Intracavity cooperative regulation and control device and method of high-order Hermitian Gaussian mode and Orens Gaussian mode

Abstract

The invention discloses a high-order Hermite-Gaussian and Enth-Gaussian mode intracavity cooperative regulation and control device which comprises a pumping source, a focusing optical device, a plane input mirror, a gain medium, a plane-concave output cavity mirror and a detection assembly are sequentially arranged at the output end of the pumping source, and a plane-concave resonant cavity is formed among the plane input mirror, the gain medium and the plane-concave output cavity mirror. The pumping source outputs pumping light, and the focusing optical device focuses the pumping light to the gain medium; a multi-axis optical platform is arranged at the lower ends of the gain medium and the plano-concave output cavity mirror, the plano-concave output cavity mirror translates along x and y directions of the orthogonal multi-axis optical platform to introduce off-axis displacement, and the gain medium rotates around a pitch axis of the multi-axis optical platform to break cylindrical symmetry of a resonant cavity so as to introduce controllable astigmatism; the detection assembly is used for capturing a laser transverse mode pattern. According to the technical scheme, the high-order Hermite Gaussian mode laser cavity and the high-order Hermite Gaussian mode laser cavity which are compact in structure, low in loss, flexible in mode regulation and control and high in parameter adaptability are directly generated, regulated, controlled and mutually converted in the laser cavity.

Description

Technical Field

[0001] This invention relates to the fields of laser technology and structured optical field manipulation technology, specifically to an intracavity synergistic manipulation device and method for higher-order Hermitian and Ingensian modes. Background Technology

[0002] Structured light fields, due to their unique spatial distribution and physical properties, play an irreplaceable role in fields such as optical communication, particle manipulation, and quantum information. Among them, the Insgaussian (IG) mode, as the third complete orthogonal solution of the paraxial wave equation in elliptical coordinates, possesses both rectangular and circular symmetry characteristics. Furthermore, it can achieve continuous tuning of the transverse light field through the ellipticity parameter ε, serving as a crucial bridge connecting the Hermetic Gaussian (HG) mode (corresponding to the Cartesian coordinate solution) and the LG mode (corresponding to the cylindrical coordinate solution).

[0003] Existing IG mode generation technologies are mainly divided into intracavity methods and extracavity methods. Extracavity methods rely on components such as spatial light modulators, which suffer from low diffraction efficiency, limited power handling capability, and high insertion loss. Intracavity methods often achieve single IG mode output by breaking the symmetry of the resonant cavity, such as by shifting the output cavity mirror or introducing opaque metal wires. However, these methods have drawbacks such as fixed modes, the need for realignment or component replacement when switching modes, and the inability to utilize the intrinsic correlation between HG and IG modes (IG degenerates into HG as ε→∞). Furthermore, existing solutions are often limited to specific gain media and optical component parameters, resulting in poor flexibility and limiting the development of reconfigurable structured light sources. In addition, existing technologies do not clearly define the core logic of achieving mode generation and conversion through the coordinated control of "output cavity mirror translation + crystal pitch angle adjustment," leading to low technology reproducibility.

[0004] Therefore, developing a technical solution that is not limited to specific parameters, can generate directly within the cavity, has adjustable modes, and allows for dynamic HG-IG conversion has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a compact, low-loss, flexible, and highly adaptable intracavity co-control device and method for directly generating, controlling, and mutually converting high-order HG and IG mode lasers into high-order Hermitian and Insgaussian modes.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an intracavity co-regulation device for high-order Hermitian and Ins Gaussian modes, comprising a pump source, wherein a focusing optics device, a planar input mirror, a gain medium, a plano-concave output cavity mirror, and a detection component are sequentially arranged at the output end of the pump source; the planar input mirror, the gain medium, and the plano-concave output cavity mirror constitute a plano-concave resonant cavity; the pump source outputs pump light; the focusing optics device includes a lens coated with an anti-reflection film on the pump light, and the focusing optics device focuses the pump light onto the gain medium; the planar input mirror has high transmission in the pump light band and high reflection in the laser oscillation band; the gain medium is a doped laser crystal and is temperature-controlled to room temperature; the plano-concave output cavity mirror has a preset transmittance in the laser oscillation band; a multi-axis optical platform is arranged at the lower end of the gain medium and the plano-concave output cavity mirror along the orthogonal multi-axis optical platform x, y Directional translation is used to introduce off-axis displacement, and the gain medium is rotated about the pitch axis of the multi-axis optical platform to break the cylindrical symmetry of the resonant cavity, thereby introducing controllable astigmatism; the detection component is used to capture the laser lateral mode pattern.

[0007] The present invention is further configured such that: the center wavelength of the pump source is 808nm or 885nm, the core diameter is 50–400μm, and the numerical aperture is 0.15–0.25; the focal length of the lens in the focusing optical device is 30-100mm, and the size of the pump light focusing spot is adapted to the gain medium; The focusing optical device consists of two lenses coated with anti-reflective coatings for the pump light, with focal lengths of 50mm, 30mm, or 100mm. The two lenses are coaxially mounted, and the pump light is focused to the center region of the gain medium. The diameter of the planar input mirror is adapted to the aperture of the resonant cavity, with a transmittance of ≥90% in the pump light band and a reflectance of ≥99% in the laser oscillation band; the radius of curvature of the plano-concave output cavity mirror is 50–200 mm, and the transmittance in the laser oscillation band is 1–5%. The planar input mirror and the plano-concave output cavity mirror together constitute a plano-concave resonant cavity with a cavity length of 100 mm. The gain medium is an Nd-doped laser crystal with a crystal size adapted to the resonant cavity structure. It is wrapped in indium foil and placed in a copper block with a temperature control range of 18–25°C to ensure stable output of high-order modes. The detection component is a CCD camera, used to acquire pattern light spots in real time.

[0008] In addition, the present invention also provides an intracavitary coordinated control method for higher-order Hermitian and Ingensian modes, comprising the following steps: Step 1: Generation and Control of Higher-Order Hermetic Gaussian (HG) Modes By independently controlling the off-axis displacement of the plano-concave output cavity mirror in the x and y directions through a multi-axis optical platform, the focused pump light deviates from the optical axis of the resonant cavity, selectively suppressing the oscillation of the fundamental mode and redundant higher-order modes, and realizing a one-dimensional HG mode output that is independently adjustable in the horizontal and vertical directions; by coordinating the off-axis displacement of the plano-concave output cavity mirror in the x and y directions, the range of mode orders is expanded. Step 2: Convert between Higher-Order Hermetic (HG) Mode and Ingenus (IG) Mode By keeping the off-axis displacement of the plano-concave output cavity mirror fixed and maintaining stable oscillation of the target HG mode, the pitch angle of the gain medium is adjusted through a multi-axis optical platform to break the cylindrical symmetry of the resonant cavity and introduce controllable intracavity astigmatism. This astigmatism is equivalent to continuously adjusting the ellipticity parameter ε. When ε→∞, the IG mode degenerates into the HG mode. When ε is continuously adjustable, the HG mode is driven to transform into the odd-even superposition IG mode. By adjusting the pitch angle of the gain medium in the opposite direction, the IG mode can be restored to the HG mode, completing the bidirectional conversion between the two modes. Step 3: IG Mode Tier Adjustment By adjusting the magnitude of the off-axis displacement in the x and y directions of the plano-concave output cavity mirror, the p-index of the IG mode can be precisely controlled; by adjusting the pitch angle of the gain medium, the intracavity astigmatism intensity can be changed to adjust the ellipticity parameter ε, thereby controlling the m-index of the IG mode and the superposition weight of the odd and even modes, and finally obtaining a high-order IG mode with controllable p and m-indexes.

[0009] Preferably, in step 1, the order of the HG mode is positively correlated with the off-axis displacement, and HG is obtained by controlling the horizontal off-axis independently. m In the 0 series mode, HG0 can be obtained by independently controlling the vertical off-axis direction. n The series of modes expands to hundreds of modes when the dual-axis cooperative off-axis mode is used, and the output power of each HG mode increases linearly with the input power.

[0010] Preferably, in step 2, the pitch angle of the gain medium is adjusted within a range of 0–5°. By continuously adjusting this angle, a wide range of ellipticity parameter ε can be adjusted, thereby driving the lossless dynamic conversion between HG and IG modes. During the conversion process, the mode stability is monitored in real time by the imaging device.

[0011] Preferably, in step 3, when the HG mode is off-axis in only one direction, it is converted into a non-superimposed single even mode or odd mode; when the HG mode is off-axis in both directions simultaneously, it is converted into an odd-even superimposed IG mode, and the total order of the HG mode is equal to the p-index of the converted IG mode.

[0012] The beneficial effects of this invention are as follows: Compared with the prior art, this invention has a compact structure, low loss, flexible mode control, and strong parameter adaptability. It can directly generate, control, and convert high-order HG and IG mode lasers within the cavity. Through the core technology of "orthogonal translation of the output cavity mirror + adjustment of the gain medium pitch angle", it can achieve stable output and dynamic switching of high-order modes, thus meeting the needs of cutting-edge photonics technology for reconfigurable structured light sources.

[0013] Innovation: For the first time, the core technology is clearly defined as "orthogonal translation of plano-concave output cavity mirror + gain medium pitch angle adjustment", which synergistically realizes the generation, control and bidirectional conversion of HG-IG mode, making full use of the inherent relationship between the two and filling the technical gap of reconfigurable IG mode light source; Advantages: Not limited to specific gain media (compatible with various laser crystals) and optical component parameters (pump source, lens, input mirror and other parameters can be flexibly adjusted), with wide applicability; HG mode has a maximum order of over 100, IG mode has a wide coverage, p and m exponents are precisely controllable, mode switching does not require component replacement, and operation is simple; no external optical components are required, and insertion loss and diffraction loss are low. Practicality: The device has a compact structure and good thermal stability. The core HG mode optical-to-optical conversion efficiency can reach more than 45%, which can meet the requirements of high power and high stability applications. It is suitable for multiple fields such as optical communication, quantum information processing, and optical micro-manipulation.

[0014] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a partial structural diagram of an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the principle of an embodiment of the present invention; Figure 4 This is a diagram illustrating the effect of HG mode generation in an embodiment of the present invention. Figure 5 These are illustrations showing the effects of converting different HG modes into IG modes according to embodiments of the present invention. Figure 6 This is a diagram illustrating the HG-IG mode conversion effect in an embodiment of the present invention. Figure 7 This is a diagram illustrating the effect of IG mode order control in an embodiment of the present invention. Detailed Implementation

[0016] In the description of this embodiment, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0017] See Figures 1 to 7 This invention discloses an intracavity co-regulation device for high-order Hermitian and Ingensian modes, comprising a pump source 1. The output end of the pump source 1 is sequentially equipped with a focusing optics device 2, a planar input mirror 3, a gain medium 4, a plano-concave output cavity mirror 5, and a detection component 6. The planar input mirror 3, the gain medium 4, and the plano-concave output cavity mirror 5 form a plano-concave resonant cavity. The pump source 1 outputs pump light. The focusing optics device 2 includes a lens coated with an anti-reflection film on the pump light, and focuses the pump light onto the gain medium 4. The planar input mirror 3 has high transmission in the pump light band and high reflection in the laser oscillation band. The gain medium 4 is an Nd-doped laser crystal, and its temperature is controlled to room temperature. The plano-concave output cavity mirror 5 has a preset transmittance in the laser oscillation band. A multi-axis optical platform is provided at the lower end of the gain medium 4 and the plano-concave output cavity mirror along the orthogonal multi-axis optical platform x, y... Directional translation is used to introduce off-axis displacement, and the gain medium 4 is rotated about the pitch axis of the multi-axis optical platform to break the cylindrical symmetry of the resonant cavity, thereby introducing controllable astigmatism; the detection component 6 is used to capture the laser lateral mode pattern.

[0018] Preferably, the pump source 1 has a center wavelength of 808nm or 885nm, a fiber core diameter of 50–400μm, and a numerical aperture of 0.15–0.25; the focal length of the lens in the focusing optical device is 30-100mm, and the size of the pump light focusing spot is adapted to the gain medium. The focusing optical device 2 consists of two lenses coated with anti-reflection coatings for the pump light, with focal lengths of 50mm, 30mm or 100mm. The two lenses are coaxially mounted, and the pump light is focused to the center region of the gain medium. The diameter of the planar input mirror 3 is adapted to the aperture of the resonant cavity, with a pump light transmittance ≥90% and a laser oscillation reflectance ≥99%. The radius of curvature of the plano-concave output cavity mirror is 50–200 mm, and the transmittance of the laser oscillation band is 1–5%. The planar input mirror and the plano-concave output cavity mirror together constitute a plano-concave resonant cavity with a cavity length of 100 mm. The gain medium 4 is an Nd-doped laser crystal. Preferably, it can be any one of Nd:YVO4 crystal, Nd:YLF crystal, or Nd:LuVO4 crystal, or it can be an Nd:YAG crystal or Nd:GdVO4 crystal. The crystal size is adapted to the resonant cavity structure. After being wrapped with indium foil, it is placed in a copper block. The temperature control range is 18–25℃ to ensure stable output of high-order modes. The detection component 6 is a CCD camera used to acquire pattern light spots in real time.

[0019] Preferably, the gain medium and the plano-concave output cavity mirror are respectively mounted on a multi-axis optical platform with a translation accuracy of 0.1 μm and a pitch angle rotation accuracy of 0.01°.

[0020] In addition, the present invention also provides an intracavitary coordinated control method for higher-order Hermitian and Ingensian modes, comprising the following steps: Step 1: Generation and Control of Higher-Order Hermetic Gaussian (HG) Modes By independently controlling the off-axis displacement of the plano-concave output cavity mirror in the x and y directions through a multi-axis optical platform, the focused pump light deviates from the optical axis of the resonant cavity, selectively suppressing the oscillation of the fundamental mode and redundant higher-order modes, and realizing a one-dimensional HG mode output that is independently adjustable in the horizontal and vertical directions; by coordinating the off-axis displacement of the plano-concave output cavity mirror in the x and y directions, the range of mode orders is expanded. Step 2: Convert between Higher-Order Hermetic (HG) Mode and Ingenus (IG) Mode By keeping the off-axis displacement of the plano-concave output cavity mirror fixed and maintaining stable oscillation of the target HG mode, the pitch angle of the gain medium is adjusted through a multi-axis optical platform to break the cylindrical symmetry of the resonant cavity and introduce controllable intracavity astigmatism. This astigmatism is equivalent to continuously adjusting the ellipticity parameter ε. When ε→∞, the IG mode degenerates into the HG mode. When ε is continuously adjustable, the HG mode is driven to transform into the odd-even superposition IG mode. By adjusting the pitch angle of the gain medium in the opposite direction, the IG mode can be restored to the HG mode, completing the bidirectional conversion between the two modes. Step 3: IG Mode Tier Adjustment By adjusting the magnitude of the off-axis displacement in the x and y directions of the plano-concave output cavity mirror, the p-index of the IG mode (p=nx+ny, where nx and ny are the number of rows and columns of the IG mode array) can be precisely controlled. By adjusting the pitch angle of the gain medium, the intracavity astigmatism intensity can be changed to adjust the ellipticity parameter ε, thereby controlling the m-index of the IG mode and the superposition weight of the odd and even modes, and finally obtaining a high-order IG mode with controllable p and m-indexes.

[0021] Preferably, in step 1, the order of the HG mode is positively correlated with the off-axis displacement, and HG is obtained by controlling the horizontal off-axis independently. m,0 series mode (in our verification experiment, the cross-sectional size of the gain medium used was 3*3mm) 2 (Limitation) Maximum order 84; HG0 can be obtained by controlling the vertical off-axis direction independently. n Series mode (in our verification experiment, the cross-sectional size of the gain medium used was 3*3mm) 2 (Limitation) The maximum number of modes is 84. When the dual-axis cooperative off-axis mode is used, the number of modes can be extended to hundreds. As a preferred embodiment, the number of modes is 103, and the output power of each HG mode increases linearly with the input power.

[0022] Preferably, in step 2, the pitch angle of the gain medium is adjusted within a range of 0–5°. By continuously adjusting this angle, a wide range of ellipticity parameter ε can be adjusted, thereby driving the lossless dynamic conversion between HG and IG modes. During the conversion process, the mode stability is monitored in real time by the imaging device.

[0023] Preferably, in step 3, when the HG mode is off-axis in only one direction, it is converted into a non-superimposed single even mode or odd mode; when the HG mode is off-axis in both directions at the same time, it is converted into an odd-even superimposed IG mode, and the total order of the HG mode is equal to the p-index of the converted IG mode (that is, the sum of the order of the HG mode in the x direction and the order in the y direction is equal to p).

[0024] This invention is based on a plano-concave resonator. Off-axis pumping is achieved by translating the plano-concave output cavity mirror in the orthogonal direction, which precisely controls the order of the HG mode. The cylindrical symmetry within the cavity is broken by rotating the pitch angle of the gain medium, and controllable astigmatism is introduced to effectively adjust the ellipticity parameter ε, driving the dynamic conversion between HG and IG modes. Through dual-parameter coordinated control, the p and m exponents of the IG mode are precisely controlled, and it is not limited to specific gain media and optical element parameters, thus improving the applicability of the technology.

[0025] This invention integrates a pump source, focusing optics, planar input mirror, gain medium, plano-concave output cavity mirror, and imaging device, which work together without the need for external modulation elements and have a compact structure. The gain medium can be selected from various laser crystals, and the optical element parameters can be adjusted within a reasonable range to adapt to different application scenarios. Method flow: High-order HG mode output is achieved by translating the plano-concave output cavity mirror; astigmatism is introduced by rotating the pitch angle of the gain medium to achieve bidirectional conversion between HG and IG modes; and precise control of the IG mode order is achieved through dual-parameter coordinated regulation. The entire process is completed within a single resonant cavity, avoiding external cavity losses.

[0026] To make the structure of the present invention clearer, the preferred embodiment is as follows: (1) Setup of the device In this embodiment, the pump source is an 808nm fiber-coupled laser diode with a core diameter of 105μm, a numerical aperture of 0.22, and an output power that is continuously adjustable from 0 to 4W (or an 885nm pump source with a core diameter of 200μm and a numerical aperture of 0.25 can be used). The focusing optics consists of two lenses with anti-reflective coatings for the pump light, with a focal length of 50mm (or 30mm, 100mm), and are coaxially mounted to ensure that the pump light is focused to the center region of the gain medium. The planar input mirror has a diameter of 20mm (or 15mm, 25mm), with a transmittance ≥90% in the 796–812nm (pump band) and a reflectance ≥99% in the 1000–1180nm (oscillation band); the plano-concave output cavity mirror has a radius of curvature of 100mm (or 50mm, 200mm), with a transmittance of 3% (or 1%, 5%) at 1064nm; the two together form a plano-concave resonant cavity with a cavity length of 100mm; The gain medium is an Nd:YVO4 crystal (or an Nd:YLF crystal), with dimensions of 3×3×5 mm. 3 The doping concentration was 1%, and after being wrapped with indium foil, it was placed in a water-cooled copper block and the temperature was controlled to room temperature of 20°C. The gain medium and the plano-concave output cavity mirror are respectively mounted on a high-precision multi-axis optical platform with a translation accuracy of 0.1 μm and a pitch and rotation accuracy of 0.01°. The detection component uses a CCD camera with a resolution of 1024×768 pixels to acquire pattern light spots in real time.

[0027] (2) Experimental procedure High-order HG mode generation: The pump source is turned on, and the off-axis displacement in the x-direction of the plano-concave output cavity mirror is gradually increased from 0 to 1.2 mm. The CCD camera sequentially captures HG1,0, HG3,0…HG. 84 ,0 mode; adjust the off-axis displacement in the y direction to obtain HG0,1 to HG0, 84 Mode; simultaneously adjust the off-axis displacement in the x and y directions to obtain an HG mode with a maximum tilt of 103 orders, such as Figure 4 As shown; HG-IG mode conversion: After obtaining the one-dimensional HG mode, keeping the off-axis displacement of the plano-concave output cavity mirror unchanged in the x and y directions, controllable intracavity astigmatism is introduced by rotating the pitch angle of the gain medium through a multi-axis optical platform, thus realizing the conversion from HG mode to IG mode. Figure 5 As shown. Among them, the horizontally distributed HG7,0 mode (with a y-direction offset of 0, i.e., nᵧ=0), after being rotated by the crystal to transform the intracavity coordinate system from Cartesian coordinates to elliptical coordinates, is transformed into... The mode, whose intensity still exhibits a horizontal distribution, is a non-superimposed even mode (n x=7、nᵧ=0); HG9,0 mode, due to offsets in both the x and y directions, becomes two-dimensional after conversion. The pattern is a superposition of odd and even states (n x =7、nᵧ=2);HG 13 ,0 mode converted to two dimensions The pattern is also a superposition of odd and even states (n x =7, nᵧ=6). It is worth noting that the order of the HG mode is equal to the p-exponent of the transformed IG mode, and HG7,0,HG9,0,HG 13 Although the horizontal offset is the same, the IG modes after astigmatism conversion all maintain n. x =7 is a horizontal distribution characteristic.

[0028] Figure 5 (c) Simulation results show that the generated two-dimensional pattern and the odd-even superposition The intensity distribution of the model is consistent. By selecting the ellipticity parameter ε and the odd-even mode weighting coefficients A and B (the phase difference between the odd and even components is 0 or π) that match the experimental results, the simulated intensity distribution is in high agreement with the experimentally obtained IG spot, verifying the model purity.

[0029] Figure 6 The paper presents the physical mechanism of symmetry breaking by capturing the dynamic evolution of the optical field using a CCD camera: initially, the off-axis pumped resonator supports a pure HG mode (corresponding to the eigenstates of an asymptotically Cartesian symmetric system as ε→∞); as the laser crystal tilts, the induced intracavity astigmatism acts as a tunable perturbation, changing the effective ellipticity parameter ε of the resonator and driving the HG mode to transform into an IG mode. Figure 5 As shown, the initial striped HG 15 The 0 pattern evolved sequentially into a double-striped, four-striped structure, and finally transformed into a regular array distribution. The model confirms that off-axis pumping combined with astigmatism effectively modulates the mode, thereby guiding mode competition to evolve towards the target IG mode.

[0030] IG mode order control: Based on the HG mode output with different off-axis displacements in the lateral x and y directions, combined with crystal placement angle adjustment, it is possible to achieve multiple parity superposition IGp,meo mode outputs with various p and m values, such as... Figure 7 As shown. Figure 7 (a) As the off-axis displacement in the transverse orthogonal direction gradually increases, the HG mode is converted and the IG mode pattern is recorded by the CCD. As the off-axis displacement increases, the number of rows and columns (n) of the two-dimensional IG mode... x The scope of the model has been gradually improved from nᵧ. Coverage .

[0031] Figure 7(b) shows IG mode spots of different orders obtained under different off-axis directions compared to Figure 7(a), with the same mode range from... Extend to . Figure 7 (b) The phase difference is π, and they are superimposed in opposite phases, eventually forming an interference pattern with complementary intensity distribution.

[0032] In practical applications, this invention provides a compact, low-loss, flexible, and highly adaptable device and method for the direct generation, control, and interconversion of high-order HG and IG mode lasers within a cavity. Through the core technology of "orthogonal translation of the output cavity mirror + elevation angle adjustment of the gain medium," it achieves stable output and dynamic switching of high-order modes, meeting the demands of cutting-edge photonics technology for reconfigurable structured light sources. Specifically, based on a plano-concave resonant cavity, through coordinated control of off-axis pumping and astigmatic perturbation within the cavity, it achieves stable output of high-order HG modes, direct generation of a wide range of odd-even superposition IG modes, and dynamic conversion and precise mode control between HG and IG modes.

[0033] This invention eliminates the need for external optical components, features a compact structure and low loss, and is not limited to specific gain media and optical component parameters. It solves the problems of fixed IG mode output, complex switching, and underutilization of the correlation between HG and IG modes in existing technologies. It provides a high-performance reconfigurable structured light source for fields such as optical communication, quantum information processing, and optical micromanipulation, and has significant practical value and application prospects.

[0034] Innovation: For the first time, the core technology is clearly defined as "orthogonal translation of plano-concave output cavity mirror + adjustment of gain medium pitch angle", which synergistically realizes the generation, control and bidirectional conversion of HG-IG mode, making full use of the inherent relationship between the two and filling the technical gap of reconfigurable IG mode light source; Advantages: Not limited to specific gain media (compatible with various laser crystals) and optical component parameters (pump source, lens, input mirror and other parameters can be flexibly adjusted), with wide applicability; HG mode has a maximum order of over 100, IG mode has a wide coverage, p and m exponents are precisely controllable, mode switching does not require component replacement, and operation is simple; no external optical components are required, and insertion loss and diffraction loss are low. Practicality: The device has a compact structure and good thermal stability. The core HG mode optical-to-optical conversion efficiency can reach more than 45%, which can meet the requirements of high power and high stability applications. It is suitable for multiple fields such as optical communication, quantum information processing, and optical micro-manipulation.

[0035] The above embodiments, which describe the specific features of the present invention, are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description of the invention shall fall within the scope of protection of the present invention.

Claims

1. An intracavitary coordinated control device for higher-order Hermitian and Ingensian modes, comprising a pump source, characterized in that: The pump source output end is sequentially provided with a focusing optics device, a planar input mirror, a gain medium, a plano-concave output cavity mirror, and a detection component. The planar input mirror, gain medium, and plano-concave output cavity mirror form a plano-concave resonant cavity. The pump source outputs pump light. The focusing optics device includes a lens coated with an anti-reflection film for the pump light and focuses the pump light onto the gain medium. The planar input mirror has high transmission in the pump light band and high reflection in the laser oscillation band. The gain medium is a doped laser crystal and is temperature-controlled to room temperature. The plano-concave output cavity mirror has a preset transmittance in the laser oscillation band. A multi-axis optical platform is provided at the lower end of the gain medium and the plano-concave output cavity mirror. The plano-concave output cavity mirror is translated along the x and y directions of the orthogonal multi-axis optical platform to introduce off-axis displacement. The gain medium rotates around the pitch axis of the multi-axis optical platform to break the cylindrical symmetry of the resonant cavity, thereby introducing controllable astigmatism. The detection component is used to capture the laser transverse mode pattern.

2. The intracavity coordinated control device for high-order Hermitian and Ingensian modes according to claim 1, characterized in that: The pump source has a center wavelength of 808nm or 885nm, a fiber core diameter of 50–400μm, and a numerical aperture of 0.15–0.25; the focal length of the lens in the focusing optical device is 30-100mm, and the size of the pump light focused spot is adapted to the gain medium. The focusing optical device consists of two lenses coated with anti-reflective coatings for the pump light, with focal lengths of 50mm, 30mm, or 100mm. The two lenses are coaxially mounted, and the pump light is focused to the center region of the gain medium. The diameter of the planar input mirror is adapted to the aperture of the resonant cavity, with a transmittance of ≥90% in the pump light band and a reflectance of ≥99% in the laser oscillation band; the radius of curvature of the plano-concave output cavity mirror is 50–200 mm, and the transmittance in the laser oscillation band is 1–5%. The planar input mirror and the plano-concave output cavity mirror together constitute a plano-concave resonant cavity with a cavity length of 100 mm. The gain medium is an Nd-doped laser crystal with a crystal size adapted to the resonant cavity structure. It is wrapped in indium foil and placed in a copper block with a temperature control range of 18–25°C to ensure stable output of high-order modes. The detection component is a CCD camera, used to acquire pattern light spots in real time.

3. The intracavity coordinated control device for higher-order Hermitian and Ingensian modes according to claim 2, characterized in that: The gain medium and the plano-concave output cavity mirror are respectively mounted on a multi-axis optical platform with a translation accuracy of 0.1 μm and a pitch angle rotation accuracy of 0.01°.

4. A method for intracavitary coordinated control of higher-order Hermitian and Insgaussian modes, characterized in that: Includes the following steps: Step 1: Generation and Control of Higher-Order Hermetic Gaussian (HG) Modes By independently controlling the off-axis displacement of the plano-concave output cavity mirror in the x and y directions through a multi-axis optical platform, the focused pump light deviates from the optical axis of the resonant cavity, selectively suppressing the oscillation of the fundamental mode and redundant higher-order modes, and realizing a one-dimensional HG mode output that is independently adjustable in the horizontal and vertical directions; by coordinating the off-axis displacement of the plano-concave output cavity mirror in the x and y directions, the range of mode orders is expanded. Step 2: Convert between Higher-Order Hermetic (HG) Mode and Ingenus (IG) Mode By keeping the off-axis displacement of the plano-concave output cavity mirror fixed and maintaining stable oscillation of the target HG mode, the pitch angle of the gain medium is adjusted through a multi-axis optical platform to break the cylindrical symmetry of the resonant cavity and introduce controllable intracavity astigmatism. This astigmatism is equivalent to continuously adjusting the ellipticity parameter ε. When ε→∞, the IG mode degenerates into the HG mode. When ε is continuously adjustable, the HG mode is driven to transform into the odd-even superposition IG mode. By adjusting the pitch angle of the gain medium in the opposite direction, the IG mode can be restored to the HG mode, completing the bidirectional conversion between the two modes. Step 3: IG Mode Tier Adjustment By adjusting the magnitude of the off-axis displacement in the x and y directions of the plano-concave output cavity mirror, the p-index of the IG mode can be precisely controlled; by adjusting the pitch angle of the gain medium, the intracavity astigmatism intensity can be changed to adjust the ellipticity parameter ε, thereby controlling the m-index of the IG mode and the superposition weight of the odd and even modes, and finally obtaining a high-order IG mode with controllable p and m-indexes.

5. The intracavity coordinated control method of higher-order Hermitian and Insgaussian modes according to claim 4, characterized in that: In step 1, the order of the HG mode is positively correlated with the off-axis displacement. HG is obtained by controlling the horizontal off-axis direction alone. m In the 0 series mode, HG0 can be obtained by independently controlling the vertical off-axis direction. n The series of modes expands to hundreds of modes when the dual-axis cooperative off-axis mode is used, and the output power of each HG mode increases linearly with the input power.

6. The intracavity coordinated control method of higher-order Hermitian and Insgaussian modes according to claim 4, characterized in that: In step 2, the pitch angle of the gain medium is adjusted within a range of 0–5°. This angle is continuously adjusted to achieve a wide range of adjustment of the ellipticity parameter ε, thereby driving the lossless dynamic conversion between HG and IG modes. The mode stability is monitored in real time by the imaging device during the conversion process.

7. The intracavity coordinated control method of higher-order Hermitian and Insgaussian modes according to claim 4, characterized in that: In step 3, when the HG mode is off-axis in only one direction, it is transformed into a non-superimposed single even mode or odd mode; when the HG mode is off-axis in both directions at the same time, it is transformed into an odd-even superimposed IG mode, and the total order of the HG mode is equal to the p-exponent of the transformed IG mode.

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