High-power single-frequency phase-locked laser

Abstract

The invention provides a high-power single-frequency phase-locked laser, and relates to the technical field of laser, the high-power single-frequency phase-locked laser comprises a single-frequency seed source, a first isolator, a multi-stage amplification module, an acousto-optic modulator, an optical coupler, a signal phase-locked module and a signal generation module, the single-frequency seed source is connected with the multi-stage amplification module through the first isolator; the multi-stage amplification module is connected with the optical coupler and the signal phase lock module. The first isolator is also connected with one end of the acousto-optic modulator, and the optical coupler is connected with the other end of the acousto-optic modulator and the signal phase lock module; the signal phase locking module is electrically connected with the signal generation module; and the signal generation module is electrically connected with the acousto-optic modulator. According to the invention, the phase stability and frequency purity of laser output can be improved.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a high-power single-frequency phase-locked laser. Background Art

[0002] Single-frequency fiber lasers can be widely used in nonlinear processes, optical measurements, quantum optics, fiber sensing technology, coherent synthesis, etc. due to their narrow linewidth, long coherence length, low noise, and high conversion efficiency. High-power single-frequency fiber lasers have the advantages of high power density and narrow linewidth, which are very suitable for the above-mentioned nonlinear frequency conversion application requirements.

[0003] The Chinese patent with publication number CN116667117A discloses a single-frequency narrow-linewidth fiber laser, including a seed source and an amplifying optical path; the seed source includes a light source and a first-stage pre-amplifying unit; the light source outputs a wavelength-adjustable continuous laser; the first-stage pre-amplifying unit is used to amplify the wavelength-adjustable continuous laser and then output the seed light, and block the return light from entering the light source; the amplifying optical path is used to amplify the seed light and then output it; wherein, the light source includes an active optical fiber, and the active optical fiber is provided with a distributed feedback grating; the first-stage pre-amplifying unit includes at least one filter and at least one circulator. The above scheme cannot perform a long-distance space detection loop due to the low power output of a single oscillator, and in the process of multi-stage amplification, phase noise is caused by factors such as temperature drift and environmental vibration, thereby causing line width broadening, which in turn affects the coherent detection accuracy. Therefore, it is very necessary to provide a high-power single-frequency phase-locked laser to improve the phase stability and frequency purity of the laser output. Summary of the invention

[0004] In view of this, the present invention proposes a high-power single-frequency phase-locked laser, which amplifies the single-frequency seed light source step by step through a multi-stage amplification module, and the signal phase-locked module uses the electrical signal converted from the interference beat frequency signal combined with PID closed-loop control to effectively suppress the phase noise generated in the optical amplification process and improve the phase stability and frequency purity of the laser output.

[0005] The present invention provides a high-power single-frequency phase-locked laser, comprising a single-frequency seed source, a first isolator, a multi-stage amplification module, an acousto-optic modulator, an optical coupler, a signal phase-locking module and a signal generation module, wherein:

[0006] The single-frequency seed source is connected to the multi-stage amplification module through the first isolator, and the single-frequency seed source is used to output a seed light source and provide a phase reference signal;

[0007] The multi-stage amplification module is connected to the optical coupler and the signal phase-locked module respectively, and the multi-stage amplification module is used to perform multi-stage power amplification on the seed light output by the single-frequency seed source;

[0008] The first isolator is also connected to one end of the AOM, and the optical coupler is respectively connected to the other end of the AOM and the signal phase-locked module, and the optical coupler is used to couple the frequency-shifted light beam output by the AOM and the sampling light beam output by the multi-stage amplification module into one path to generate an interference beat frequency signal;

[0009] The signal phase-locking module is electrically connected to the signal generating module, and is used to convert the interference beat frequency signal into an electrical signal and implement PID closed-loop control to lock the laser phase;

[0010] The signal generating module is electrically connected to the acousto-optic modulator, and the signal generating module is used to generate and amplify a radio frequency signal and drive the acousto-optic modulator to shift the frequency of the seed light.

[0011] On the basis of the above technical solution, preferably, the multi-stage amplification module includes an electro-optical phase modulator, a first pre-amplification unit, a second isolator, a second pre-amplification unit, a circulator, a mode field adapter, a main power amplification unit, a collimation output head and an adjustable optical attenuator, the electro-optical phase modulator is respectively connected to the first pre-amplification unit and the signal phase-locked module, the first pre-amplification unit is connected to the second pre-amplification unit through the second isolator, the second pre-amplification unit is connected to the first port of the circulator, the second port of the circulator is connected to the main power amplification unit, the third port of the circulator is connected to the main power amplification unit through the mode field adapter, the main power amplification unit is connected to the adjustable optical attenuator through the collimation output head, and the adjustable optical attenuator is also connected to the optical coupler.

[0012] On the basis of the above technical solution, preferably, the first pre-amplifier unit includes a first gain fiber, a first multimode pump source and a first combiner, the electro-optical phase modulator is connected to the first port of the first combiner, the first multimode pump source is connected to the second port of the first combiner, and the first gain fiber is connected to the third port of the first combiner; the second pre-amplifier unit includes a second gain fiber, a second multimode pump source and a second combiner, the second isolator is connected to the first port of the second combiner, the second multimode pump source is connected to the second port of the second combiner, and the second gain fiber is connected to the third port of the second combiner.

[0013] Further preferably, the main power amplification unit includes a third gain fiber, a third multimode pump source and a third combiner, the second ports of the mode field adapter and the circulator are connected to the first port of the second combiner, the third multimode pump source is connected to the second port of the third combiner, and the third gain fiber is connected to the third port of the third combiner.

[0014] Further preferably, the first gain fiber and the second gain fiber are both 10 / 125 double-clad ytterbium-doped gain fibers, the third gain fiber is a 30 / 250 double-clad ytterbium-doped gain fiber, the output power of the first multimode pump source is 5 W, the output power of the second multimode pump source is 20 W, and the output power of the third multimode pump source is 400 W.

[0015] More preferably, one end of the mode field adapter is connected to the circulator via a 10 / 125 optical fiber, and the other end of the mode field adapter is connected to the main power amplifier unit via a 30 / 250 optical fiber.

[0016] More preferably, the first port of the first isolator is connected to the single-frequency seed source, the second port of the first isolator is connected to the electro-optic phase modulator, the third port of the first isolator is connected to the acousto-optic modulator, and the splitting ratio between the second port and the third port in the first isolator is 9:1.

[0017] Further preferably, the signal phase-locked module includes a photodetector, a mixer phase detector, a low-pass filter and a PID control unit, one end of the photodetector is connected to the optical coupler, the mixer phase detector is electrically connected to the other end of the photodetector and the low-pass filter respectively, and the PID control unit is electrically connected to the low-pass filter and the electro-optical phase modulator respectively.

[0018] Further preferably, the signal generating module includes an RF amplifying unit and a dual-channel RF source, one end of the RF amplifying unit is electrically connected to the acousto-optic modulator, and the other end of the RF amplifying unit is electrically connected to the mixer phase detector through the dual-channel RF source, and the dual-channel RF source outputs two sinusoidal RF signals, one sinusoidal RF signal enters the mixer phase detector, and the other sinusoidal RF signal passes through the RF amplifying unit and is input into the acousto-optic modulator to shift the frequency of the seed light.

[0019] More preferably, the power handling capacity of the second isolator is greater than 1 W, the isolation of the second isolator is greater than 55 dB, the filtering range of the second isolator is 2 nm, the power handling capacity of the circulator is greater than 20 W, and the isolation from the second port to the first port of the circulator is greater than 55 dB.

[0020] The high-power single-frequency phase-locked laser provided by the present invention has the following beneficial effects compared with the prior art:

[0021] (1) The single-frequency seed light source is amplified step by step through a multi-stage amplification module, which significantly improves the laser output power and maintains the stability of the single frequency. The signal phase-locked module uses the electrical signal converted from the interference beat signal combined with PID closed-loop control to achieve precise locking of the laser phase, effectively suppressing the phase noise generated during the optical amplification process and improving the phase stability and frequency purity of the laser output. Driven by the signal generation module, the acousto-optic modulator can effectively shift the frequency of the seed light. At the same time, the optical coupler effectively couples the frequency-shifted light beam with the sampling light beam of the amplification module to generate an interference beat signal. The frequency-shifted beat signal can reduce the influence of signal intensity noise on the beat signal, which helps to enhance the feedback control effect of the signal phase-locked module, so that the laser can achieve high power output and high stability of frequency and phase as a whole.

[0022] (2) The optical signal is precisely modulated and controlled by an electro-optic phase modulator, and the phase-locking stability of the system is ensured by cooperating with the signal phase-locking module. The dual-stage pre-amplification structure of the first and second pre-amplification units is adopted in combination with the protection of the second isolator to achieve stable step-by-step amplification of the optical signal, effectively avoiding the instability that may be caused by single-stage large-scale amplification. The three-port design of the circulator and the use of the mode field adapter not only optimize the beam transmission path, but also ensure the matching degree of the beam mode and improve the efficiency of the main power amplification. The main power amplifier unit outputs a high-quality beam through a collimated output head, and finally the output power is precisely adjusted through an adjustable optical attenuator, providing the laser with flexible power control capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure of a high-power single-frequency phase-locked laser provided by the present invention;

[0025] Explanation of the accompanying drawings: 1. Single-frequency seed source; 2. First isolator; 3. Multi-stage amplification module; 31. Electro-optic phase modulator; 32. First pre-amplification unit; 33. Second isolator; 34. Second pre-amplification unit; 35. Circulator; 36. Mode field adapter; 37. Main power amplifier unit; 38. Collimated output head; 39. Adjustable optical attenuator; 4. Acousto-optic modulator; 5. Optical coupler; 6. Signal phase-locked module; 61. Photodetector; 62. Mixer phase detector; 63. Low-pass filter; 64. PID control unit; 7. Signal generation module; 71. RF amplification unit; 72. Dual-channel RF source. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, the present invention provides a high-power single-frequency phase-locked laser, including a single-frequency seed source 1, a first isolator 2, a multi-stage amplification module 3, an acousto-optic modulator 4, an optical coupler 5, a signal phase-locking module 6 and a signal generating module 7, wherein:

[0028] The single-frequency seed source 1 is connected to the multi-stage amplification module 3 through the first isolator 2. The single-frequency seed source 1 is used to output a seed light source and provide a phase reference signal.

[0029] In this embodiment, a single-frequency seed source 1 is connected to a multi-stage amplification module 3 via a first isolator 2, wherein the single-frequency seed source 1 has characteristics such as narrow linewidth and stable frequency. The output seed light source serves as the basic light source of the entire laser system, providing a high-quality initial light field for subsequent amplification. At the same time, the phase reference signal provided is the key to achieving laser phase locking, ensuring the phase stability of the system output laser. The first isolator 2 effectively blocks the reversely transmitted stray light through its unidirectional light transmission characteristics, preventing it from having an adverse effect on the seed source, thereby ensuring the stable operation of the seed source.

[0030] The multi-stage amplification module 3 is connected to the optical coupler 5 and the signal phase-locked module 6 respectively, and is used to perform multi-stage power amplification on the seed light output by the single-frequency seed source 1 .

[0031] The multi-stage amplification module 3 includes an electro-optical phase modulator 31, a first pre-amplification unit 32, a second isolator 33, a second pre-amplification unit 34, a circulator 35, a mode field adapter 36, a main power amplifier unit 37, a collimation output head 38 and an adjustable optical attenuator 39. The electro-optical phase modulator 31 is respectively connected to the first pre-amplification unit 32 and the signal phase-locked module 6, the first pre-amplification unit 32 is connected to the second pre-amplification unit 34 through the second isolator 33, the second pre-amplification unit 34 is connected to the first port of the circulator 35, the second port of the circulator 35 is connected to the main power amplifier unit 37, the third port of the circulator 35 is connected to the main power amplifier unit 37 through the mode field adapter 36, the main power amplifier unit 37 is connected to the adjustable optical attenuator 39 through the collimation output head 38, and the adjustable optical attenuator 39 is also connected to the optical coupler 5.

[0032] In this embodiment, precise modulation control of the optical signal is achieved through the electro-optical phase modulator 31, and the phase-locked stability of the system is ensured in cooperation with the signal phase-locked module 6. The dual-stage pre-amplification structure of the first and second pre-amplification units 34 is adopted in combination with the protection function of the second isolator 33 to achieve step-by-step stable amplification of the optical signal, effectively avoiding the instability that may be caused by single-stage large-scale amplification. The three-port design of the circulator 35 and the use of the mode field adapter 36 not only optimize the light beam transmission path, but also ensure the matching degree of the light beam mode and improve the efficiency of the main power amplification. The main power amplification unit 37 outputs a high-quality light beam through the collimated output head 38, and finally the output power is accurately adjusted through the adjustable optical attenuator 39, providing flexible power control capabilities for the laser.

[0033] The first pre-amplifier unit 32 includes a first gain fiber, a first multimode pump source and a first combiner, the electro-optic phase modulator 31 is connected to the first port of the first combiner, the first multimode pump source is connected to the second port of the first combiner, and the first gain fiber is connected to the third port of the first combiner. The second pre-amplifier unit 34 includes a second gain fiber, a second multimode pump source and a second combiner, the second isolator 33 is connected to the first port of the second combiner, the second multimode pump source is connected to the second port of the second combiner, and the second gain fiber is connected to the third port of the second combiner. The main power amplifier unit 37 includes a third gain fiber, a third multimode pump source and a third combiner, the second ports of the mode field adapter 36 and the circulator 35 are both connected to the first port of the second combiner, the third multimode pump source is connected to the second port of the third combiner, and the third gain fiber is connected to the third port of the third combiner.

[0034] In this embodiment, a three-stage amplification structure is adopted, and each stage is composed of a gain fiber, a multimode pump source and a combiner. The series configuration of the three-stage gain fiber realizes progressive amplification of the optical signal, avoiding the nonlinear effect and instability that may be caused by a single-stage large-scale amplification. Each stage is equipped with an independent multimode pump source, which not only provides sufficient pump energy, but also can flexibly adjust the pump power according to the amplification requirements of each stage to optimize the energy utilization efficiency. The three-port design of the combiner at each stage realizes efficient coupling of signal light and pump light, ensuring sufficient absorption and conversion of pump energy. This hierarchical amplification structure effectively maintains the beam quality while achieving high power output through the reasonable configuration of devices such as isolators, mode field adapters 36 and circulators 35, and has good system stability and controllability.

[0035] Further, the first gain fiber and the second gain fiber are both 10 / 125 double-clad ytterbium-doped gain fibers, the third gain fiber is 30 / 250 double-clad ytterbium-doped gain fiber, the output power of the first multimode pump source is 5 W, the output power of the second multimode pump source is 20 W, and the output power of the third multimode pump source is 400 W. One end of the mode field adapter 36 is connected to the circulator 35 through a 10 / 125 optical fiber, and the other end of the mode field adapter 36 is connected to the main power amplifier unit 37 through a 30 / 250 optical fiber.

[0036] The power handling capability of the second isolator 33 is greater than 1 W, the isolation degree of the second isolator 33 is greater than 55 dB, the filtering range of the second isolator 33 is 2 nm, the power handling capability of the circulator 35 is greater than 20 W, and the isolation degree from the second port to the first port of the circulator 35 is greater than 55 dB.

[0037] In this embodiment, 10 / 125 double-clad ytterbium-doped fiber is used as the first two-stage gain medium, with relatively low pump power, which is suitable for stable amplification in the low-power range, and 30 / 250 large mode field fiber is used in the main power amplifier unit 37 with a 400W high-power pump source, which not only provides sufficient pump energy, but also effectively suppresses nonlinear effects through a larger core area, thereby achieving efficient and stable power amplification. Secondly, the mode field adapter 36 ensures efficient coupling of light beams between optical fibers with different mode field areas through precise conversion from 10 / 125 to 30 / 250 optical fiber, minimizing the power loss caused by mode mismatch. Thirdly, the high isolation and reasonable power tolerance of the second isolator 33 and the circulator 35 provide reliable protection for the laser, and the narrowband filtering characteristics of the second isolator 332nm can also effectively suppress amplified spontaneous radiation and improve signal purity.

[0038] The first isolator 2 is also connected to one end of the acousto-optic modulator 4, and the optical coupler 5 is respectively connected to the other end of the acousto-optic modulator 4 and the signal phase-locked module 6. The optical coupler 5 is used to couple the frequency-shifted light beam output by the acousto-optic modulator 4 and the sampling light beam output by the multi-stage amplification module 3 into one path to generate an interference beat signal.

[0039] The first port of the first isolator 2 is connected to the single-frequency seed source 1, the second port of the first isolator 2 is connected to the electro-optic phase modulator 31, the third port of the first isolator 2 is connected to the acousto-optic modulator 4, and the splitting ratio between the second port and the third port in the first isolator 2 is 9:1.

[0040] The signal phase-locking module 6 is electrically connected to the signal generating module 7, and is used to convert the interference beat frequency signal into an electrical signal, and implement PID closed-loop control to lock the laser phase. The signal phase-locking module 6 includes a photodetector 61, a mixer phase detector 62, a low-pass filter 63, and a PID control unit 64. One end of the photodetector 61 is connected to the optical coupler 5, the mixer phase detector 62 is electrically connected to the other end of the photodetector 61 and the low-pass filter 63, respectively, and the PID control unit 64 is electrically connected to the low-pass filter 63 and the electro-optical phase modulator 31, respectively.

[0041] In this embodiment, the photodetector 61 efficiently converts the interference beat frequency optical signal output by the optical coupler 5 into an electrical signal, ensuring the accurate acquisition of the initial signal. The mixer phase detector 62 performs phase detection and comparison on the signal to achieve accurate phase difference measurement. The low-pass filter 63 effectively filters out high-frequency noise and interference components, improving the signal-to-noise ratio of the signal. The PID control unit 64 forms a closed-loop control system based on the processed signal through electrical connection with the electro-optical phase modulator 31 to adjust the laser phase in real time, ensuring the stability and reliability of phase locking. This multi-level signal processing and closed-loop control structure provides high-precision phase detection and control capabilities.

[0042] The signal generating module 7 is electrically connected to the acousto-optic modulator 4. The signal generating module 7 is used to generate and amplify the radio frequency signal and drive the acousto-optic modulator 4 to shift the frequency of the seed light. The signal generating module 7 includes a radio frequency amplifying unit 71 and a dual-channel radio frequency source 72. One end of the radio frequency amplifying unit 71 is electrically connected to the acousto-optic modulator 4. The other end of the radio frequency amplifying unit 71 is electrically connected to the mixer phase detector 62 through the dual-channel radio frequency source 72. The dual-channel radio frequency source 72 outputs two sinusoidal radio frequency signals. One sinusoidal radio frequency signal enters the mixer phase detector 62, and the other sinusoidal radio frequency signal is input to the acousto-optic modulator 4 after passing through the radio frequency amplifying unit 71 to shift the frequency of the seed light.

[0043] In this embodiment, the dual-channel RF source 72 outputs two homologous sinusoidal RF signals to ensure the strict synchronization and phase correlation between the frequency-shifted signal and the reference signal. One signal is directly input into the mixer phase detector 62 as a reference signal for phase detection, and the other signal is amplified by the RF amplifier unit 71 to drive the acousto-optic modulator 4. This dual-channel design not only ensures the synchronization of the signal, but also meets the differentiated requirements of different functional modules for signal strength. The RF amplifier unit 71 accurately amplifies the drive signal to provide the acousto-optic modulator 4 with the most suitable drive power, ensuring the optimization of the frequency shifting efficiency of the optical signal. The entire module forms a closed-loop system that works in coordination with the acousto-optic modulator 4 and the mixer phase detector 62, achieving high-precision frequency shift and phase control.

[0044] The single-frequency seed light source is amplified step by step by the multi-stage amplification module 3, which significantly improves the laser output power and maintains the stability of the single frequency. The signal phase-locked module 6 uses the electrical signal converted from the interference beat frequency signal combined with PID closed-loop control to achieve precise locking of the laser phase, effectively suppressing the phase noise generated during the optical amplification process, and improving the phase stability and frequency purity of the laser output. The acousto-optic modulator 4, driven by the signal generating module 7, can effectively shift the frequency of the seed light. At the same time, the optical coupler 5 effectively couples the frequency-shifted light beam with the sampling light beam of the amplification module to generate an interference beat frequency signal, thereby improving the interference efficiency of the signal and helping to enhance the feedback control effect of the signal phase-locked module 6, so that the laser can achieve high power output and high stability of frequency and phase as a whole.

[0045] In one example, the single-frequency seed source 1 is used as both a laser seed and a beat frequency signal. The typical wavelength of the single-frequency seed source 1 is 1064nm, the line width is about 10kHz, and the output power is 50mW. The oscillator of the single-frequency seed source 1 is on a temperature-controlled TEC, which can ensure the stability of the oscillator's working state. The single-frequency seed source 1 is connected to the first isolator 2 with a port through an optical fiber. The splitting ratio between the third port and the second port of the first isolator 2 is 1:9, of which 90% of the power enters the multi-stage amplification module 3 and 10% of the power enters the acousto-optic modulator 4. At the same time, the isolation effect ensures that the return light of the subsequent optical path does not damage the seed source.

[0046] The electro-optic phase modulator 31 is arranged in the multi-stage amplification module 3. The half-wave voltage of the electro-optic phase modulator 31 is 1.5V, the bandwidth is 300MHz, and the modulation range is 0-9V. The electro-optic phase modulator 31 is connected to the first isolator 2 with a port through the optical fiber input end, and the output end of the electro-optic phase modulator 31 is connected to the first pre-amplification unit 32. The radio frequency port of the first pre-amplification unit 32 is connected to the phase-locked circuit through the radio frequency wire. The first pre-amplification unit 32 uses the electro-optical effect and the voltage model fed back by the phase-locked circuit to change the refractive index in real time to compensate for the phase jitter in the optical fiber transmission process of the amplification link.

[0047] Furthermore, the first pre-amplifier unit 32 generally uses 10 / 125 double-clad Yb gain fiber, a beam combiner, a 5W multi-mode pump and other devices to amplify the 50mW power output of the seed to 800mW, and the 800mW laser after the first-level prevention 103 is injected into the subsequent optical path through the isolator 104. The typical withstand power of the second isolator 33 is greater than 1W, and the isolation is greater than 55dB. At the same time, the device has a filtering effect with a filtering range of 2nm, which mainly filters out ASE radiation. The second pre-amplifier unit 34 also uses 10 / 125 double-clad Yb gain fiber, a beam combiner, and a 20W multi-mode pump to amplify the laser power output by the first pre-amplifier unit 32 from 800mW to 15W. The laser amplified by the second pre-amplifier unit 34 is input to the circulator 35. The typical withstand power of the circulator 35 is greater than 20W. The laser output by the second pre-amplifier unit 34 enters from the first port of the circulator 35, and the second port of the circulator 35 outputs to the main power amplifier unit 37. The power isolation from the second port of the circulator 35 to the first end is greater than 55dB. The return laser of the main power amplifier unit 37 enters from the second port of the circulator 35 and is output from the third port. When the laser is working, the power of the third port of the circulator 35 is monitored to prevent the stability of the optical amplification system from being affected by Ki-Brillouin scattering. At the same time, the circulator 35 also has a filtering effect, and the filtering range is 2nm.

[0048] One end of the mode field adapter 36 uses 10 / 125 optical fiber to connect to the second pre-amplifier unit 34, and the other end uses 30 / 250 optical fiber to connect to the main power amplifier unit 37. The main power amplifier unit 37 also uses 30 / 250 double-clad Yb gain fiber, a beam combiner, and a 400W multi-mode pump to amplify the laser power output by the second pre-amplifier unit 34 from 15W to more than 200W. The collimated output head 38 with a port outputs the laser amplified by the main power amplifier unit 37, and samples the amplified laser at the same time. The typical sampling ratio is 1:10000, and the sampled laser enters the beat frequency optical path.

[0049] The beat frequency optical path causes the seed light after acousto-optic modulation and the amplified laser to beat each other. The optical signal after the beat frequency is converted into an electrical signal through the photodetector 61. The beat frequency electrical signal and the electrical signal modulated for the seed are mixed and then pass through the low-pass filter 63 to extract only the phase change of the laser during the amplification process. After the phase error signal enters the PID control unit 64, the PID control unit 64 is used to output a compensation signal to the electro-optical phase modulator, thereby completing the phase locking of the laser amplification process.

[0050] The dual-channel RF source 72 provides two sinusoidal RF signals with a frequency of 80 MHz, one of which enters the mixer phase detector 62, and the other passes through the RF amplification unit 71 and is input to the acousto-optic modulator 4 to perform an 80 MHz frequency shift on the sampled seed light. The purpose of the frequency shift is to eliminate the signal jitter caused by the strong interference in the beat process of the two lights of the same frequency. The adjustable attenuator attenuates the optical path sampled from the collimated output head 38, so that its output power is almost equivalent to the power output by the acousto-optic modulator 4. The optical coupler 5 combines the two beams for beat frequency, and the photodetector 61 with a bandwidth of 150MHz detects the intensity change of the beat frequency signal. The intensity signal has 80Mhz and low-frequency peaks in the frequency domain (the phase change introduced by temperature is usually in the Hz order, and the phase change introduced by vibration is usually in the kHz order). The phase error signal from Hz to kHz is filtered out by the combination of the mixer phase detector 62207 and the low-pass filter 63208 and then enters the PID control unit 64. The PID control unit 64 outputs a feedback signal to the electro-optic phase modulator 31 based on the error information of the phase change, and adjusts the refractive index of the electro-optic phase modulator 31 to compensate for the phase noise caused by temperature change and vibration to the amplifier link optical fiber stretching, and finally realizes high-power stable frequency phase-locked laser output.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-power single-frequency phase-locked laser, characterized in that: It comprises a single-frequency seed source (1), a first isolator (2), a multi-stage amplification module (3), an acousto-optic modulator (4), an optical coupler (5), a signal phase-locking module (6) and a signal generation module (7), wherein: The single-frequency seed source (1) is connected to the multi-stage amplification module (3) via the first isolator (2), and the single-frequency seed source (1) is used to output a seed light source and provide a phase reference signal; The multi-stage amplification module (3) is connected to the optical coupler (5) and the signal phase-locking module (6) respectively, and the multi-stage amplification module (3) is used to perform multi-stage power amplification on the seed light output by the single-frequency seed source (1); The first isolator (2) is also connected to one end of the acousto-optic modulator (4), and the optical coupler (5) is respectively connected to the other end of the acousto-optic modulator (4) and the signal phase-locking module (6), and the optical coupler (5) is used to couple the frequency-shifted light beam output by the acousto-optic modulator (4) and the sampling light beam output by the multi-stage amplification module (3) into one path, so as to generate an interference beat frequency signal; The signal phase-locking module (6) is electrically connected to the signal generating module (7), and the signal phase-locking module (6) is used to convert the interference beat frequency signal into an electrical signal and implement PID closed-loop control to lock the laser phase; The signal generating module (7) is electrically connected to the acousto-optic modulator (4), and the signal generating module (7) is used to generate and amplify a radio frequency signal and drive the acousto-optic modulator (4) to shift the frequency of the seed light.

2. The high-power single-frequency phase-locked laser according to claim 1, characterized in that: The multi-stage amplification module (3) comprises an electro-optical phase modulator (31), a first pre-amplification unit (32), a second isolator (33), a second pre-amplification unit (34), a circulator (35), a mode field adapter (36), a main power amplification unit (37), a collimation output head (38) and an adjustable optical attenuator (39), wherein the electro-optical phase modulator (31) is connected to the first pre-amplification unit (32) and the signal phase-locking module (6) respectively, and the first pre-amplification unit (32) is connected to the second pre-amplification unit (34) via the second isolator (33). The optical coupler (5) is connected to a pre-amplifier unit (34), the second pre-amplifier unit (34) is connected to a first port of the circulator (35), the second port of the circulator (35) is connected to the main power amplifier unit (37), the third port of the circulator (35) is connected to the main power amplifier unit (37) through the mode field adapter (36), the main power amplifier unit (37) is connected to the adjustable optical attenuator (39) through the collimation output head (38), and the adjustable optical attenuator (39) is also connected to the optical coupler (5).

3. The high-power single-frequency phase-locked laser according to claim 2, characterized in that: The first pre-amplifier unit (32) comprises a first gain fiber, a first multimode pump source and a first beam combiner, the electro-optic phase modulator (31) is connected to the first port of the first beam combiner, the first multimode pump source is connected to the second port of the first beam combiner, and the first gain fiber is connected to the third port of the first beam combiner; the second pre-amplifier unit (34) comprises a second gain fiber, a second multimode pump source and a second beam combiner, the second isolator (33) is connected to the first port of the second beam combiner, the second multimode pump source is connected to the second port of the second beam combiner, and the second gain fiber is connected to the third port of the second beam combiner.

4. The high-power single-frequency phase-locked laser according to claim 3, characterized in that: The main power amplification unit (37) comprises a third gain optical fiber, a third multimode pump source and a third beam combiner, the second ports of the mode field adapter (36) and the circulator (35) are both connected to the first port of the second beam combiner, the third multimode pump source is connected to the second port of the third beam combiner, and the third gain optical fiber is connected to the third port of the third beam combiner.

5. The high-power single-frequency phase-locked laser according to claim 4, characterized in that: The first gain fiber and the second gain fiber are both 10 / 125 double-clad ytterbium-doped gain fibers, the third gain fiber is a 30 / 250 double-clad ytterbium-doped gain fiber, the output power of the first multi-mode pump source is 5W, the output power of the second multi-mode pump source is 20W, and the output power of the third multi-mode pump source is 400W.

6. The high-power single-frequency phase-locked laser according to claim 5, characterized in that: One end of the mode field adapter (36) is connected to the circulator (35) via a 10 / 125 optical fiber, and the other end of the mode field adapter (36) is connected to the main power amplification unit (37) via a 30 / 250 optical fiber.

7. The high-power single-frequency phase-locked laser according to claim 2, characterized in that: The first port of the first isolator (2) is connected to the single-frequency seed source (1), the second port of the first isolator (2) is connected to the electro-optic phase modulator (31), the third port of the first isolator (2) is connected to the acousto-optic modulator (4), and the splitting ratio between the second port and the third port in the first isolator (2) is 9:

1.

8. The high-power single-frequency phase-locked laser according to claim 2, characterized in that: The signal phase lock module (6) comprises a photodetector (61), a mixer phase detector (62), a low-pass filter (63) and a PID control unit (64); one end of the photodetector (61) is connected to the optical coupler (5); the mixer phase detector (62) is electrically connected to the other end of the photodetector (61) and the low-pass filter (63); and the PID control unit (64) is electrically connected to the low-pass filter (63) and the electro-optical phase modulator (31).

9. The high-power single-frequency phase-locked laser according to claim 8, characterized in that: The signal generating module (7) comprises a radio frequency amplifying unit (71) and a dual-channel radio frequency source (72); one end of the radio frequency amplifying unit (71) is electrically connected to the acousto-optic modulator (4); the other end of the radio frequency amplifying unit (71) is electrically connected to the mixer phase detector (62) via the dual-channel radio frequency source (72); the dual-channel radio frequency source (72) outputs two sinusoidal radio frequency signals, one sinusoidal radio frequency signal enters the mixer phase detector (62), and the other sinusoidal radio frequency signal passes through the radio frequency amplifying unit (71) and is input into the acousto-optic modulator (4) to perform frequency shifting on the seed light.

10. The high-power single-frequency phase-locked laser according to claim 2, characterized in that: The power handling capability of the second isolator (33) is greater than 1 W, the isolation degree of the second isolator (33) is greater than 55 dB, the filtering range of the second isolator (33) is 2 nm, the power handling capability of the circulator (35) is greater than 20 W, and the isolation degree from the second port to the first port of the circulator (35) is greater than 55 dB.

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