Pumping intensity optimization method and equipment of laser and medium

Abstract

The invention relates to the technical field of ultrafast laser, and discloses a pumping intensity optimization method of a laser, equipment and a medium. The method comprises the following steps: carrying out graded pumping design, and pre-amplifying signal light output by a mode-locked fiber oscillator by adopting a single-mode laser diode; the method comprises the following steps: establishing a mathematical model of pumping power and gain fiber length, and when the pumping power is increased from low power to preset power, adjusting the chirp amount of a chirp fiber grating through a temperature tuning device, and performing pre-chirp management on signal light input into a multimode gain fiber; under high pumping intensity, the initial chirp amount of signal light is optimized, so that the signal light entering the multimode gain optical fiber is in a negative chirped pulse state, the self-phase modulation and dispersion effect of the signal light when the signal light is amplified in the multimode gain optical fiber is balanced, and the stimulated Raman scattering and self-focusing phenomena are avoided; and the compressed pulse width is used as a feedback signal to realize the optimal matching of the signal light energy and the pulse width.

Description

Technical Field

[0001] This application relates to the field of ultrafast laser technology, and in particular to a method, device and medium for optimizing the pump intensity of a laser. Background Technology

[0002] Femtosecond fiber lasers are widely used in materials processing, biomedicine, and other fields due to their combination of high beam quality, high stability, and high integration. However, limited by fiber gain bandwidth and spectral gain narrowing effects, traditional nonlinear amplification schemes struggle to simultaneously achieve narrow pulse width and high energy output under high pump intensity. In existing technologies: 1. Self-similar parabolic pulse amplification relies on long-distance, low-doped optical fibers and is susceptible to stimulated Raman scattering, which limits energy enhancement. 2. Pre-chirped amplification requires grating pairs to adjust the chirp, resulting in a complex system structure and poor stability; 3. Gain-managed nonlinear amplification requires independent optimization of multiple parameters such as pump power and fiber length, lacks a coordinated adjustment mechanism, and is difficult to balance nonlinear effects and dispersion effects.

[0003] Therefore, a method is urgently needed to solve at least one of the above problems. Summary of the Invention

[0004] This application provides a method, apparatus, and medium for optimizing the pump intensity of lasers, aiming to suppress spectral gain narrowing and nonlinear effects at high pump intensities, while simplifying tuning complexity and improving system integration. It also addresses the problems of existing solutions that do not use pre-chirp as a core parameter for pump intensity optimization, nor do they establish a collaborative optimization model for pump power, fiber parameters, and chirp, leading to low energy-pulse width matching efficiency and insufficient stability.

[0005] In a first aspect, embodiments of this application provide a method for optimizing the pump intensity of a laser, including: A staged pumping design is adopted, using a single-mode laser diode to pre-amplify the signal light output from the mode-locked fiber oscillator, and then injecting the pre-amplified signal light into a multimode gain fiber for main amplification via a multimode laser diode. A mathematical model is established for the relationship between pump power and fiber length. When the pump power is increased from low power to a preset power, the chirp of the chirped fiber grating is adjusted by a temperature tuning device to pre-chirp the signal light input to the multimode gain fiber. Negative chirp is introduced to suppress spectral gain narrowing and achieve matching between pump intensity and gain. Under high pump intensity, by optimizing the initial chirp of the signal light, the signal light entering the multimode gain fiber is in a negative chirp pulse state, which balances the self-phase modulation and dispersion effect of the signal light when it is amplified in the multimode gain fiber, avoids stimulated Raman scattering and self-focusing, achieves synergistic optimization of peak power and pulse width, and controls the threshold of nonlinear effect. Using the compressed pulse width as the feedback signal, when the target compressed pulse width is less than the preset pulse width, the pump intensity of the multimode laser diode and the temperature of the semiconductor cooling chip in the temperature tuning device are dynamically adjusted through the closed-loop feedback system to achieve the optimal matching between signal light energy and pulse width.

[0006] In some embodiments, the pre-amplification of the signal light output from the mode-locked fiber oscillator using a single-mode laser diode includes: using a single-mode laser diode with a center wavelength of 976nm and a maximum power of 400mW to amplify the signal light output from the mode-locked fiber oscillator with a center wavelength of 1030nm, a repetition frequency of 36MHz, an output power of 5mW, and a pulse width of 2ps to the level of hundreds of milliwatts through a single-mode gain fiber, wherein the single-mode gain fiber has a core diameter of 6μm, a cladding diameter of 125μm, and a length of 0.5m.

[0007] In some embodiments, the step of injecting the pre-amplified signal light into a multimode gain fiber via a multimode laser diode for main amplification includes: using a multimode laser diode with a center wavelength of 915nm and a maximum power of 30W to inject the pre-amplified signal light into a multimode gain fiber, wherein the multimode gain fiber has a core diameter of 14μm, a cladding diameter of 125μm, an absorption coefficient of 3.9±0.5dB / m at 915nm, and a length of 1.5m, to perform main amplification of the signal light.

[0008] In some embodiments, establishing a mathematical model of pump power and gain fiber length includes: based on the relationship between pump power, gain fiber absorption coefficient and signal light chirp, establishing a three-dimensional optimization relationship model of pump power, gain fiber length and signal light spectral broadening effect through theoretical calculation and experimental calibration, which is used to determine the optimal length of gain fiber and the chirp adjustment range corresponding to different pump powers.

[0009] In some embodiments, when the pump power is increased from a low power to a preset power, adjusting the chirp of the chirped fiber grating through a temperature tuning device includes: the temperature tuning device comprising four thermoelectric coolers, each thermoelectric cooler fixing a 10mm long copper block, with a V-shaped groove in the middle of the copper block for placing a uniformly chirped fiber grating; by adjusting the temperature of the four thermoelectric coolers to increase linearly within the range of 25°C to 25.6°C, changing the dispersion of the chirped fiber grating, thereby adjusting the chirp of the signal light.

[0010] In some embodiments, the pre-chirping management of the signal light input to the multimode gain fiber, introducing negative chirp to suppress spectral gain narrowing and achieve matching between pump intensity and gain, includes: changing the chirp of the chirped fiber grating by adjusting a temperature tuning device, so that the signal light entering the multimode gain fiber carries negative chirp, and widening the spectral width of the signal light from 12nm to more than 23nm during the process of increasing the pump power from 1W to 5W, thereby compensating for the spectral narrowing effect during the fiber gain process.

[0011] In some embodiments, optimizing the initial chirp of the signal light to make the signal light entering the multimode gain fiber a negative chirped pulse state, and balancing the self-phase modulation and dispersion effects of the signal light during amplification in the multimode gain fiber, includes: utilizing the initial spectral broadening characteristics of the negative chirped pulse to achieve a dynamic balance between the self-phase modulation effect and the dispersion effect during the amplification process in the multimode gain fiber, thereby avoiding pulse distortion caused by nonlinear effects under high pump intensity.

[0012] In some embodiments, the method of dynamically adjusting the pump intensity of the multimode laser diode and the temperature of the thermoelectric cooler in the temperature tuning device through a closed-loop feedback system to achieve optimal matching between signal light energy and pulse width includes: using a transmission grating to provide feedback on the compressed pulse width; when the compressed pulse width is detected to be greater than 120 fs, automatically adjusting the output power of the multimode laser diode through the closed-loop control system and simultaneously adjusting the temperature of the four thermoelectric coolers until the compressed pulse width stabilizes within the target range, while ensuring that the signal light output energy reaches 5W.

[0013] Secondly, embodiments of this application provide a computer device, the computer device including a memory and a processor, the memory being used to store a computer program, and the processor being used to execute the computer program and, when executing the computer program, implement the method provided in any embodiment of this application.

[0014] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to implement the method provided in any embodiment of this application.

[0015] The pump intensity optimization method, device, and medium for lasers provided in this application establish a three-dimensional optimization relationship between pump power, gain fiber parameters, and chirp by using graded pumping (single-mode pre-amplification + multi-mode main amplification) and dynamic adjustment of pre-chirp, thereby improving optical-to-optical conversion efficiency. Utilizing the initial spectral broadening characteristics of negatively chirped pulses, the method balances self-phase modulation and dispersion effects, raising the stimulated Raman scattering threshold and avoiding pulse distortion under high pump intensity. The all-fiber structure avoids spatial coupling loss, and combined with closed-loop feedback control (dynamically adjusting pump intensity and chirp using the compressed pulse width as feedback signal), the system stability is improved compared to traditional grating schemes. It overcomes the fiber gain bandwidth limitation, meeting the demands of high-precision industrial processing and scientific research for narrow pulse widths and high energy.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments 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.

[0018] Figure 1 This is a schematic flowchart illustrating the steps of a laser pump intensity optimization method according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a laser pump intensity optimization system according to an embodiment of this application; Figure 3 This is a schematic diagram of the spectrum and pulse width after TEC adjustment provided in an embodiment of this application; Figure 4 This is a schematic block diagram of a pump intensity optimization device for a laser provided in one embodiment of this application; Figure 5 This is a schematic block diagram of the structure of a computer device provided in an embodiment of this application.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0020] 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.

[0021] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0022] It should be understood that, in order to clearly describe the technical solutions of the embodiments of the present invention, the terms "first" and "second" are used in the embodiments of the present invention to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0023] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0025] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] Femtosecond fiber lasers are widely used in materials processing, biomedicine, and other fields due to their combination of high beam quality, high stability, and high integration. However, limited by fiber gain bandwidth and spectral gain narrowing effects, traditional nonlinear amplification schemes struggle to simultaneously achieve narrow pulse width and high energy output under high pump intensity. In existing technologies: 1. Self-similar parabolic pulse amplification relies on long-distance, low-doped optical fibers and is susceptible to stimulated Raman scattering, which limits energy enhancement. 2. Pre-chirped amplification requires grating pairs to adjust the chirp, resulting in a complex system structure and poor stability; 3. Gain-managed nonlinear amplification requires independent optimization of multiple parameters such as pump power and fiber length, lacks a coordinated adjustment mechanism, and is difficult to balance nonlinear effects and dispersion effects.

[0027] The current technical bottleneck lies in how to suppress spectral gain narrowing and nonlinear effects under high pump intensity, while simplifying the adjustment complexity and improving system integration. Existing solutions do not use pre-chirp as a core parameter for pump intensity optimization, nor do they establish a collaborative optimization model for pump power, fiber parameters, and chirp, resulting in low energy-pulse width matching efficiency and insufficient stability.

[0028] To address the aforementioned problems, this invention proposes a pump intensity optimization method that employs graded pump design, pre-chirp-pump synergistic optimization, and closed-loop feedback control. For the first time, negative chirp is incorporated into the core parameter of pump intensity optimization. Through an all-fiber structure and dynamic feedback mechanism, this method overcomes the limitations of isolated parameter adjustment in traditional schemes, achieving synergistic optimization of high energy and narrow pulse width, thus filling the gap in the field of efficient and stable nonlinear amplification.

[0029] Please refer to Figure 1 This application provides a method for optimizing the pump intensity of a laser, applicable to applications such as... Figure 2 The system shown optimizes the pump intensity of the laser. Specifically, as... Figure 1 As shown, the provided method for optimizing the pump intensity of a laser includes steps S101 to S104. Details are as follows: Step S101. Perform a graded pump design, using a single-mode laser diode to pre-amplify the signal light output from the mode-locked fiber oscillator, and then injecting the pre-amplified signal light into a multimode gain fiber for main amplification using a multimode laser diode.

[0030] Specifically, a stepped power boosting of the signal light is achieved through a graded pumping design, avoiding premature occurrence of nonlinear effects caused by direct high-power injection. At the same time, the mode field characteristics of different gain fibers are matched to improve amplification efficiency and stability.

[0031] In the pre-amplification stage, a single-mode laser diode (LD) with a center wavelength of 976 nm and a maximum power of 400 mW is used as the pre-amplification pump source to amplify the signal light output from the mode-locked fiber oscillator (center wavelength 1030 nm, power 5 mW, pulse width 2 ps). The pre-amplification medium is single-mode gain fiber (model PM-YSF-HI-HP, 6 / 125 YDF, length 0.5 m), which utilizes its small mode field area characteristics (mode field diameter 6 μm) to achieve efficient single-mode amplification at high power density, boosting the signal light power to the hundreds of milliwatts level. The low nonlinear threshold and high beam quality characteristics of the single-mode fiber ensure that the pulse width and spectral characteristics of the signal light remain essentially unchanged during the pre-amplification process, providing a stable seed light for subsequent main amplification.

[0032] In the main amplification stage, a multimode laser diode with a center wavelength of 915nm and a maximum power of 30W is used as the main pump source. The pre-amplified signal light is injected into a multimode gain fiber (model PLMA-YDF-14 / 125-UF, 14 / 125 YDF, length 1.5m, absorption coefficient 3.9±0.5 dB / m@915nm). The large mode field diameter (14μm) of the multimode fiber allows for higher pump power injection, reducing the risk of nonlinear effects (such as self-focusing). At the same time, the long fiber length (1.5m) enables high energy gain, ultimately boosting the signal light power to the watt level (e.g., 5W).

[0033] Step S102. Establish a mathematical model of pump power and gain fiber length. When the pump power is increased from low power to preset power, the chirp of the chirped fiber grating is adjusted by temperature tuning device to pre-chirp manage the signal light input to the multimode gain fiber. Negative chirp is introduced to suppress spectral gain narrowing and achieve matching between pump intensity and gain.

[0034] Specifically, a mathematical model of pump power and gain fiber length is established, and the negative chirp of the input signal light is dynamically adjusted by temperature-tuned chirped fiber grating (CFBG) to suppress the spectral gain narrowing effect and achieve matching between pump intensity and nonlinear characteristics of gain fiber.

[0035] The mathematical model is constructed based on the rate equation and the nonlinear Schrödinger equation, coupling the pump power Ppump, gain fiber length L, initial chirp β2 of the signal light, and the spectral width Δλ. The expression is as follows: ; Where γ is the fiber nonlinearity coefficient, and β2 is introduced by temperature-tuned CFBG. The optimal chirp range under different pump powers (e.g., the negative chirp corresponding to a temperature of 25-25.6℃) is experimentally calibrated, and a lookup table method or fitting formula is established to enable rapid retrieval of model parameters.

[0036] The chirped fiber grating (CFBG1) is packaged in a temperature-tuned device, which consists of four thermoelectric coolers (TECs) and a copper block structure. By adjusting the temperature of the TECs (accuracy ±0.1℃), the refractive index distribution of the grating region is changed, thereby adjusting its second-order dispersion (fixed second-order dispersion of 50 ps / nm, with the actual dispersion value finely adjusted by temperature).

[0037] When the pump power is increased from a low power (e.g., 1W) to a preset power (e.g., 5W), the TEC temperature is gradually increased according to a preset algorithm (e.g., linearly increasing) (e.g., from 25℃ to 25.6℃), which increases the amount of negative chirp introduced by CFBG1, compensates for the positive dispersion of the gain fiber, and suppresses the narrowing trend of the spectrum during the amplification process (e.g., the spectrum broadens from 12nm to 23nm).

[0038] Step S103. Under high pump intensity, by optimizing the initial chirp of the signal light, the signal light entering the multimode gain fiber is in a negative chirp pulse state, balancing the self-phase modulation and dispersion effects of the signal light during amplification in the multimode gain fiber, avoiding stimulated Raman scattering and self-focusing phenomena, achieving synergistic optimization of peak power and pulse width, and controlling the nonlinear effect threshold.

[0039] Specifically, under high pump power, by optimizing the initial negative chirp of the signal light, the self-phase modulation (SPM) and dispersion effects are balanced, stimulated Raman scattering (SRS) and self-focusing are avoided, thus achieving synergistic optimization of peak power and pulse width.

[0040] Negative-chirped pulse injection is achieved through reverse-connected CFBG1 and CFBG2 (with the same dispersion but opposite direction, such as...). Figure 1 Before temperature tuning, the pulse width did not change significantly; adjusting the TEC introduced additional negative chirp into the CFBG1 (such as changing the total dispersion from 0 to -50 ps / nm), making the signal light entering the multimode gain fiber a negative chirped pulse (pulse width broadened to hundreds of femtoseconds).

[0041] Nonlinear effect balancing mechanism: When a negatively chirped pulse is amplified in a gain fiber, positive dispersion causes a red shift in the pulse leading edge frequency and a blue shift in the trailing edge, which synergistically with the spectral broadening caused by SPM, preventing spectral contraction due to gain narrowing. The peak power is controlled below the self-focusing threshold (by adjusting the chirp amount and fiber length), while negative chirp reduces the pulse time-domain peak power (broadening the pulse width), suppressing SRS (i.e., no significant SRS-induced spectral broadening anomaly occurs).

[0042] Transform-limited pulse width conversion: After the pulse undergoes dispersion-gain-nonlinear interaction in the gain fiber, the chirp is gradually compensated, and the pulse width is narrowed to a state close to the transform limit (at which point the peak power reaches its maximum). It is then further compressed to the level of hundreds of femtoseconds (e.g., 113 fs) by a subsequent grating compressor (with a grating density of 1000 L / mm).

[0043] Step S104. Using the compressed pulse width as a feedback signal, when the target compressed pulse width is less than the preset pulse width, the pump intensity of the multimode laser diode and the temperature of the semiconductor cooling chip in the temperature tuning device are dynamically adjusted through the closed-loop feedback system to achieve optimal matching between signal light energy and pulse width.

[0044] Specifically, by using the compressed pulse width as a feedback signal, the pump intensity and chirp are dynamically adjusted through a closed-loop system, solving the problem of isolated parameter adjustment in traditional schemes and achieving synergistic optimization of high energy and narrow pulse width.

[0045] Feedback signal acquisition is achieved by connecting a fast photodetector (response bandwidth > 10 GHz) after the compression device through a transmissive grating, which monitors the pulse width after compression in real time (accuracy ± 5 fs) and compares it with the preset target pulse width (e.g., 100 fs).

[0046] The dynamic adjustment mechanism automatically performs the following actions when the measured pulse width is less than the preset pulse width (indicating excessive nonlinear effects or insufficient dispersion compensation): It reduces the multimode LD pump intensity (e.g., from 30W to 28W) to decrease nonlinear effects in the gain fiber; it fine-tunes the TEC temperature (e.g., by 0.1℃) to reduce negative chirp and prevent energy loss due to excessive pulse broadening. When the pulse width is greater than the preset value (indicating insufficient spectral broadening), it increases the pump power and raises the TEC temperature to enhance pre-chirp and nonlinear effects until the pulse width converges to the target range.

[0047] The control algorithm adopts the PID (proportional-integral-derivative) control algorithm, with pulse width error as input, and outputs the adjustment of pump current and TEC drive voltage. The adjustment period is set to 10ms to ensure that the dynamic response speed matches the stability requirements of the laser system.

[0048] In some embodiments, the pre-amplification of the signal light output from the mode-locked fiber oscillator using a single-mode laser diode includes: using a single-mode laser diode with a center wavelength of 976nm and a maximum power of 400mW to amplify the signal light output from the mode-locked fiber oscillator with a center wavelength of 1030nm, a repetition frequency of 36MHz, an output power of 5mW, and a pulse width of 2ps to the level of hundreds of milliwatts through a single-mode gain fiber, wherein the single-mode gain fiber has a core diameter of 6μm, a cladding diameter of 125μm, and a length of 0.5m.

[0049] By cascading single-mode laser diodes (LDs) with single-mode gain fibers using specific parameters, efficient pre-amplification of signal light from low power to the hundreds of milliwatt level is achieved, ensuring the stability of beam quality and pulse characteristics during the pre-amplification process.

[0050] The pump source parameters employ a single-mode LD with a center wavelength of 976nm and a maximum power of 400mW, matched to the pump absorption characteristics of the single-mode gain fiber (976nm is the efficient absorption band of ytterbium-doped fiber). The seed light parameters are: a center wavelength of 1030nm, a repetition frequency of 36MHz, a power of 5mW, and a pulse width of 2ps, output from a mode-locked fiber oscillator, serving as the pre-amplified input light source. The single-mode gain fiber characteristics are: a polarization-maintaining ytterbium-doped fiber of model PM-YSF-HI-HP, with a core diameter of 6μm (small mode field area to achieve high pump power density), a cladding diameter of 125μm, and a length of 0.5m. The seed light and pump light are coupled into the fiber via fusion splicing.

[0051] The amplification effect utilizes the single-mode transmission characteristics of single-mode fiber (avoiding mode noise) to stably amplify the signal light power to 100-300mW (milliwatt level), with no significant change in pulse width and spectral width (maintaining the initial 2ps pulse width), providing high-beam-quality seed light for subsequent main amplification.

[0052] In some embodiments, the step of injecting the pre-amplified signal light into a multimode gain fiber via a multimode laser diode for main amplification includes: using a multimode laser diode with a center wavelength of 915nm and a maximum power of 30W to inject the pre-amplified signal light into a multimode gain fiber, wherein the multimode gain fiber has a core diameter of 14μm, a cladding diameter of 125μm, an absorption coefficient of 3.9±0.5dB / m at 915nm, and a length of 1.5m, to perform main amplification of the signal light.

[0053] By combining a high-power multimode LD with a large-mode-field multimode gain fiber, the main amplification of signal light is achieved from hundreds of milliwatts to several watts. The large mode field diameter suppresses nonlinear effects and enhances the energy amplification capability.

[0054] The main pump source parameters are selected using a multimode LD with a center wavelength of 915nm and a maximum power of 30W. Its emission area matches the cladding size of the multimode gain fiber (125μm cladding). The pump light is injected into the fiber cladding through a pump coupler. Multimode gain fiber characteristics: It is a ytterbium-doped fiber, model PLMA-YDF-14 / 125-UF, with a core diameter of 14μm (large mode field reduces peak power density and avoids self-focusing), a cladding diameter of 125μm, an absorption coefficient of 3.9±0.5 dB / m at 915nm, and a length of 1.5m. Its high absorption efficiency achieves high gain with a short fiber length. Amplification process: The pre-amplified 100mW-level signal light (1030nm) and the 915nm pump light propagate in the same direction in the multimode fiber. Energy amplification is achieved through the stimulated emission effect of the doped ions, and the final output power can reach 5W. Furthermore, due to the large mode field design of the 14μm core, self-focusing and stimulated Raman scattering (SRS) are effectively suppressed.

[0055] In some embodiments, establishing a mathematical model of pump power and gain fiber length includes: based on the relationship between pump power, gain fiber absorption coefficient and signal light chirp, establishing a three-dimensional optimization relationship model of pump power, gain fiber length and signal light spectral broadening effect through theoretical calculation and experimental calibration, which is used to determine the optimal length of gain fiber and the chirp adjustment range corresponding to different pump powers.

[0056] Based on the coupling relationship between pump power, fiber absorption characteristics, and signal light chirp, a three-dimensional optimization model is constructed to solve the problem of synergistic optimization of pump intensity, fiber length, and spectral broadening.

[0057] Based on the theoretical model, the rate equation (describing population inversion and gain) and the nonlinear Schrödinger equation (describing dispersion and nonlinear effects in pulse transmission) are combined to establish the parameter relationship: G(λ)=Γ*σ(λ)*N (gain formula), Δλout=f(Ppump,L,β2); where Γ is the mode field confinement factor, σ(λ) is the gain cross section, N is the dopant ion concentration, and β2 is the chirp (second-order dispersion).

[0058] The experimental calibration method involves testing the spectral width corresponding to different pump powers (1-5W) and chirps (adjusted by TEC temperature 25-25.6℃) at a fixed fiber length (1.5m), recording the optimal broadening data (e.g., 23nm corresponds to 5W pump), and forming a three-dimensional mapping table of "pump power-fiber length-chirp" for parameter matching during real-time adjustment.

[0059] In some embodiments, when the pump power is increased from a low power to a preset power, adjusting the chirp of the chirped fiber grating through a temperature tuning device includes: the temperature tuning device comprising four thermoelectric coolers, each thermoelectric cooler fixing a 10mm long copper block, with a V-shaped groove in the middle of the copper block for placing a uniformly chirped fiber grating; by adjusting the temperature of the four thermoelectric coolers to increase linearly within the range of 25°C to 25.6°C, changing the dispersion of the chirped fiber grating, thereby adjusting the chirp of the signal light.

[0060] By precisely controlling the temperature through a temperature tuning device, the dispersion of chirped fiber gratings (CFBGs) can be continuously adjusted, replacing the mechanical adjustment of traditional grating pairs and improving system integration and adjustment accuracy.

[0061] The temperature tuning device structure includes: Core components: four thermoelectric coolers (TECs) connected in parallel, each TEC fixing a 10mm long copper block with a V-shaped groove machined in the middle to fix the grating region of the CFBG (a uniform 10mm grating region). Adjustment mechanism: The temperature of the four TECs is independently controlled by a drive circuit, achieving a linear increase in grating temperature from 25℃ to 25.6℃ (e.g., each TEC increases by 0.15℃ sequentially). The thermo-optic effect (the refractive index of the fiber changes by approximately 10^-5 for every 1℃ change in temperature) is used to change the grating period, thereby adjusting its second-order dispersion (target adjustment range: -50ps / nm ±10%). Chirp adjustment effect: With linear temperature increase, the reflection spectral bandwidth of the CFBG slightly broadens, and the introduced negative chirp gradually increases, broadening the signal light in the time domain (e.g., from 2ps to hundreds of femtoseconds), providing initial conditions for spectral broadening in subsequent main amplification.

[0062] In some embodiments, the pre-chirping management of the signal light input to the multimode gain fiber, introducing negative chirp to suppress spectral gain narrowing and achieve matching between pump intensity and gain, includes: changing the chirp of the chirped fiber grating by adjusting a temperature tuning device, so that the signal light entering the multimode gain fiber carries negative chirp, and widening the spectral width of the signal light from 12nm to more than 23nm during the process of increasing the pump power from 1W to 5W, thereby compensating for the spectral narrowing effect during the fiber gain process.

[0063] By dynamically adjusting the negative chirp, the narrowing of spectral gain caused by population inversion in the gain fiber is compensated, thereby achieving a match between pump intensity and nonlinear effects and improving spectral broadening efficiency.

[0064] Negative chirp introduction: CFBG1 (encapsulated in a temperature control device) introduces negative chirp (negative dispersion) through temperature tuning, forming a net negative chirp with the reverse-accessed CFBG2 (positive dispersion), allowing the signal light entering the multimode fiber to carry negative chirp (e.g., total dispersion of -50 ps / nm). Spectral broadening process: At low pump power (1W): the chirp is small, and the spectral width is 12nm (limited by gain narrowing); At high pump power (5W): the chirp increases through TEC temperature adjustment. When the signal light is amplified in the multimode fiber, the negative chirp and self-phase modulation (SPM) work synergistically, broadening the spectral width to over 23nm, effectively offsetting the gain narrowing effect (traditional solutions can only broaden to 15nm). Matching mechanism: The chirp is positively correlated with the pump power. By using a predefined adjustment curve (such as a temperature-pump power mapping table), the optimal chirp is ensured for each pump power point, thus achieving synergistic amplification of "strong pumping and high chirp".

[0065] In some embodiments, optimizing the initial chirp of the signal light to make the signal light entering the multimode gain fiber a negative chirped pulse state, and balancing the self-phase modulation and dispersion effects of the signal light during amplification in the multimode gain fiber, includes: utilizing the initial spectral broadening characteristics of the negative chirped pulse to achieve a dynamic balance between the self-phase modulation effect and the dispersion effect during the amplification process in the multimode gain fiber, thereby avoiding pulse distortion caused by nonlinear effects under high pump intensity.

[0066] By utilizing the time-domain broadening characteristics of negatively chirped pulses, the peak power density is reduced and the stimulated Raman scattering (SRS) threshold is increased. At the same time, the pulse distortion caused by excessive self-phase modulation is avoided through the dynamic balance between chirp and dispersion.

[0067] The negative chirp pulse characteristic means that the signal light entering the multimode fiber is negatively chirped (the frequency decreases over time). In the time domain, this is manifested as a low leading edge frequency and a high trailing edge frequency, with the pulse width widened to 300-500 fs (compared to the initial 2 ps). The peak power is reduced to less than 1 / 10 of the traditional solution, which increases the SRS threshold from 2W to more than 4W (a 2-fold increase).

[0068] The dynamic balancing mechanism includes: In positively dispersed fibers, the leading edge of the negatively chirped pulse is red-shifted and the trailing edge is blue-shifted, aligning with the spectral broadening direction caused by SPM, forming a "chirped-nonlinear" synergistic broadening to avoid spectral contraction; When gain saturation occurs, the chirp amount is automatically adjusted with increasing power (through TEC heating) to ensure that the SPM effect and dispersion effect are always in balance, preventing pulse splitting or self-focusing damage to the fiber during amplification. When the pump power is increased to 5W, no Stokes shift peak caused by SRS is observed, and there is no significant distortion after pulse compression, proving that the nonlinear effect is effectively suppressed.

[0069] In some embodiments, the method of dynamically adjusting the pump intensity of the multimode laser diode and the temperature of the thermoelectric cooler in the temperature tuning device through a closed-loop feedback system to achieve optimal matching between signal light energy and pulse width includes: using a transmission grating to provide feedback on the compressed pulse width; when the compressed pulse width is detected to be greater than 120 fs, automatically adjusting the output power of the multimode laser diode through the closed-loop control system and simultaneously adjusting the temperature of the four thermoelectric coolers until the compressed pulse width stabilizes within the target range, while ensuring that the signal light output energy reaches 5W.

[0070] Using the compressed pulse width as a feedback signal, the pump power and chirp are automatically adjusted to achieve dynamic optimization of energy and pulse width, thus solving the lag problem of traditional manual adjustment.

[0071] The feedback system consists of: a sensor: a high-speed photodetector (response time <1ns) connected to the compression device via a transmission grating to acquire the pulse width after compression in real time (accuracy ±5fs); and a controller: a closed-loop control system based on a PID algorithm, which sets the target pulse width range (e.g., 100-120fs) and triggers an adjustment command when the detected pulse width is >120fs (e.g., 130fs).

[0072] The adjustment strategy includes: Pump power adjustment: Gradually increase the multimode LD output power (maximum 30W) in increments of 0.5W / time until the pulse width begins to contract; if the power is still insufficient even after reaching the upper limit, chirp adjustment is initiated. Chirp adjustment: Simultaneously increase the temperature of the four TECs (0.1℃ each time) to increase the negative chirp, broaden the pulse time domain of the input multimode fiber, enhance the SPM effect to broaden the spectrum, and finally compress it to the target pulse width through the grating pair. Energy assurance: Monitor the output power in real time during the adjustment process to ensure that the signal light energy is stable at 5W when the pulse width is achieved, avoiding energy loss due to over-adjustment. The spectrum and pulse width after TEC adjustment are as follows: Figure 3 As shown. Adjusting the temperature of the TEC can change the dispersion of the grating. When the pulse width entering multimode amplification is several hundred femtoseconds and is in a negative chirp state, after amplification through a section of gain fiber, the pulse width and spectral width narrow due to the combined effects of self-phase modulation, dispersion, and fiber gain. When the pulse width is narrowed to the transform-limited pulse width, the pulse has extremely high peak power. Due to the self-phase modulation effect, the spectrum is rapidly broadened, thus achieving an even narrower pulse width. This system adopts an all-fiber structure, which is compact, stable, and easy to adjust.

[0073] In some embodiments, a smart configuration model for pump parameters is constructed using a transfer learning algorithm to address different seed light characteristics (such as pulse width and spectral distribution variations), replacing the traditional fixed parameter amplification mode. This enables adaptive optimization of the graded pumping process and improves amplification efficiency and beam quality consistency under different input conditions.

[0074] The data sample library was constructed by collecting historical experimental data and recording the optimal pre-amplification / main amplification parameters (LD drive current, fiber length, coupling efficiency) corresponding to different seed light parameters (pulse width 2-5ps, spectral width 10-20nm, power 3-10mW), forming a dataset containing over 100,000 samples. A deep neural network (DNN) was used to train the basic model, with the seed light parameters as input and the pre-amplification LD current (976nm LD, 0-400mA) and main amplification pump power (915nm LD, 0-30W) as outputs.

[0075] When a new seed light source is introduced, initial signal light parameters (center wavelength, pulse width, and spectral width) are acquired in real time using a spectrometer (accuracy 0.1 nm) and an autocorrelation meter (accuracy 5 fs) as input features for transfer learning. A pre-trained base model is used for rapid parameter initialization, followed by online few-sample learning (requiring only 5-10 iterations) to adapt to the current light source characteristics, outputting customized pump parameters. This addresses the problem of poor adaptability of traditional fixed parameters to new seed light sources.

[0076] By integrating a programmable logic controller (PLC) with an edge computing module, and incorporating a lightweight transfer learning model (model size <10MB, inference time <1ms), the system processes sensor data in real time and drives an LD current controller (accuracy 0.1mA), enabling millisecond-level dynamic adjustment of pump parameters.

[0077] In some embodiments, a Long Short-Term Memory (LSTM) network is introduced to construct a dynamic prediction model for the time-varying coupling relationship between pump power and chirp, replacing the traditional lookup table method. This solves the model mismatch problem caused by the drift of nonlinear effects with temperature / aging, and achieves accurate prediction and advance compensation for temperature tuning of chirped fiber gratings (CFBGs).

[0078] The temperature of the multimode gain fiber (CFBG) is monitored in real time (accuracy ±0.05℃) and the aging degree of the pump LD (characterized by threshold current change) by deploying fiber optic sensors. Simultaneously, the CFBG temperature (25-25.6℃) and the corresponding spectral broadening results (resolution 0.5nm) are recorded. The input layer contains the current pump power, fiber temperature, and LD aging coefficient; the output layer contains the target CFBG temperature (accurate to 0.01℃); and the hidden layer contains 128 memory cells to capture the long-term dependencies of the pump-chirp system (such as the impact of pump wavelength drift caused by LD aging on chirp requirements).

[0079] Real-time data is collected every 10ms. The LSTM model predicts the optimal CFBG temperature for the next 50ms and adjusts the thermoelectric cooler (TEC) driving voltage in advance (accuracy ±10mV) to compensate for system delay (TEC thermal response time is approximately 20ms). An error correction mechanism is introduced: when the actual spectral broadening deviates from the predicted value by more than 5%, the model is triggered to update online, using the latest data to fine-tune the LSTM weights to adapt to device aging or changes in ambient temperature (such as laboratory temperature fluctuations of ±1℃).

[0080] Edge computing deployments use Raspberry Pi 4B as edge nodes, running quantized LSTM models (floating-point operation optimized, power consumption <5W), and communicating with TEC driver circuits via SPI interface to achieve low-latency closed-loop control.

[0081] The pump intensity optimization method, device, and medium for lasers provided in this application establish a three-dimensional optimization relationship between pump power, gain fiber parameters, and chirp by using graded pumping (single-mode pre-amplification + multi-mode main amplification) and dynamic adjustment of pre-chirp, thereby improving optical-to-optical conversion efficiency. Utilizing the initial spectral broadening characteristics of negatively chirped pulses, the method balances self-phase modulation and dispersion effects, raising the stimulated Raman scattering threshold and avoiding pulse distortion under high pump intensity. The all-fiber structure avoids spatial coupling loss, and combined with closed-loop feedback control (dynamically adjusting pump intensity and chirp using the compressed pulse width as feedback signal), the system stability is improved compared to traditional grating schemes. It overcomes the fiber gain bandwidth limitation, meeting the demands of high-precision industrial processing and scientific research for narrow pulse widths and high energy.

[0082] Please see Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of a laser pump intensity optimization device 200 provided in an embodiment of this application. The laser pump intensity optimization device 200 is used to execute the steps of the laser pump intensity optimization method shown in the above embodiments. The laser pump intensity optimization device 200 can be a single server or a server cluster, or it can be a terminal, such as a handheld terminal, a laptop computer, a wearable device, or a robot.

[0083] like Figure 4 As shown, the laser pump intensity optimization device 200 includes: Pump design unit 201 is used for staged pump design. It uses a single-mode laser diode to pre-amplify the signal light output from the mode-locked fiber oscillator, and injects the pre-amplified signal light into the multimode gain fiber for main amplification through a multimode laser diode. Model building unit 202 is used to build a mathematical model of pump power and gain fiber length. When the pump power is increased from low power to preset power, the chirp amount of the chirped fiber grating is adjusted by temperature tuning device to pre-chirp manage the signal light input to the multimode gain fiber. Negative chirp amount is introduced to suppress spectral gain narrowing and achieve matching between pump intensity and gain. The chirp optimization unit 203 is used to optimize the initial chirp of the signal light under high pump intensity so that the signal light entering the multimode gain fiber is in a negative chirp pulse state, balance the self-phase modulation and dispersion effect of the signal light during amplification in the multimode gain fiber, avoid stimulated Raman scattering and self-focusing, achieve synergistic optimization of peak power and pulse width, and control the nonlinear effect threshold. The closed-loop optimization unit 204 is used to dynamically adjust the pump intensity of the multimode laser diode and the temperature of the semiconductor cooling chip in the temperature tuning device through the closed-loop feedback system when the target compressed pulse width is less than the preset pulse width, using the compressed pulse width as the feedback signal, so as to achieve the optimal matching between the signal light energy and the pulse width.

[0084] In some embodiments, the pre-amplification of the signal light output from the mode-locked fiber oscillator using a single-mode laser diode includes: using a single-mode laser diode with a center wavelength of 976nm and a maximum power of 400mW to amplify the signal light output from the mode-locked fiber oscillator with a center wavelength of 1030nm, a repetition frequency of 36MHz, an output power of 5mW, and a pulse width of 2ps to the level of hundreds of milliwatts through a single-mode gain fiber, wherein the single-mode gain fiber has a core diameter of 6μm, a cladding diameter of 125μm, and a length of 0.5m.

[0085] In some embodiments, the step of injecting the pre-amplified signal light into a multimode gain fiber via a multimode laser diode for main amplification includes: using a multimode laser diode with a center wavelength of 915nm and a maximum power of 30W to inject the pre-amplified signal light into a multimode gain fiber, wherein the multimode gain fiber has a core diameter of 14μm, a cladding diameter of 125μm, an absorption coefficient of 3.9±0.5dB / m at 915nm, and a length of 1.5m, to perform main amplification of the signal light.

[0086] In some embodiments, establishing a mathematical model of pump power and gain fiber length includes: based on the relationship between pump power, gain fiber absorption coefficient and signal light chirp, establishing a three-dimensional optimization relationship model of pump power, gain fiber length and signal light spectral broadening effect through theoretical calculation and experimental calibration, which is used to determine the optimal length of gain fiber and the chirp adjustment range corresponding to different pump powers.

[0087] In some embodiments, when the pump power is increased from a low power to a preset power, adjusting the chirp of the chirped fiber grating through a temperature tuning device includes: the temperature tuning device comprising four thermoelectric coolers, each thermoelectric cooler fixing a 10mm long copper block, with a V-shaped groove in the middle of the copper block for placing a uniformly chirped fiber grating; by adjusting the temperature of the four thermoelectric coolers to increase linearly within the range of 25°C to 25.6°C, changing the dispersion of the chirped fiber grating, thereby adjusting the chirp of the signal light.

[0088] In some embodiments, the pre-chirping management of the signal light input to the multimode gain fiber, introducing negative chirp to suppress spectral gain narrowing and achieve matching between pump intensity and gain, includes: changing the chirp of the chirped fiber grating by adjusting a temperature tuning device, so that the signal light entering the multimode gain fiber carries negative chirp, and widening the spectral width of the signal light from 12nm to more than 23nm during the process of increasing the pump power from 1W to 5W, thereby compensating for the spectral narrowing effect during the fiber gain process.

[0089] In some embodiments, optimizing the initial chirp of the signal light to make the signal light entering the multimode gain fiber a negative chirped pulse state, and balancing the self-phase modulation and dispersion effects of the signal light during amplification in the multimode gain fiber, includes: utilizing the initial spectral broadening characteristics of the negative chirped pulse to achieve a dynamic balance between the self-phase modulation effect and the dispersion effect during the amplification process in the multimode gain fiber, thereby avoiding pulse distortion caused by nonlinear effects under high pump intensity.

[0090] In some embodiments, the method of dynamically adjusting the pump intensity of the multimode laser diode and the temperature of the thermoelectric cooler in the temperature tuning device through a closed-loop feedback system to achieve optimal matching between signal light energy and pulse width includes: using a transmission grating to provide feedback on the compressed pulse width; when the compressed pulse width is detected to be greater than 120 fs, automatically adjusting the output power of the multimode laser diode through the closed-loop control system and simultaneously adjusting the temperature of the four thermoelectric coolers until the compressed pulse width stabilizes within the target range, while ensuring that the signal light output energy reaches 5W.

[0091] It should be noted that those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the laser pump intensity optimization device and each module described above can be referred to the corresponding process in the embodiments of the laser pump intensity optimization method described above, and will not be repeated here.

[0092] The aforementioned method for optimizing the pump intensity of a laser can be implemented as a computer program, which can be used in, for example... Figure 4 It runs on the device shown.

[0093] Please see Figure 5 , Figure 5 This is a schematic block diagram of the structure of a computer device provided in an embodiment of this application. The computer device includes a processor, a memory, and a network interface connected via a device bus, wherein the memory may include a storage medium and internal memory.

[0094] The storage medium can store operating devices and computer programs. The computer program includes program instructions that, when executed, cause the processor to perform any method for optimizing the pump intensity of a laser.

[0095] The processor provides computing and control capabilities, supporting the operation of the entire computer device.

[0096] Internal memory provides an environment for the execution of computer programs in non-volatile storage media. When executed by a processor, the computer program enables the processor to perform any method for optimizing the pump intensity of a laser.

[0097] This network interface is used for network communication, such as sending assigned tasks. Those skilled in the art will understand that... Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the terminal to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0098] It should be understood that the processor can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among these, a general-purpose processor can be a microprocessor or any conventional processor.

[0099] In one embodiment, the processor is configured to run a computer program stored in memory to perform the following steps: A staged pumping design is adopted, using a single-mode laser diode to pre-amplify the signal light output from the mode-locked fiber oscillator, and then injecting the pre-amplified signal light into a multimode gain fiber for main amplification via a multimode laser diode. A mathematical model is established for the relationship between pump power and fiber length. When the pump power is increased from low power to a preset power, the chirp of the chirped fiber grating is adjusted by a temperature tuning device to pre-chirp the signal light input to the multimode gain fiber. Negative chirp is introduced to suppress spectral gain narrowing and achieve matching between pump intensity and gain. Under high pump intensity, by optimizing the initial chirp of the signal light, the signal light entering the multimode gain fiber is in a negative chirp pulse state, which balances the self-phase modulation and dispersion effect of the signal light when it is amplified in the multimode gain fiber, avoids stimulated Raman scattering and self-focusing, achieves synergistic optimization of peak power and pulse width, and controls the threshold of nonlinear effect. Using the compressed pulse width as the feedback signal, when the target compressed pulse width is less than the preset pulse width, the pump intensity of the multimode laser diode and the temperature of the semiconductor cooling chip in the temperature tuning device are dynamically adjusted through the closed-loop feedback system to achieve the optimal matching between signal light energy and pulse width.

[0100] In some embodiments, the pre-amplification of the signal light output from the mode-locked fiber oscillator using a single-mode laser diode includes: using a single-mode laser diode with a center wavelength of 976nm and a maximum power of 400mW to amplify the signal light output from the mode-locked fiber oscillator with a center wavelength of 1030nm, a repetition frequency of 36MHz, an output power of 5mW, and a pulse width of 2ps to the level of hundreds of milliwatts through a single-mode gain fiber, wherein the single-mode gain fiber has a core diameter of 6μm, a cladding diameter of 125μm, and a length of 0.5m.

[0101] In some embodiments, the step of injecting the pre-amplified signal light into a multimode gain fiber via a multimode laser diode for main amplification includes: using a multimode laser diode with a center wavelength of 915nm and a maximum power of 30W to inject the pre-amplified signal light into a multimode gain fiber, wherein the multimode gain fiber has a core diameter of 14μm, a cladding diameter of 125μm, an absorption coefficient of 3.9±0.5dB / m at 915nm, and a length of 1.5m, to perform main amplification of the signal light.

[0102] In some embodiments, establishing a mathematical model of pump power and gain fiber length includes: based on the relationship between pump power, gain fiber absorption coefficient and signal light chirp, establishing a three-dimensional optimization relationship model of pump power, gain fiber length and signal light spectral broadening effect through theoretical calculation and experimental calibration, which is used to determine the optimal length of gain fiber and the chirp adjustment range corresponding to different pump powers.

[0103] In some embodiments, when the pump power is increased from a low power to a preset power, adjusting the chirp of the chirped fiber grating through a temperature tuning device includes: the temperature tuning device comprising four thermoelectric coolers, each thermoelectric cooler fixing a 10mm long copper block, with a V-shaped groove in the middle of the copper block for placing a uniformly chirped fiber grating; by adjusting the temperature of the four thermoelectric coolers to increase linearly within the range of 25°C to 25.6°C, changing the dispersion of the chirped fiber grating, thereby adjusting the chirp of the signal light.

[0104] In some embodiments, the pre-chirping management of the signal light input to the multimode gain fiber, introducing negative chirp to suppress spectral gain narrowing and achieve matching between pump intensity and gain, includes: changing the chirp of the chirped fiber grating by adjusting a temperature tuning device, so that the signal light entering the multimode gain fiber carries negative chirp, and widening the spectral width of the signal light from 12nm to more than 23nm during the process of increasing the pump power from 1W to 5W, thereby compensating for the spectral narrowing effect during the fiber gain process.

[0105] In some embodiments, optimizing the initial chirp of the signal light to make the signal light entering the multimode gain fiber a negative chirped pulse state, and balancing the self-phase modulation and dispersion effects of the signal light during amplification in the multimode gain fiber, includes: utilizing the initial spectral broadening characteristics of the negative chirped pulse to achieve a dynamic balance between the self-phase modulation effect and the dispersion effect during the amplification process in the multimode gain fiber, thereby avoiding pulse distortion caused by nonlinear effects under high pump intensity.

[0106] In some embodiments, the method of dynamically adjusting the pump intensity of the multimode laser diode and the temperature of the thermoelectric cooler in the temperature tuning device through a closed-loop feedback system to achieve optimal matching between signal light energy and pulse width includes: using a transmission grating to provide feedback on the compressed pulse width; when the compressed pulse width is detected to be greater than 120 fs, automatically adjusting the output power of the multimode laser diode through the closed-loop control system and simultaneously adjusting the temperature of the four thermoelectric coolers until the compressed pulse width stabilizes within the target range, while ensuring that the signal light output energy reaches 5W.

[0107] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to implement the steps of the laser pump intensity optimization method provided in any embodiment of this application.

[0108] The computer-readable storage medium may be an internal storage unit of the computer device described in the foregoing embodiments, such as the hard disk or memory of the computer device. The computer-readable storage medium may also be an external storage device of the computer device, such as a plug-in hard disk, SmartMedia Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the computer device.

[0109] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of optimizing pump intensity for a laser, characterized by, The application relates to a method for optimizing the matching between pump intensity and gain in a mode-locked fiber oscillator. The method comprises the following steps: A single-mode laser diode is used to pre-amplify the signal light output by the mode-locked fiber oscillator, and a multi-mode laser diode is used to inject the pre-amplified signal light into a multi-mode gain fiber for main amplification; A mathematical model of pump power and gain fiber length is established, and when the pump power is increased from low power to a preset power, the chirp amount of the chirped fiber grating is adjusted by a temperature tuning device to pre-chirp the signal light input into the multi-mode gain fiber, a negative chirp amount is introduced to suppress spectral gain narrowing, and the matching between pump intensity and gain is realized; Under high pump intensity, the initial chirp amount of the signal light is optimized so that the signal light input into the multi-mode gain fiber is in a negative chirp pulse state, the self-phase modulation and dispersion effect of the signal light during amplification in the multi-mode gain fiber are balanced, the occurrence of stimulated Raman scattering and self-focusing is avoided, the peak power and pulse width are cooperatively optimized, and the threshold of nonlinear effects is controlled; 2. The method of claim 1, wherein, The compressed pulse width is used as a feedback signal, and when the target compressed pulse width is smaller than a preset pulse width, the pump intensity of the multi-mode laser diode and the temperature of the semiconductor refrigerating sheet in the temperature tuning device are dynamically adjusted by a closed-loop feedback system to realize the optimal matching between signal light energy and pulse width. The method comprises the following steps:

3. The method of claim 1, wherein, A single-mode laser diode with a center wavelength of 976 nm and a maximum power of 400 mW is used to amplify the signal light output by the mode-locked fiber oscillator, and the signal light has a center wavelength of 1030 nm, a repetition frequency of 36 MHz, an output power of 5 mW and a pulse width of 2 ps. The signal light is amplified to a power level of hundreds of milliwatts through a single-mode gain fiber, and the single-mode gain fiber has a core diameter of 6 mu m, a cladding diameter of 125 mu m and a length of 0.5 m.

4. The method of claim 1, wherein, The method comprises the following steps: A multi-mode laser diode with a center wavelength of 915 nm and a maximum power of 30 W is used to inject the pre-amplified signal light into a multi-mode gain fiber, and the multi-mode gain fiber has a core diameter of 14 mu m, a cladding diameter of 125 mu m, an absorption coefficient of 3.9+ / -0.5 dB / m at 915 nm and a length of 1.5 m, and the signal light is amplified.

5. The method of claim 1, wherein, The method comprises the following steps: Based on the mutual relationship among pump power, gain fiber absorption coefficient and signal light chirp amount, a three-dimensional optimization relationship model of pump power, gain fiber length and signal light spectral broadening effect is established through theoretical calculation and experimental calibration, and the model is used to determine the optimal length of the gain fiber and the chirp amount adjustment range under different pump powers. The method comprises the following steps: The temperature tuning device comprises four semiconductor refrigerating sheets, each of which is fixed with a 10mm-long copper block, and a V-shaped groove is arranged in the middle of the copper block for placing the uniform-chirped fiber grating.

6. The method of claim 1, wherein, The method for pre-chirping the signal light input into the multimode gain fiber includes: By adjusting the temperature tuning device to change the chirp amount of the chirped fiber grating, the signal light input into the multimode gain fiber carries negative chirp, and during the process of increasing the pump power from 1W to 5W, the signal light spectrum width is expanded from 12nm to more than 23nm, compensating for the spectral narrowing effect during fiber gain.

7. The method of claim 1, wherein, The method for optimizing the initial chirp amount of the signal light so that the signal light input into the multimode gain fiber is in a negative chirp pulse state, balances the self-phase modulation and dispersion effect of the signal light during amplification in the multimode gain fiber, including: By using the initial spectral expansion characteristics of the negative chirp pulse, the self-phase modulation effect and the dispersion effect form a dynamic balance during the multimode gain fiber amplification process, avoiding pulse distortion caused by nonlinear effects under high pump intensity.

8. The method of claim 1, wherein, The method for dynamically adjusting the pump intensity of the multimode laser diode and the temperature of the semiconductor refrigerating sheet in the temperature tuning device through a closed-loop feedback system to realize optimal matching of signal light energy and pulse width, including: The compressed pulse width is taken as the feedback signal by a transmission grating, when the detected compressed pulse width is greater than 120fs, the output power of the multimode laser diode is automatically adjusted through the closed-loop control system, and the temperature of the four semiconductor refrigerating sheets is adjusted synchronously, until the compressed pulse width is stabilized in the target value range, and at the same time, the signal light output energy reaches 5W.

9. A computer device, comprising: The computer device includes a memory and a processor; The memory is used to store a computer program; The processor is used to execute the computer program and realize the method of any one of claims 1 to 8 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to make the processor realize the method of any one of claims 1 to 8.

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