A method and apparatus for beam self-cleaning based on ring-core optical fiber

Abstract

This application provides a method and apparatus for beam self-cleaning based on a ring-core fiber. The method includes: obtaining operational attribute parameters of a signal source; generating a required initial pulse signal based on these parameters; the operational attribute parameters include the pulse duration, input peak power, and pulse energy of the signal source; inputting the initial pulse signal into a preset target ring-core fiber; and analyzing the nonlinear effect of the initial pulse signal in the target ring-core fiber by adjusting the input peak power and pulse energy of the signal source to excite a Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped spot under the Kerr beam self-cleaning effect; the target ring-core fiber is constructed based on preset structural parameters. The method provided in this application can achieve beam shaping during propagation in a ring-core fiber, effectively improving the spatial quality of the output spot of the ring-core fiber.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, specifically to a method and apparatus for achieving beam self-cleaning based on a ring-core optical fiber. Additionally, it relates to a ring-core optical fiber, electronic equipment, and a processor-readable storage medium. Background Technology

[0002] Single-mode fiber provides a convenient environment for studying various nonlinear phenomena and forms the basis of technologies such as optical communication systems and mode-locked lasers. Over the past few decades, the propagation of light in single-mode fiber has been extensively studied. As the performance of communication systems and short-pulse lasers gradually approaches its limits, multimode fiber is regaining attention to overcome the capacity limitations of current single-mode fiber systems. Beam propagation in multimode fiber is subject to complex spatiotemporal interactions. Multimode fiber can provide various solutions to drive new breakthroughs in the control and manipulation of light in communications, high-power fiber lasers, and metrology. In fundamental physics, multimode fiber is a natural tool for revealing new nonlinear phenomena. Significant progress has been made in the study of complex nonlinear phenomena in multimode fiber, such as multimode solitons, geometric modulation instabilities, spatiotemporal mode-locking, and the generation of ultrawide supercontinuum spectra.

[0003] When light propagates in multimode fiber, it undergoes inherent randomness. A high spatial quality input laser beam gradually transforms into an irregular granular structure, known as speckle. Furthermore, fiber stress or bending, as well as irregularities in fiber drawing techniques, couple different guided modes, similarly causing randomness in light transmission characteristics. Therefore, techniques for controlling light propagation in multimode fiber have attracted widespread research interest. Specific signal processing algorithms can predict or manage the output beam shape by controlling the input field of the multimode fiber. In particular, the application of multiple-input multiple-output (MIMO) digital signal processing techniques has enabled space-division multiplexing based on multimode fiber. Wavefront shaping is also a widely used method, typically relying on the linear properties of the medium or feedback mechanisms to optimize the wavefront. This method is very flexible, but currently not ideal for certain applications because it requires complex and slow measurements, sensitive adjustments, and complex adaptive optics. Moreover, although feedback-based wavefront shaping schemes can accommodate nonlinearities, medium-property-based schemes are generally unsuitable for applications with significant nonlinear effects, such as ultrafast lasers. Especially for high-power beam transmission applications, in existing technologies, the spontaneous recovery of spatial beam quality in multimode fiber can be achieved through nonlinear dissipation processes such as stimulated Raman scattering and stimulated Brillouin scattering. However, these techniques cannot achieve self-cleaning of the input laser beam, resulting in poor spatial quality of the output beam spot in the ring core fiber. Summary of the Invention

[0004] Therefore, this application provides a method and apparatus for realizing beam self-cleaning based on ring core fiber, in order to solve the defects of the existing beam processing schemes, which have high limitations and result in poor spatial quality of the output beam spot of ring core fiber.

[0005] In a first aspect, this application provides a method for achieving beam self-cleaning based on a ring-core optical fiber, comprising: obtaining operating attribute parameters of a signal source, and generating a required initial pulse signal based on the operating attribute parameters; wherein, the operating attribute parameters include the pulse duration of the signal source, the input peak power of the signal source, and the pulse energy of the signal source; The initial pulse signal is input into a preset target ring core fiber, and the nonlinear effect of the initial pulse signal in the target ring core fiber is analyzed by adjusting the input peak power and pulse energy of the signal source, so as to excite the Kerr beam self-cleaning effect to shape the beam during the propagation process and generate a ring spot under the Kerr beam self-cleaning effect; wherein, the target ring core fiber is constructed based on preset structural parameters.

[0006] Furthermore, before obtaining the operational attribute parameters of the signal light source, the following steps are also included: Obtain the structural parameters of the ring-core optical fiber; The structural parameters include the inner ring radius of the ring core in the ring core fiber, the outer ring radius of the ring core in the ring core fiber, the refractive index of the inner cladding in the ring core fiber, the refractive index of the ring core layer in the ring core fiber, the refractive index of the outer cladding in the ring core fiber, the length of the ring core fiber, the differential group delay corresponding to the ring core fiber, and the group velocity dispersion corresponding to the ring core fiber. The target ring core optical fiber is obtained based on the correspondence between the structural parameters.

[0007] Furthermore, after generating the annular spot under the Kerr beam self-cleaning effect, the method further includes: acquiring the spectral information of the annular spot under the Kerr beam self-cleaning effect and the pulse energy ratio information of each mode; and optimizing the structural parameters of the annular core fiber based on the spectral information and the pulse energy ratio information of each mode to obtain optimized new structural parameters.

[0008] Furthermore, the pulse duration setting of the signal light source corresponds to the length of the ring core fiber and the differential group delay of the ring core fiber at the center wavelength of the optical pulse; the input peak power setting range of the signal light source is 1kW~300kW; the pulse energy of the signal light source corresponds to the pulse duration of the signal light source and the input peak power of the signal light source.

[0009] Furthermore, the target ring-core optical fiber includes an inner cladding, an outer cladding, and a ring core; the inner ring radius and the outer ring radius of the ring core satisfy a preset target ratio; the inner cladding and the outer cladding are made of silicon dioxide, and the ring core is made of silicon dioxide doped with ions.

[0010] Furthermore, the maximum refractive index of the annular fiber core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the annular fiber core differs from the refractive index of the outer cladding by a preset second target value.

[0011] Secondly, this application also provides a beam self-cleaning device based on a ring-core fiber, comprising: An initial pulse signal generation unit is used to obtain the operating attribute parameters of the signal light source and generate the required initial pulse signal based on the operating attribute parameters; wherein, the operating attribute parameters include the pulse duration of the signal light source, the input peak power of the signal light source, and the pulse energy of the signal light source; A beam self-cleaning unit is used to input the initial pulse signal into a preset target ring-core fiber, and to analyze the nonlinear effect of the initial pulse signal in the target ring-core fiber by adjusting the input peak power and pulse energy of the signal source, so as to excite the Kerr beam self-cleaning effect to shape the beam during propagation and generate a ring-shaped light spot under the Kerr beam self-cleaning effect; wherein, the target ring-core fiber is constructed based on preset structural parameters.

[0012] Furthermore, before obtaining the operating attribute parameters of the signal source, the system also includes: a target ring core fiber acquisition unit, used for: Obtain the structural parameters of the ring-core optical fiber; The structural parameters include the inner ring radius of the ring core in the ring core fiber, the outer ring radius of the ring core in the ring core fiber, the refractive index of the inner cladding in the ring core fiber, the refractive index of the ring core layer in the ring core fiber, the refractive index of the outer cladding in the ring core fiber, the length of the ring core fiber, the differential group delay corresponding to the ring core fiber, and the group velocity dispersion corresponding to the ring core fiber. The target ring core optical fiber is obtained based on the correspondence between the structural parameters.

[0013] Furthermore, after generating the annular spot under the Kerr beam self-cleaning effect, the system further includes: a structural parameter optimization processing unit, used to acquire the spectral information of the annular spot under the Kerr beam self-cleaning effect and the pulse energy ratio information of each mode; and to optimize the structural parameters of the annular core fiber based on the spectral information and the pulse energy ratio information of each mode to obtain optimized new structural parameters.

[0014] Furthermore, the pulse duration setting of the signal light source corresponds to the length of the ring core fiber and the differential group delay of the ring core fiber at the center wavelength of the optical pulse; the input peak power setting range of the signal light source is 1kW~300kW; the pulse energy of the signal light source corresponds to the pulse duration of the signal light source and the input peak power of the signal light source.

[0015] Furthermore, the target ring-core optical fiber includes an inner cladding, an outer cladding, and a ring core; the inner ring radius and the outer ring radius of the ring core satisfy a preset target ratio; the inner cladding and the outer cladding are made of silicon dioxide, and the ring core is made of silicon dioxide doped with ions.

[0016] Furthermore, the maximum refractive index of the annular fiber core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the annular fiber core differs from the refractive index of the outer cladding by a preset second target value.

[0017] Thirdly, this application also provides a ring-core optical fiber, employing the beam self-cleaning method based on the ring-core optical fiber as described above, comprising: an inner cladding, an outer cladding, and a ring core; the inner ring radius and the outer ring radius of the ring core satisfy a preset target ratio; the maximum refractive index of the ring core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the ring core differs from the refractive index of the outer cladding by a preset second target value; The preset structural parameters corresponding to the ring core optical fiber include the inner ring radius of the ring core in the ring core optical fiber, the outer ring radius of the ring core in the ring core optical fiber, the refractive index of the inner cladding in the ring core optical fiber, the refractive index of the ring core layer in the ring core optical fiber, the refractive index of the outer cladding in the ring core optical fiber, the length of the ring core optical fiber, the differential group delay corresponding to the ring core optical fiber, and the group velocity dispersion corresponding to the ring core optical fiber.

[0018] Fourthly, this application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the beam self-cleaning method based on the ring core fiber as described in any of the above claims.

[0019] Fifthly, this application also provides a processor-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the beam self-cleaning method based on a ring-core fiber as described in any of the above claims.

[0020] The method for beam self-cleaning based on a ring-core fiber provided in this application obtains the operating attribute parameters of a signal source, generates a required initial pulse signal based on the operating attribute parameters, and inputs the initial pulse signal into a preset target ring-core fiber. By adjusting the input peak power and pulse energy of the signal source, the nonlinear effect of the initial pulse signal in the target ring-core fiber is analyzed to excite the Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped light spot under the Kerr beam self-cleaning effect. The target ring-core fiber is constructed based on preset structural parameters, which can realize the shaping of the beam during propagation in the ring-core fiber, effectively improving the spatial quality of the output light spot of the ring-core fiber. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic flowchart of the beam self-cleaning method based on ring core fiber provided in the embodiments of this application; Figure 2 This is a schematic diagram of the refractive index distribution of the ring-core optical fiber provided in the embodiments of this application; Figure 3 This is a schematic diagram showing the proportion of each mode in the ring core fiber provided in this application as a function of the input peak power. Figure 4 This is a schematic diagram of the pulse energy variation with distance for each mode in the ring core optical fiber provided in this application at an input peak power of 200kW; Figure 5 The spectrum of each mode in the ring core fiber provided in this application embodiment is at an input peak power of 200kW and a distance of 1.11m. Figure 6 These are the spectra of each mode in the ring core optical fiber provided in this application embodiment at an input peak power of 200kW and a distance of 1.62m; Figure 7This is a schematic diagram of the beam self-cleaning device based on a ring-core fiber provided in the embodiments of this application; Figure 8 This is a schematic diagram of the structure of the ring-core optical fiber provided in the embodiments of this application; Figure 9 This is a schematic diagram of the physical structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The following section first describes in detail the embodiments of the beam self-cleaning method based on ring-core fiber described in this application. For example... Figure 1 The diagram shown is a flowchart illustrating the beam self-cleaning method based on a ring-core fiber provided in this application embodiment. The specific implementation process includes the following steps: Step 101: Obtain the operating attribute parameters of the signal light source, and generate the required initial pulse signal based on the operating attribute parameters; wherein, the operating attribute parameters include the pulse duration of the signal light source, the input peak power of the signal light source, and the pulse energy of the signal light source.

[0025] In this embodiment of the invention, the pulse duration of the signal light source is set to correspond with the length of the ring-core fiber and the differential group delay of the ring-core fiber at the center wavelength of the optical pulse; the input peak power of the signal light source is set to a range of 1kW to 300kW; the pulse energy of the signal light source is also set to correspond with the pulse duration and the input peak power. For example, the pulse duration of the signal light source is set to correspond with the length of the ring-core fiber and the differential group delay of the ring-core fiber at a center wavelength of 1550nm; the pulse energy of the signal light source is also set to correspond with the pulse duration and the input peak power.

[0026] Before obtaining the operating attribute parameters of the signal source, the method further includes: obtaining the structural parameters of the ring-core optical fiber; wherein, the structural parameters include the inner ring radius of the ring core in the ring-core optical fiber, the outer ring radius of the ring core in the ring-core optical fiber, the refractive index of the inner cladding in the ring-core optical fiber, the refractive index of the ring core layer in the ring-core optical fiber, the refractive index of the outer cladding in the ring-core optical fiber, the length of the ring-core optical fiber, the differential group delay corresponding to the ring-core optical fiber, and the group velocity dispersion corresponding to the ring-core optical fiber; the target ring-core optical fiber is obtained based on the correspondence between the structural parameters. The ring-core optical fiber has multiple selectable structural parameters.

[0027] Step 102: Input the initial pulse signal into the preset target ring core fiber, and analyze the nonlinear effect of the initial pulse signal in the target ring core fiber by adjusting the input peak power and pulse energy of the signal light source, so as to excite the Kerr beam self-cleaning effect to shape the beam during the propagation process and generate the ring spot under the Kerr beam self-cleaning effect; wherein, the target ring core fiber is constructed based on preset structural parameters.

[0028] In this embodiment of the invention, the initial pulse signal is input into a preset target ring core fiber, and the Kerr beam self-cleaning effect can be detected. By adjusting the input peak power and pulse energy of the signal source, the nonlinear effect of the initial pulse signal in the target ring core fiber is analyzed, and the Kerr beam self-cleaning effect is excited to shape the beam during the propagation process, thereby generating a ring spot under the Kerr beam self-cleaning effect.

[0029] In this embodiment of the invention, the target ring-core optical fiber is sequentially wrapped from the inside out with an inner cladding, a ring core (i.e., a ring fiber core), and an outer cladding; the inner ring radius and the outer ring radius of the ring fiber core satisfy a preset target ratio; the inner cladding and the outer cladding can be silicon dioxide components, and the ring fiber core can be a silicon dioxide doped ion component. The maximum refractive index of the ring fiber core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the ring fiber core differs from the refractive index of the outer cladding by a preset second target value. The preset target ratio of the inner ring radius to the outer ring radius of the ring fiber core in the ring-core optical fiber can be 0.92. The refractive index distribution of the ring-core optical fiber is a graded refractive index distribution. The preset first target value of the difference between the maximum refractive index of the ring fiber core and the refractive index of the inner cladding can be 0.013, and the preset second target value of the difference between the maximum refractive index of the ring fiber core and the refractive index of the outer cladding can be 0.013. The differential group delay range of the ring-core fiber at a center wavelength of 1550 nm is 0~0.25 fs / mm. The group velocity dispersion of the ring-core fiber at a center wavelength of 1550 nm is 28.94 fs^2 / mm.

[0030] Furthermore, after generating the annular spot under the Kerr beam self-cleaning effect, the method further includes: acquiring the spectral information of the annular spot under the Kerr beam self-cleaning effect and the pulse energy ratio information of each mode; and optimizing the structural parameters of the annular core fiber based on the spectral information and the pulse energy ratio information of each mode to obtain optimized new structural parameters.

[0031] The annular core fiber provided by this invention can increase the refractive index of the fiber core through doping and other methods, confining the optical field distribution to the annular core region. Compared with ordinary multimode fiber, the mode field distribution is denser and the intermode interaction is more intense. A significant Kerr beam self-cleaning effect is observed at 1550 nm in the anomalous dispersion region, which cannot currently be achieved in ordinary multimode fiber. The proportion of the fundamental mode in the Kerr beam self-cleaning effect in the annular core fiber is higher than that in ordinary multimode fiber. The Kerr beam self-cleaning effect in the annular core fiber is not suppressed by stimulated Raman scattering and may even be enhanced by stimulated Raman scattering, while the Kerr beam self-cleaning effect in ordinary multimode fiber and photonic crystal fiber is suppressed by stimulated Raman scattering.

[0032] In the specific implementation of this invention, it is necessary to first design the structure of the ring-core optical fiber, whose refractive index distribution satisfies the following formula: In the formula, and These are the refractive indices of the inner cladding and the outer cladding of the ring-core optical fiber, respectively. The center of the ring core fiber (i.e. Figure 8 From 801 in the middle to the center of the annular core region (i.e., the annular core layer) (i.e. Figure 8 The distance of 802 in the middle; As a variable, it can represent the distance from the center of the loop-core fiber to any point in the loop-core fiber, for example, it can be . or ; The maximum refractive index of the ring-core optical fiber; It is half the width of the annular core region, for example, it can be... ; is the refractive index distribution parameter (i.e., power law); The relative refractive index difference between the inner and outer cladding layers and the annular core region satisfies: After designing the structure of the ring-core fiber, the finite difference method can be used to solve for each mode in the ring-core fiber. Then, the first nine modes are selected for analysis. The first nine modes are as follows: , , , , , , , , .

[0033] Numerical simulation was performed on the initial pulse signal. The pulse type was a Gaussian pulse, and its amplitude expression was: In the formula, This represents the amplitude of the initial pulse signal. The total energy (i.e., pulse energy) of the initial pulse signal corresponding to the 9 modes is allocated as follows: 95% of the total energy is allocated to the first 5 modes, and 5% of the total energy is allocated to the last 4 modes, which are treated as noise. For the initial pulse signal Half-width at intensity point, full width at half-height of initial pulse signal The full width at half maximum (FWHM) The width of the pulse signal is the value corresponding to a drop of half the height from the peak of the initial pulse signal. This indicates the position of the time window corresponding to the amplitude of the initial pulse signal. This indicates the position of the time window corresponding to the maximum amplitude of the initial pulse signal. The nonlinear effects experienced by the initial pulse signal during propagation in a ring-core fiber are analyzed. The underlying theory is the Generalized Multimode Nonlinear Schrödinger Equation (GMMNLSE). The GMMNLSE has the following form, containing a series of coupling equations to describe the changes in the mode envelope: The equation uses two approximations: (1) Within a single pulse period, the pulse envelope and the Raman response function change very slowly, so the terms of rapid oscillation are ignored. (2) The value is independent of frequency transformation. In the above formula, for The pulse envelope of the pattern; for The pulse envelope of the pattern; for The pulse envelope of the pattern; for The pulse envelope of the pattern; and These are preset parameters; For dispersion operators, The specific expression is as follows: in, Represents The dispersion effect of the mode, Represents The propagation constant of the pattern, Represents the propagation constant of the fundamental mode. Represents The first-order dispersion of the mode, The first-order dispersion of the fundamental mode; the propagation constant. It includes an imaginary part, which represents wavelength-dependent loss. It represents the real part.

[0034] The second term on the right-hand side of the above formula corresponding to GMMNLSE describes the nonlinear effects in multimode fiber, where, The nonlinear refractive index coefficient is typically 1. , The angular frequency of the fundamental mode. At the speed of light, This is the contribution of the Raman response to the nonlinear polarization, typically 0.18. and These are the nonlinear coupling coefficients of the Kerr effect and the Raman response, respectively. It is the delayed Raman response function in optical fiber. , , They are respectively model, model, The pulse envelope of the mode. To simplify the formula, we assume that the excited modes are in a single linear polarization and ignore spontaneous modes that may couple to these modes to simplify the tensor, in which case we have: in, , , , They represent model, model, model, The pattern distribution function of the pattern. The mode can be any one of the nine modes mentioned above. The mode can also be any of the nine modes mentioned above. The mode can also be any of the nine modes mentioned above. The pattern can also be any of the nine patterns mentioned above, and may include multiple combinations to form the pattern's distribution function.

[0035] The input peak power was changed by adjusting the total energy of the initial pulse signal, and then the Kerr beam self-cleaning effect was observed.

[0036] The self-focusing characteristics and nonlinear mode coupling of graded-index ring-core multimode fibers play a crucial role in the generation of the Kerr beam self-cleaning effect. In the multimode case, intermode four-wave mixing occurs when phase-matching conditions are met between modes, allowing energy exchange between modes. The self-focusing characteristic results in the highest superposition value between the input multimode and the fundamental mode, which is beneficial for energy conversion from higher-order modes to lower-order modes. The nonlinear phase shift accumulation rate caused by the self-phase modulation of the fundamental mode is faster, leading to nonlinear non-reciprocity. The phase difference between the fundamental mode and higher-order modes increases, causing the four-wave mixing process of fundamental mode to higher-order mode conversion to no longer occur. Ultimately, the energy of the fundamental mode increases, and the energy of the higher-order modes decreases. The fundamental mode can be mode 1.

[0037] The generation process of the Kerr beam self-cleaning effect provided in this embodiment of the invention specifically includes the following steps: First, a graded-index ring-core fiber is designed, and parameters such as ring thickness, power ratio, and relative refractive index difference are adjusted to reduce the differential group delay between modes, facilitating coupling between modes and achieving the conditions for generating the beam cleaning effect; then, the initial pulse signal is set, including parameters such as pulse duration, center wavelength, and peak power; based on the generalized multimode nonlinear Schrödinger equation, the nonlinear effect of the initial pulse signal in the ring-core fiber is analyzed to find the Kerr beam self-cleaning effect; the ring spot, spectrum, and energy ratio of each mode under the Kerr beam self-cleaning effect are analyzed to further optimize the structural parameters of the ring-core fiber. The ring-core fiber is a multimode fiber, also known as a graded-index ring-core multimode fiber or graded-index multimode fiber.

[0038] like Figure 8 The figure shows the cross-sectional structure of a graded refractive index ring core multimode fiber with a radius of 50. The refractive index at the core is determined to be 1.444 at a wavelength of 1550 nm using the Selmeyer formula. The refractive index difference between the core and the cladding is 0.013, so the refractive index of the cladding is 1.457.

[0039] Figure 2 To determine the refractive index distribution of a graded-index multimode fiber, with a power of 2 to ensure a parabolic refractive index distribution, the length of the ring-core fiber is 3m. After designing the structure of the ring-core fiber, the modes of the ring-core fiber are solved using the finite difference method. For efficiency and simplicity, the first nine modes are selected for analysis. The dispersion of each of the first nine modes is then analyzed. , , The nonlinear coupling coefficient between the Kerr effect and the Raman response , Solve the problem. Set the initial pulse signal and input a Gaussian pulse. In the time window, center=0, full width at half height. Determined by the first-order dispersion of the mode and the length of the loop-core fiber, it is set to 12 ps. The total energy consists of the input peak power and the full width at half maximum (FWHM). The input peak power was determined to be within the range of 1kW to 300kW. 95% of the total energy was allocated to the first five modes, and the remaining 5% was allocated to the last four modes, which were treated as noise. After setting the initial pulse signal, it was injected into the designed graded-index ring-core multimode fiber. The input peak power and total energy were continuously varied, and the output spectrum and energy distribution of each mode were observed.

[0040] Figure 3This is a graph showing the relationship between the energy percentage of each mode and the peak input power. When the peak input power is less than 100kW, the energy percentage of each mode remains basically unchanged. When the peak input power exceeds 100kW, the energy percentage of the fundamental mode begins to increase. When the peak input power reaches 200kW, the energy percentage of the fundamental mode reaches about 52% and remains stable.

[0041] Figure 4 This is a graph showing the relationship between the energy percentage of each mode and the fiber length at an input peak power of 200kW. The bottom image shows the spectrum of mode 1, increasing sequentially upwards. At a fiber length of 1.11m, the beam cleaning effect begins to appear, and the fundamental mode energy percentage starts to increase. Figure 5 The spectrum shows that there is no obvious stimulated Raman scattering at this point, so the beam cleaning effect can be considered to be caused by the Kerr effect. The spectrum at a fiber length of 1.62m is shown; the bottommost spectrum is for mode 1, with the mode numbers increasing sequentially upwards. Figure 6 As shown, stimulated Raman scattering (SRS) is clearly present at this point, but the fundamental mode energy percentage is not suppressed and continues to increase. This indicates that stimulated Raman scattering does not suppress the Kerr beam self-cleaning effect and may even enhance it. The Kerr beam self-cleaning effect, excited by the Kerr effect, can automatically reshape the beam during propagation at power levels far below the Raman cleaning threshold, transforming the speckle at the multimode fiber output into a focused bell-shaped structure, thereby obtaining a high spatial quality and high brightness beam. It should be noted that... Figure 5 The table shown contains nine waveform structures from bottom to top, corresponding to modes 1, 2, ..., 9. Accordingly, Figure 6 The nine waveform structures shown in the table, from bottom to top, also correspond to modes 1, 2, ..., 9 in the nine modes.

[0042] The beam self-cleaning method based on a ring-core fiber described in this application obtains the operating attribute parameters of a signal source, generates a required initial pulse signal based on the operating attribute parameters, and inputs the initial pulse signal into a preset target ring-core fiber. By adjusting the input peak power and pulse energy of the signal source, the nonlinear effect of the initial pulse signal in the target ring-core fiber is analyzed to excite the Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped light spot under the Kerr beam self-cleaning effect. The target ring-core fiber is constructed based on preset structural parameters, which can realize the shaping of the beam during propagation in the ring-core fiber, effectively improving the spatial quality of the output light spot of the ring-core fiber.

[0043] Corresponding to the above-described method for achieving beam self-cleaning based on a ring-core fiber, this application also provides a device for achieving beam self-cleaning based on a ring-core fiber. Since the embodiments of this device are similar to the above-described method embodiments, the description is relatively simple. For relevant details, please refer to the description in the above-described method embodiment section. The embodiments of the beam self-cleaning device based on a ring-core fiber described below are merely illustrative. Please refer to... Figure 7 The diagram shown is a structural schematic of a beam self-cleaning device based on a ring-core fiber provided in an embodiment of this application. The beam self-cleaning device based on a ring-core fiber described in this application includes the following parts: An initial pulse signal generation unit 701 is used to obtain the operating attribute parameters of the signal light source and generate the required initial pulse signal based on the operating attribute parameters; wherein, the operating attribute parameters include the pulse duration of the signal light source, the input peak power of the signal light source, and the pulse energy of the signal light source; The beam self-cleaning realization unit 702 is used to input the initial pulse signal into a preset target ring core fiber, and analyze the nonlinear effect of the initial pulse signal in the target ring core fiber by adjusting the input peak power and pulse energy of the signal source, so as to excite the Kerr beam self-cleaning effect to shape the beam during the propagation process and generate a ring spot under the Kerr beam self-cleaning effect; wherein, the target ring core fiber is constructed based on preset structural parameters.

[0044] Furthermore, before obtaining the operating attribute parameters of the signal source, the system also includes: a target ring core fiber acquisition unit, used for: Obtain the structural parameters of the ring-core optical fiber; The structural parameters include the inner ring radius of the ring core in the ring core fiber, the outer ring radius of the ring core in the ring core fiber, the refractive index of the inner cladding in the ring core fiber, the refractive index of the ring core layer in the ring core fiber, the refractive index of the outer cladding in the ring core fiber, the length of the ring core fiber, the differential group delay corresponding to the ring core fiber, and the group velocity dispersion corresponding to the ring core fiber. The target ring core optical fiber is obtained based on the correspondence between the structural parameters.

[0045] Furthermore, after generating the annular spot under the Kerr beam self-cleaning effect, the system further includes: a structural parameter optimization processing unit, used to acquire the spectral information of the annular spot under the Kerr beam self-cleaning effect and the pulse energy ratio information of each mode; and to optimize the structural parameters of the annular core fiber based on the spectral information and the pulse energy ratio information of each mode to obtain optimized new structural parameters.

[0046] Furthermore, the pulse duration setting of the signal light source corresponds to the length of the ring core fiber and the differential group delay of the ring core fiber at the center wavelength of the optical pulse; the input peak power setting range of the signal light source is 1kW~300kW; the pulse energy of the signal light source corresponds to the pulse duration of the signal light source and the input peak power of the signal light source.

[0047] Furthermore, the target ring-core optical fiber includes an inner cladding, an outer cladding, and a ring core; the inner ring radius and the outer ring radius of the ring core satisfy a preset target ratio; the inner cladding and the outer cladding are made of silicon dioxide, and the ring core is made of silicon dioxide doped with ions.

[0048] Furthermore, the maximum refractive index of the annular fiber core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the annular fiber core differs from the refractive index of the outer cladding by a preset second target value.

[0049] The beam self-cleaning device based on a ring-core fiber described in this application obtains the operating attribute parameters of a signal source, generates a required initial pulse signal based on the operating attribute parameters, and inputs the initial pulse signal into a preset target ring-core fiber. By adjusting the input peak power and pulse energy of the signal source, the nonlinear effect of the initial pulse signal in the target ring-core fiber is analyzed to excite the Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped light spot under the Kerr beam self-cleaning effect. The target ring-core fiber is constructed based on preset structural parameters, which can realize the shaping of the beam during propagation in the ring-core fiber, effectively improving the spatial quality of the output light spot of the ring-core fiber.

[0050] Corresponding to the above-described method and apparatus for beam self-cleaning based on a ring-core fiber, this application also provides a ring-core fiber for use in the described method and apparatus. Since the embodiment of this ring-core fiber is similar to the above-described method embodiment, it is described simply. For relevant details, please refer to the description in the above-described method embodiment section. The ring-core fiber embodiment described below is merely illustrative. Please refer to... Figure 8The diagram shown is a structural schematic of a ring-core optical fiber provided in an embodiment of this application. The ring-core optical fiber of this application includes the following parts: an inner cladding, an outer cladding, and a ring core; the inner ring radius and outer ring radius of the ring core satisfy a preset target ratio; the maximum refractive index of the ring core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the ring core differs from the refractive index of the outer cladding by a preset second target value; the preset structural parameters corresponding to the ring-core optical fiber include the inner ring radius of the ring core, the outer ring radius of the ring core, the refractive index of the inner cladding, the refractive index of the ring core layer, the refractive index of the outer cladding, the length of the ring-core optical fiber, the differential group delay corresponding to the ring-core optical fiber, and the group velocity dispersion corresponding to the ring-core optical fiber.

[0051] Corresponding to the above-described method for beam self-cleaning based on ring-core fiber, this application also provides an electronic device. Since the embodiment of this electronic device is similar to the above-described method embodiment, it is described simply. For relevant details, please refer to the description in the above-described method embodiment section. The electronic device described below is merely illustrative. Figure 9 The diagram shows a schematic representation of the physical structure of an electronic device disclosed in this application. The electronic device may include a processor 901, a memory 902, and a communication bus 903. The processor 901 and memory 902 communicate with each other via the communication bus 903 and communicate with external systems via a communication interface 904. The processor 901 can call logical instructions in the memory 902 to execute a beam self-cleaning method based on a ring-core fiber. This method includes: obtaining operating attribute parameters of a signal source; generating a required initial pulse signal based on the operating attribute parameters; wherein the operating attribute parameters include the pulse duration of the signal source, the input peak power of the signal source, and the pulse energy of the signal source; inputting the initial pulse signal into a preset target ring-core fiber; and analyzing the nonlinear effect of the initial pulse signal in the target ring-core fiber by adjusting the input peak power and pulse energy of the signal source to excite a Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped light spot under the Kerr beam self-cleaning effect; wherein the target ring-core fiber is constructed based on preset structural parameters.

[0052] Furthermore, the logical instructions in the aforementioned memory 902 can be implemented as software functional modules and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as memory chips, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0053] On the other hand, embodiments of this application also provide a computer program product, which includes a computer program stored on a processor-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by a computer, the computer can execute the beam self-cleaning method based on the ring-core fiber provided in the above-described method embodiments. The method includes: obtaining operating attribute parameters of a signal source; generating a required initial pulse signal based on the operating attribute parameters; wherein the operating attribute parameters include the pulse duration of the signal source, the input peak power of the signal source, and the pulse energy of the signal source; inputting the initial pulse signal into a preset target ring-core fiber, and analyzing the nonlinear effect of the initial pulse signal in the target ring-core fiber by adjusting the input peak power and pulse energy of the signal source to excite a Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped light spot under the Kerr beam self-cleaning effect; wherein the target ring-core fiber is constructed based on preset structural parameters.

[0054] In another aspect, embodiments of this application also provide a processor-readable storage medium storing a computer program, which, when executed by a processor, performs the beam self-cleaning method based on a ring-core fiber provided in the above embodiments. The method includes: obtaining operational attribute parameters of a signal source; generating a required initial pulse signal based on the operational attribute parameters; wherein the operational attribute parameters include the pulse duration of the signal source, the input peak power of the signal source, and the pulse energy of the signal source; inputting the initial pulse signal into a preset target ring-core fiber; and analyzing the nonlinear effect of the initial pulse signal in the target ring-core fiber by adjusting the input peak power and pulse energy of the signal source to excite a Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped light spot under the Kerr beam self-cleaning effect; wherein the target ring-core fiber is constructed based on preset structural parameters.

[0055] The processor-readable storage medium can be any available medium or data storage device that the processor can access, including but not limited to magnetic memory (e.g., floppy disk, hard disk, magnetic tape, magneto-optical disk (MO)), optical memory (e.g., CD, DVD, BD, HVD), and semiconductor memory (e.g., ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)).

[0056] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0057] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for achieving beam self-cleaning based on ring-core optical fiber, characterized in that, include: The operating attribute parameters of the signal light source are obtained, and the required initial pulse signal is generated based on the operating attribute parameters; wherein, the operating attribute parameters include the pulse duration of the signal light source, the input peak power of the signal light source, and the pulse energy of the signal light source; The initial pulse signal is input into a preset target ring-core fiber, and the nonlinear effect of the initial pulse signal in the target ring-core fiber is analyzed by adjusting the input peak power and pulse energy of the signal source to excite the Kerr beam self-cleaning effect to shape the beam during propagation, generating a ring-shaped spot under the Kerr beam self-cleaning effect; wherein, the target ring-core fiber is constructed based on preset structural parameters; the target ring-core fiber includes an inner cladding, an outer cladding, and a ring core; the inner ring radius and outer ring radius of the ring core satisfy a preset target ratio; the maximum refractive index of the ring core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the ring core differs from the refractive index of the outer cladding by a preset second target value; In this case, adjusting the input peak power of the signal light source to stimulated Raman scattering will not suppress the Kerr beam self-cleaning effect, but will instead enhance it.

2. The method for achieving beam self-cleaning based on ring-core optical fiber according to claim 1, characterized in that, Before obtaining the operational attribute parameters of the signal light source, the following is also included: Obtain the structural parameters of the ring-core optical fiber; The structural parameters include the inner ring radius of the ring core in the ring core fiber, the outer ring radius of the ring core in the ring core fiber, the refractive index of the inner cladding in the ring core fiber, the refractive index of the ring core layer in the ring core fiber, the refractive index of the outer cladding in the ring core fiber, the length of the ring core fiber, the differential group delay corresponding to the ring core fiber, and the group velocity dispersion corresponding to the ring core fiber. The target ring core optical fiber is obtained based on the correspondence between the structural parameters.

3. The method for achieving beam self-cleaning based on ring-core optical fiber according to claim 2, characterized in that, After generating the annular spot under the Kerr beam self-cleaning effect, the method further includes: acquiring the spectral information of the annular spot under the Kerr beam self-cleaning effect and the pulse energy ratio information of each mode; and optimizing the structural parameters of the annular core fiber based on the spectral information and the pulse energy ratio information of each mode to obtain optimized new structural parameters.

4. The method for achieving beam self-cleaning based on ring-core optical fiber according to claim 1, characterized in that, The pulse duration of the signal light source is set to correspond to the length of the ring core fiber and the differential group delay of the ring core fiber at the center wavelength of the optical pulse; the input peak power of the signal light source is set to a range of 1kW to 300kW; the pulse energy of the signal light source is related to the pulse duration of the signal light source and the input peak power of the signal light source.

5. The method for achieving beam self-cleaning based on ring-core fiber according to claim 1, characterized in that, The inner cladding and the outer cladding are made of silicon dioxide, and the annular fiber core is made of silicon dioxide doped with ions.

6. A beam self-cleaning device based on a ring-core optical fiber, characterized in that, include: An initial pulse signal generation unit is used to obtain the operating attribute parameters of the signal light source and generate the required initial pulse signal based on the operating attribute parameters; wherein, the operating attribute parameters include the pulse duration of the signal light source, the input peak power of the signal light source, and the pulse energy of the signal light source; A beam self-cleaning unit is used to input the initial pulse signal into a preset target ring-core fiber, and to analyze the nonlinear effect of the initial pulse signal in the target ring-core fiber by adjusting the input peak power and pulse energy of the signal source, so as to excite the Kerr beam self-cleaning effect to shape the beam during propagation and generate a ring-shaped light spot under the Kerr beam self-cleaning effect; wherein, the target ring-core fiber is constructed based on preset structural parameters; the target ring-core fiber includes an inner cladding, an outer cladding, and a ring core; the inner ring radius and the outer ring radius of the ring core satisfy a preset target ratio; the maximum refractive index of the ring core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the ring core differs from the refractive index of the outer cladding by a preset second target value; In this case, adjusting the input peak power of the signal light source to stimulated Raman scattering will not suppress the Kerr beam self-cleaning effect, but will instead enhance it.

7. A ring-core optical fiber, employing the beam self-cleaning method based on a ring-core optical fiber as described in claim 1, characterized in that, include: Inner cladding, outer cladding, and annular core; The inner ring radius and outer ring radius of the annular fiber core meet the preset target ratio. The maximum refractive index of the annular fiber core differs from the refractive index of the inner cladding by a preset first target value, and the maximum refractive index of the annular fiber core differs from the refractive index of the outer cladding by a preset second target value; The preset structural parameters corresponding to the ring core optical fiber include the inner ring radius of the ring core in the ring core optical fiber, the outer ring radius of the ring core in the ring core optical fiber, the refractive index of the inner cladding in the ring core optical fiber, the refractive index of the ring core layer in the ring core optical fiber, the refractive index of the outer cladding in the ring core optical fiber, the length of the ring core optical fiber, the differential group delay corresponding to the ring core optical fiber, and the group velocity dispersion corresponding to the ring core optical fiber.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the beam self-cleaning method based on any one of claims 1 to 5.

9. A processor-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the beam self-cleaning method based on any one of claims 1 to 5.

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