High-power pulse time domain synthesis system

Abstract

The invention provides a high-power pulse time domain synthesis system, and relates to the field of laser. The system comprises N paths of low-repetition-frequency pulse seed sources with different central wavelengths, and pulses output by each path of seed source are arranged according to an equal time interval time sequence and are coupled into a path of high-repetition-frequency pulse seed source through a wavelength division multiplexer. After being amplified by the gain amplification module, a high repetition frequency pulse is input through a circulator port and enters the port, the port is connected with high-reflectivity fiber grating arrays which are arranged at equal intervals and have central wavelengths corresponding to seed sources, pulses with different wavelengths are reflected by gratings to generate different delays, and finally, the pulses are synchronously output from the circulator port, so that pulse accumulation time domain synthesis is realized. The pulse peak power is reduced to 1 / N of the original pulse peak power, the nonlinear effect is effectively inhibited, the duty ratio of signal light is increased to N times of the original duty ratio, the pulse energy after accumulation reaches N times of single-path energy, the output power can reach 500-1000W, and the high-power laser is simple in structure and suitable for high-power laser application scenes.

Description

Technical Field

[0001] This invention relates to the field of lasers, and more particularly to a high-power pulse time-domain synthesis system. Background Technology

[0002] In the field of pulsed fiber lasers, low repetition rate (LPR) pulsed lasers, due to their long pulse intervals, concentrated single-pulse energy, and extremely high peak power, have extremely important applications in laser ranging, lidar, and industrial processing and manufacturing. However, the characteristics of long pulse intervals and extremely high peak power make pulsed fiber lasers prone to nonlinear effects such as stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS), as well as stimulated spontaneous emission (ASE). This not only causes laser beam quality degradation and limited output power, but may also damage fiber optic devices, severely restricting the development of LPR pulsed fiber lasers towards high power. Summary of the Invention

[0003] To address the problem that low-repetition-rate pulsed fiber lasers suffer from severe nonlinear and ASE effects due to their high peak power and low duty cycle, thus preventing them from achieving high-power output, this invention provides a high-power pulse time-domain synthesis system. By using multi-wavelength low-repetition-rate pulse seed source timing arrangement and pulse stacking techniques, the system reduces peak power, suppresses nonlinear effects, and ultimately achieves high-power, high-energy pulse output.

[0004] This invention provides a high-power time-domain synthesis system, comprising: multiple laser seed sources, each seed source outputting pulsed laser signals with different center wavelengths; a timing control module connected to each laser seed source, controlling each seed source to output the pulsed laser signals sequentially at preset time intervals; a gain amplification module connected to each seed source, amplifying the laser pulse signals to form amplified laser signals with different center frequencies; and a circulator connected to the gain amplification module, controlling the transmission delay of each amplified laser signal in the circulator to ensure synchronous output and superposition of the amplified laser signals to form a high-power pulse.

[0005] In some embodiments, the high-power pulse time-domain synthesis system includes multiple gain amplification modules, each of which amplifies the pulsed laser signal output by each laser seed source.

[0006] In some embodiments, the number of gain amplification modules is one; wherein, the high-power pulse time-domain synthesis system further includes: a wavelength division multiplexer, connected in parallel with each of the laser seed sources, used to couple the pulsed laser signals output by each of the laser seed sources into a single path to form a synthesized laser pulse signal, wherein the center pulses of each of the pulsed laser signals in the synthesized pulse signal do not overlap with each other.

[0007] In some embodiments, the circulator includes: a plurality of fiber Bragg gratings, each fiber Bragg grating being used to reflect amplified laser signals with different center frequencies; a circulator body having an input port, a reflection port, and an output port, wherein the input port is used to receive amplified laser signals with different center wavelengths, the reflection port is used to output each of the amplified laser signals to the fiber Bragg gratings and to receive the amplified laser signals reflected by each of the fiber Bragg gratings, and the output port is used to output the amplified laser signals received by the reflection port; wherein the spacing between each fiber Bragg grating and the reflection port is different, so that each of the amplified laser signals is synchronously transmitted to the reflection end and synthesized into the high-power pulse.

[0008] In some embodiments, the center wavelengths of the pulsed laser signals output by each of the laser seed sources form an arithmetic sequence, and the timing control module is used to control each of the laser seed sources to output the pulsed laser signals sequentially at the same time interval.

[0009] In some embodiments, the fiber Bragg grating is a fiber Bragg grating.

[0010] In some embodiments, the gain amplification module includes: a gain fiber; and a pump laser for pumping laser transmission into the gain fiber.

[0011] In some embodiments, the gain fiber is a double-clad ytterbium-doped fiber.

[0012] In some embodiments, the number of pump lasers is four.

[0013] In some embodiments, the number of laser seed sources is three, the center wavelengths of each pulsed laser signal are 1050 nm, 1052 nm and 1054 nm respectively, the single-channel repetition frequency is 2 kHz and the single pulse energy is 0.5 millijoules; the timing control unit sets the output interval of each laser signal to 166.67 microseconds.

[0014] The beneficial effects achieved by this invention are as follows: 1. By arranging and coupling N low-repetition-rate pulses in sequence, the pulse repetition frequency is increased by N times, and the peak power is reduced to 1 / N of the original, effectively suppressing nonlinear effects such as SBS and SRS as well as ASE effect, and greatly improving the SBS threshold of the laser. 2. By utilizing the equidistant arrangement and wavelength matching design of fiber optic grating arrays, precise delay and synchronous stacking of pulses of different wavelengths can be achieved, and the stacked pulse energy reaches N times the single-channel amplification energy. 3. It has a high degree of modularity and can flexibly adjust the pulse stacking multiple by increasing or decreasing the number of pulse seed sources and fiber gratings, adapting to different power demand scenarios and having strong compatibility. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a high-power pulse time-domain synthesis system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the circulator body in a high-power pulse time-domain synthesis system provided in an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures 1. Timing control module; 2.1. First laser seed source; 2.2. Second laser seed source; 2.3. Third laser seed source; 3. Wavelength division multiplexer; 4. Gain fiber; 5. Beam combiner; 6. Pump laser; 7. Circulator body; 7.1. Input port; 7.2. Reflection port; 7.3. Output port; 8.1. First fiber grating; 8.2. Second fiber grating; 8.3. Third fiber grating; 9. Fiber output cap. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The specific technical features described in the various embodiments in the detailed implementation can be combined in various ways without contradiction. For example, different implementation methods can be formed by combining different specific technical features. In order to avoid unnecessary repetition, the various possible combinations of the specific technical features in this invention will not be described separately.

[0019] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0020] Additionally, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In the following description, the terms "first," "second," etc., are used merely to distinguish different objects and do not indicate any similarity or connection between them. It should be understood that the directional descriptions such as "above," "below," "inside," and "outside" refer to the orientation under normal use conditions.

[0021] In some embodiments, such as Figure 1 As shown, the high-power pulse time-domain synthesis system includes: multiple laser seed sources, timing control module 1, gain amplification module, and circulator.

[0022] Multiple laser seed sources are used to output pulsed laser signals with different center wavelengths, for example, Figure 1 It includes multiple three-laser seed sources, namely the first laser seed source 2.1, the second laser seed source 2.2, and the third seed source 2.3.

[0023] The timing control module 1 is used to control each laser seed source to output laser pulse signals sequentially at a predetermined time interval. The time interval is long enough so that the center pulses of each laser pulse signal will not overlap after being combined into one.

[0024] The gain amplification module is used to amplify each laser pulse signal separately. It can be understood that each laser pulse signal with lower power is amplified by the gain amplification module before being combined into a high-power laser pulse signal. Such lower power pulse signals are less likely to produce nonlinear effects such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and stimulated spontaneous emission (ASE) effects in the gain amplification module.

[0025] The gain amplification module amplifies each laser pulse signal in different ways. Optionally, the number of amplification modules can be increased to multiple, with each gain amplification module corresponding to a laser seed source. The output of each laser seed source is input to a gain amplification module and amplified by that module. Alternatively, as... Figure 1As shown, the high-power pulse time-domain synthesis system also includes a wavelength division multiplexer 3, which is connected in parallel with each laser seed source. The wavelength division multiplexer 3 is used to couple the pulsed laser signals output by each laser seed source into a single synthesized laser pulse signal according to the time sequence. The center pulses of each pulsed laser signal in the synthesized laser pulse signal do not overlap with each other, so that the pulsed laser signals with different center wavelengths in the synthesized laser pulse signal can be transmitted to the gain amplification module in sequence. Thus, a single gain amplification module can be used to amplify the pulsed laser signals with different center wavelengths in sequence.

[0026] It should be noted that the gain amplification module can be any module capable of signal amplification; for example, a semiconductor optical amplifier; or an optical fiber amplifier, such as... Figure 1 As shown, the gain amplification module includes a gain fiber 4 and a pump laser 6. The pump laser 6 transmits the pump laser to the gain fiber 4 to amplify the laser pulse signal. The gain fiber 4 is a double-clad ytterbium-doped fiber (core diameter 30 micrometers, cladding diameter 400 micrometers). The gain amplification module is equipped with four 100-watt, 976-nanometer pump lasers 6. The gain amplification module also includes a beam combiner 5, which is used to combine the four pump lasers 6 and transmit them to the gain fiber 4.

[0027] The circulator is connected to the gain amplification module and is used to control the transmission delay of each amplified laser signal in the circulator. This transmission delay refers to the time between receiving the laser signal and outputting the laser signal. By outputting amplified laser signals with different center wavelengths at different time delays, the amplified laser signals with different center wavelengths can be synchronously output by the circulator and superimposed to form the required power pulse. The circulator can control the transmission delay of amplified laser signals with different center wavelengths in different ways. For example, the circulator includes multiple delay optical fibers, and amplified laser signals with different center wavelengths are transmitted in each delay optical fiber. By controlling the length of each delay optical fiber, the transmission delay of amplified laser signals with different center wavelengths can be controlled, thereby enabling the synchronous output of each amplified laser signal.

[0028] Optional, such as Figure 1 As shown, the circulator includes: a circulator body 7 and a plurality of fiber optic gratings, exemplarily, such as... Figure 1 As shown, there are three fiber Bragg gratings: 8.1 (first fiber Bragg grating), 8.2 (second fiber Bragg grating), and 8.3 (third fiber Bragg grating). These three fiber Bragg gratings are connected in series. Different fiber Bragg gratings can reflect pulsed laser signals of specific wavelengths, while pulsed laser signals of other wavelengths pass through them. The three fiber Bragg gratings are used to reflect amplified pulsed laser signals with three different center wavelengths. Figure 1 and Figure 2The circulator body 7 includes an input port 7.1, a reflection port 7.2, and an output port 7.3. The input port 7.1 is used to receive amplified laser signals with different center wavelengths. The reflection port 7.2 is used to output each amplified laser signal to each fiber grating and to receive the amplified laser signals reflected by each fiber grating. The output port 7.3 is used to output the amplified laser signal received by the reflection port 7.2. The spacing between each fiber grating and the reflection port 7.2 is different so that each amplified laser signal forms a different optical path, thereby controlling the synchronous transmission of laser signals with different center wavelengths to the reflection port 7.2. This allows the laser signals with different center wavelengths to be superimposed to form a high-power pulse, which is then output from the output port 7.3.

[0029] Optionally, the center wavelengths of the pulsed laser signals output by each laser seed source form an arithmetic sequence. The timing control module 1 controls each laser seed source to output pulsed laser signals sequentially at the same time interval, thereby ensuring that the spacing between each fiber grating and the reflection port 7.2 also forms an arithmetic sequence, making it easier to synchronously transmit each amplified laser signal to the reflection port 7.2. Optionally, the fiber grating is a Bragg grating.

[0030] In some embodiments, the number of laser seed sources is three, the center wavelengths of each pulsed laser signal are 1050 nm, 1052 nm and 1054 nm respectively, the single-channel repetition frequency is 2 kHz and the single pulse energy is 0.5 millijoules; the timing control unit sets the output interval of each laser signal to 166.67 microseconds.

[0031] In some embodiments, such as Figure 1 As shown, the high-power pulse time-domain synthesis system includes a timing control module, a pulse seed source module, a wavelength division multiplexer, a gain fiber, a signal combiner, a pump source, a circulator, a high-reflectivity fiber grating array, and a fiber output cap. The pulse seed source module, wavelength division multiplexer 3, gain fiber, signal combiner 5, circulator, and fiber output cap 9 are connected sequentially through a signal power transfer fiber. The signal combiner 5 transmits the pump laser from the semiconductor pump laser 6 to the inner cladding of the gain fiber 4 through the pump power transfer fiber.

[0032] The pulse seed source module consists of three low-repetition-rate pulse seed sources with center wavelengths of 1050nm, 1052nm, and 1054nm, respectively. Each source has a repetition frequency f=2kHz and a single pulse energy of 0.5mJ. The timing control unit sets the pulse output interval Δt=1 / (3×2kHz)=166.67μs to ensure sequential pulse output. The wavelength division multiplexer is a 3-channel multiplexer with 96% transmittance for 1050nm, 1052nm, and 1054nm wavelengths, 32dB isolation between adjacent channels, and a high-repetition-rate pulse repetition frequency of 6kHz after coupling. The gain amplification module is a 3m double-clad ytterbium-doped fiber (30μm core diameter, 400μm cladding diameter) equipped with four 100W 976nm pump lasers.

[0033] The circulator is a three-port polarization-maintaining circulator with an insertion loss of 0.8 dB and an isolation of 42 dB.

[0034] The high-reflectivity fiber Bragg grating array consists of three fiber Bragg gratings with center wavelengths of 1050nm, 1052nm, and 1054nm, respectively. The reflectivity is 99.5%, and the bandwidth is 0.3nm. The spacing between adjacent gratings is d=15m, and the fiber refractive index is n=1.468. The calculated delay Δτ=15×1.468 / (3×10^8)=73.4ns ensures that the three pulses are output synchronously at port 3.

[0035] Achievable effects: after stacking, the pulse repetition frequency is 2kHz, the pulse width is 2ns, the single pulse energy is 15mJ, the power is 30W, the beam quality M²≤1.4, the power fluctuation is ≤±2.5% after 500 hours of continuous operation, and the SBS effect is not obvious.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-power pulse time-domain synthesis system, characterized in that, The high-power pulse time-domain synthesis system includes: Multiple laser seed sources, each of which is used to output pulsed laser signals with different center wavelengths; A timing control module is connected to each of the laser center sources and is used to control each of the laser seed sources to output the pulsed laser signals sequentially at a preset time interval. A gain amplification module is connected to each of the laser seed sources and is used to amplify the laser pulse signals respectively to form amplified laser signals with different center frequencies; A circulator, connected to the gain amplification module, is used to control the transmission delay of each amplified laser signal in the circulator, so that each amplified laser signal is output synchronously and superimposed to form a high-power pulse.

2. The high-power pulse time-domain synthesis system according to claim 1, characterized in that, The high-power pulse time-domain synthesis system includes multiple gain amplification modules, each of which amplifies the pulsed laser signal output by each laser seed source.

3. The high-power pulse time-domain synthesis system according to claim 1, characterized in that, The number of the gain amplification modules is one; The high-power pulse time-domain synthesis system further includes: A wavelength division multiplexer, connected in parallel with each of the laser seed sources, is used to couple the pulsed laser signals output by each of the laser seed sources into a single synthesized laser pulse signal according to the time sequence. The center pulses of each of the pulsed laser signals in the synthesized pulse signal do not overlap with each other.

4. The high-power pulse time-domain synthesis system according to any one of claims 1 to 3, characterized in that, The circulator includes: Multiple fiber Bragg gratings, each of which is used to reflect amplified laser signals with different center frequencies; The circulator body has an input port, a reflection port, and an output port. The input port is used to receive amplified laser signals with different center wavelengths. The reflection port is used to output each of the amplified laser signals to the fiber grating and to receive the amplified laser signals reflected by each of the fiber gratings. The output port is used to output the amplified laser signals received by the reflection port. The spacing between each fiber grating and the reflection port is different, so that each amplified laser signal is transmitted synchronously to the reflection end and synthesized into the high-power pulse.

5. The high-power pulse time-domain synthesis system according to claim 4, characterized in that, The center wavelengths of the pulsed laser signals output by each of the laser seed sources form an arithmetic sequence, and the timing control module is used to control each of the laser seed sources to output the pulsed laser signals sequentially at the same time interval.

6. The high-power pulse time-domain synthesis system according to claim 4, characterized in that, The fiber Bragg grating is a fiber Bragg grating.

7. The high-power pulse time-domain synthesis system according to any one of claims 1 to 3, characterized in that, The gain amplification module includes: Gain fiber; A pump laser is used to pump laser light into the gain fiber.

8. The high-power pulse time-domain synthesis system according to claim 7, characterized in that, The gain fiber is a double-clad ytterbium-doped fiber.

9. The high-power pulse time-domain synthesis system according to claim 7, characterized in that, The number of pump lasers is 4.

10. The high-power pulse time-domain synthesis system according to any one of claims 1 to 3, characterized in that, The number of laser seed sources is 3, and the center wavelengths of each pulsed laser signal are 1050 nm, 1052 nm and 1054 nm, respectively. The single-channel repetition frequency is 2 kHz and the single pulse energy is 0.5 millijoules. The timing control unit sets the output interval of each laser signal to 166.67 microseconds.

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