed-intercept variable-focus ring pumped by an orthogonal polarization, wherein the topological charge of the laser phase can be continuously adjusted.

[0005] To solve the technical problem, the technical solution of the present invention is as follows:

[0006] Based on a fixed-intercept zoom ring-pumped orthogonally polarized tunable vortex dual-ring laser, it includes: a semiconductor laser array with fiber-coupled output, and further includes a plano-convex lens arranged along the optical axis of the emitted beam, a fixed-intercept zoom ring-pumped beam generation system, a first conical mirror, a laser gain medium, a V-shaped crystal conical mirror, a plane mirror, and a second conical mirror.

[0007] The fixed-intercept zoom ring pump beam generation system includes: a first axial cone lens, a first concave lens, a second concave lens, and a second axial cone lens; the first axial cone lens, the first concave lens, the second concave lens, and the second axial cone lens are distributed sequentially along the optical axis of the emitted beam.

[0008] Furthermore, the semiconductor laser array coupled from the optical fiber serves as the pump source for the laser; the cone angle of the first axial-cone lens is 90°<α<150°, the cone angle of the second axial-cone lens is 90°<β<150°, and the light-transmitting surfaces of the first axial-cone lens, the first concave lens, the second concave lens, and the second axial-cone lens are coated with anti-reflection films on the pump light.

[0009] Furthermore, the plano-convex lens collimates the pump beam, and its light-transmitting surface is coated with an anti-reflection film on the pump light; the first conical mirror is the input mirror of the resonant cavity, and its cone angle... Its conical surface is coated with an antireflection film for the pump light and a high-reflection film for the laser, while its bottom surface is coated with an antireflection film for both the pump light and the laser. The laser gain medium is coated with an antireflection film for both the pump light and the laser and is subjected to TEC cooling.

[0010] Furthermore, the V-shaped crystal conical mirror is made of a uniaxial crystal with a cone angle of 30° < γ < 150°, the light-transmitting surface is laser-coated with an anti-reflection film, and the optical axis is parallel to the cylindrical surface of the V-shaped crystal conical mirror.

[0011] Furthermore, the plane mirror is the output coupling mirror of the laser resonant cavity, and its light-transmitting surface is coated with a dielectric film with a laser transmittance of 5-10%.

[0012] Furthermore, the cone angle ω = 90° of the second conical mirror serves as the total reflection mirror of the resonant cavity, and its conical surface is coated with a high-reflectivity film for the laser. The first and second conical mirrors constitute the laser resonant cavity.

[0013] Furthermore, the incident and exit reference planes of the fixed-intercept zoom ring pump beam generation system are set as PR1 and PR2, respectively. The cone angle of the first axial-cone lens is α (90° < α < 150°), the focal length of the convex surface is f1, and the image-side focal point is F1′. The focal length of the first concave lens is f2, and the object-side and image-side focal points are F2 and F2′, respectively. The focal length of the second concave lens is f3, and the object-side and image-side focal points are F3 and F3′, respectively. The cone angle of the second axial-cone lens is β (90° < β < 150°), the focal length of the convex surface is f4, and the object-side and image-side focal points are F4 and F4′, respectively. The defocusing amount between the first axial-cone lens and the first concave lens is Δd1, the defocusing amount between the first concave lens and the second concave lens is Δd2, and the defocusing amount between the second concave lens and the second axial-cone lens is Δd3. The combined principal plane, combined focal length, and combined intercept of the fixed-intercept zoom ring pump beam generation system are H, H, and H, respectively. Σ f Σ and S Σ ; Calculations show that the combined focal length f Σ and combined intercept S Σ Equations (1) and (2) are respectively:

[0014]

[0015]

[0016] As can be seen from equation (1), the amount of defocusing between the lenses can make the combined focal length f of the system more efficient. Σ To ensure a compact zoom system, we choose Δd1<0, Δd2<0, and Δd3<0, keeping the defocus amount Δd2 constant. Adjusting the defocus amounts Δd1 and Δd3 changes the combined focal length f. Σ This allows for the alteration of the pump focal ring size. With different focal ring radii and widths, vortex laser oscillations with different topological charges can be excited. By changing the pump focal ring parameters, vortex lasers with different topological charges can be output.

[0017] From equation (2), it can be seen that adjusting the defocus amounts Δd1 and Δd3 can change the combined intercept S of the zoom system. Σ The combined focal length f remains constant. Σ While the pump focal ring changes continuously, its position in the gain medium remains constant, ensuring that the laser maintains a high mode matching degree during the adjustment process.

[0018] Furthermore, the laser beam, incident at a non-positive angle θ onto the negative cone surface of the V-shaped crystal, undergoes birefringence to produce o-rays and e-rays; assuming the V-shaped crystal is a negative uniaxial crystal, n o >n e n o and n edenoted by , respectively, the refractive indices of the o-ray and e-ray. Viewed from the 2π direction, i.e., rotating once along the system axis, the collection of o-rays forms tangential polarization, and the collection of e-rays forms radial polarization.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] This invention achieves orthogonally polarized tunable vortex dual-ring laser output. The topological charge of the laser vortex phase can be continuously adjusted, and a fixed-intercept variable-focus ring pumping system is used to maintain high mode matching during the adjustment process. The spin angular momentum and orbital angular momentum carried by the laser beam can improve particle trapping efficiency and reduce thermal damage to biological cells caused by the beam. It fully utilizes the dual polarization characteristics of the inner ring tangential and the outer ring radial, achieving both particle trapping and high-resolution imaging, which can greatly expand the application of vector vortex light fields in the biomedical field. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the laser structure of the present invention;

[0022] Figure 2 For a fixed-intercept zoom ring pumped beam generation system;

[0023] Figure 3 A schematic diagram of radially and tangentially orthogonally polarized light fields;

[0024] Figure 4 The relationship between the lens defocusing amounts Δd1 and Δd3;

[0025] Figure 5 Interference patterns of vortex lasers with different topological charges and theoretical simulations of plane waves and spherical waves.

[0026] Figure Labels

[0027] 1-Semiconductor laser array; 2-Planar-convex lens; 3-Fixed-intercept zoom ring pump beam generation system; 4-First conical mirror; 5-Laser gain medium; 6-V-shaped crystal conical mirror; 7-Plane mirror; 8-Second conical mirror; 9-First axial conical lens; 10-First concave lens; 11-Second concave lens; 12-Second axial conical lens. Detailed Implementation

[0028] The specific implementation of the present invention is described below with reference to embodiments:

[0029] It should be noted that the structures, proportions, sizes, etc. shown in this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0030] Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Any changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0031] Example 1:

[0032] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a tunable vortex double-ring laser based on a fixed-intercept zoom ring-pumped orthogonally polarized vortex laser, wherein the topological charge of the laser phase can be continuously adjusted. This invention is achieved through the following technical solution: a tunable vortex double-ring laser based on a fixed-intercept zoom ring-pumped orthogonally polarized vortex laser, such as... Figure 1 As shown, from left to right, the following components are arranged sequentially: a semiconductor laser array 1 with fiber-coupled output, a plano-convex lens 2, a fixed-intercept zoom ring pump beam generation system 3, a first conical mirror 4, a laser gain medium 5, a V-shaped crystal conical mirror 6, a plane mirror 7, and a second conical mirror 8. The fiber-coupled semiconductor laser array 1 serves as the pump source for the laser; the plano-convex lens 2 is a collimating lens, with its light-transmitting surface coated with an anti-reflection film on the pump light; the fixed-intercept zoom ring pump beam generation system 3... Figure 2 As shown, from left to right, a first axial cone lens 9, a first concave lens 10, a second concave lens 11, and a second axial cone lens 12 are arranged, and their light-transmitting surfaces are coated with anti-reflective films for the pump light.

[0033] The incident and exit reference planes of the intercept zoom ring pump beam generation system 3 are set as PR1 and PR2, respectively. The cone angle of the first axial cone lens 9 is α (90° < α < 150°), the focal length of its convex surface is f1, and the image-side focal point is F1′. The focal length of the first concave lens 10 is f2, and the object-side and image-side focal points are F2 and F2′, respectively. The focal length of the second concave lens 11 is f3, and the object-side and image-side focal points are F3 and F3′, respectively. The cone angle of the second axial cone lens 12 is α (90° < α < 150°), the focal length of its convex surface is f1, and the image-side focal point is F3′, respectively. Angle β (90° < β < 150°), focal length of the convex surface f4, object-side and image-side focal points F4 and F4′ respectively, defocusing amount between the first axial cone lens 9 and the first concave lens 10 is Δd1, defocusing amount between the first concave lens 10 and the second concave lens 11 is Δd2, defocusing amount between the second concave lens 11 and the second axial cone lens 12 is Δd3, and the combined principal plane, combined focal length, and combined intercept of the fixed-intercept zoom ring pump beam generation system 3 are H. Σ f Σ and S Σ Calculations show that the combined focal length f is... Σ and combined intercept S Σ Equations 1 and 2 are respectively;

[0034]

[0035]

[0036] As can be seen from equation (1), appropriately selecting the defocusing amount between the lenses can make the combined focal length f of the system more efficient. Σ To ensure a compact zoom system, the design selects Δd1<0, Δd2<0, and Δd3<0. Keeping the defocus amount Δd2 constant, adjusting Δd1 and Δd3 changes the combined focal length f. Σ This allows for the alteration of the pump focal ring size. Different focal ring radii and widths can induce vortex laser oscillations with varying topological charges. Therefore, by changing the pump focal ring parameters, vortex lasers with different topological charges can be output. Equation (2) shows that appropriately adjusting the defocusing amounts Δd1 and Δd3 can adjust the combined intercept S of the zoom system. Σ The combined focal length f remains constant. Σ While continuously changing, the position of the pump focal ring in the gain medium remains constant, ensuring high mode matching of the laser during tuning. The laser beam, incident non-positively at θ onto the negative conical surface of the V-shaped crystal 6, undergoes birefringence to produce o-rays and e-rays. Let the V-shaped crystal 6 be a negative uniaxial crystal (n... o >n e n o and n e (Refractive indices of o-ray and e-ray, respectively). Viewed from the 2π direction (rotating one revolution along the system axis), the collection of o-rays forms tangential polarization, as shown below. Figure 3The inner ring, where the e-beams converge to form radial polarization, such as... Figure 3 The outer ring.

[0037] The first conical mirror 4 is the input mirror of the resonant cavity, and its cone angle is... The cone-shaped surface of the laser is coated with an anti-reflection film on the pump light and a high-reflection film on the laser. The bottom surface of the laser is coated with an anti-reflection film on both the pump light and the laser. The laser gain medium 5 is coated with an anti-reflection film on both the pump light and the laser and is TEC cooled. The V-shaped crystal conical mirror 6 is made of a uniaxial crystal with a cone angle of 30° < γ < 150°. The light-transmitting surface of the mirror is coated with an anti-reflection film on the laser, and the optical axis is parallel to the cylindrical surface of the V-shaped crystal conical mirror 6. The plane mirror 7 is the output coupling mirror of the resonant cavity. Its light-transmitting surface of the mirror is coated with a dielectric film with a transmittance of 5-10% on the laser. The orthogonally polarized vortex double-ring laser is output by the plane output coupling mirror 7. The second conical mirror 8 has a cone angle of ω = 90° and serves as the total reflection mirror of the resonant cavity. Its cone-shaped surface of the mirror is coated with a high-reflection film on the laser. The first conical mirror 4 and the second conical mirror 8 constitute the laser resonant cavity.

[0038] Example 2:

[0039] Specifically, the following unit components can be used to realize a tunable vortex dual-ring laser based on a fixed-intercept variable-focus ring pumped by an orthogonal polarization: the output wavelength of the fiber-coupled semiconductor laser array 1 is 808nm, the fiber core diameter is 400μm, and the numerical aperture is 0.22; the focal length of the plano-convex lens 2 is 500mm, and its light-transmitting surface is coated with an 808nm anti-reflection film; the first conical mirror 4, the plane mirror 7, the second conical mirror 8, the first axial conical lens 9, the first concave lens 10, the second concave lens 11, and the second axial conical lens 12 are all made of K9 glass; the cone angle of the first conical mirror 4 is... The conical surface of the laser mirror 7 is coated with an 808nm antireflection coating and a 1064nm high-reflection coating, while the bottom surface is coated with 808nm and 1064nm antireflection coatings. The laser gain medium 5 is made of Nd:YAG crystal, and its light-transmitting surface is coated with 808nm and 1064nm antireflection coatings. The pump source and the Nd:YAG crystal are TEC cooled, with the temperature controlled within the range of 15°±0.5°. The V-shaped crystal conical mirror 6 is made of positive uniaxial quartz crystal with a cone angle γ=120°. The optical axis of the crystal is parallel to the cylindrical surface of the V-shaped crystal conical mirror 6, and its light-transmitting surface is coated with a 1064nm antireflection coating. The light-transmitting surface of the plane mirror 7 is coated with a medium with a transmittance of 10% at 1064nm. The second conical lens 8 has a cone angle ω = 90°, and its conical surface is coated with a 1064nm high-reflection film; the first axial conical lens 9 has a cone angle α = 120°, a focal length f1 = 150mm on its convex surface, and an 808nm anti-reflection film on its light-transmitting surface; the first concave lens 10 has a focal length f2 = -50mm, and its light-transmitting surface is coated with an 808nm anti-reflection film; the second concave lens 11 has a focal length f3 = -100mm, and its light-transmitting surface is coated with an 808nm anti-reflection film; the second axial conical lens 12 has a cone angle β = 120°, a focal length f4 = 100mm on its convex surface, and its light-transmitting surface is coated with an 808nm anti-reflection film; the combined intercept S of the fixed-intercept zoom ring pump beam generation system 3 is... Σ When the focal length is 50mm, the defocusing amount Δd2 = -20mm. From equations (1) and (2), the dependence of the defocusing amounts Δd1 and Δd3 can be obtained as follows: Figure 4 As shown, adjusting the defocusing amounts Δd1 and Δd3 can change the size of the pump beam, thereby controlling the laser vortex phase topological charge. Figure 5 Interference patterns of vortex lasers with different topological charges and plane waves (a)-(c) and spherical waves (d)-(f) based on theoretical simulations are presented, where the topological charge number of (a) and (d) is 1, the topological charge number of (b) and (e) is 2, and the topological charge number of (c) and (f) is 3.

[0040] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0041] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A tunable vortex dual-ring laser pumped by a fixed-intercept variable-focus ring, characterized in that, include: The fiber-coupled semiconductor laser array (1) also includes a plano-convex lens (2) arranged along the optical axis of the emitted beam, a fixed-intercept zoom ring pump beam generation system (3), a first conical mirror (4), a laser gain medium (5), a V-shaped crystal conical mirror (6), a plane mirror (7), and a second conical mirror (8). The fixed-intercept zoom ring pump beam generation system (3) includes: a first axial cone lens (9), a first concave lens (10), a second concave lens (11), and a second axial cone lens (12); the first axial cone lens (9), the first concave lens (10), the second concave lens (11), and the second axial cone lens (12) are distributed sequentially along the optical axis of the emitted beam. The V-shaped crystal conical mirror (6) is made of a uniaxial crystal with a cone angle of 30°. o <γ<150 o The light-transmitting surface is laser-coated with an anti-reflective coating, and the optical axis is parallel to the cylindrical surface of the V-shaped crystal conical mirror (6).

2. The orthogonally polarized tunable vortex dual-ring laser pumped by a fixed-intercept variable-focus ring according to claim 1, characterized in that, The semiconductor laser array (1) coupled from the optical fiber serves as the pump source for the laser; the cone angle of the first axial-cone lens (9) is 90°. o <α<150 o The cone angle of the cone surface of the second axis cone lens (12) is 90°. o <β<150 o The light-transmitting surfaces of the first axial cone lens (9), the first concave lens (10), the second concave lens (11), and the second axial cone lens (12) are coated with anti-reflective film for the pump light.

3. The orthogonally polarized tunable vortex dual-ring laser pumped by a fixed-intercept variable-focus ring according to claim 1, characterized in that, The plano-convex lens (2) collimates the pump beam, and its light-transmitting surface is coated with an anti-reflection film on the pump beam; the first conical mirror (4) is the input mirror of the resonant cavity, and its cone angle φ=90°. o Its cone faces the pump light to be coated with an antireflective coating and the laser to be coated with a high reflective coating, and its bottom faces the pump light and the laser to be coated with an antireflective coating; the laser gain medium (5) coats the pump light and the laser with an antireflective coating and TEC-cools it.

4. The orthogonally polarized tunable vortex dual-ring laser pumped by a fixed-intercept zoom ring according to claim 1, characterized in that, The plane mirror (7) is the output coupling mirror of the laser resonator, and its light-transmitting surface is coated with a dielectric film with a laser transmittance of 5-10%.

5. The tunable vortex dual-ring laser based on a fixed-intercept zoom ring-pumped orthogonal polarization as described in claim 1, characterized in that, The cone angle ω of the second conical mirror (8) is 90°. o As a total reflection mirror of the resonant cavity, its conical surface is coated with a high reflection film for laser. The first conical mirror (4) and the second conical mirror (8) constitute the laser resonant cavity.

6. The orthogonally polarized tunable vortex dual-ring laser pumped by a fixed-intercept zoom ring according to claim 1, characterized in that, The incident and exit reference planes of the intercept zoom ring pump beam generation system (3) are set to PR1 and PR2, respectively, and the cone angle of the cone surface of the first axial cone lens (9) is α (90°). o <α<150 o The focal length of the convex surface is f1, and the image-side focal point is... The focal length of the first concave lens (10) is f2, and the object-side and image-side focal points are respectively... and The focal length of the second concave lens (11) is f3, and the object-side and image-side focal points are respectively... and The cone angle of the cone surface of the second axial cone lens (12) is β, 90°. o <β<150 o The focal length of the convex surface is f4, and the object-side and image-side focal points are respectively... and The defocusing amount between the first axial cone lens (9) and the first concave lens (10) is Δd1, the defocusing amount between the first concave lens (10) and the second concave lens (11) is Δd2, and the defocusing amount between the second concave lens (11) and the second axial cone lens (12) is Δd3. The combined principal plane, combined focal length, and combined intercept of the fixed-intercept zoom ring pump beam generation system (3) are H, ... Σ f Σ and S Σ ; Calculations show that the combined focal length f Σ and combined intercept S Σ Equations (1) and (2) are respectively: （1） （2） As can be seen from equation (1), the amount of defocusing between the lenses can make the combined focal length f of the system more efficient. Σ To ensure a compact zoom system, we choose Δd1<0, Δd2<0, and Δd3<0, keeping the defocus amount Δd2 constant. Adjusting the defocus amounts Δd1 and Δd3 changes the combined focal length f. Σ This allows for the alteration of the pump focal ring size. With different focal ring radii and widths, vortex laser oscillations with different topological charges can be excited. By changing the pump focal ring parameters, vortex lasers with different topological charges can be output. From equation (2), it can be seen that adjusting the defocus amounts Δd1 and Δd3 can change the combined intercept S of the zoom system. Σ The combined focal length f remains constant. Σ While the pump focal ring changes continuously, its position in the gain medium remains constant, ensuring that the laser maintains a high mode matching degree during the adjustment process.

7. The tunable vortex dual-ring laser based on a fixed-intercept zoom ring-pumped orthogonal polarization as described in claim 1, characterized in that, A laser beam is incident non-positively at θ onto the negative cone surface of a V-shaped crystal conical mirror (6), where it undergoes birefringence to produce o-rays and e-rays; assuming the V-shaped crystal conical mirror (6) is a negative uniaxial crystal, n o >n e n o and n e denoted by , respectively, the refractive indices of the o-ray and e-ray. Viewed from the 2π direction, i.e., rotating once along the system axis, the collection of o-rays forms tangential polarization, and the collection of e-rays forms radial polarization.

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