A pulsed laser frequency control device and method

Abstract

This invention proposes a frequency control device and method for a pulsed laser, belonging to the field of pulsed fiber laser technology. It includes a frequency measurement module for acquiring the frequency of a first external control signal; a frequency selection and division module for generating and outputting a seed frequency signal and a division coefficient based on the frequency of the first external control signal acquired by the frequency measurement module; a frequency generation module for receiving the seed frequency signal output by the frequency selection and division module and outputting a seed frequency trigger signal; a pulse generation module for acquiring the seed frequency trigger signal output by the frequency generation module and providing a seed pulse signal to a seed driver, which outputs pulsed light based on the input seed pulse signal; a current control module for receiving a second external control signal and providing current drive signals to each pump driver; and a RAM controller for receiving a third external control signal and the division coefficient output by the frequency selection and division module, and controlling the operation of an acousto-optic modulator.

Description

Technical Field

[0001] This invention relates to the field of pulsed fiber laser technology, and in particular to a pulsed laser frequency control device and method. Background Technology

[0002] In the field of laser industrial processing, lasers typically operate at frequencies ranging from 0.1 to 10000 kHz. Low-repetition-rate (MRPR) pulsed fiber amplifiers (FFA) operating in the 0.1–10 kHz range suffer from drawbacks such as excessively low signal power and excessive amplified spontaneous emission (ASE). From a time-domain perspective, when one pulse leaves the amplifier, the next pulse has not yet entered. During this inter-pulse interval, no seed pulse is injected, but pumping continues. The ASE dominates the amplifier's gain consumption. Furthermore, in high-power main amplifiers, spontaneous emission exceeding a threshold can rapidly saturate and self-oscillate into giant pulses, releasing energy instantaneously and causing fiber burnout. This asynchrony between the seed light frequency and amplifier operation not only reduces the energy extraction rate of the signal pulse but also, if the pulsed laser employs a MOPA structure, the ASE is amplified stage by stage, limiting the peak pulse power and affecting the laser's output performance.

[0003] Therefore, it is essential to provide a pulsed laser frequency control device and method that, by adjusting the correspondence between the seed frequency and the control signal frequency, links the seed frequency with the acousto-optic modulator (AOM) frequency, and activates the AOM only when the seed light is effective, thereby avoiding stepwise amplification of the acousto-optic signal (ASE) and ensuring stable and reliable laser output performance. Summary of the Invention

[0004] In view of this, the present invention proposes a pulsed laser frequency control device and method that can synchronize the operation of pulsed light, external control signals and acousto-optic modulator, extract energy of the pre-pumping stage only during light emission, and suppress ASE.

[0005] On one hand, the present invention provides a pulsed 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 arranged sequentially and optically connected, and further comprising:

[0006] A frequency measurement module is used to receive a first external control signal and acquire the frequency of the first external control signal;

[0007] The frequency selection and division module is electrically connected to the frequency measurement module and the acousto-optic modulator. Based on the frequency of the first external control signal obtained by the frequency measurement module, it generates and outputs a seed frequency signal and a division coefficient.

[0008] The frequency generation module is electrically connected to the frequency selection and division module, and is used to receive the seed frequency signal output by the frequency selection and division module and output the seed frequency trigger signal; the frequency generation module also receives a second external control signal.

[0009] The pulse generation module is electrically connected to the frequency generation module and the seed driver. It is used to acquire the seed frequency trigger signal output by the frequency generation module and provide the seed pulse signal to the seed driver. The seed driver outputs 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] The current control module is electrically connected to the seed driver, the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver, respectively, and is used to receive the second external control signal and provide the current drive signal for the amplifier.

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

[0012] Based on the above technical solutions, 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 rising edge of the seed frequency trigger signal is aligned with that 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.

[0013] Preferably, the frequency selection and division module generates and outputs the seed frequency signal and the division coefficient by setting the frequency of the first external control signal to 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 acousto-optic modulator n Then the seed frequency signal f seed and frequency division coefficient D n Satisfy the following relationship: when f i >f o At that time, f seed =f i D n =1; when f i When f ≤ f, f seed =f i ×D n D n =floor(f o / fi The floor() operator represents the down-fetching operation, ensuring the seed frequency signal f is maintained. seed The frequency f of the first external control signal is always present. i Integer multiples of the frequency of the acousto-optic modulator and the seed frequency signal f seed To coordinate.

[0014] More preferably, the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver all provide energy through pulse pumping according to the current drive signal received from the current control module. The energy is pre-stored by the pump. 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 ends and the output is immediately amplified.

[0015] More preferably, the output power of the first-stage pump driver follows the seed frequency signal f. seed Linear variation; 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 change.

[0016] In a further preferred embodiment, the first-stage pump driver amplifies the pulsed light to obtain a seed light. The acousto-optic modulator is turned on before the seed light arrives, and remains on for a certain period of time after the seed light ends before turning off. It is then turned on in advance before the next seed light arrives, and this cycle repeats. When the acousto-optic modulator is off, the second-stage or third-stage pump driver only stores energy and has no output. All the pre-pumping energy is stored in the gain medium. When the acousto-optic modulator is turned on, the second-stage or third-stage pump driver outputs immediately when the seed light arrives and turns off after the seed light passes.

[0017] Preferably, the RAM controller receives a third external control signal and the frequency division coefficient output by the frequency selection and 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 synchronization logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, it drives the address counter inside the memory to perform RAM address searching until valid data is found. Each RAM address stores a control signal for the acousto-optic modulator. The content of the control signal for 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 DAC and used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronization logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal.

[0018] Based on the above technical solutions, preferably, the pulse generation module provides the seed pulse signal to the seed driver as a macro pulse train, and the amplitude of each pulse in the macro pulse train is not exactly the same.

[0019] On the other hand, the present invention provides a pulsed laser frequency control method, comprising the following steps:

[0020] S1: Configure the above-mentioned pulsed laser frequency control device; seed driver for outputting pulsed light; first-stage pump driver for first-stage pumping and amplification of pulsed light; acousto-optic modulator; acousto-optic modulator for modulating the first-stage amplified pulsed light; second-stage pump driver and third-stage pump driver for continuous pumping and amplification of the modulated pulsed light before output.

[0021] S2: The frequency measurement module receives the first external control signal and acquires 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 division coefficient based on 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 the 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 acquires 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 synchronization logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, it drives the address counter inside the memory to perform RAM address searching until valid data is found. Each RAM address stores a control signal for an acousto-optic modulator. The control signal for 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 signal by the DAC and used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronization logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal.

[0025] S6: The pulsed light sequentially passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver, and the third-stage pump driver. The first-stage, second-stage, and third-stage pump drivers all provide energy via pulse pumping based on the current drive signal received from the current control module. Energy is pre-stored by the pump. Pumping ends when the pulsed light output from the seed driver reaches the first-stage, second-stage, or third-stage pump driver, and the signal is immediately amplified and output. The acousto-optic modulator is activated before the seed light arrives, modulating the seed light acousto-optically. It maintains this modulation for a certain time after the seed light ends and then turns off. It is pre-activated before the next seed light arrives. After the seed light ends, the acousto-optic modulator maintains this modulation for a certain time and then turns off, serving as a signal isolation mechanism.

[0026] S7: The current drive signal of the current control module has the characteristic of linear change below the 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 drive signal of the first-stage pump driver is determined by the seed frequency signal and the pulse width of the pulse generation module; the current drive 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 generation module.

[0028] The pulse width of each seed frequency signal is cached in the memory of the current control module for the peak currents corresponding to the first-stage pump driver, second-stage pump driver, and third-stage pump driver. Once the seed frequency signal is confirmed, an index signal is sent to the memory of the current control module to retrieve the peak current of the first-stage pump driver. The actual first-stage pump current I is then calculated based on the functional relationship between the peak current of the first-stage pump driver and the seed frequency signal. s Once the external frequency control signal is confirmed, an index signal is sent to the memory of the current control module. Based on the index signal, the peak currents of the second-stage pump driver and the third-stage pump driver are retrieved. The actual second-stage pump current and the third-stage pump current I are calculated based on the functional relationship between the peak currents of the second-stage and third-stage pump drivers and the external control frequency. Where I bs ks are the current coefficients of the first-stage pump driver; I smax f is the peak current of the first-stage pump driver; sh It 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 maxFor the peak currents of the second-stage and third-stage pump drivers; f h This is the frequency point at which the laser power is reduced.

[0029] The pulsed laser frequency control device and method provided by this invention have the following advantages compared with the prior art:

[0030] (1) Before generating pulsed 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 pulsed light or seed light arrives, and pumping or waiting is performed when the pulsed light or seed light has not arrived. This successfully realizes the synchronization of the seed frequency with the external frequency control signal, as well as the synchronization of the seed frequency trigger signal with the second external control signal. This can effectively suppress ASE.

[0031] (2) The multi-stage amplification process of pulsed light has gone through the stages of pre-pumping, waiting for the pulsed light to arrive, pumping out light and stopping output, ensuring that the energy of pre-pumping is output immediately when the pulsed light or seed light arrives, realizing synchronous output without leakage light and improving the extraction rate of pre-pumping energy by the signal pulse.

[0032] (3) The current drive 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 high pump energy extraction efficiency under continuous pulse or macro pulse input. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic block diagram of the structure of a pulsed laser frequency control device and method according to the present invention;

[0035] Figure 2 This is a schematic diagram of the seed frequency signal of the pulsed laser frequency control device and method of the present invention.

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

[0037] Figure 4This is a schematic diagram of the output frequency curve of the second-stage pump driver of the pulsed laser frequency control device and method of the present invention. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] Existing pulsed lasers may suffer from a missynchronization between the seed light frequency and the amplifier's operation. This not only reduces the energy extraction rate of the signal pulse but also increases the amplified self-emission (ASE) with each stage of the amplification structure, affecting the laser's output performance. Therefore, if... Figure 1 As shown, in one aspect, the present invention provides a pulsed 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 arranged sequentially 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 pulsed laser with an MOPA structure; further comprising:

[0040] A frequency measurement module is used to receive a first external control signal and acquire the 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. Based on the frequency of the first external control signal obtained by the frequency measurement module, it generates and outputs a seed frequency signal and a division coefficient.

[0042] The frequency generation module is electrically connected to the frequency selection and division module. It is used to receive the seed frequency signal output by the frequency selection and division module and output the seed frequency trigger signal. The frequency generation module also receives a second external control signal. On the one hand, the frequency generation module generates the seed frequency trigger signal, and on the other hand, it aligns the seed frequency trigger signal with the received second external control signal.

[0043] The pulse generation module is electrically connected to the frequency generation module and the seed driver. It is used to acquire the seed frequency trigger signal output by the frequency generation module and provide the seed pulse signal to the seed driver. The seed driver outputs 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, is configured to receive a second external control signal and provide a current drive signal for the amplifier.

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

[0046] In the above solution, the first external control signal mentioned 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 synchronous with the seed frequency trigger signal output by the frequency generation module.

[0047] The above frequency selection and frequency division module generates and outputs a seed frequency signal and a frequency division coefficient. Specifically, the frequency of the first external control signal is set to 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 n of the acousto-optic modulator is such that the seed frequency signal f seed and the frequency division coefficient D n satisfy the following relationship: when f i > f o , f seed = f i , D n = 1; when f i ≤ f, f seed = f i × D n , D n = floor(f o / f i ), where floor(·) represents the floor operation. This ensures that the seed frequency signal f seed and [remainder] are always integer multiples of the frequency f i of the first external control signal, and the frequency of the acousto-optic modulator is linked to the seed frequency signal f seed . This operation of the frequency division module can ensure that the power of the seed frequency signal is high enough to reduce the ASE power and prevent self-excited oscillation.

[0048] To ensure synchronization with the external frequency control signal, in conventional control mode, the seed frequency signal generally remains unchanged after confirmation. The acousto-optic modulator can only output by down-converting the frequency, resulting in a deviation between the output frequency and the desired frequency. This invention adjusts the seed frequency signal to 0.5f... o -f o In between, it can always be guaranteed that the seed frequency signal is an integer 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 These correspond to the seed frequency signal and the frequency division curve of the acousto-optic modulator at different frequencies corresponding to different external frequency control signals. Figure 4 This demonstrates the relationship between the seed light frequency output of the second-stage pump driver and the frequency of the external control signal when the seed frequency signal and the frequency of the acousto-optic modulator are linked, and when the external frequency control signal is at a low frequency.

[0049] The first-stage, second-stage, and third-stage pump drivers all provide energy via pulse pumping based on the current drive signal received from the current control module. Energy is pre-stored by the pump. Pumping terminates when the pulsed light output from the seed driver reaches the first-stage, second-stage, or third-stage pump driver, and the signal is immediately amplified and output. The output power of the first-stage pump driver follows the seed frequency signal f. seed Linear variation; 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 change.

[0050] In the above description, the first-stage pump driver is essentially a constant current source. Controlled by the current control module, it generates a corresponding current and pumps the pulsed light, providing pump power. As the seed frequency signal changes, the output power of the first-stage pump driver changes linearly with the seed frequency signal, ensuring the stability of the output pulse energy. The pump output power of the second and third-stage pump drivers changes linearly with the frequency of the first external control signal. Since the acousto-optic modulator (AOM) is only activated when the seed light is active, it can be used as an isolator.

[0051] In this invention, before the pulsed 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). This ensures that the height of the first pulse at the moment of light emission is basically consistent with that of the subsequent pulses. However, during this period, each stage of the pump driver is performing pre-pumping, which will eventually result in light leakage. This light leakage 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 next stage. The second-stage and third-stage pump drivers only store energy and have no output before the seed light arrives. When the seed light arrives, they can output immediately, thus achieving no light leakage and the first pulse of the pulsed light or seed light is usable.

[0052] The second external control signal of a MOPA pulsed laser, namely the output control signal, is generally two: MO and PA. MO represents the pre-pump signal. After MO is active, the laser begins pre-pumping, charging the gain medium. The power is very low at this time, and it requires a certain duration, which is the pre-pump time. After the pre-pump time (pre-energy storage process) is satisfied, the PA signal arrives, and the laser begins 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, resulting in a relatively low laser output. This is not allowed when processing sensitive materials. However, when the AOM is turned off, the second-stage pump driver and the third-stage pump driver have no pulse light input, so all the pre-pump energy is trapped in the gain medium and has no output, thus having no effect on sensitive materials. At the same time, since all the pre-pump energy is contained in the gain medium, the output light settling time will be faster when the pulse light arrives, thus ensuring that the first pulse is usable.

[0053] The first-stage pump driver amplifies the pulsed light to obtain the seed light. The acousto-optic modulator (AOM) turns on before the seed light arrives, maintains its position for a certain period after the seed light ends, and then turns off. It turns on again before the next seed light arrives, and this cycle repeats. When the AOM is off, the second or third-stage pump driver only stores energy and has no output; all pre-pump energy is stored in the gain medium. When the AOM turns on, the second or third-stage pump driver outputs immediately upon the arrival of the seed light and turns off after the seed light passes. The main principle is that each seed light is turned on before reaching the AOM. The main factors affected are the optical path length and the AOM setup time. A holding period is also required after the seed light ends, mainly because the AOM modulation requires a holding time after modulation.

[0054] The aforementioned RAM controller receives a third external control signal and the frequency division coefficient output by the frequency selection and 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 synchronization logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, it drives the address counter inside the memory to perform RAM address searching until valid data is found. Each RAM address stores a control signal for the acousto-optic modulator. The content of the control signal for 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 DAC and used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronization logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal.

[0055] In a preferred embodiment, the pulse generation module provides the seed pulse signal to the seed driver as a macro pulse train, wherein the amplitudes of the pulses in the macro pulse train are not exactly the same.

[0056] In optical amplifiers, the amplification efficiency is high at the leading edge and low at the trailing edge of a pulse. Simply increasing the pump energy is insufficient to further increase the single-pulse energy, as this would damage the device due to excessively high peak power at the leading edge, thus limiting the maximum single-pulse energy of the laser. By employing a macropulse train, the amplitude of each micropulse within the macropulse is adjusted, allowing for a very high overall macropulse energy without the risk of excessive peak power and device damage. The height of each micropulse within the macropulse increases from low to high, reflecting the high amplification efficiency at the leading edge and low at the trailing edge, thereby reducing the peak power.

[0057] On the other hand, the present invention provides a pulsed laser frequency control method, comprising the following steps:

[0058] S1: Configure the above-mentioned pulsed laser frequency control device; seed driver for outputting pulsed light; first-stage pump driver for first-stage pumping and amplification of pulsed light; acousto-optic modulator; acousto-optic modulator for modulating the first-stage amplified pulsed light; second-stage pump driver and third-stage pump driver for continuous pumping and amplification of the modulated pulsed light before output.

[0059] S2: The frequency measurement module receives the first external control signal and acquires 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 division coefficient based on 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 the 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 acquires 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 synchronization logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, it drives the address counter inside the memory to perform RAM address searching until valid data is found. Each RAM address stores a control signal for an acousto-optic modulator. The control signal for 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 signal by the DAC and used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronization logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal.

[0063] S6: The pulsed light sequentially passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver, and the third-stage pump driver. The first-stage, second-stage, and third-stage pump drivers all provide energy via pulse pumping based on the current drive signal received from the current control module. Energy is pre-stored by the pump. Pumping ends when the pulsed light output from the seed driver reaches the first-stage, second-stage, or third-stage pump driver, and the signal is immediately amplified and output. The acousto-optic modulator is activated before the seed light arrives, modulating the seed light acousto-optically. It maintains this modulation for a certain time after the seed light ends and then turns off. It is pre-activated before the next seed light arrives. After the seed light ends, the acousto-optic modulator maintains this modulation for a certain time and then turns off, serving as a signal isolation mechanism.

[0064] S7: The current drive signal of the current control module has the characteristic of linear change below the 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 drive signal of the first-stage pump driver is determined by the seed frequency signal and the pulse width of the pulse generation module; the current drive 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 generation module.

[0066] The pulse width of each seed frequency signal is cached in the memory of the current control module for the peak currents corresponding to the first-stage pump driver, second-stage pump driver, and third-stage pump driver. Once the seed frequency signal is confirmed, an index signal is sent to the memory of the current control module to retrieve the peak current of the first-stage pump driver. The actual first-stage pump current I is then calculated based on the functional relationship between the peak current of the first-stage pump driver and the seed frequency signal. s Once the external frequency control signal is confirmed, an index signal is sent to the memory of the current control module. Based on the index signal, the peak currents of the second-stage pump driver and the third-stage pump driver are retrieved. The actual second-stage pump current and the third-stage pump current I are calculated based on the functional relationship between the peak currents of the second-stage and third-stage pump drivers and the external control frequency. Where I bs ks are the current coefficients of the first-stage pump driver; I smax f is the peak current of the first-stage pump driver; sh It 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 The peak currents of the second-stage and third-stage pump drivers show a consistent pattern of difference; f h This is the frequency point at which the laser power is reduced.

[0067] This method ensures that the power of the pulsed light or seed light is high enough, thus making the power of the ASE very low and less prone to self-oscillation.

[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 within the protection scope of the present invention.

Claims

1. A pulsed 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 arranged sequentially and optically connected, characterized in that, Also includes: A frequency measurement module is used to receive a first external control signal and acquire the frequency of the first external control signal; The frequency selection and division module is electrically connected to the frequency measurement module and the acousto-optic modulator. Based on the frequency of the first external control signal obtained by the frequency measurement module, it generates and outputs a seed frequency signal and a division coefficient. Let the frequency of the first external control signal be 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 acousto-optic modulator n Then the seed frequency signal f seed and frequency division coefficient D n Satisfy the following relationship: when f i >f o At that time, f seed =f i D n =1; when f i When f ≤ f, f seed =f i ×D n D n =floor(f o / f i The floor() operator represents the down-fetching operation, ensuring the seed frequency signal f is maintained. seed The frequency f of the first external control signal is always present. i Integer multiples of the frequency of the acousto-optic modulator and the seed frequency signal f seed To coordinate; The frequency generation module is electrically connected to the frequency selection and division module, and is used to receive the seed frequency signal output by the frequency selection and division module and output the seed frequency trigger signal. The frequency generation module also receives a second external control signal; The pulse generation module is electrically connected to the frequency generation module and the seed driver. It is used to acquire the seed frequency trigger signal output by the frequency generation module and provide the seed pulse signal to the seed driver. The seed driver outputs 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. The current control module is electrically connected to the seed driver, the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver, respectively, and is used to receive the second external control signal and provide the current drive signal for the amplifier. The RAM controller is electrically connected to the frequency selection and division module and the acousto-optic modulator, respectively. It is used to receive the third external control signal and the division coefficient output by the frequency selection and division module, and to control the operation of the acousto-optic modulator.

2. The pulsed 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. The pulsed laser frequency control device according to claim 1, characterized in that, The first-stage pump driver, the second-stage pump driver, and the third-stage pump driver all provide energy through pulse pumping based on the current drive signal received from the current control module. The energy is pre-stored by the pump. 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 ends and the output is immediately amplified.

4. The pulsed laser frequency control device according to claim 3, characterized in that, The output power of the first-stage pump driver follows the seed frequency signal f. seed Linear variation; 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 change.

5. The pulsed laser frequency control device according to claim 3, characterized in that, The first-stage pump driver amplifies the pulsed light to obtain the seed light. The acousto-optic modulator turns on before the seed light arrives, maintains its position for a certain period after the seed light ends, and then turns off. It turns on again before the next seed light arrives, and this cycle repeats. When the acousto-optic modulator is off, the second-stage or third-stage pump driver only stores energy and has no output. All the pre-pump energy is stored in the gain medium. When the acousto-optic modulator turns on, the second-stage or third-stage pump driver outputs immediately when the seed light arrives and turns off after the seed light passes.

6. The pulsed laser frequency control device according to claim 1, characterized in that, The RAM controller receives a third external control signal and the frequency division coefficient output by the frequency selection and 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 synchronization logic control unit. When the RAM controller receives the seed frequency trigger signal from the frequency generation module, it drives the address counter inside the memory to perform RAM address searching until valid data is found. Each RAM address stores a control signal for the acousto-optic modulator. The control signal for 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 DAC and used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronization logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal.

7. The pulsed laser frequency control device according to claim 1, characterized in that, The pulse generation module provides the seed pulse signal to the seed driver as a macro pulse train, in which the amplitudes of each pulse are not exactly the same.

8. A method for controlling the frequency of a pulsed laser, characterized in that, Includes the following steps: S1: Configure the pulsed laser frequency control device as described in any one of claims 2-7; a seed driver is used to output pulsed light; a first-stage pump driver is used to perform first-stage pumping and amplification of the pulsed light; Acousto-optic modulator; The acousto-optic modulator is used to modulate the pulsed light after the first stage of amplification; The second stage pump driver and the third stage pump driver continuously pump and amplify the modulated pulsed light before output; S2: The frequency measurement module receives the first external control signal and acquires the frequency of the first external control signal; S3: The frequency selection and division module generates and outputs a seed frequency signal and a division coefficient based on 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 the 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 acquires 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: The RAM controller includes 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, it drives the internal address counter of the memory to perform RAM address searching until valid data is found. Each RAM address stores a control signal for the acousto-optic modulator. The control signal for 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 signal by a digital-to-analog converter (DAC) and used to control the light intensity of the seed light passing through the acousto-optic modulator. The synchronization logic control unit is used to synchronize the rising edge of the seed pulse signal and the seed frequency trigger signal. S6: The pulsed light sequentially passes through the first-stage pump driver, the acousto-optic modulator, the second-stage pump driver, and the third-stage pump driver. The first-stage, second-stage, and third-stage pump drivers all provide energy via pulse pumping based on the current drive signal received from the current control module. Energy is pre-stored by the pump. Pumping ends when the pulsed light output from the seed driver reaches the first-stage, second-stage, or third-stage pump driver, and the signal is immediately amplified and output. The acousto-optic modulator is activated before the seed light arrives, modulating the seed light acousto-optically. It maintains this modulation for a certain time after the seed light ends and then turns off. It is pre-activated before the next seed light arrives. After the seed light ends, the acousto-optic modulator maintains this modulation for a certain time and then turns off, serving as a signal isolation mechanism. S7: The current drive signal of the current control module has the characteristic of linear change below the 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.

9. A pulsed laser frequency control method according to claim 8, characterized in that, The current drive signal of the first-stage pump driver is determined by the seed frequency signal and the pulse width of the pulse generation module; the current drive signals of the second-stage and third-stage pump drivers are determined by the external frequency control signal and the pulse width of the pulse generation module. The pulse width of each seed frequency signal is cached in the memory of the current control module for the peak current corresponding to the first-stage pump driver, the second-stage pump driver, and the third-stage pump driver. Once 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. Based on the functional relationship between the peak current of the first-stage pump driver and the seed frequency signal, the actual first-stage pump current I is calculated. s Once the external frequency control signal is confirmed, an index signal is sent to the memory of the current control module. Based on the index signal, the peak currents of the second-stage pump driver and the third-stage pump driver are retrieved. The actual second-stage pump current and the third-stage pump current I are calculated based on the functional relationship between the peak currents of the second-stage and third-stage pump drivers and the external control frequency. Where I bs ks are the current coefficients of the first-stage pump driver; I smax f is the peak current of the first-stage pump driver; sh It 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 For the peak currents of the second-stage and third-stage pump drivers; f h This is the frequency point at which the laser power is reduced.

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