Low-repetition-frequency narrow-pulse-width pulse fiber laser beneficial to inhibiting ASE light

Abstract

The invention relates to a low-repetition-frequency narrow-pulse-width pulse fiber laser beneficial for inhibiting ASE light, and the laser comprises a low-repetition-frequency narrow-pulse-width seed source which is used for providing a low-repetition-frequency narrow-pulse-width seed pulse with the repetition frequency of 1-500 KHz and the pulse width of 1-50 ns, and outputting the seed pulse to a wave combining module; the continuous injection source is used for providing continuous laser and outputting the continuous laser to the wave combining module; wherein the peak power of the seed pulse is at least 10 times of the peak power of the continuous laser, and the average power of the seed pulse is equal to-0.5 to 1.5 times of the average power of the continuous laser; the wave combining module is used for simultaneously transmitting the seed pulse and the continuous laser to the amplification module; the amplification module is used for amplifying the power of the seed pulse to form pulse laser with low repetition frequency, narrow pulse width and high peak value and transmitting the pulse laser to the filter; wherein in the seed pulse power amplification process, the continuous laser forms a gain suppression effect on the ASE light; the filter is used for filtering the continuous laser provided by the continuous injection source and outputting amplified pulse laser, the continuous injection source is utilized in the seed pulse amplification process, generation of ASE light is effectively restrained, the control difficulty of the system for the pumping source and the injection source is lowered, the signal-to-noise ratio of the system is further improved, and the service life of the system is prolonged. And powerful support is provided for application of the fiber laser in multiple fields.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber lasers, and in particular to a low repetition rate and narrow pulse width pulse optical fiber laser which is beneficial for suppressing ASE light. Background Art

[0002] The challenges faced by low repetition rate (1KHz ~ 100KHz) nanosecond narrow pulses in the amplification process of fiber amplifiers mainly come from the extremely low duty cycle of laser pulses, which means that in the long time interval between two adjacent laser pulses, the pump light is not effectively used to amplify the laser pulse, but is converted into ASE (Amplification of Spontaneous Emission) light. ASE light not only consumes the energy of the pump light, but also further absorbs the pump light and is amplified, thus forming an environment that is not conducive to the effective amplification of laser pulses, resulting in limited gain of laser pulses.

[0003] To address this challenge, the current implementation solutions for low repetition rate nanosecond pulse fiber lasers are mainly summarized into the following three types:

[0004] 1. Pulse pumping scheme: Both the seed source and the pump source use pulse signals, and the timing and pulse width of the pump light are precisely controlled to match the pulse characteristics of the seed source. In this way, the generation of ASE light can be reduced and the amplification factor of the laser pulse can be increased. However, since the pump pulse width is usually difficult to reach the 10us level, this scheme is not effective in suppressing the ASE light of fiber lasers with a repetition frequency higher than 1KHz and a pulse width of several ns. In addition, precise timing and pulse width control also increase the complexity of the system.

[0005] 2. Long pulse width and low repetition rate solution: The duty cycle is reduced by increasing the pulse width, thereby reducing the generation of ASE light. Due to the longer pulse width, the pump light can be more effectively used to amplify the laser during the pulse period, but the increase in duty cycle also means that the peak power of the laser pulse is difficult to reach a high level, which is a limitation for applications that require high peak power.

[0006] 3. Pulse injection source solution: Introduce an additional pulse injection source into the system, and use the gain clamping principle to suppress ASE light. By accurately controlling the timing of the pulse injection source and the seed source signal, it can be ensured that ASE light is effectively suppressed during the laser pulse amplification process. However, a complex timing and pulse width control system is required to accurately control the timing and pulse width of the two pulse sources. This puts high demands on the circuit control system. At the same time, the complexity and cost of the system are relatively high, making it difficult to achieve miniaturization.

[0007] Therefore, there is an urgent need in the art to propose a laser system that can both reduce the difficulty of system control and suppress the amplification of ASE light. Summary of the invention

[0008] Based on this, in order to solve the above problems, the present invention provides a low repetition rate and narrow pulse width pulse fiber laser which is beneficial to suppressing ASE light, which not only reduces the control difficulty of the system, but also can effectively suppress the ASE light generated by the seed pulse during the amplification process.

[0009] To achieve the above-mentioned purpose, the present invention provides a low repetition rate narrow pulse width pulse fiber laser which is beneficial to suppressing ASE light, comprising: a low repetition rate narrow pulse width seed source, used to provide a low repetition rate narrow pulse width seed pulse with a repetition frequency of 1KHz to 500KHz and a pulse width of 1ns to 50ns and output it to a combiner module; a continuous injection source, used to provide a continuous laser and output it to the combiner module; wherein the peak power of the seed pulse is at least 10 times the peak power of the continuous laser, and the average power of the seed pulse is equal to -0.5 times to 1.5 times the average power of the continuous laser; the combiner module is used to simultaneously transmit the seed pulse and the continuous laser to the amplifier module; the amplifier module is used to amplify the power of the seed pulse to form a pulse laser with a low repetition rate narrow pulse width and a high peak value and transmit it to a filter; wherein, in the process of amplifying the power of the seed pulse, the continuous laser forms a gain suppression effect on the ASE light; the filter is used to filter out the continuous laser provided by the continuous injection source and output the amplified pulse laser.

[0010] In one specific embodiment, the filter is a bandpass filter.

[0011] In one specific embodiment, the seed source is a semiconductor laser with polarization-maintaining output, which can be directly modulated into a seed pulse signal with adjustable repetition frequency and pulse width through driven ionization, and the central wavelength of the seed pulse is between 1525nm and 1565nm.

[0012] In one specific embodiment, the continuous injection source is a polarization-maintaining semiconductor laser that outputs a continuous laser signal.

[0013] In one specific embodiment, the combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, and then the seed pulse and the continuous laser are simultaneously input into the amplification module, the amplification module comprises a cladding light filter, a gain fiber, a combiner and a continuously output pump source, the output end of the fiber polarization combiner is connected to the input end of the cladding light filter, the output end of the cladding light filter is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the input end of the combiner, the output end of the combiner is connected to the filter, and the output end of the continuously output pump source is connected to the pump light input end of the combiner.

[0014] In one specific embodiment, the combining module includes a circulator and a fiber Bragg grating, a seed pulse is input into the first port of the circulator, a continuous laser is input into the fiber Bragg grating and the second port of the circulator in sequence, and then the seed pulse and the continuous laser are simultaneously input into the amplification module through the third port of the circulator, the amplification module includes a cladding light filter, a gain fiber, a combiner and a continuously output pump source, the third port of the circulator is connected to the input end of the cladding light filter, the output end of the cladding light filter is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the input end of the combiner, the output end of the combiner is connected to the filter, and the output end of the continuously output pump source is connected to the pump light input end of the combiner.

[0015] In one specific embodiment, the combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, and then the seed pulse and the continuous laser are simultaneously input into the amplification module, the amplification module comprises a gain fiber, a wavelength division multiplexer and a continuous output pump source, the output end of the fiber polarization combiner is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected to the filter, and the output end of the continuous output pump source is connected to the REF end of the wavelength division multiplexer.

[0016] In one specific embodiment, the combining module includes a circulator, the amplification module includes a gain fiber, a fiber grating, a wavelength division multiplexer and a continuous output pump source, the output end of the seed source is connected to the first port of the circulator, the output end of the gain fiber is connected to the second port of the circulator, the output end of the fiber grating is connected to the input end of the gain fiber, the COM end of the wavelength division multiplexer is connected to the output end of the fiber grating, the output end of the pump source is connected to the REF end of the wavelength division multiplexer, the output end of the continuous injection source is connected to the PASS end of the wavelength division multiplexer, and the third port of the circulator is connected to the filter.

[0017] In one specific embodiment, the combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, the continuous injection source includes a continuously output pump source, a combiner, a high reflectivity fiber grating, a double-clad gain fiber, a low reflectivity fiber grating, a cladding light filter and a polarization beam splitter, the output end of the pump source is connected to the input end of the combiner, the output end of the combiner is connected to the long wavelength end of the high reflectivity fiber grating, the short wavelength end of the high reflectivity fiber grating is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the short wavelength end of the low reflectivity fiber grating, the long wavelength end of the low reflectivity fiber grating is connected to the input end of the cladding light filter, the output end of the cladding light filter is connected to the input end of the polarization beam splitter, the output end of the polarization beam splitter is connected to the fast axis of the fiber polarization combiner, the output end of the fiber polarization combiner is connected to the input end of the amplification module, and the output end of the amplification module is connected to the filter.

[0018] In one specific embodiment, the combining module is a fiber polarization combiner, the seed pulse is input into the slow axis of the fiber polarization combiner, the continuous laser is input into the fast axis of the fiber polarization combiner, the continuous injection source includes a polarization beam splitter, a wavelength division multiplexer, a continuously output pump source, a low-reflectivity fiber grating, a gain fiber and a high-reflectivity fiber grating, the high-reflectivity fiber grating is connected to the low-reflectivity fiber grating through the gain fiber and then to the COM end of the wavelength division multiplexer, the pump source is connected to the REF end of the wavelength division multiplexer, the PASS end of the wavelength division multiplexer is connected to the input end of the polarization beam splitter, the output end of the polarization beam splitter is connected to the fast axis of the fiber polarization combiner, the output of the fiber polarization combiner is connected to the input end of the amplification module, and the output end of the amplification module is connected to the filter.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a low repetition rate, narrow pulse width fiber laser which is beneficial to suppressing ASE light. The fiber laser integrates key components such as a wave combining module, an amplification module and a filter, realizes effective amplification of low repetition rate, narrow pulse width seed pulses, and effectively suppresses the generation of ASE light by using continuous laser during the seed pulse amplification process. This not only reduces the difficulty of controlling the pump source and the injection source of the system, but also improves the signal-to-noise ratio of the system, providing strong support for the application of fiber lasers in multiple fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a low repetition rate and narrow pulse width pulse fiber laser which is beneficial for suppressing ASE light in the first embodiment of the present invention.

[0022] Figure 2It is a schematic structural diagram of a low repetition rate and narrow pulse width pulse fiber laser which is beneficial for suppressing ASE light in the second embodiment of the present invention.

[0023] Figure 3 It is a schematic structural diagram of a low repetition rate and narrow pulse width pulse fiber laser which is beneficial for suppressing ASE light in the third embodiment of the present invention.

[0024] Figure 4 It is a schematic structural diagram of a low repetition rate and narrow pulse width pulse fiber laser which is beneficial for suppressing ASE light in the fourth embodiment of the present invention.

[0025] Figure 5 It is a schematic structural diagram of a low repetition rate and narrow pulse width pulse fiber laser which is beneficial for suppressing ASE light in the fifth embodiment of the present invention.

[0026] Figure 6 It is a schematic structural diagram of a low repetition rate and narrow pulse width pulse fiber laser which is beneficial for suppressing ASE light in the sixth embodiment of the present invention.

[0027] Figure 7 The spectrum comparison diagram before and after using a low repetition rate and narrow pulse width pulse fiber laser that is beneficial to suppressing ASE light provided by the present invention. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1-6As shown, this embodiment provides a low repetition rate narrow pulse width pulse fiber laser that is beneficial to suppressing ASE (Amplified Spontaneous Emission) light, including: a low repetition rate narrow pulse width seed source 10, used to provide a low repetition rate narrow pulse width seed pulse with a repetition frequency of 1KHz to 500KHz and a pulse width of 1ns to 50ns and output it to a combiner module 30; a continuous injection source 20, used to provide a continuous laser and output it to the combiner module 30; wherein the peak power of the seed pulse is at least 10 times the peak power of the continuous laser, preferably, the peak power of the seed pulse is at least 50 times, 100 times, 20 times the peak power of the continuous laser 0 times, 500 times or more than 1000 times, the average power of the seed pulse is equal to -0.5 times to 1.5 times the average power of the continuous laser; the combining module 30 is used to transmit the seed pulse and the continuous laser to the amplifying module 40 at the same time; the amplifying module 40 is used to amplify the power of the seed pulse to form a pulse laser with a low repetition rate, narrow pulse width and high peak value and transmit it to the filter 50; wherein, in the process of amplifying the power of the seed pulse, the continuous laser forms a gain suppression effect on the ASE light, which can effectively reduce the generation of ASE light; the filter 50 is used to filter out the continuous laser provided by the continuous injection source and output the amplified pulse laser. The present embodiment provides a low repetition rate, narrow pulse width pulse fiber laser that is conducive to suppressing ASE light, which integrates key components such as combining modules, amplifying modules and filters, realizes the effective amplification of low repetition rate, narrow pulse width seed pulses, and effectively suppresses the generation of ASE light by using continuous lasers during the amplification process, which not only reduces the difficulty of the system to control the pump source and injection source, but also improves the signal-to-noise ratio of the system, providing strong support for the application of fiber lasers in multiple fields.

[0036] In one specific embodiment, the filter 50 is a bandpass filter, which is used to filter out the continuous laser signal while minimizing the impact on the amplified pulsed laser, and only retains the amplified pulsed laser as the final output to ensure the quality and stability of the output pulse.

[0037] In one specific embodiment, the seed source 10 is a semiconductor laser with polarization-maintaining output, which can be directly modulated into a seed pulse signal with adjustable repetition frequency and pulse width by driven ionization, and the central wavelength of the seed pulse is between 1525nm and 1565nm.

[0038] In one specific embodiment, the continuous injection source 20 is a polarization-maintaining semiconductor laser that outputs a continuous laser signal.

[0039] like Figure 1As shown, in one of the specific embodiments, the combining module is an optical fiber polarization combiner 301, which can combine and transmit optical signals of different polarization directions. The seed source 10 is a semiconductor laser with polarization-maintaining output, which can be directly modulated into a seed pulse signal with adjustable repetition frequency and pulse width through a driving circuit. The seed pulse is input to the slow axis of the optical fiber polarization combiner 301, and the continuous injection source 20 is a semiconductor laser with polarization-maintaining output, which outputs a continuous laser signal. The continuous laser is input to the fast axis of the optical fiber polarization combiner 301. The seed pulse repetition frequency is 25KHz and the pulse width is 25KHz. The duty cycle is 3ns, and the duty cycle is extremely low. The average power of the seed laser is equal to the average power of the continuous injection source, but the peak power of the seed pulse is 200 times the peak power of the continuous injection source. Then, the seed pulse and the continuous laser are combined in the fiber polarization combiner 301 and input into the amplification module 40 at the same time. During the interval time of the low repetition rate seed pulse, the continuous laser and the ASE light form a gain clamping effect, which effectively suppresses the generation of ASE light. Since the peak power of the seed pulse is much greater than the peak power of the continuous laser, the gain effect of the continuous laser on the seed pulse can be ignored. After the seed pulse and the continuous laser are amplified by the amplification module, the continuous laser is filtered out by the filter 50, and only the seed pulse is output. The amplification module 40 includes a cladding light filter 401, a gain fiber 402, a combiner 403 and a continuous output pump source 404. The output end of the optical fiber polarization combiner 301 is connected to the input end of the cladding light filter 401 for filtering out unnecessary cladding light. The output end of the cladding light filter 401 is connected to the input end of the gain fiber 402. The gain fiber 402 amplifies the optical signal. The output end of the gain fiber 402 is connected to the input end of the combiner 403. The output end of the combiner 403 is connected to the filter 50. The filter 50 has a passband wavelength range including the central wavelength of the seed pulse, and a stopband wavelength range including the central wavelength of the continuous injection source, which is used to filter out the continuous laser and ASE light, and only retain the amplified optical signal output of the seed pulse. The output end of the continuous output pump source 404 is connected to the pump input end of the combiner 403 to provide the necessary pump energy for the gain fiber 402 to support the amplification process of the optical signal. The entire system achieves efficient and stable optical pulse amplification output through precise control and adjustment. The present embodiment provides a low repetition rate, narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light. Since the continuous laser forms a gain suppression effect on the ASE light during the seed pulse amplification process, the ASE light generated in the laser can be effectively reduced, the signal-to-noise ratio can be improved, and a high-peak pulse laser with a low repetition rate and a narrow pulse width of ns can be output.

[0040] like Figure 2As shown, in one specific embodiment, the combiner module 30 includes a circulator 303 and a fiber Bragg grating 302, the seed pulse is input to the first port of the circulator 303, and the continuous laser output by the continuous injection source 20 is sequentially input to the fiber Bragg grating 302 and the second port of the circulator 303. The stopband wavelength range of the fiber Bragg grating 302 includes the central wavelength of the seed pulse, and the passband wavelength range includes the central wavelength of the continuous injection source 20. The seed pulse repetition frequency is 100KHz, the pulse width is 10ns, and the duty cycle is extremely low. The average power of the seed laser is equal to 0.5 times the average power of the continuous injection source, but the peak power of the seed pulse is 500 times the peak power of the continuous injection source. Then the seed pulse and the continuous laser are simultaneously input into the amplification module 40 through the third port of the circulator 303. In the low repetition rate seed pulse interval time period, the continuous laser and the ASE light form a gain clamping effect, which can effectively suppress the generation of ASE light. Since the peak power of the seed pulse is much greater than the peak power of the continuous laser, the effect of the continuous laser on the gain of the seed pulse can be ignored, thereby ensuring the stability of the seed pulse during the amplification process. The amplification module 40 includes a cladding light filter 401 and a gain fiber 402. , a beam combiner 403 and a continuously output pump source 404, the third port of the circulator 303 is connected to the input end of the cladding light filter 401, the output end of the cladding light filter 401 is connected to the input end of the gain fiber 402, the output end of the gain fiber 402 is connected to the input end of the beam combiner 403, the output end of the beam combiner 403 is connected to the filter 50, the output end of the continuously output pump source 404 is connected to the pump light input end of the beam combiner 403, the embodiment provides a low repetition rate narrow pulse width pulse fiber laser that is beneficial to suppressing ASE light, because the continuous laser forms a gain suppression effect on the ASE light during the process of amplifying the seed pulse, which can significantly reduce the generation of ASE light, improve the signal-to-noise ratio of the laser, and greatly improve the performance of the laser.

[0041] like Figure 3As shown, in one specific embodiment, the combining module is a fiber polarization combiner 301, the seed pulse is input into the slow axis of the fiber polarization combiner 301, and the continuous injection source 20 is input into the fast axis of the fiber polarization combiner 301, which ensures the separation of the seed pulse and the continuous laser in the polarization direction, and at the same time can achieve efficient merging through the fiber polarization combiner 301, thereby avoiding direct interference between the two. The seed pulse repetition frequency is 200KHz, the pulse width is 20ns, the duty cycle is extremely low, the average power of the seed laser is equal to 1.5 times the average power of the continuous injection source, but the seed pulse peak power is 300 times the peak power of the continuous injection source. The seed pulse and the continuous laser are simultaneously input into the amplification module 40. In the interval time period of the low repetition rate seed pulse, the continuous laser and the ASE light form a gain clamping effect, which can effectively suppress the generation of ASE light. Since the peak power of the seed pulse is much greater than the peak power of the continuous laser, the gain effect of the continuous laser on the seed pulse can be ignored, thereby ensuring the amplification efficiency and purity of the seed pulse. The amplification module 40 includes a gain fiber 402, a wavelength division multiplexer 405 and a continuously output pump source 404. The output end of the optical fiber polarization combiner 301 is connected to the input end of the gain fiber 402. The gain fiber 402 is the core component of the amplification module 40 and is used to amplify the input optical signal. The output end of the gain fiber 402 is connected to the input end of the wavelength division multiplexer 405. The output end of the wavelength division multiplexer 405 is connected to the filter 50. The output end of the continuously output pump source 404 is connected to the REF end of the wavelength division multiplexer 405. The wavelength division multiplexer 405 separates the amplified optical signal from the pump light. , for subsequent processing; secondly, as an input channel of pump light, the continuously output pump source 404 is allowed to send the pump light into the gain fiber 402, and the output end of the continuously output pump source 404 is connected to the pump light input end of the wavelength division multiplexer 405 through an optical fiber or other appropriate connection method to ensure that the pump light can efficiently excite the particle transition in the gain fiber 402, thereby realizing the amplification of the optical signal. Finally, after being processed by the amplification module 40 and the filter 50, the low repetition rate narrow pulse width pulse fiber laser provided in this embodiment, which is conducive to suppressing ASE light, can output a low repetition rate, 10ns narrow pulse width high peak pulse laser. Since the continuous laser forms an effective gain suppression effect on the ASE light during the amplification of the seed pulse, the laser can significantly reduce the generation and amplification of the ASE light, and improve the signal-to-noise ratio and output quality of the system. This design not only improves the overall performance of the laser, but also provides a broader space and possibility for its application in multiple fields such as communication, sensing, medical treatment and scientific research.

[0042] like Figure 4As shown, in one specific embodiment, the combining module includes a circulator 303, the amplification module 40 includes a gain fiber 402, a fiber Bragg grating 302, a wavelength division multiplexer 405 and a continuous output pump source 404, the gain fiber 402 is the core part of the amplification module, and is responsible for amplifying the input optical signal, the fiber Bragg grating 302 is used to select the wavelength of the optical signal input to the gain fiber 402, to ensure that only the optical signal of a specific wavelength can enter the gain fiber 402 for amplification, the output end of the seed source 10 is connected to the first port of the circulator 303, the output end of the gain fiber 402 is connected to the second port of the circulator 303, the output end of the fiber Bragg grating 302 is connected to the input end of the gain fiber 402, and the COM end of the wavelength division multiplexer 405 is connected to the output end of the fiber Bragg grating 302. The output end of the pump source 404 is connected to the REF end of the wavelength division multiplexer 405, which is used to inject the pump light into the gain fiber 402. The output end of the continuous injection source 20 is connected to the PASS end of the wavelength division multiplexer 405, which is used to merge the continuous laser and the seed pulse and input them into the gain fiber 402 together. The central wavelength of the continuous laser is 1558nm, and the central wavelength of the seed pulse is 1550nm. Since the wavelengths of the continuous laser and the seed pulse are different, they can be separated and selected by the fiber grating and the wavelength division multiplexer. The third port of the circulator 303 is connected to the filter 50. The seed pulse repetition frequency output by the seed source is 80KHz, the pulse width is 10ns, the duty cycle is extremely low, the average power of the seed laser is equal to 0.8 times the average power of the continuous injection source, but the peak power of the seed pulse is 500 times the peak power of the continuous injection source. In the low repetition rate seed pulse interval time period, the continuous laser and ASE light form a gain clamping effect, which can effectively inhibit the generation and amplification of ASE light. Since the peak power of the seed pulse is much larger than the peak power of the continuous laser, the gain effect of the continuous laser on the seed pulse is negligible. After the seed pulse and the continuous laser are amplified, the continuous laser is filtered out by the filter, and only the seed pulse is output. This embodiment achieves efficient and low-noise laser pulse amplification through clever wave combining and amplification design, and provides a high-performance light source solution.

[0043] like Figure 5As shown, in one specific embodiment, the combining module is a fiber polarization combiner 301, a seed pulse is input to the slow axis of the fiber polarization combiner 301, and a continuous laser is input to the fast axis of the fiber polarization combiner 301. The continuous injection source 20 includes a pump source 201, a combiner 202, a high reflectivity fiber grating 203, a double-clad gain fiber 204, a low reflectivity fiber grating 205, a cladding light filter 206 and a polarization beam splitter 207. The output end of the pump source 201 is connected to the input end of the combiner 202. The output end of is connected to the long wavelength end of the high reflectivity fiber Bragg grating 203, the short wavelength end of the high reflectivity fiber Bragg grating 203 is connected to the gain fiber 204, the other end of the gain fiber 204 is connected to the short wavelength end of the low reflectivity fiber Bragg grating 205, the long wavelength end of the low reflectivity fiber Bragg grating 205 is connected to the input end of the cladding light filter 206, wherein the light transmission of the high reflectivity fiber Bragg grating 203 and the low reflectivity fiber Bragg grating 205 is directional, the short wavelength end of the two is the input end, the long wavelength end is the output end, and the output end of the cladding light filter 206 is connected to the input end of the cladding light filter 206. The input end of the polarization beam splitter 207 is connected to the fast axis of the optical fiber polarization combiner 301. The pump light generated by the pump source 201 is input to the high reflectivity fiber grating 203 through the combiner 202, and the pump light is reflected into the gain fiber 204 to amplify the pump light, and then output through the low reflectivity fiber grating 205. The low reflectivity fiber grating 205 allows a part of the light to pass through, and reflects a part of the light back to the gain fiber 204 for further amplification, forming positive feedback. The cladding light filter 206 is used to remove The unnecessary cladding light ensures that only the core light is transmitted to the polarization beam splitter 207. The polarization beam splitter 207 adjusts the light to a specific polarization state and then inputs it to the fast axis of the optical fiber polarization combiner 301. The output end of the optical fiber polarization combiner 301 is connected to the input end of the amplification module 40. The output end of the amplification module 40 is connected to the filter 50. In the optical fiber polarization combiner 301, the seed pulse on the slow axis and the continuous laser on the fast axis are combined. Due to their different polarization states, they can be transmitted in parallel in the same optical fiber without interfering with each other.The seed pulse repetition frequency output by the seed source is 400KHz, the pulse width is 30ns, the duty cycle is extremely low, the average power of the seed laser is equal to 1.2 times the average power of the continuous injection source, but the peak power of the seed pulse is 1000 times the peak power of the continuous injection source. In the low repetition rate seed pulse interval time period, the continuous laser and ASE light form a gain clamping effect, which can effectively suppress the generation and amplification of ASE light. Since the peak power of the seed pulse is much larger than the peak power of the continuous laser, the gain effect of the continuous laser on the seed pulse is negligible. The amplification module is mainly used to amplify the seed pulse, and the continuous laser is mainly used to suppress the generation of ASE light. In this embodiment, the seed pulse and the continuous laser are combined and amplified, and the gain clamping effect formed by the continuous laser in the seed pulse interval time is used to suppress the generation of ASE light, thereby outputting a high-quality laser beam.

[0044] like Figure 6As shown, in one specific embodiment, the combining module is a fiber polarization combiner 301, a seed pulse is input to the slow axis of the fiber polarization combiner 301, a continuous laser is input to the fast axis of the fiber polarization combiner 301, the continuous injection source 20 includes a polarization beam splitter 207, a wavelength division multiplexer 208, a pump source 201, a low reflectivity fiber grating 205, a gain fiber 204 and a high reflectivity fiber grating 203, the high reflectivity fiber grating 203 is connected to the low reflectivity fiber grating 205 through the gain fiber 204 and then to the COM end of the wavelength division multiplexer 208, the pump source 201 is connected to the REF end of the wavelength division multiplexer 208, the PASS end of the wavelength division multiplexer 208 is connected to the input end of the polarization beam splitter 207, the output end of the polarization beam splitter 207 is connected to the fast axis of the fiber polarization combiner 301, and the high reflectivity fiber grating 203 reflects the core optical signal back to the gain fiber 204. Optical fiber 204 forms positive feedback, thereby amplifying the optical signal. After the optical signal in the gain optical fiber 204 is amplified, it is output through the low-reflectivity fiber grating 205. A part of the optical signal is reflected back to the gain optical fiber 204, and the other part continues to be transmitted. The wavelength division multiplexer 208 combines the pump light and the returned core light and inputs them into the gain optical fiber 204, while allowing the pump light to be absorbed in the gain optical fiber, while the signal light is amplified. The polarization beam splitter 207 adjusts the amplified continuous laser to a specific polarization state, and then inputs it into the fast axis of the optical fiber polarization combiner 301. In the optical fiber polarization combiner 301, the seed pulse on the slow axis and the continuous laser on the fast axis are combined. Due to their different polarization states, they can be transmitted in parallel in the same optical fiber without interfering with each other. The output of the optical fiber polarization combiner 301 is connected to the input end of the amplification module 40, and the output end of the amplification module 40 is connected to the filter 50. The seed pulse repetition frequency output by the seed source 10 is 200KHz, the pulse width is 45ns, and the duty cycle is extremely low. The average power of the seed laser is equal to 1.4 times the average power of the continuous injection source, but the peak power of the seed pulse is 2000 times the peak power of the continuous injection source. In the low repetition rate seed pulse interval time period, the continuous laser and the ASE light form a gain clamping effect, which can effectively suppress the generation of ASE light. Since the peak power of the seed pulse is much larger than the peak power of the continuous laser, the gain effect of the continuous laser on the seed pulse is negligible. The amplification module is mainly used to amplify the seed pulse, and the continuous laser is mainly used to suppress the generation of ASE light. The amplified optical signal passes through a filter, which is used to remove unnecessary wavelength components and noise to ensure the purity and stability of the output optical signal. This embodiment combines the seed pulse and the continuous laser for amplification, and uses the gain clamping effect formed by the continuous laser in the seed pulse interval time to suppress the generation and amplification of ASE light, thereby outputting a high-quality laser beam. This design has significant advantages in improving the performance and stability of the laser system.

[0045] like Figure 7 As shown, by using the output spectrum of a low repetition rate, narrow pulse width pulse fiber laser that is beneficial to suppressing ASE light provided by the present invention, the laser output signal-to-noise ratio is improved by 10 dB.

[0046] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0047] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A low repetition rate narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light, characterized in that: include: A low repetition rate and narrow pulse width seed source is used to provide a low repetition rate and narrow pulse width seed pulse with a repetition frequency of 1KHz to 500KHz and a pulse width of 1ns to 50ns and output it to the wave combining module; A continuous injection source is used to provide continuous laser light and output it to the wave combining module; The peak power of the seed pulse is at least 10 times the peak power of the continuous laser, and the average power of the seed pulse is equal to -0.5 to 1.5 times the average power of the continuous laser; A wave combining module, used to simultaneously transmit the seed pulse and the continuous laser to the amplification module; An amplification module is used to amplify the power of the seed pulse to form a pulse laser with low repetition rate, narrow pulse width and high peak value and transmit it to the filter; Among them, during the process of seed pulse power amplification, the continuous laser forms a gain suppression effect on the ASE light; The filter is used for filtering out the continuous laser provided by the continuous injection source and outputting the amplified pulse laser.

2. The low repetition rate, narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The filter is a bandpass filter.

3. The low repetition rate narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The seed source is a semiconductor laser with polarization-maintaining output, which can be directly modulated into a seed pulse signal with adjustable repetition frequency and pulse width by driving ionization. The central wavelength of the seed pulse is between 1525nm and 1565nm.

4. The low repetition rate narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The continuous injection source is a polarization-maintaining semiconductor laser that outputs a continuous laser signal.

5. The low repetition rate narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, and then the seed pulse and the continuous laser are simultaneously input into the amplification module, the amplification module comprises a cladding light filter, a gain fiber, a combiner and a continuously output pump source, the output end of the fiber polarization combiner is connected to the input end of the cladding light filter, the output end of the cladding light filter is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the input end of the combiner, the output end of the combiner is connected to the filter, and the output end of the continuously output pump source is connected to the pump light input end of the combiner.

6. The low repetition rate narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The combining module comprises a circulator and a fiber Bragg grating, a seed pulse is input into the first port of the circulator, a continuous laser is input into the fiber Bragg grating and the second port of the circulator in sequence, and then the seed pulse and the continuous laser are simultaneously input into the amplification module through the third port of the circulator, the amplification module comprises a cladding light filter, a gain fiber, a beam combiner and a continuously output pump source, the third port of the circulator is connected to the input end of the cladding light filter, the output end of the cladding light filter is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the input end of the beam combiner, the output end of the beam combiner is connected to the filter, and the output end of the continuously output pump source is connected to the pump light input end of the beam combiner.

7. The low repetition rate narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, and then the seed pulse and the continuous laser are simultaneously input into the amplification module, the amplification module comprises a gain fiber, a wavelength division multiplexer and a continuously output pump source, the output end of the fiber polarization combiner is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected to the filter, and the output end of the continuously output pump source is connected to the REF end of the wavelength division multiplexer.

8. The low repetition rate and narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The combining module comprises a circulator, the amplifying module comprises a gain fiber, a fiber grating, a wavelength division multiplexer and a pump source with a continuous output, the output end of the seed source is connected to the first port of the circulator, the output end of the gain fiber is connected to the second port of the circulator, the output end of the fiber grating is connected to the input end of the gain fiber, the COM end of the wavelength division multiplexer is connected to the output end of the fiber grating, the output end of the pump source is connected to the REF end of the wavelength division multiplexer, the output end of the continuous injection source is connected to the PASS end of the wavelength division multiplexer, and the third port of the circulator is connected to the filter.

9. The low repetition rate and narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, the continuous injection source comprises a continuously output pump source, a combiner, a high reflectivity fiber grating, a double-clad gain fiber, a low reflectivity fiber grating, a cladding light filter and a polarization beam splitter, the output end of the pump source is connected to the input end of the combiner, the output end of the combiner is connected to the long wavelength end of the high reflectivity fiber grating, the short wavelength end of the high reflectivity fiber grating is connected to the input end of the gain fiber, the output end of the gain fiber is connected to the short wavelength end of the low reflectivity fiber grating, the long wavelength end of the low reflectivity fiber grating is connected to the input end of the cladding light filter, the output end of the cladding light filter is connected to the input end of the polarization beam splitter, the output end of the polarization beam splitter is connected to the fast axis of the fiber polarization combiner, the output end of the fiber polarization combiner is connected to the input end of the amplification module, and the output end of the amplification module is connected to the filter.

10. The low repetition rate and narrow pulse width pulse fiber laser that is beneficial for suppressing ASE light according to claim 1, characterized in that: The combining module is a fiber polarization combiner, a seed pulse is input into the slow axis of the fiber polarization combiner, a continuous laser is input into the fast axis of the fiber polarization combiner, the continuous injection source comprises a polarization beam splitter, a wavelength division multiplexer, a continuously output pump source, a low-reflectivity fiber grating, a gain fiber and a high-reflectivity fiber grating, the high-reflectivity fiber grating is connected to the low-reflectivity fiber grating through the gain fiber and then to the COM end of the wavelength division multiplexer, the pump source is connected to the REF end of the wavelength division multiplexer, the PASS end of the wavelength division multiplexer is connected to the input end of the polarization beam splitter, the output end of the polarization beam splitter is connected to the fast axis of the fiber polarization combiner, the output of the fiber polarization combiner is connected to the input end of the amplification module, and the output end of the amplification module is connected to the filter.

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