Adjustable pulse fiber laser module

Abstract

The invention provides an adjustable pulse fiber laser module, which comprises a pulse seed signal source, a multistage fiber amplification structure, a driving circuit and a control circuit, and is characterized in that the multistage fiber amplification structure is optically connected with the pulse seed signal source, and the driving circuit is electrically connected with the pulse seed signal source and the multistage fiber amplification structure; the control circuit is electrically connected with the driving circuit; wherein the control circuit is used for converting a preset pulse parameter into an electric pulse signal and outputting the electric pulse signal to the driving circuit; the driving circuit is used for respectively driving the pulse seed signal source to generate seed pulse light and driving the pumping source in the multi-stage optical fiber amplification structure to generate pumping pulse light according to the electric pulse signal; the falling edges of the pump pulse light and the seed pulse light in the time domain are aligned, and the seed pulse light is amplified by the multi-stage optical fiber amplification structure and then outputs a pulse string. Repetition frequency adjustment of pulse laser and generation of a pulse string can be realized without modulation devices such as an acousto-optic modulator.

Description

Technical Field

[0001] This invention relates to the field of fiber laser technology, and more particularly to an adjustable pulsed fiber laser module. Background Technology

[0002] Pulsed fiber laser modules, with their advantages of high beam quality, high conversion efficiency, and stable reliability, have been widely used in various fields such as industrial materials processing, lidar, and scientific research experiments. In practical applications, different operating conditions require flexible adjustment of the output parameters of pulsed lasers. In particular, the precise adjustment of the pulse repetition frequency and the generation of pulse trains with specific envelope shapes directly affect the accuracy of laser processing, the resolution of radar detection, and the adaptability to scientific research experiments. Therefore, these factors have become one of the core technical indicators of pulsed fiber laser modules.

[0003] In existing technologies, the mainstream solutions for pulse repetition frequency adjustment and pulse train generation typically rely on dedicated modulation devices such as acousto-optic modulators and electro-optic modulators. These solutions use modulation devices to gate and chop continuous laser or seed pulses to obtain pulse signals or pulse trains with the target repetition frequency. However, these modulation devices have inherent drawbacks: firstly, the optical structure of the modulation device introduces significant insertion loss, leading to reduced laser energy transmission efficiency and affecting the output power and energy utilization of the laser module; secondly, the modulation device has a clear power limit, making it difficult to adapt to the control requirements of high-power pulsed lasers and limiting the power upgrade potential of the laser module; furthermore, the modulation device requires dedicated drive circuits and control modules, which not only increases the complexity and manufacturing cost of the system but also leads to an increase in the overall size of the laser module, failing to meet the application trends of miniaturization and integration.

[0004] Therefore, existing pulsed laser control schemes that rely on modulation devices have shortcomings in terms of efficiency, power compatibility, and structural compactness, making it difficult to simultaneously meet the requirements for flexible control and high system performance. Based on this, developing an adjustable pulsed fiber laser module that can achieve pulse repetition frequency adjustment and pulse train generation without the need for additional modulation devices such as acousto-optic modulators, and which is also compact and energy-efficient, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide an adjustable pulsed fiber laser module to solve the technical problems of high insertion loss, poor power adaptability, and complex structure (large size / high cost) that exist in the prior art when relying on dedicated modulation devices such as acousto-optic modulators to achieve pulse parameter control and pulse train generation.

[0006] To solve the above technical problems, the present invention provides an adjustable pulsed fiber laser module, including a pulse seed signal source, a multi-stage fiber amplification structure, a driving circuit and a control circuit. The multi-stage fiber amplification structure is optically connected to the pulse seed signal source, the driving circuit is electrically connected to both the pulse seed signal source and the multi-stage fiber amplification structure, and the control circuit is electrically connected to the driving circuit. The control circuit converts preset pulse parameters into electrical pulse signals and outputs the electrical pulse signals to the drive circuit. The drive circuit drives the pulse seed signal source to generate seed pulse light according to the electrical pulse signals, and drives the pump source in the multi-stage fiber amplification structure to generate pump pulse light. The pump pulse light and the seed pulse light are aligned in the falling edge in the time domain. The seed pulse light is amplified by the multi-stage fiber amplification structure and then output as a pulse train.

[0007] Preferably, the pulse train includes multiple sub-pulses, the pulse width of the sub-pulses is the same as the pulse width of the seed pulse light, and the repetition frequency of the sub-pulses is the same as the repetition frequency of the seed pulse light.

[0008] Preferably, the envelope width of the pulse train is the same as the pulse width of the pump pulse light, and the envelope repetition frequency of the pulse train is the same as the repetition frequency of the pump pulse light.

[0009] Preferably, the pulse width of the pump pulse light is not greater than the lifetime of the doped ion upper energy level particles in the gain fiber of the multi-stage fiber amplification structure; the repetition frequency of the pump pulse light is less than the repetition frequency of the seed pulse light.

[0010] Preferably, the pulse width of the pump pulse light is denoted as τ. pump The repetition frequency of the seed pulse light is denoted as f. seed The number of sub-pulses N is determined by the number of sub-pulses N based on τ. pump with f seed The product is obtained by rounding down.

[0011] Preferably, when the driving current output from the driving circuit to the multi-stage fiber amplification structure increases but does not exceed the rated operating current of the pump source, the total envelope energy of the pulse train or the pulse energy of a single sub-pulse increases synchronously.

[0012] Preferably, the time-domain power distribution waveform of the pump pulse light includes any one of rectangular wave, Gaussian wave, Gaussian-like wave, and trapezoidal wave, and the envelope waveform of the pulse train is consistent with the time-domain power distribution waveform of the pump pulse.

[0013] Preferably, the seed pulse light that is not within the time domain of the pump pulse light gradually attenuates and disappears during the multi-stage amplification process.

[0014] Preferably, the multi-stage fiber optic amplification structure includes a first-stage amplification unit and a second-stage amplification unit that are optically connected sequentially along the signal transmission direction, and the driving circuit includes a first driving unit, a second driving unit, and a third driving unit arranged in parallel. The first driving unit is used to drive the pulse seed signal source to generate seed pulse light, the second driving unit is used to drive the first-stage amplification unit to generate the first pump light, and the third driving unit is used to drive the second-stage amplification unit to generate the second pump light.

[0015] The adjustable pulsed fiber laser module also includes a first filter isolator and a second filter isolator. The first filter isolator is located between the pulse seed signal source and the first-stage amplification unit, and the second filter isolator is located between the first-stage amplification unit and the second-stage amplification unit.

[0016] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention provides an adjustable pulsed fiber laser module, including a pulse seed signal source, a multi-stage fiber amplification structure, a driving circuit, and a control circuit. The multi-stage fiber amplification structure is optically connected to the pulse seed signal source. The driving circuit is electrically connected to both the pulse seed signal source and the multi-stage fiber amplification structure. The control circuit is electrically connected to the driving circuit. The control circuit converts preset pulse parameters into electrical pulse signals and outputs these signals to the driving circuit. The driving circuit drives the pulse seed signal source to generate seed pulse light and drives the pump source in the multi-stage fiber amplification structure to generate pump pulse light according to the electrical pulse signals. The falling edges of the pump pulse light and the seed pulse light are aligned in the time domain. The seed pulse light is amplified by the multi-stage fiber amplification structure and then output as a pulse train. This invention utilizes the synergistic action of a control circuit and a drive circuit to drive a pulse seed signal source to generate seed pulse light and a pump source with a multi-stage fiber amplification structure to generate pump pulse light, aligning their falling edges in the time domain. After multi-stage amplification, a pulse train is output, without relying on additional modulation devices such as acousto-optic modulators. This allows for flexible adjustment of the pulsed laser repetition frequency and stable generation of the pulse train. Simultaneously, it effectively avoids the problems of high insertion loss, limited power adaptability, and the need for dedicated drive circuits inherent in traditional modulation devices. This reduces laser energy loss, broadens the power adaptability range, simplifies the laser module system structure, and ultimately achieves a more compact laser module structure and more efficient energy utilization. Attached Figure Description

[0017] Figure 1 This is an overall structural framework diagram of the adjustable pulsed fiber laser module provided in an embodiment of the present invention; Figure 2 Pulse waveform diagrams of different signals of the adjustable pulsed fiber laser module provided in this embodiment 1; Figure 3Pulse waveform diagrams of different signals of the adjustable pulsed fiber laser module provided in this embodiment 2; Figure 4 Pulse waveform diagrams of different signals of the adjustable pulsed fiber laser module provided in this embodiment 3; Figure 5 Pulse waveform diagrams of different signals of the adjustable pulsed fiber laser module provided in this embodiment 4; Figure 6 This is a schematic diagram of the structure of different optical components in the adjustable pulsed fiber laser module provided in this embodiment 5; Figures 7a to 7c The pulse waveform diagrams of the pulse seed signal source and output pulse train in the adjustable pulsed fiber laser module provided in this embodiment 5 are shown. In the attached diagram: 100—Adjustable pulsed fiber laser module; 10—Pulse seed signal source; 20—Multi-stage fiber amplification structure; 201—First-stage amplification unit; 202—Second-stage amplification unit; 30—Drive circuit; 301—First drive unit; 302—Second drive unit; 303—Third drive unit; 40—Control circuit. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] The purpose of this invention is to address the shortcomings of existing technologies by providing an adjustable pulsed fiber laser module. This module generates a pump pulse signal synchronized with the falling edge of the seed pulse through a control circuit, which drives the semiconductor laser pump sources of each amplification stage in the laser module, thereby achieving energy amplification of the fiber pulsed laser signal. The output pulse width of the laser module is controlled by adjusting the seed pulse width, and the output pulse repetition frequency is achieved by coordinating the seed pulse repetition frequency and the pump pulse repetition frequency.

[0020] Please see Figure 1 , Figure 1 This is an overall structural framework diagram of the adjustable pulsed fiber laser module 100 provided in an embodiment of the present invention. The present invention provides an adjustable pulsed fiber laser module 100, including a pulse seed signal source 10, a multi-stage fiber amplification structure 20, a driving circuit 30, and a control circuit 40. The multi-stage fiber amplification structure 20 is optically connected to the pulse seed signal source 10, the driving circuit 30 is electrically connected to both the pulse seed signal source 10 and the multi-stage fiber amplification structure 20, and the control circuit 40 is electrically connected to the driving circuit 30. The control circuit 40 is used to convert the preset pulse parameters into electrical pulse signals and output the electrical pulse signals to the drive circuit 30. The drive circuit 30 is used to drive the pulse seed signal source 10 to generate seed pulse light according to the electrical pulse signals, and to drive the pump source in the multi-stage fiber amplification structure 20 to generate pump pulse light. The pump pulse light and the seed pulse light are aligned in the falling edge in the time domain. The seed pulse light is amplified by the multi-stage fiber amplification structure 20 and then output as a pulse train.

[0021] In one embodiment, the multi-stage fiber amplification structure 20 includes a first-stage amplification unit 201 and a second-stage amplification unit 202 that are optically connected sequentially along the signal transmission direction, and the driving circuit 30 includes a first driving unit 301, a second driving unit 302 and a third driving unit 303 arranged in parallel; the first-stage amplification unit 201 and the second-stage amplification unit 202 are any one of a forward pumping structure, a reverse pumping structure and a bidirectional pumping structure.

[0022] The first driving unit 301 is used to drive the pulse seed signal source 10 to generate seed pulse light, the second driving unit 302 is used to drive the first stage amplification unit 201 to generate the first pump light, and the third driving unit 303 is used to drive the second stage amplification unit 202 to generate the second pump light.

[0023] Furthermore, the adjustable pulsed fiber laser module 100 also includes a first filter isolator and a second filter isolator. The first filter isolator is disposed between the pulse seed signal source 10 and the first-stage amplification unit 201, and the second filter isolator is disposed between the first-stage amplification unit 201 and the second-stage amplification unit 202. The first filter isolator and the second filter isolator can effectively block the backlight interference between each stage unit (avoiding the backlight of the first-stage amplification unit from affecting the stability of the seed source and the backlight of the second-stage amplification unit from interfering with the first-stage amplification process), and can also filter noise such as spontaneous emission, thereby ensuring the purity of the seed pulse light and the stability of the multi-stage amplification process, and ensuring the quality of the final output pulse train.

[0024] In this embodiment of the invention, the adjustable pulsed fiber laser module 100 sets the pulse operating parameters through the control circuit 40, and then converts the corresponding pulse width, repetition frequency and pulse energy parameters into electrical pulse signals, which are then output to the first driving unit 301, the second driving unit 302 and the third driving unit 303 respectively. After receiving the electrical pulse signals, the driving circuit 30 outputs DC pulses to drive the pump semiconductor laser module in the pulse seed signal source 10 and the multi-stage fiber amplification structure 20 to generate corresponding optical pulses.

[0025] Specifically, the control circuit 40 outputs electrical pulse signals to the corresponding drive circuits 30. By aligning the falling edge of the seed electrical pulse signal with the pump electrical pulse signal in the time domain, the laser module achieves higher spectral purity and higher amplification efficiency.

[0026] In this embodiment of the invention, the pulse train includes multiple sub-pulses, the pulse width of the sub-pulses is the same as the pulse width of the seed pulse light, and the repetition frequency of the sub-pulses is the same as the repetition frequency of the seed pulse light. This design ensures that the time-domain characteristics of the sub-pulses are stable and the output parameters are accurately controllable, achieving stable output of the pulse train without the need for additional modulation devices.

[0027] In this embodiment of the invention, the envelope width of the pulse train is the same as the pulse width of the pump pulse light, and the repetition frequency of the pulse train envelope is the same as the repetition frequency of the pump pulse light. This allows for flexible control of the pulse train envelope shape by directly adjusting the core parameters of the pump pulse light, eliminating the need for additional envelope modulation devices. This ensures the accuracy and stability of the pulse train envelope output, simplifies the control logic, and further adapts to the differentiated requirements of pulse train envelope parameters in various application scenarios.

[0028] In this embodiment of the invention, the pulse width of the pump pulse is no greater than the lifetime of the upper energy level particles of the doped ions in the gain fiber of the multi-stage fiber amplification structure 20; wherein, the upper limit of the pump pulse width of the amplification stage is directly determined by the lifetime of the upper energy level particles of the doped ions in the gain fiber. If the pump pulse width is too large, it will cause spontaneous emission amplification in the gain fiber, which will lead to a decrease in spectral purity and limit the maximum amplification pulse energy of the laser module.

[0029] In this embodiment of the invention, by combining a seed pulse light with a low repetition frequency pump pulse light (with the repetition frequency of the pump pulse light being lower than that of the seed pulse light), a stable pulse train output can be achieved without the need for additional pulse gating or serialization modulation devices. This simplifies the pulse train generation logic and ensures the regularity of the time-domain structure of the output pulse train.

[0030] In this embodiment of the invention, the number of sub-pulses is controlled by both the pump pulse width and the signal pulse; wherein, the pulse width of the pump pulse light is denoted as τ. pump The repetition frequency of the seed pulse light is denoted as f. seed Then the number of sub-pulses N is determined by the relationship between τ and τ. pump with f seed The product is obtained by rounding down.

[0031] In this embodiment of the invention, within the effective control range, the driving current intensity output by the driving circuit 30 to the fiber amplification structure is approximately linearly proportional to the total envelope energy of the pulse train or the pulse energy of a single sub-pulse; the effective control range must meet the following conditions: the intensity of the driving current does not cause population inversion saturation of doped ions in the gain fiber, does not induce excessive spontaneous emission amplification, and does not exceed the rated operating current of the pump source.

[0032] In this embodiment of the invention, seed pulses not within the time domain of the pump pulse light are affected by the reabsorption of gain ions and the intrinsic loss of the gain fiber core during the multi-stage amplification process, eventually attenuating until they disappear. This process effectively avoids invalid seed pulses from interfering with the output stability and energy purity of the target pulse train after amplification, further ensuring the quality of the laser module's output pulse train.

[0033] In this embodiment of the invention, the time-domain power distribution waveform of the pump pulse light includes any one of rectangular wave, Gaussian wave, Gaussian-like wave and trapezoidal wave, and the envelope waveform of the pulse train is consistent with the time-domain power distribution waveform of the pump pulse.

[0034] The technical solution of the present invention will now be described in conjunction with specific embodiments.

[0035] Example 1: Example 1 provides an adjustable pulsed fiber laser module 100, including a pulse seed signal source 10, a multi-stage fiber amplification structure 20, a driving circuit 30 and a control circuit 40. The multi-stage fiber amplification structure 20 is optically connected to the pulse seed signal source 10, the driving circuit 30 is electrically connected to both the pulse seed signal source 10 and the multi-stage fiber amplification structure 20, and the control circuit 40 is electrically connected to the driving circuit 30. The control circuit 40 is used to convert the preset pulse parameters into electrical pulse signals and output the electrical pulse signals to the drive circuit 30. The drive circuit 30 is used to drive the pulse seed signal source 10 to generate seed pulse light according to the electrical pulse signals, and to drive the pump source in the multi-stage fiber amplification structure 20 to generate pump pulse light. The pump pulse light and the seed pulse light are aligned in the falling edge in the time domain. The seed pulse light is amplified by the multi-stage fiber amplification structure 20 and then output as a pulse train.

[0036] Specifically, the multi-stage fiber optic amplification structure 20 includes a first-stage amplification unit 201 and a second-stage amplification unit 202 that are optically connected sequentially along the signal transmission direction, and the driving circuit 30 includes a first driving unit 301, a second driving unit 302 and a third driving unit 303 arranged in parallel; the first-stage amplification unit 201 and the second-stage amplification unit 202 are any one of a forward pumping structure, a reverse pumping structure and a bidirectional pumping structure.

[0037] The first driving unit 301 is used to drive the pulse seed signal source 10 to generate seed pulse light, the second driving unit 302 is used to drive the first stage amplification unit 201 to generate the first pump light, and the third driving unit 303 is used to drive the second stage amplification unit 202 to generate the second pump light.

[0038] Please see Figure 2 , Figure 2 The diagram shows the pulse waveforms of different signals of the adjustable pulsed fiber laser module 100 provided in Embodiment 1. The input signal pulse (seed pulse) is a continuous narrow pulse sequence with a narrow pulse width and high repetition frequency, serving as the basis for subsequent amplification. The first-stage pump pulse (first pump light) is designed to align with the falling edge of the input signal pulse (ideally a square wave), but in reality, it is not an ideal square wave and has a falling edge delay. Furthermore, its repetition frequency is significantly lower than that of the input signal pulse, providing a time-domain gain window for the first-stage amplification of the input signal. The energy of the first-stage amplified output pulse (the pulsed laser after the seed pulse has been amplified by the first stage) is significantly higher than that of the input signal pulse, and its pulse width remains consistent with the input signal pulse. However, due to the falling edge delay of the first-stage pump pulse, a falling edge delay phenomenon occurs in the optical signal. The waveform and repetition frequency of the second-stage pump pulse (second pump light) are consistent with those of the first-stage pump pulse, providing a secondary gain window corresponding to the effective time period of the first-stage amplified output pulse. It also exhibits a falling edge delay. The energy of the second-stage amplified output pulse (the pulse train output after the seed pulse has been amplified by the second stage) is further increased, while the pulse width remains stable.

[0039] Example 2: Example 2 provides an adjustable pulsed fiber laser module 100. The adjustable pulsed fiber laser module 100 provided in Example 2 has the same structure as the adjustable pulsed fiber laser module 100 provided in Example 1, except that the waveforms of the input primary pump pulse and the secondary pump pulse are different.

[0040] Please see Figure 3 , Figure 3 This is a pulse waveform diagram of different signals of the adjustable pulsed fiber laser module 100 provided in Embodiment 2; by Figure 3 It can be seen that, Figure 2 The first-stage pump pulse time-domain window is narrow, only covering the time-domain interval of a single input signal pulse. Consequently, in the first-stage amplification output, only a single input signal pulse is amplified into a high-amplitude signal, while the second-stage amplification output consists of discrete high-amplitude single pulses. Figure 3The first-stage pump pulse has a segmented wide time-domain window, which can simultaneously cover the time-domain intervals of multiple consecutive input signal pulses (but there are pump gaps in the time-domain region between windows). Therefore, in the first-stage amplification output, the multiple consecutive input signal pulses covered by the pump window are amplified into a high-amplitude pulse train, while the input signal pulses in the pump gap region become low-amplitude weak signals due to the lack of gain supply, superimposed reabsorption of the gain fiber, and intrinsic loss of the fiber core. The time-domain window of the subsequent second-stage pump pulse is completely aligned with the first-stage pump pulse, and similarly does not cover the intermediate gap region. This weak signal cannot gain during the second-stage amplification process and will continue to be weakened by loss, eventually disappearing completely in the second-stage amplification output. Figure 3 The secondary amplification output is presented as a segmented continuous high-energy pulse train.

[0041] Example 3: Example 3 provides an adjustable pulsed fiber laser module 100. The adjustable pulsed fiber laser module 100 provided in Example 3 has the same structure as the adjustable pulsed fiber laser module 100 provided in Example 1, except that the waveforms of the input primary pump pulse and the secondary pump pulse are different.

[0042] Please see Figure 4 , Figure 4 This is a pulse waveform diagram of different signals of the adjustable pulsed fiber laser module 100 provided in Embodiment 3; by Figure 4 As can be seen, the input signal pulse is still a continuous narrow pulse sequence with a narrow pulse width and a high repetition frequency; the first-stage pump pulse is a pulse with a narrow time-domain window, and its repetition frequency is higher than that of the first-stage pump pulse in Example 1. Each pump window precisely matches a single input signal pulse (not continuously covering every input pulse, but selecting a single input pulse at intervals), providing only the matched input pulse with a first-stage amplification gain; correspondingly, in the first-stage amplified output pulse, the single input pulse covered by the pump window presents a high-amplitude effective signal due to the gain, while the uncovered input pulse presents a low-amplitude weak signal due to the lack of gain supply, the reabsorption of the superimposed gain fiber, and the intrinsic loss of the fiber core; the time-domain window and repetition frequency of the second-stage pump pulse are completely aligned with the first-stage pump pulse, providing only the second-stage gain for the high-amplitude single pulse after the first-stage amplification; finally, in the second-stage amplified output pulse, the single input pulse matched by the pump window is further amplified into a high-amplitude discrete single pulse, while the uncovered weak signal is continuously weakened by loss during the second-stage amplification process and disappears completely.

[0043] Example 4: Example 4 provides an adjustable pulsed fiber laser module 100. The adjustable pulsed fiber laser module 100 provided in Example 4 has the same structure as the adjustable pulsed fiber laser module 100 provided in Example 1, except that the waveforms of the input primary pump pulse and the secondary pump pulse are different.

[0044] Please see Figure 5 , Figure 5 This is a pulse waveform diagram of different signals of the adjustable pulsed fiber laser module 100 provided in Embodiment 4; by Figure 5 As can be seen, the input signal pulse in Example 4 is still a continuous narrow pulse sequence with narrow pulse width and high repetition frequency. Unlike the square wave pump in Example 1, the first-stage pump pulse in Example 4 is a Gaussian-like waveform with a gradual rise and fall. Its wide time-domain window can cover multiple consecutive input signal pulses, and the pump gain shows a gradual change characteristic of "low at the edge and high in the middle" with the waveform. Correspondingly, in the first-stage amplified output pulse, the input pulse within the pump window shows a continuous pulse train with "high amplitude in the middle and slightly lower amplitude near the pump edge" due to the gradual change of pump gain. The input pulse outside the pump window shows a low-amplitude weak signal due to the lack of gain supply, the reabsorption of the superimposed gain fiber, and the intrinsic loss of the fiber core. The waveform and time-domain window of the second-stage pump pulse are completely consistent with those of the first-stage pump pulse. It is also a Gaussian-like gradient waveform, which provides secondary gain for the gradient pulse train after the first-stage amplification. In the final second-stage amplified output pulse, the pulse energy within the pump window is further increased, and the gradient characteristic of "high amplitude in the middle and slightly lower amplitude at the edge" is continued. The weak signal outside the pump window is continuously weakened by loss during the second-stage amplification process and disappears completely.

[0045] Example 5: Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of different optical components in the adjustable pulsed fiber laser module 100 provided in this embodiment 5; Embodiment 5 provides an adjustable pulsed fiber laser module 100, including a pulsed seed signal source 10 (seed LD), a first filter isolator (ISO1), a first-stage amplification unit 201, a second filter isolator (ISO2), a second-stage amplification unit 202 and a third filter isolator (ISO3) that are sequentially optically connected along the signal transmission direction.

[0046] Specifically, the first-stage amplification unit 201 includes a first wavelength division multiplexer (WDM1), a first pump source (LD980), and a first ytterbium-doped gain fiber (YDF-6 / 125): the first wavelength division multiplexer is used to combine the seed pulse light output from the first filter isolator with the first pump light output from the first pump source (LD980, which outputs 980nm pump light); the combined optical signal is injected into the first ytterbium-doped gain fiber (YDF-6 / 125), and the first-stage energy amplification of the seed pulse light is achieved by means of stimulated emission of ytterbium-doped ions in the gain fiber.

[0047] Specifically, the secondary amplification unit 202 includes a second wavelength division multiplexer (WDM2), a second pump source (LD980), and a second ytterbium-doped gain fiber (YDF-6 / 125): the first-stage amplified optical signal output from the second filter isolator is combined with the second pump light output from the second pump source (LD980) through the second wavelength division multiplexer, and then injected into the second ytterbium-doped gain fiber (YDF-6 / 125) to complete the second-stage energy amplification of the seed pulse light; the final amplified pulse train optical signal is output through the third filter isolator to ensure the purity and stability of the output light.

[0048] In Example 5, the pulse parameters of the seed pulse light are as follows: operating wavelength of 1064 nm, output power of 800 mW, signal pulse width of 10 ns, repetition frequency of 1 kHz, and output single pulse energy of 3 nJ. Figures 7a to 7b As shown.

[0049] In Example 5, the output power of the first pump source is 1W, the pump pulse width is 700µs, the repetition frequency is 100Hz, and the signal pulse energy of the first-stage amplified optical signal (first-stage amplified output pulse) output by the second filter isolator is 150nJ.

[0050] In Example 5, the output power of the second pump source is 1W, the pump pulse width is 700µs, and the repetition frequency is 100Hz; the signal pulse energy of the pulse train (second-stage amplified output pulse) output by the third filter isolator is 4.8µJ, and its repetition frequency decreases from the initial 1kHz to 100Hz. Figure 7c As shown.

[0051] Compared with the prior art, the present invention has the following advantages: First, the present invention can achieve the repetition frequency adjustment and pulse train generation of pulsed laser without adding additional modulation devices such as acousto-optic modulators. Since the modulation devices in the prior art have defects such as large insertion loss and limited power handling, and require matching drive circuit 30, the technical solution of the present invention can effectively avoid the above problems, achieve the technical effect of more compact laser module structure and higher operating efficiency, and achieve highly efficient and adjustable pulsed laser output. Second, the present invention achieves pulse down-frequency amplification output by adjusting the repetition frequency of the pump pulse: signal pulses that are only aligned with the falling edge of the pump pulse can achieve energy enhancement through stimulated emission amplification; while signal pulses within the pump pulse interval will not produce stimulated emission amplification effect, but will gradually attenuate until they disappear in the amplification stage due to the combined effects of the reabsorption of gain ions and the intrinsic loss of the fiber core. Third, by combining high-repetition-frequency signal pulses with low-repetition-frequency amplified pump pulses, this invention can stably achieve pulse train output; at the same time, by adjusting the waveform of the amplified pump pulse, pulse train outputs with different envelope shapes can be flexibly obtained to adapt to more application scenarios.

[0052] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0053] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An adjustable pulsed fiber laser module, characterized in that, The device includes a pulse seed signal source, a multi-stage fiber amplification structure, a driving circuit, and a control circuit. The multi-stage fiber amplification structure is optically connected to the pulse seed signal source. The driving circuit is electrically connected to both the pulse seed signal source and the multi-stage fiber amplification structure. The control circuit is electrically connected to the driving circuit. The control circuit is used to convert preset pulse parameters into electrical pulse signals and output the electrical pulse signals to the driving circuit. The driving circuit is used to drive the pulse seed signal source to generate seed pulse light according to the electrical pulse signals, and to drive the pump source in the multi-stage fiber amplification structure to generate pump pulse light. The pump pulse light and the falling edge of the seed pulse light are aligned in the time domain. The seed pulse light is amplified by the multi-stage fiber amplification structure and then output as a pulse train.

2. The adjustable pulsed fiber laser module according to claim 1, characterized in that, The pulse train includes multiple sub-pulses, the pulse width of each sub-pulse being the same as the pulse width of the seed pulse light, and the repetition frequency of each sub-pulse being the same as the repetition frequency of the seed pulse light.

3. The adjustable pulsed fiber laser module according to claim 2, characterized in that, The envelope width of the pulse train is the same as the pulse width of the pump pulse light, and the envelope repetition frequency of the pulse train is the same as the repetition frequency of the pump pulse light.

4. The adjustable pulsed fiber laser module according to claim 3, characterized in that, The pulse width of the pump pulse light is not greater than the lifetime of the doped ion upper level particles in the gain fiber of the multi-stage fiber amplification structure; the repetition frequency of the pump pulse light is less than the repetition frequency of the seed pulse light.

5. The adjustable pulsed fiber laser module according to claim 3, characterized in that, The pulse width of the pump pulse light is denoted as τ. pump The repetition frequency of the seed pulse light is denoted as f. seed The number N of sub-pulses is determined by the number of sub-pulses N based on τ. pump with f seed The product is obtained by rounding down.

6. The adjustable pulsed fiber laser module according to claim 3, characterized in that, When the driving current output from the driving circuit to the multi-stage fiber amplifier structure increases but does not exceed the rated operating current of the pump source, the total envelope energy of the pulse train or the pulse energy of a single sub-pulse increases synchronously.

7. The adjustable pulsed fiber laser module according to claim 4, characterized in that, The time-domain power distribution waveform of the pump pulse light includes any one of rectangular wave, Gaussian wave, Gaussian-like wave and trapezoidal wave, and the envelope waveform of the pulse train is consistent with the time-domain power distribution waveform of the pump pulse.

8. The adjustable pulsed fiber laser module according to claim 1, characterized in that, The seed pulse light that is not within the time domain of the pump pulse light gradually attenuates and disappears during the multi-stage amplification process.

9. The adjustable pulsed fiber laser module according to claim 1, characterized in that, The multi-stage fiber optic amplification structure includes a first-stage amplification unit and a second-stage amplification unit that are optically connected sequentially along the signal transmission direction, and the driving circuit includes a first driving unit, a second driving unit, and a third driving unit that are arranged in parallel. Wherein, the first driving unit is used to drive the pulse seed signal source to generate the seed pulse light, the second driving unit is used to drive the first-stage amplification unit to generate the first pump light, and the third driving unit is used to drive the second-stage amplification unit to generate the second pump light.

10. The adjustable pulsed fiber laser module according to claim 9, characterized in that, The adjustable pulsed fiber laser module further includes a first filter isolator and a second filter isolator. The first filter isolator is disposed between the pulse seed signal source and the first-stage amplification unit, and the second filter isolator is disposed between the first-stage amplification unit and the second-stage amplification unit.

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