Pulse laser frequency control device and method

Abstract

The invention provides a pulse laser frequency control device and method, and belongs to the technical field of pulse fiber lasers. Comprising a frequency measurement module used for acquiring the frequency of a first external control signal; the frequency selection and frequency division module generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module; the frequency generation module is used for receiving the seed frequency signal output by the frequency selection and division module and outputting a seed frequency trigger signal; the pulse generation module is used for acquiring the seed frequency trigger signal output by the frequency generation module and providing a seed pulse signal for the seed driver, and the seed driver outputs pulse light according to the input seed pulse signal; the current control module is used for receiving a second external control signal and providing a current driving signal for each pump driver; and the RAM controller is used for receiving a third external control signal and the frequency division coefficient output by the frequency selection and frequency division module, and controlling the acousto-optic modulator to work.

Description

Technical Field

[0001] The present invention relates to the technical field of pulsed optical fiber lasers, and in particular to a pulsed laser frequency control device and method. Background Art

[0002] In the field of laser industrial processing, the operating frequency of the laser is generally 0.1 to 10000kHz; in the 0.1 to 10kHz low repetition rate pulse fiber amplifier, there are shortcomings such as too low signal light power and too strong amplified self-radiation ASE. From the time domain point of view, when a pulse just leaves the amplifier, the next pulse has not yet entered the amplifier. During the gap between these pulses, there is no seed pulse injection, but the pump is still continuing. The amplified self-radiation ASE will dominate the gain consumption of the amplifier, and in the high-power main amplifier, the spontaneous radiation light exceeding the threshold will quickly reach saturation and self-excited oscillation giant pulse, and the energy will be released instantly, causing the fiber to burn. It is precisely because of the asynchrony between the seed light frequency and the amplifier operation that not only leads to a decrease in the energy extraction rate of the signal pulse, but also if the pulse laser adopts the MOPA structure, the amplified self-radiation ASE will be amplified step by step with the multi-stage amplification structure, which will limit the peak power of the pulse and affect the output performance of the laser.

[0003] Therefore, it is very necessary to provide a pulse laser frequency control device and method, which can adjust the corresponding relationship between the seed frequency and the control signal frequency, so that the seed frequency is linked with the AOM frequency, and the AOM is turned on only when the seed light is effective, so as to avoid the step-by-step amplification of ASE and make the output performance of the laser stable and reliable. Summary of the invention

[0004] In view of this, the present invention proposes a pulse laser frequency control device and method that can synchronize the actions of pulse light, external control signals and an acousto-optic modulator, extract the energy of the pre-pumping stage when emitting light, and suppress ASE.

[0005] In one aspect, the present invention provides a pulse laser frequency control device, comprising a seed driver, a first-stage pump driver, an acousto-optic modulator, a second-stage pump driver, and a third-stage pump driver, which are sequentially arranged and optically connected, and further comprising:

[0006] A frequency measurement module, used for receiving a first external control signal and obtaining a frequency of the first external control signal;

[0007] A frequency selection and division module is electrically connected to the frequency measurement module and the acousto-optic modulator, and generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module;

[0008] The frequency generating module is electrically connected to the frequency selecting and dividing module, and is used to receive the seed frequency signal output by the frequency selecting and dividing module, and output the seed frequency trigger signal; the frequency generating module also receives a second external control signal;

[0009] A pulse generating module is electrically connected to the frequency generating module and the seed driver, and is used to obtain the seed frequency trigger signal output by the frequency generating module, and provide a seed pulse signal to the seed driver, and the seed driver outputs a pulse light according to the input seed pulse signal; the pulse light passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver, and the third-stage pump driver in sequence;

[0010] A current control module, electrically connected to the seed driver, the first-stage pump driver, the second-stage pump driver and the third-stage pump driver, respectively, for receiving a second external control signal and providing a current driving signal for the amplifier;

[0011] The RAM controller is electrically connected to the frequency selection and division module and the acousto-optic modulator, respectively, and is used to receive the third external control signal and the frequency division coefficient output by the frequency selection and division module, and control the operation of the acousto-optic modulator.

[0012] On the basis of the above technical solution, preferably, the first external control signal is an external frequency control signal; the second external control signal is a light output control signal, and the seed frequency trigger signal is aligned with the rising edge of the second external control signal; the third external control signal is a clock phase control signal, and the third external control signal is synchronized with the seed frequency trigger signal output by the frequency generating module.

[0013] Preferably, the frequency selection and frequency division module generates and outputs a seed frequency signal and a frequency division coefficient, so that the frequency of the first external control signal is f i , the highest frequency of the seed frequency signal is f o , the seed frequency signal is f seed , and f o / 2≤f seed ≤f o , the frequency division coefficient D of the AOM n , then the seed frequency signal f seed And the frequency division coefficient D n The following relationship is satisfied: when f i >f o When f seed =f i , D n =1; when f i When ≤f, f seed =f i ×D n , D n =floor(f o / fi ), floor(·) represents the downward value operation, ensuring that the seed frequency signal f seed and is always the frequency f of the first external control signal i The frequency of the AOM is an integer multiple of the seed frequency signal f seed Carry out linkage.

[0014] Further preferably, the first-stage pump driver, the second-stage pump driver and the third-stage pump driver all provide energy by means of a pulse pump according to the current drive signal received from the current control module, and the pump stores energy in advance. When the pulse light output by the seed driver reaches the first-stage pump driver, the second-stage pump driver or the third-stage pump driver, the pumping is terminated and the amplified output is immediately performed.

[0015] More preferably, the output power of the first stage pump driver follows the seed frequency signal f seed Linear change; the output power of the second-stage pump driver and the third-stage pump driver follows the frequency f of the first external control signal i Linear changes.

[0016] More preferably, the first-stage pump driver amplifies the pulse light to obtain the seed light, the acousto-optic modulator is turned on before the seed light arrives, and is maintained for a certain time after the seed light ends and turned off, and is turned on in advance before the next seed light arrives, and the cycle is repeated; when the acousto-optic modulator is turned off, the second-stage pump driver or the third-stage pump driver only stores energy without output, and the pre-pump energy is completely stored in the gain medium. When the acousto-optic modulator is turned on, the second-stage pump driver or the third-stage pump driver outputs immediately when the seed light arrives, and is turned off after the seed light passes.

[0017] Preferably, the RAM controller receives the third external control signal and the frequency division coefficient output by the frequency selection and frequency division module, and controls the operation of the acousto-optic modulator. Specifically, the RAM controller includes a memory, a digital-to-analog converter DAC and a synchronous logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, the RAM controller drives the address counter inside the memory to perform RAM addressing until valid data is found. A control signal of the acousto-optic modulator is stored under each RAM address. The content of the control signal of the acousto-optic modulator stored under the RAM address includes a single-bit signal and a multi-bit signal. The single-bit signal is used to control the on or off state of the acousto-optic modulator. The multi-bit signal is converted into an analog quantity by the digital-to-analog converter DAC and is used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronous logic control unit is used to synchronize the rising edge of the seed pulse signal with the seed frequency trigger signal.

[0018] On the basis of the above technical solution, preferably, the pulse generating module provides the seed pulse signal to the seed driver as a macro pulse train, and the amplitudes of the pulses in the macro pulse train are not completely the same.

[0019] In another aspect, the present invention provides a pulse laser frequency control method, comprising the following steps:

[0020] S1: The above-mentioned pulse laser frequency control device is configured; the seed driver is used to output pulse light; the first-stage pump driver is used to perform the first-stage pumping and amplification on the pulse light; the acousto-optic modulator; the acousto-optic modulator is used to modulate the pulse light after the first-stage amplification; the second-stage pump driver and the third-stage pump driver continuously pump and amplify the modulated pulse light and then output;

[0021] S2: The frequency measurement module receives the input first external control signal and obtains the frequency of the first external control signal;

[0022] S3: The frequency selection and division module generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module;

[0023] S4: The frequency generation module receives the seed frequency signal output by the frequency selection and division module, and outputs a seed frequency trigger signal; the frequency generation module also receives a second external control signal, which is a light output control signal, and the seed frequency trigger signal is aligned with the rising edge of the second external control signal; the pulse generation module obtains the seed frequency trigger signal output by the frequency generation module, and provides a seed pulse signal to the seed driver, and the seed driver outputs pulse light according to the input seed pulse signal;

[0024] S5: The RAM controller includes a memory, a digital-to-analog converter DAC and a synchronous logic control unit; when the RAM controller receives the seed frequency trigger signal from the frequency generation module, the RAM controller drives the address counter inside the memory to perform RAM addressing until valid data is found, and a control signal of an acousto-optic modulator is stored under each RAM address. The content of the control signal of the acousto-optic modulator stored under the RAM address includes a single-bit signal and a multi-bit signal, and the single-bit signal is used to control the on or off state of the acousto-optic modulator; the multi-bit signal is converted into an analog quantity by the digital-to-analog converter DAC, and is used to control the light intensity of the seed light passing through the acousto-optic modulator; the synchronous logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal;

[0025] S6: The pulse light passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver and the third-stage pump driver in sequence; the first-stage pump driver, the second-stage pump driver and the third-stage pump driver all provide energy by means of a pulse pump according to the current driving signal received from the current control module, and the pump stores energy in advance. When the pulse light output by the seed driver reaches the first-stage pump driver, the second-stage pump driver or the third-stage pump driver, the pumping is terminated, and the amplified output is immediately performed; the acousto-optic modulator is turned on before the seed light arrives, performs acousto-optic modulation on the seed light, and maintains it for a certain time after the seed light ends and then turns it off, and turns it on in advance before the next seed light arrives. After the seed light ends, the acousto-optic modulator is delayed and maintained for a certain time and turns off, which plays a role in signal isolation;

[0026] S7: The current driving signal of the current control module has a linear variation characteristic below a specified frequency point. The current control module performs current compensation on the first-stage pump driver, the second-stage pump driver or the third-stage pump driver at different frequencies to ensure the power amplification effect of the first-stage pump driver, the second-stage pump driver or the third-stage pump driver.

[0027] Preferably, the current driving signal of the first-stage pump driver is jointly determined by the seed frequency signal and the pulse width of the pulse generating module; the current driving signals of the second-stage pump driver and the third-stage pump driver are jointly determined by the external frequency control signal and the pulse width of the pulse generating module;

[0028] The pulse width of each seed frequency signal is cached in the memory of the current control module at the peak current corresponding to the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver; when the seed frequency signal is confirmed, an index signal is sent to the memory of the current control module to index the peak current of the first-stage pump driver, and the actual first-stage pump current I is calculated based on the functional relationship between the peak current of the first-stage pump driver and the seed frequency signal. s When the external frequency control signal is confirmed, an index signal is sent to the memory of the current control module. According to the index signal, the peak currents of the second-stage pump driver and the third-stage pump driver are indexed, and the actual second-stage pump current and the third-stage pump current I are calculated according to the functional relationship between the peak currents of the second-stage pump driver and the third-stage pump driver and the external control frequency: Among them I bs and ks is the current coefficient of the first stage pump driver; I smax is the peak current of the first stage pump driver; f sh is the seed power reduction frequency point; I b and k are the current coefficients of the second-stage pump driver and the third-stage pump driver; I maxis the peak current of the second-stage pump driver and the third-stage pump driver; f h It is the frequency point where the laser power is reduced.

[0029] The pulse laser frequency control device and method provided by the present invention have the following beneficial effects compared with the prior art:

[0030] (1) Before generating pulse light, the present invention synchronizes the pulse generation module with the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver and the third-stage pump driver, that is, pumping or acousto-optic modulation is performed only when the pulse light or seed light arrives, and pumping or waiting is performed when the pulse light or seed light does not arrive, thereby successfully achieving synchronization between the seed frequency and the external frequency control signal, and synchronization between the seed frequency trigger signal and the second external control signal, so that ASE can be well suppressed;

[0031] (2) The multi-stage amplification process of pulse light goes through the stages of pre-pumping, waiting for the arrival of pulse light, pumping light and stopping output, ensuring that the pre-pump energy is output immediately when the pulse light or seed light arrives, achieving synchronous output without leakage light, and improving the extraction rate of pre-pump energy by signal pulses;

[0032] (3) The current driving signal of the current control module drives the first-stage pump driver, the second-stage pump driver or the third-stage pump driver to work normally, and also provides current compensation at low frequency, so that the laser has a higher pump energy extraction efficiency under continuous pulse or macro pulse input. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] 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.

[0034] Figure 1 A schematic block diagram of the structure of a pulse laser frequency control device and method of the present invention;

[0035] Figure 2 A schematic diagram of a curve of a seed frequency signal of a pulse laser frequency control device and method of the present invention;

[0036] Figure 3 A schematic diagram of a frequency division curve of an acousto-optic modulator of a pulse laser frequency control device and method of the present invention;

[0037] Figure 4The figure is a schematic diagram of an output frequency curve of a second-stage pump driver of a pulse laser frequency control device and method of the present invention. DETAILED DESCRIPTION

[0038] 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.

[0039] Existing pulsed lasers may have the phenomenon of asynchronous operation between the seed light frequency and the amplifier operation, which not only reduces the energy extraction rate of the signal pulse, but also increases the amplified self-emission ASE step by step with the amplification structure, affecting the output performance of the laser. Figure 1 As shown, on the one hand, the present invention provides a pulse laser frequency control device, comprising a seed driver, a first-stage pump driver, an acousto-optic modulator, a second-stage pump driver and a third-stage pump driver which are sequentially arranged and optically connected, wherein the seed driver, the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver and the third-stage pump driver constitute a pulse laser with a MOPA structure; and further comprising:

[0040] A frequency measurement module, used for receiving a first external control signal and obtaining a frequency of the first external control signal;

[0041] The frequency selection and division module is electrically connected to the frequency measurement module and the acousto-optic modulator, and generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module.

[0042] The frequency generating module is electrically connected to the frequency selecting and dividing module, and is used to receive the seed frequency signal output by the frequency selecting and dividing module, and output the seed frequency trigger signal; the frequency generating module also receives the second external control signal; the frequency generating module generates the seed frequency trigger signal on the one hand, and aligns the seed frequency trigger signal with the received second external control signal on the other hand.

[0043] A pulse generating module is electrically connected to the frequency generating module and the seed driver, and is used to obtain the seed frequency trigger signal output by the frequency generating module, and provide a seed pulse signal to the seed driver, and the seed driver outputs a pulse light according to the input seed pulse signal; the pulse light passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver, and the third-stage pump driver in sequence;

[0044] A current control module, electrically connected to the seed driver, the first-stage pump driver, the second-stage pump driver and the third-stage pump driver, respectively, for receiving a second external control signal and providing a current driving signal for the amplifier;

[0045] The RAM controller is electrically connected to the frequency selection and division module and the acousto-optic modulator, respectively, and is used to receive the third external control signal and the frequency division coefficient output by the frequency selection and division module, and control the operation of the acousto-optic modulator.

[0046] The first external control signal mentioned in the above scheme is an external frequency control signal; the second external control signal is a light output control signal, and the seed frequency trigger signal is aligned with the rising edge of the second external control signal; the third external control signal is a clock phase control signal, and the third external control signal is synchronized with the seed frequency trigger signal output by the frequency generation module.

[0047] The frequency selection and division module generates and outputs a seed frequency signal and a frequency division coefficient. Specifically, the frequency of the first external control signal is f i , the highest frequency of the seed frequency signal is f o , the seed frequency signal is f seed , and f o / 2≤f seed ≤f o , the frequency division coefficient D of the AOM n , then the seed frequency signal f seed And the frequency division coefficient D n The following relationship is satisfied: when f i >f o When f seed =f i , D n =1; when f i When ≤f, f seed =f i ×D n , D n =floor(f o / f i ), floor(·) represents the downward value operation, ensuring that the seed frequency signal f seed and is always the frequency f of the first external control signal i The frequency of the AOM is an integer multiple of the seed frequency signal f seed The operation of this frequency division module can ensure that the power of the seed frequency signal is high enough, so that the ASE power is reduced and self-oscillation will not occur.

[0048] In order to ensure synchronization with the external frequency control signal, the seed frequency signal generally does not change after confirmation in the conventional control mode, and the acousto-optic modulator can only output in a frequency-reducing manner, so that the output frequency deviates from the required frequency. o -f o It can always be ensured that the seed frequency signal is an integral multiple of the frequency of the external control signal, so that the seed light frequency output after frequency selection by the acousto-optic modulator AOM is consistent with the frequency of the external control signal. Figure 2 and Figure 3 They correspond to the seed frequency signal and the frequency division curve of the acousto-optic modulator at the frequencies corresponding to different external frequency control signals. Figure 4 It shows that under the frequency linkage of the seed frequency signal and the acousto-optic modulator, when the external frequency control signal is low-frequency, the seed light frequency output by the second-stage pump driver is consistent with the frequency of the external control signal.

[0049] The first-stage pump driver, the second-stage pump driver, and the third-stage pump driver all provide energy through a pulse pump according to the current drive signal received from the current control module. The pump stores energy in advance. When the pulse light output by the seed driver reaches the first-stage pump driver, the second-stage pump driver, or the third-stage pump driver, the pumping is terminated and the amplified output is immediately performed. The output power of the first-stage pump driver follows the seed frequency signal f seed Linear change; the output power of the second-stage pump driver and the third-stage pump driver follows the frequency f of the first external control signal i Linear changes.

[0050] In the above content, the essence of the first-stage pump driver is a constant current source, which is controlled by the current control module to generate corresponding current and pump to provide pump power for the pulsed light. As the seed frequency signal changes, the output power of the first-stage pump driver changes linearly with the seed frequency signal to ensure the stability of the output pulse energy of the first-stage pump driver. The pump output power of the second-stage pump driver and the third-stage pump driver changes linearly with the frequency of the first external control signal. Since the acousto-optic modulator AOM is only turned on when the seed light is effective, it can be used as an isolator.

[0051] In the present invention, before the pulse light or seed light is emitted, the first-stage pump driver, the second-stage pump driver and the third-stage pump driver all have a pre-energy storage process (Simmer), which can ensure that the height of the first pulse at the moment of light emission is basically consistent with the subsequent ones. However, during this period of time, the pump drivers at each stage are performing pre-pumping and there will eventually be leakage light output. In particular, the leakage light is particularly strong in high-power lasers and may damage the processing materials. However, the acousto-optic modulator AOM is turned off during the pre-energy storage process, so the signal light cannot be transmitted to the subsequent stage. The second-stage pump driver and the third-stage pump driver only store energy without output when the seed light has not arrived. When the seed light arrives, they can output immediately, that is, no leakage light is achieved and the first pulse of the pulse light or seed light is available.

[0052] The second external control signal of the MOPA pulse laser, that is, the light output control signal, generally has two, namely MO and PA. MO represents the pre-pump signal. After MO is effective, the laser starts pre-pumping inside and starts to charge the gain medium. The power at this time is very low and requires a period of time. This period of time is the pre-pump time. When the pre-pump time (pre-energy storage process) is met, the PA signal arrives and the laser starts to emit light. During the pre-pump time, if the acousto-optic modulator AOM is turned on, the entire optical path will begin to resonate, and there will be a relatively low laser output. If processing is performed on sensitive materials, this is not allowed. However, when the acousto-optic modulator AOM is turned off, the second-stage pump driver and the third-stage pump driver have no pulse light input, and the pre-pump energy is all stuffy in the gain medium without output, so there will be no effect on sensitive materials. At the same time, since all the pre-pump energy exists in the gain medium, when the pulse light arrives, the output light establishment time will be faster, so that the first pulse can be available.

[0053] The first-stage pump driver amplifies the pulse light to obtain the seed light. The AOM is turned on before the seed light arrives, and is maintained for a certain period of time after the seed light ends and then turned off. It is turned on in advance before the next seed light arrives, and the cycle continues. When the AOM is turned off, the second-stage pump driver or the third-stage pump driver only stores energy without output. The pre-pump energy is all stored in the gain medium. When the AOM is turned on, the second-stage pump driver or the third-stage pump driver outputs immediately when the seed light arrives, and is turned off after the seed light passes. The main principle is that each seed light is turned on in advance before it reaches the AOM, which is mainly affected by the optical path and the AOM opening establishment time. It also needs to be maintained for a period of time after the seed light ends. This is mainly because the AOM modulation ends and a period of holding time is required.

[0054] The RAM controller receives the third external control signal and the frequency division coefficient output by the frequency selection and frequency division module, and controls the operation of the acousto-optic modulator. Specifically, the RAM controller includes a memory, a digital-to-analog converter DAC and a synchronous logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, the RAM controller drives the address counter inside the memory to perform RAM addressing until valid data is found. A control signal of the acousto-optic modulator is stored under each RAM address. The content of the control signal of the acousto-optic modulator stored under the RAM address includes a single-bit signal and a multi-bit signal. The single-bit signal is used to control the on or off state of the acousto-optic modulator. The multi-bit signal is converted into an analog quantity by the digital-to-analog converter DAC and is used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronous logic control unit is used to synchronize the rising edge of the seed pulse signal with the seed frequency trigger signal.

[0055] As a preferred implementation, the pulse generating module provides the seed pulse signal to the seed driver as a macro pulse train, and the amplitudes of the pulses in the macro pulse train are not completely the same.

[0056] In an optical amplifier, the leading edge amplification efficiency of a pulse is high while the trailing edge amplification efficiency is low. If you want to continue to increase the energy of a single pulse, it is not enough to simply increase the pump energy. This will cause damage to the device due to the excessive peak power of the leading edge, thus limiting the maximum single pulse energy of the laser. By adopting the form of a macro pulse train, the amplitude of each micro pulse in the macro pulse is adjusted, so that the energy of the entire macro pulse can be made very high, and at the same time, the peak power will not be too high to cause device damage. The height of each micro pulse in the macro pulse is from low to high, because the leading edge amplification efficiency is high and the trailing edge is low, and this method can be used to reduce the peak power.

[0057] In another aspect, the present invention provides a pulse laser frequency control method, comprising the following steps:

[0058] S1: The above-mentioned pulse laser frequency control device is configured; the seed driver is used to output pulse light; the first-stage pump driver is used to perform the first-stage pumping and amplification on the pulse light; the acousto-optic modulator; the acousto-optic modulator is used to modulate the pulse light after the first-stage amplification; the second-stage pump driver and the third-stage pump driver continuously pump and amplify the modulated pulse light and then output;

[0059] S2: The frequency measurement module receives the input first external control signal and obtains the frequency of the first external control signal;

[0060] S3: The frequency selection and division module generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module;

[0061] S4: The frequency generation module receives the seed frequency signal output by the frequency selection and division module, and outputs a seed frequency trigger signal; the frequency generation module also receives a second external control signal, which is a light output control signal, and the seed frequency trigger signal is aligned with the rising edge of the second external control signal; the pulse generation module obtains the seed frequency trigger signal output by the frequency generation module, and provides a seed pulse signal to the seed driver, and the seed driver outputs pulse light according to the input seed pulse signal;

[0062] S5: The RAM controller includes a memory, a digital-to-analog converter DAC and a synchronous logic control unit; when the RAM controller receives the seed frequency trigger signal from the frequency generation module, the RAM controller drives the address counter inside the memory to perform RAM addressing until valid data is found, and a control signal of an acousto-optic modulator is stored under each RAM address. The content of the control signal of the acousto-optic modulator stored under the RAM address includes a single-bit signal and a multi-bit signal, and the single-bit signal is used to control the on or off state of the acousto-optic modulator; the multi-bit signal is converted into an analog quantity by the digital-to-analog converter DAC, and is used to control the light intensity of the seed light passing through the acousto-optic modulator; the synchronous logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal;

[0063] S6: The pulse light passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver and the third-stage pump driver in sequence; the first-stage pump driver, the second-stage pump driver and the third-stage pump driver all provide energy by means of a pulse pump according to the current driving signal received from the current control module, and the pump stores energy in advance. When the pulse light output by the seed driver reaches the first-stage pump driver, the second-stage pump driver or the third-stage pump driver, the pumping is terminated, and the amplified output is immediately performed; the acousto-optic modulator is turned on before the seed light arrives, performs acousto-optic modulation on the seed light, and maintains it for a certain time after the seed light ends and then turns it off, and turns it on in advance before the next seed light arrives. After the seed light ends, the acousto-optic modulator is delayed and maintained for a certain time and turns off, which plays a role in signal isolation;

[0064] S7: The current driving signal of the current control module has a linear variation characteristic below a specified frequency point. The current control module performs current compensation on the first-stage pump driver, the second-stage pump driver or the third-stage pump driver at different frequencies to ensure the power amplification effect of the first-stage pump driver, the second-stage pump driver or the third-stage pump driver.

[0065] The specific content of current compensation is as follows: the current driving signal of the first-stage pump driver is determined by the seed frequency signal and the pulse width of the pulse generating module; the current driving signals of the second-stage pump driver and the third-stage pump driver are determined by the external frequency control signal and the pulse width of the pulse generating module;

[0066] The pulse width of each seed frequency signal is cached in the memory of the current control module at the peak current corresponding to the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver; when the seed frequency signal is confirmed, an index signal is sent to the memory of the current control module to index the peak current of the first-stage pump driver, and the actual first-stage pump current I is calculated based on the functional relationship between the peak current of the first-stage pump driver and the seed frequency signal. s When the external frequency control signal is confirmed, an index signal is sent to the memory of the current control module. According to the index signal, the peak currents of the second-stage pump driver and the third-stage pump driver are indexed, and the actual second-stage pump current and the third-stage pump current I are calculated according to the functional relationship between the peak currents of the second-stage pump driver and the third-stage pump driver and the external control frequency: Among them I bs and ks is the current coefficient of the first stage pump driver; I smax is the peak current of the first stage pump driver; f sh is the seed power reduction frequency point; I b and k are the current coefficients of the second-stage pump driver and the third-stage pump driver; I max is the peak current of the second-stage pump driver and the third-stage pump driver, and their values ​​have the same difference pattern; f h It is the frequency point where the laser power is reduced.

[0067] This method can ensure that the power of the pulse light or the seed light is high enough, so that the power of the ASE is very low and self-oscillation is not likely to occur.

[0068] 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 pulse laser frequency control device, comprising a seed driver, a first-stage pump driver, an acousto-optic modulator, a second-stage pump driver and a third-stage pump driver which are sequentially arranged and optically connected, characterized in that: Also includes: A frequency measurement module, used for receiving a first external control signal and obtaining a frequency of the first external control signal; A frequency selection and division module is electrically connected to the frequency measurement module and the acousto-optic modulator, and generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module; The frequency generating module is electrically connected to the frequency selecting and dividing module, and is used to receive the seed frequency signal output by the frequency selecting and dividing module, and output the seed frequency trigger signal; the frequency generating module also receives a second external control signal; A pulse generating module is electrically connected to the frequency generating module and the seed driver, and is used to obtain the seed frequency trigger signal output by the frequency generating module, and provide a seed pulse signal to the seed driver, and the seed driver outputs a pulse light according to the input seed pulse signal; the pulse light passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver, and the third-stage pump driver in sequence; A current control module, electrically connected to the seed driver, the first-stage pump driver, the second-stage pump driver and the third-stage pump driver, respectively, for receiving a second external control signal and providing a current driving signal for the amplifier; The RAM controller is electrically connected to the frequency selection and division module and the acousto-optic modulator, respectively, and is used to receive the third external control signal and the frequency division coefficient output by the frequency selection and division module, and control the operation of the acousto-optic modulator.

2. A pulse laser frequency control device according to claim 1, characterized in that: The first external control signal is an external frequency control signal; the second external control signal is a light output control signal, and the seed frequency trigger signal is aligned with the rising edge of the second external control signal; the third external control signal is a clock phase control signal, and the third external control signal is synchronized with the seed frequency trigger signal output by the frequency generation module.

3. A pulse laser frequency control device according to claim 2, characterized in that: The frequency selection and division module generates and outputs a seed frequency signal and a frequency division coefficient, which makes the frequency of the first external control signal f i , the highest frequency of the seed frequency signal is f o , the seed frequency signal is f seed , and f o / 2≤f seed ≤f o , the frequency division coefficient D of the AOM n , then the seed frequency signal f seed And the frequency division coefficient D n The following relationship is satisfied: when f i >f o When f seed =f, i D n =1; when f i When ≤f, f seed =f× i D, n D n =floor(f o / f i ), floor(·) represents the downward value operation, ensuring that the seed frequency signal f seed and is always the frequency f of the first external control signal i The frequency of the AOM is an integer multiple of the seed frequency signal f seed Carry out linkage.

4. A pulse laser frequency control device according to claim 3, characterized in that: The first-stage pump driver, the second-stage pump driver and the third-stage pump driver all provide energy by means of a pulse pump according to the current driving signal received from the current control module. The pump stores energy in advance. When the pulse light output by the seed driver reaches the first-stage pump driver, the second-stage pump driver or the third-stage pump driver, the pumping is terminated and the amplified output is immediately performed.

5. A pulse laser frequency control device according to claim 4, characterized in that: The output power of the first stage pump driver follows the seed frequency signal f seed Linear change; the output power of the second-stage pump driver and the third-stage pump driver follows the frequency f of the first external control signal i Linear changes.

6. A pulse laser frequency control device according to claim 4, characterized in that: The first-stage pump driver amplifies the pulse light to obtain the seed light. The acousto-optic modulator is turned on before the seed light arrives, and is maintained for a certain period of time after the seed light ends and then turned off. It is turned on in advance before the next seed light arrives, and the cycle continues. When the acousto-optic modulator is turned off, the second-stage pump driver or the third-stage pump driver only stores energy without output, and all the pre-pump energy is stored in the gain medium. When the acousto-optic modulator is turned on, the second-stage pump driver or the third-stage pump driver outputs immediately when the seed light arrives, and is turned off after the seed light passes.

7. A pulse laser frequency control device according to claim 3, characterized in that: The RAM controller receives a third external control signal and a frequency division coefficient output by the frequency selection and frequency division module, and controls the operation of the acousto-optic modulator. Specifically, the RAM controller includes a memory, a digital-to-analog converter DAC, and a synchronous logic control unit. When the RAM controller receives a seed frequency trigger signal from the frequency generation module, the RAM controller drives an address counter inside the memory to perform RAM addressing until valid data is found. A control signal of the acousto-optic modulator is stored under each RAM address. The content of the control signal of the acousto-optic modulator stored under the RAM address includes a single-bit signal and a multi-bit signal. The single-bit signal is used to control the on or off state of the acousto-optic modulator. The multi-bit signal is converted into an analog quantity by the digital-to-analog converter DAC and is used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronous logic control unit is used to synchronize the rising edge of the seed pulse signal with the seed frequency trigger signal.

8. A pulse laser frequency control device according to claim 1, characterized in that: The pulse generating module provides the seed driver with a seed pulse signal in the form of a macro pulse train, wherein the amplitudes of the pulses in the macro pulse train are not completely the same.

9. A pulse laser frequency control method, characterized in that: The steps include: S1: a pulse laser frequency control device as described in any one of claims 2 to 8; a seed driver for outputting pulse light; a first-stage pump driver for performing first-stage pumping and amplification on the pulse light; Acousto-optic modulator; the acousto-optic modulator is used to modulate the pulse light after the first stage amplification; the second stage pump driver and the third stage pump driver continuously pump and amplify the modulated pulse light and then output; S2: The frequency measurement module receives the input first external control signal and obtains the frequency of the first external control signal; S3: The frequency selection and division module generates and outputs a seed frequency signal and a frequency division coefficient according to the frequency of the first external control signal obtained by the frequency measurement module; S4: The frequency generation module receives the seed frequency signal output by the frequency selection and division module, and outputs a seed frequency trigger signal; the frequency generation module also receives a second external control signal, which is a light output control signal, and the seed frequency trigger signal is aligned with the rising edge of the second external control signal; the pulse generation module obtains the seed frequency trigger signal output by the frequency generation module, and provides a seed pulse signal to the seed driver, and the seed driver outputs pulse light according to the input seed pulse signal; S5: RAM controller includes memory, digital-to-analog converter DAC and synchronous logic control unit; When the RAM controller receives the seed frequency trigger signal from the frequency generation module, the RAM controller drives the address counter inside the memory to perform RAM addressing until valid data is found. A control signal of an acousto-optic modulator is stored under each RAM address. The content of the control signal of the acousto-optic modulator stored under the RAM address includes a single-bit signal and a multi-bit signal. The single-bit signal is used to control the on or off state of the acousto-optic modulator; the multi-bit signal is converted into an analog quantity by a digital-to-analog converter DAC and is used to control the light intensity of the seed light passing through the acousto-optic modulator; the synchronous logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal; S6: The pulse light passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver and the third-stage pump driver in sequence; the first-stage pump driver, the second-stage pump driver and the third-stage pump driver all provide energy by means of a pulse pump according to the current driving signal received from the current control module, and the pump stores energy in advance. When the pulse light output by the seed driver reaches the first-stage pump driver, the second-stage pump driver or the third-stage pump driver, the pumping is terminated, and the amplified output is immediately performed; the acousto-optic modulator is turned on before the seed light arrives, performs acousto-optic modulation on the seed light, and maintains it for a certain time after the seed light ends and then turns it off, and turns it on in advance before the next seed light arrives. After the seed light ends, the acousto-optic modulator is delayed and maintained for a certain time and turns off, which plays a role in signal isolation; S7: The current driving signal of the current control module has a linear variation characteristic below a specified frequency point. The current control module performs current compensation on the first-stage pump driver, the second-stage pump driver or the third-stage pump driver at different frequencies to ensure the power amplification effect of the first-stage pump driver, the second-stage pump driver or the third-stage pump driver.

10. A pulse laser frequency control method according to claim 9, characterized in that: The current driving signal of the first-stage pump driver is determined by the seed frequency signal and the pulse width of the pulse generating module; the current driving signals of the second-stage pump driver and the third-stage pump driver are determined by the external frequency control signal and the pulse width of the pulse generating module; The pulse width of each seed frequency signal is cached in the memory of the current control module at the peak current corresponding to the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver; When the seed frequency signal is confirmed, an index signal is sent to the memory of the current control module to index the peak current of the first-stage pump driver. The actual first-stage pump current I is calculated based on the functional relationship between the peak current of the first-stage pump driver and the seed frequency signal. s When the external frequency control signal is confirmed, an index signal is sent to the memory of the current control module. According to the index signal, the peak currents of the second-stage pump driver and the third-stage pump driver are indexed, and the actual second-stage pump current and the third-stage pump current I are calculated according to the functional relationship between the peak currents of the second-stage pump driver and the third-stage pump driver and the external control frequency: Among them I bs and ks is the current coefficient of the first stage pump driver; I smax is the peak current of the first stage pump driver; f sh is the seed power reduction frequency point; I b and k are the current coefficients of the second-stage pump driver and the third-stage pump driver; I max is the peak current of the second-stage pump driver and the third-stage pump driver; f h It is the frequency point where the laser power is reduced.

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