High-stability optical fiber pulse MOPA laser control method and optical fiber pulse laser

Abstract

The invention discloses a high-stability optical fiber pulse MOPA laser control method and an optical fiber pulse laser, and belongs to the technical field of driving circuits. The laser circuit is connected with the control board card; the control board card is used for outputting a pulse width adjusting signal, a repetition frequency signal, a switch optical signal and a power signal; in a laser circuit, a frequency modulation circuit outputs a frequency modulation signal according to a repetition frequency signal; the seed pulse generation circuit outputs a seed pulse and an index signal according to the pulse width adjustment signal and the frequency modulation signal under the condition of receiving the trigger signal; the emergent light adjusting circuit obtains an emergent light phase compensation signal and outputs the emergent light phase compensation signal according to the switch light signal and the index signal; the power adjusting circuit outputs a power compensation signal according to the power signal and the index signal; and the gain circuit compensates the seed pulse according to the light-emitting phase compensation signal and the power compensation signal, and outputs a laser pulse. The power linearity and single pulse energy of the laser pulses with different frequencies output by the method are kept stable, and the stability of the laser pulses is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of drive circuits, and in particular relates to a high-stability fiber pulse MOPA laser control method and a fiber pulse laser. Background Art

[0002] Pulsed fiber lasers have the advantages of small size, high single pulse energy and high conversion efficiency, so they can further replace traditional lasers and be widely used in many fields.

[0003] At present, the most difficult problem for high-power fiber lasers with pulse fiber structures is a new type of nonlinear limiting factor, transverse mode instability (TMI). The TMI threshold can be increased by bending the main fiber, and the control system can also be improved by controlling the pump width and seed phase. It can be improved by adjusting the pulse pump width and the time domain phase with the seed pulse.

[0004] Since the extraction efficiency of the amplifier is different at different output frequencies, the single pulse energy corresponding to the pulse pump width at different frequencies is unstable, which affects the stability of the laser pulse. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a high-stability fiber pulse MOPA laser control method and a fiber pulse laser, which outputs different frequencies of laser pulse power linearity and single pulse energy to maintain stability, thereby improving the stability of the laser pulse.

[0006] In a first aspect, the present application provides a high-stability fiber pulse MOPA laser control method, which is applied to a laser circuit, wherein the laser circuit is connected to a control board;

[0007] The laser circuit comprises: a board controller and a laser generating circuit;

[0008] The control board is used to output a pulse width modulation signal, a repetition rate signal, a switching optical signal and a power signal;

[0009] The board controller includes a frequency modulation circuit, a light output adjustment circuit and a power adjustment circuit which are connected to each other;

[0010] The laser generating circuit includes a seed pulse generating circuit and a gain circuit connected in sequence;

[0011] The method comprises:

[0012] Outputting a frequency modulation signal according to the re-frequency signal through the frequency modulation circuit;

[0013] By means of the seed pulse generating circuit, when a trigger signal is received, a seed pulse and an index signal are output according to the pulse width modulation signal and the frequency modulation signal;

[0014] Obtaining a light output phase compensation signal according to the switch light signal and the index signal through the light output adjustment circuit and outputting the signal;

[0015] Outputting a power compensation signal according to the power signal and the index signal through the power regulation circuit;

[0016] The seed pulse is compensated for by the gain circuit according to the light output phase compensation signal and the power compensation signal, and a laser pulse is output.

[0017] According to an embodiment of the present application, the light output adjustment circuit includes a light output control module, a light output duration control module and a light output phase control module connected in sequence; the light output adjustment circuit obtains and outputs a light output phase compensation signal according to the switch optical signal and the index signal, including:

[0018] Obtaining a light output control signal according to the switch light signal through the light output control module;

[0019] Outputting a pumping duration signal through the light emission duration control module according to the light emission control signal, the input frequency, the index signal and the trigger pulse;

[0020] The light output phase compensation signal is outputted through the light output phase control module according to the pump duration signal and the input frequency.

[0021] According to an embodiment of the present application, the power regulation circuit includes a current intensity control module and a power control module connected in sequence; the power regulation circuit outputs a power compensation signal according to the power signal and the index signal, including:

[0022] Outputting a current intensity signal and a current control signal according to the input frequency and the index signal through the current intensity control module;

[0023] Performing gain control on the laser pulse according to the current control signal through the gain circuit;

[0024] The power control module outputs the power compensation signal according to the current intensity signal.

[0025] According to one embodiment of the present application, the seed pulse generating circuit includes a pulse generating module and a seed module connected in sequence, and the seed pulse generating circuit, when receiving a trigger signal, outputs a seed pulse and an index signal according to the pulse width modulation signal and the frequency modulation signal, including:

[0026] The pulse generating module is triggered by the trigger signal and outputs a pulse signal and an index signal according to the pulse width modulation signal and the frequency modulation signal;

[0027] The seed module outputs the seed pulse according to the pulse signal.

[0028] According to an embodiment of the present application, the frequency modulation circuit includes a frequency measurement module, a frequency generation module and a frequency phase control module connected in sequence, and the frequency modulation circuit outputs a frequency modulation signal according to the re-frequency signal, including:

[0029] The frequency measurement module measures the repetition frequency signal to obtain an input frequency;

[0030] Outputting a trigger pulse through the frequency generating module according to the light-on signal and the input frequency, wherein the light-on signal is output by the light-out adjustment circuit according to the switch light signal;

[0031] The frequency modulation signal is outputted through the frequency phase control module according to the trigger pulse, the input frequency and the index signal.

[0032] According to an embodiment of the present application, the gain circuit includes a pre-amplifier module and a main amplifier module connected in sequence, and the seed pulse is compensated by the gain circuit according to the output light phase compensation signal and the power compensation signal to output a laser pulse, including:

[0033] Through the pre-amplifier module, the light emission duration of the seed pulse is controlled according to the light emission phase compensation signal and the current intensity signal, and an amplified signal is output;

[0034] The main amplifier module performs phase compensation on the amplified signal according to the output light phase compensation signal and the power compensation signal to obtain and output the laser pulse.

[0035] According to one embodiment of the present application, the laser circuit further includes a clock circuit, and the clock circuit is connected to the control board. The method further includes:

[0036] Generate an output clock signal according to the internal clock signal of the laser through the clock circuit;

[0037] Clock synchronization is performed through the control board according to the output clock signal.

[0038] According to one embodiment of the present application, the method further includes:

[0039] The clock circuit also receives an input clock signal from the control board, and performs clock synchronization on a pulse width modulation signal, a repetition frequency signal, a switching optical signal and a power signal through the input clock signal.

[0040] According to one embodiment of the present application, the laser circuit further includes: a central processing unit, and the method further includes:

[0041] The central processor is used to configure parameters of the frequency modulation circuit, the light output adjustment circuit and the power adjustment circuit in the board controller.

[0042] In a second aspect, the present application provides a fiber pulse laser for executing the high-stability fiber pulse MOPA laser control method as described in the first aspect.

[0043] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application.

[0044] The present application provides a high-stability fiber pulse MOPA laser control method and fiber pulse laser, which have the following beneficial effects compared with the prior art:

[0045] (1) By compensating the output phase compensation signal and the power compensation signal, the power linearity of the laser pulses with different frequencies and the energy of the single pulse are kept stable, so that the energy of the single pulses with different frequencies can be consistent, thereby improving the stability of the laser pulses and the output consistency.

[0046] (2) In the pre-amplifier module, the seed pulse is amplified by a smaller pump energy to increase the power of the seed pulse to a suitable level to achieve maximum gain while avoiding over-saturation or nonlinear effects; in the main amplifier module, the signal is further amplified to achieve the required output power to ensure that the output laser pulse has higher power and stability. In a multi-stage high-power system, there are differences in the control circuit signals of each stage of the amplifier, which can easily cause timing problems. The amplifier synchronous light output phase adjustment logic ensures the safety of the light output timing of each stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0048] Figure 1It is one of the structural schematic diagrams of the laser circuit provided in the embodiment of the present application;

[0049] Figure 2 It is a flow chart of a high-stability fiber pulse MOPA laser control method provided in an embodiment of the present application;

[0050] Figure 3 This is the second structural schematic diagram of the laser circuit provided in the embodiment of the present application;

[0051] Figure 4 It is one of the curve diagrams of power reduction frequency provided in the embodiment of the present application;

[0052] Figure 5 This is the second curve diagram of the power reduction frequency provided in the embodiment of the present application;

[0053] Figure 6 It is a structural diagram of the FIFO delay module provided in an embodiment of the present application;

[0054] Figure 7 The pump width provided in the embodiment of the present application is 1 / f o Schematic diagram of single pulse energy curve at (40μs);

[0055] Figure 8 It is a schematic diagram of a single pulse energy curve when the pump width is 1 / fo+fl provided in an embodiment of the present application;

[0056] Fig. 9 It is a schematic diagram of a single pulse pump pulse width when the pump width provided in an embodiment of the present application is 1 / fo+fl;

[0057] Fig.10 It is a schematic diagram of a 200kHz power reduction point deviation curve provided in an embodiment of the present application;

[0058] Fig.11 It is a schematic diagram of the 200kHz power reduction point attenuation curve provided in an embodiment of the present application.

[0059] Reference numerals:

[0060] Laser circuit 100 ; board controller 110 ; frequency modulation circuit 111 ; light output adjustment circuit 112 ; power adjustment circuit 113 ; laser generating circuit 120 ; seed pulse generating circuit 121 ; gain circuit 122 ; control board 200 . DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0062] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0063] In the following, in conjunction with the accompanying drawings, the high-stability fiber pulse MOPA laser control method and the fiber pulse laser provided in the embodiments of the present application are described in detail through specific embodiments and their application scenarios.

[0064] The high-stability fiber pulse MOPA laser control method is applied to laser circuits;

[0065] like Figure 1 As shown, the laser circuit 100 is connected to the control board 200;

[0066] The laser circuit includes: a board controller 110 and a laser generating circuit 120;

[0067] The control board 200 is used to output a pulse width modulation signal, a repetition rate signal, a switching optical signal and a power signal;

[0068] The board controller 110 includes a frequency modulation circuit 111, a light output adjustment circuit 112 and a power adjustment circuit 113 which are connected to each other;

[0069] The laser generating circuit 120 includes a seed pulse generating circuit 121 and a gain circuit 122 connected in sequence;

[0070] like Figure 2 As shown, the method includes:

[0071] S1, outputting a frequency modulation signal according to the re-frequency signal through the frequency modulation circuit 111;

[0072] S2, when receiving a trigger signal, the seed pulse generating circuit 121 outputs a seed pulse and an index signal according to the pulse width modulation signal and the frequency modulation signal;

[0073] S3, obtaining a light output phase compensation signal according to the switch light signal and the index signal through the light output adjustment circuit 112 and outputting the signal;

[0074] S4, outputting a power compensation signal according to the power signal and the index signal through the power adjustment circuit 113;

[0075] S5, using the gain circuit 122, the seed pulse is compensated according to the output light phase compensation signal and the power compensation signal, and a laser pulse is output.

[0076] Among them, the master oscillator power amplifier (MOPA) can provide high-quality and high-power laser output.

[0077] The control board may include a control chip, such as a Field-Programmable Gate Array (FPGA).

[0078] The pulse width modulation signal is used to control the pulse width of the seed pulse. The repetition rate signal is used as a reference signal of the frequency to limit the number of laser pulses output per unit time. The switching light signal is used to control whether the laser emits a laser beam. The power signal is used to limit the power of the laser beam emitted by the laser.

[0079] It can be understood that the pulse width modulation signal, the repetition rate signal, the switching light signal and the power signal have clock synchronization.

[0080] The output light phase compensation signal is used to adjust the frequency of the seed pulse, and the output light phase of the pump is affected by the frequency.

[0081] In actual execution, the control board 200 outputs the pulse width modulation signal to the seed pulse generating circuit 121 , outputs the repetition frequency signal to the frequency modulation circuit 111 , outputs the switching light signal to the light output adjustment circuit 112 , and outputs the power signal to the power adjustment circuit 113 .

[0082] The frequency modulation circuit 111 outputs a frequency modulation signal according to the re-frequency signal, and outputs the frequency modulation signal to the seed pulse generating circuit 121;

[0083] In the laser generating circuit 120, the seed pulse generating circuit 121, upon receiving the trigger signal, outputs a seed pulse and an index signal according to the pulse width modulation signal and the frequency modulation signal, wherein the frequency modulation signal is used to adjust the phases of the pulse signal and the index signal, and outputs the seed pulse to the gain circuit 122, and outputs the index signal to the frequency modulation circuit 111, the light output adjustment circuit 112 and the power adjustment circuit 113 respectively;

[0084] The light output adjustment circuit 112 outputs a light output phase compensation signal for controlling the pumping duration according to the switch optical signal and the index signal;

[0085] The power regulating circuit 113 outputs the power compensation signal according to the power signal and the index signal;

[0086] The gain circuit 122 performs phase compensation and power compensation according to the output light phase compensation signal and the power compensation signal, and outputs a laser pulse.

[0087] According to the high-stability fiber pulse MOPA laser control method provided in the embodiment of the present application, compensation is performed through the output light phase compensation signal and the power compensation signal, and the power linearity of the output laser pulses of different frequencies and the single pulse energy remain stable, so that the energy of single pulses of different frequencies can be consistent, thereby improving the stability of the laser pulses and the output consistency.

[0088] In some embodiments, Figure 3 As shown, the frequency modulation circuit 111 includes a frequency measurement module, a frequency generation module and a frequency phase control module connected in sequence. The frequency modulation circuit outputs a frequency modulation signal according to the re-frequency signal, including:

[0089] The frequency measurement module measures the repetition frequency signal to obtain an input frequency;

[0090] Outputting a trigger pulse through the frequency generating module according to the light-on signal and the input frequency, wherein the light-on signal is output by the light-out adjustment circuit according to the switch light signal;

[0091] The frequency modulation signal is outputted through the frequency phase control module according to the trigger pulse, the input frequency and the index signal.

[0092] Among them, the trigger pulse is used for frequency phase control, and the index signal is used to control the pulse phase in the frequency phase control module.

[0093] In actual execution, the frequency measurement module measures the repetitive frequency signal input by the control board 200 to obtain the real-time input frequency;

[0094] The current intensity control module determines the current intensity of the pre-amplifier module and the main amplifier module according to the input frequency and the index signal, and generates a current intensity signal;

[0095] The light emission duration control module determines the pump duration of the pre-amplifier module and the main amplifier module according to the input frequency to compensate for the frequency single pulse energy stability;

[0096] The optical phase control module mainly generates a phase compensation signal based on the input frequency and pump duration, and outputs it to the preamplifier module and the main amplifier module, so as to compensate the frequency-phase characteristics of the seed pulse and the preamplifier module and the main amplifier module at different frequencies, so that the pulse phase of the seed pulse and the pump phase remain unchanged, thereby ensuring the amplifier efficiency and reducing the ASE (Amplified Spontaneous Emission) of the amplifier, especially when working at a low repetition rate.

[0097] The frequency generation module generates a trigger pulse consistent with the input frequency under the control of the light-on signal and gives it to the frequency phase control module; at the same time, the output trigger pulse also serves as a synchronization signal for the light-emitting duration control module.

[0098] The frequency phase control module generates a frequency modulation signal according to the input frequency, index signal and trigger pulse. The frequency modulation signal is used to adjust the phase of the seed pulse under different seed widths and compensate the frequency and phase characteristics of the preamplifier module.

[0099] In some embodiments, the gain circuit 122 includes a pre-amplifier module and a main amplifier module connected in sequence, and the gain circuit compensates the seed pulse according to the output light phase compensation signal and the power compensation signal to output a laser pulse, including:

[0100] Through the pre-amplifier module, the light emission duration of the seed pulse is controlled according to the light emission phase compensation signal and the current intensity signal, and an amplified signal is output;

[0101] The main amplifier module performs phase compensation on the amplified signal according to the output light phase compensation signal and the power compensation signal to obtain and output the laser pulse.

[0102] It can be understood that both the pre-amplifier module and the main amplifier module in the gain circuit 122 can adjust the gain of the seed pulse through pump power regulation and timing control.

[0103] For pump power regulation, the output power of the pump light source (such as laser diode, xenon lamp, etc.) can be adjusted to accurately control the particle excitation level in the gain medium.

[0104] For timing control, the pump energy can be transferred to the seed pulse at the appropriate time by adjusting the on and off time of the pump light.

[0105] In the pre-amplifier module, the pumping duration and amplitude are adjusted according to the current intensity signal to control the light intensity, which can control the excitation level of the laser gain medium, thereby adjusting the gain of the seed pulse. The seed pulse is phase compensated according to the light phase compensation signal, and the phase of the seed pulse is corrected to restore its phase to the ideal state, ensuring that the seed pulse maintains the best coherence after amplification.

[0106] Among them, the appropriate current intensity ensures that the gain of the laser medium is within an ideal range, avoiding over-saturation or insufficient gain.

[0107] When a signal passes through a gain medium, it may be affected by medium nonlinearity, dispersion effects or other environmental factors, causing the signal phase to shift.

[0108] In the main amplifier module, the output light phase compensation signal can correct the phase error of the amplified signal and the phase of the seed pulse; the power compensation signal can fine-tune the power of the amplified signal to ensure that the power of the output laser pulse is always stable at the target value.

[0109] The output phase compensation signal and the power compensation signal work together to ensure that the gain process of the output laser pulse can provide sufficient output power while ensuring the coherence and stability of the signal.

[0110] In this embodiment, in the pre-amplifier module, the seed pulse is amplified by a smaller pump energy to increase the power of the seed pulse to a suitable level to achieve maximum gain while avoiding over-saturation or nonlinear effects; in the main amplifier module, the signal is further amplified to achieve the required output power to ensure that the output laser pulse has higher power and stability. In a multi-stage high-power system, there are differences in the control circuit signals of each stage of the amplifier, which can easily cause timing problems. The amplifier synchronous light output phase adjustment logic ensures the safety of the light output timing of each stage.

[0111] In some embodiments, the power regulation circuit 113 includes a current intensity control module and a power control module connected in sequence; the power regulation circuit outputs a power compensation signal according to the power signal and the index signal, including:

[0112] Outputting a current intensity signal and a current control signal according to the input frequency and the index signal through the current intensity control module;

[0113] By means of the gain circuit 122, gain control is performed on the laser pulse according to the current control signal;

[0114] The power control module outputs the power compensation signal according to the current intensity signal.

[0115] The index signal is used in the current intensity control module to control the current intensity.

[0116] Since different seed pulses require different pump widths, real-time seed phase adjustment is required.

[0117] The pulse width of the seed pulse is 0.5 to 500 ns, and the corresponding pump width may vary from 5 ns to 100 μs. Therefore, the phase control of the seed requires high delay accuracy and a wide range. The frequency phase control module is internally provided with FIFO (First In, First Out) delay logic.

[0118] like Figure 4 As shown, the horizontal axis is frequency, the unit is kHz, and the vertical axis is average power, the unit is W, such as Figure 5 As shown, the horizontal axis is frequency in kHz, and the vertical axis is energy in mJ. When the working clock is 200MHz, the laser power reduction frequency is 40kHz, and the frequency works at 20kHz, the frequency phase control module needs to achieve a lag of 180° (delay of 25μs).

[0119] The phase control module mainly includes phase conversion delay logic and FIFO delay logic.

[0120] like Figure 6 As shown, in the FIFO delay logic implementation principle, the input is CLK, IN, the setting logic (delay value), and the output is OUT.

[0121] At the delay value T d After confirmation, calculate the number of delay clocks D required n :

[0122] D n =T d / T c

[0123] Among them, T c is the clock period of FIFO.

[0124] Assume that the maximum storage depth of FIFO is D epth , single bit, then the RAM occupied is D epth *bit resources, from storage unit 0 to D epth –D n If all the storage units are set to 0, then n After CLK, the IN state is output, that is, T d After the delay time, the output is in IN state.

[0125] In the pre-amplifier module, the frequency-phase characteristic is compensated. The pump drive generally adopts a linear constant current source. Its frequency-amplitude characteristic is similar to a low-pass filter, and the bandwidth is approximately close to 1MHz. Therefore, at different frequencies, the actual current phase has an offset (maximum lag of 90°). In order to ensure the stability of the pre-discharge current and seed pulse phase, it is necessary to compensate for the seed phase at different frequencies.

[0126] The pulse generating module receives the trigger pulse and outputs a seed pulse with the pulse width required by the control board 200, which is loaded into the radio frequency amplifier to drive the seed pump to output a laser pulse with the corresponding pulse width.

[0127] The pulse signal can be generated by delay multiplication, phase-locked loop or DDS.

[0128] In some embodiments, the seed pulse generating circuit 121 includes a pulse generating module and a seed module connected in sequence, and the seed pulse generating circuit, when receiving a trigger signal, outputs a seed pulse and an index signal according to the pulse width modulation signal and the frequency modulation signal, including:

[0129] The pulse generating module is triggered by the trigger signal and outputs a pulse signal and an index signal according to the pulse width modulation signal and the frequency modulation signal;

[0130] The seed module outputs the seed pulse according to the pulse signal.

[0131] In some embodiments, the light output adjustment circuit 112 includes a light output control module, a light output duration control module, and a light output phase control module connected in sequence; the light output adjustment circuit obtains and outputs a light output phase compensation signal according to the switch optical signal and the index signal, including:

[0132] Obtaining a light output control signal according to the switch light signal through the light output control module;

[0133] Outputting a pumping duration signal through the light emission duration control module according to the light emission control signal, the input frequency, the index signal and the trigger pulse;

[0134] The light output phase compensation signal is outputted through the light output phase control module according to the pump duration signal and the input frequency.

[0135] The light control module mainly performs clock synchronization processing on the switch light control signal of the control board, which will solve the problem of cross-clock domain. One channel outputs the light-on signal to the frequency generation module to force synchronization with the light-on signal; the other channel outputs the light control signal to the light duration control module.

[0136] After receiving the light emission control signal, the light emission duration control module generates a pump duration signal by synchronizing the seed pulse width (index signal) and the current frequency (input frequency) through a trigger pulse to control the pump light emission time to ensure the stability of the light pulse energy.

[0137] When working at low frequency, the amplifier pump extraction efficiency in the gain circuit 122 is low, so the light emission time is prolonged; the functional relationship is: The functional relationship is expressed by o Below the frequency of / 2, the pump width is adjusted without changing the energy.

[0138] Formula 2: y = ax b +c; coefficient a = 105.37, b = -0.348, c = -40. The above coefficients will be adjusted according to different machines, x represents the input frequency f, y represents the adjustment amount of the pump width under low frequency operation f l , we can get the functional relationship:

[0139] f l =af b +c

[0140] like Figure 7-Figure 9 As shown in the figure, after compensation by formula 2, the single pulse energy is significantly improved. Figure 7 is the uncompensated energy curve. After compensation, Figure 8 , the pulse energy stability is significantly improved.

[0141] When working at high frequency, due to the low-pass characteristics of the constant current source, the pump output power will become higher in the frequency transition band, and the light output time will be reduced in this frequency band. h , the functional relationship is f h =ψ(f); the functional relationship is obtained by o / 2 to f o The pump width is adjusted while the frequency and energy remain unchanged. The fitting formula is as follows:

[0142] like Fig.10 As shown in 11, for formula 3: f h =af+b; coefficient a=0.5454, b=-84.136; where the independent variable x is the operating frequency divided by the power reduction frequency point. The above deviations are mainly caused by the circuit bandwidth and the pump's own characteristics.

[0143] The power reduction frequency point is f o , then the pump light emission time T on for:

[0144] T on =1 / f o +f l –fh ;

[0145] Where 1 / f o is the reference width of the pulse pump, used as the reference time.

[0146] The light output phase control module receives the pumping duration signal from the light output duration control module, combines the input frequency, and outputs the light output phase compensation signal through the light output phase control module to control the pumping light output of the pre-amplifier module and the main amplifier module. The light output intensity is controlled by the light output intensity control logic.

[0147] Due to the current value, wire length, constant current source loop parameters, and frequency-phase characteristics of the pump constant current source in the pre-amplifier module and the main amplifier module, there is a difference in the phase of the gain control of the seed pulse by the pre-amplifier module and the main amplifier module. The light output phase control signal can compensate for the difference, achieve synchronization, and further improve the energy stability of the laser pulse.

[0148] In the light intensity control logic, in the current intensity control module, the peak current corresponding to each seed pulse width in the pre-amplifier module and the main amplifier module is cached in its memory. After the pulse width is confirmed according to the input frequency, the peak current of the pre-amplifier module and the main amplifier module is indexed according to the index signal. The actual current of the pre-amplifier module and the main amplifier module is calculated through the peak current and frequency function relationship of the pre-amplifier module and the main amplifier module, and the current control signal and the current intensity signal are obtained, which are directly loaded onto the pump of the pre-amplifier module, and the current intensity signal is output to the power control module.

[0149]

[0150] Where, f is the laser frequency, f o is the pulse pump frequency (reference), f h To reduce the power frequency.

[0151] When the laser frequency f is less than the pulse pump frequency boundary point f o When the pulse pump is working, the duty cycle will decrease as the frequency decreases, and the pulse pump output peak current I max ; When the laser frequency f is greater than the pulse pump frequency boundary point f o , and is less than the power reduction frequency f h When the laser frequency f is greater than the power reduction frequency f h , continuous pump output peak current I max ; Added f o For the pulse pump frequency, the linear constant current source has a maximum frequency. When the frequency is greater than this, the linear constant current source will not respond.

[0152] The power control module determines the output power compensation signal according to the process application requirements based on the current intensity signal and the power signal, controls the output power of the main amplifier module, and loads the power percentage multiplied by the current of the main amplifier module to the pump of the main amplifier module.

[0153] The power compensation signal is mainly used for attenuation. The current intensity is used to calculate the maximum current under the corresponding frequency and pulse. The pre-amplifier module directly outputs it, and the main amplifier module attenuates the power percentage before outputting the laser pulse.

[0154] In this embodiment, after the pulse width is determined, the pump width is different at each frequency. The laser circuit can ensure the stability of the power linearity and single pulse energy of the final output laser pulse, and can solve the problem of efficiency differences at different frequencies. Since the pump width of each frequency is different, the seed pulse phase is adjusted to ensure the maximum pump extraction efficiency of the amplifier and the safety of the laser when the parameters are changed. In order to ensure the alignment of the starting end of the marking process and the adjustment of the seed phase, the seed pulse is forced to be synchronized after the opening signal is valid. The seed phase adjustment range of different laser types is 5ns to 200μs, which is the synchronization of the timing system and a wide range of delay. The FIFO method is used to achieve delay, which has the characteristics of high precision, wide range, and complete synchronization. This is also an innovation of the present invention.

[0155] The high-stability fiber pulse MOPA laser control method provided in the embodiment of the present application can realize pump control to improve the TMI threshold, while correcting the frequency power nonlinear distortion and performing synchronization processing on the starting position control in the processing system.

[0156] In some embodiments, the laser circuit further includes a clock circuit, and the clock circuit is connected to the control board. The method further includes:

[0157] Generate an output clock signal according to the internal clock signal of the laser through the clock circuit;

[0158] Clock synchronization is performed through the control board according to the output clock signal.

[0159] In some embodiments, the method further comprises:

[0160] The clock circuit receives the input clock signal of the control board, and the input clock signal is used to perform clock synchronization on the pulse width modulation signal, the repetition frequency signal, the switching optical signal and the power signal.

[0161] Among them, the clock circuit has a built-in phase-locked loop (PLL).

[0162] In this embodiment, by outputting a clock signal or inputting a clock signal, the laser circuit and the control board are completely synchronized to achieve high-precision pulse control.

[0163] In some embodiments, the laser circuit further comprises: a central processing unit, and the method further comprises:

[0164] The central processor is used to configure parameters of the frequency modulation circuit, the light output adjustment circuit and the power adjustment circuit in the board controller.

[0165] The board controller can be implemented through FPGA logic, and the communication interface of the central processing unit (CPU) includes an Ethernet port and a serial port.

[0166] The present application also provides a fiber pulse laser for executing the high-stability fiber pulse MOPA laser control method as described in the above embodiment.

[0167] In the description of this application, "first feature" or "second feature" may include one or more of the features.

[0168] In the description of the present application, “plurality” means two or more.

[0169] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0170] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0171] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A high-stability fiber pulse MOPA laser control method, characterized in that: Applied to a laser circuit, the laser circuit is connected to a control board; The laser circuit comprises: a board controller and a laser generating circuit; The control board is used to output a pulse width modulation signal, a repetition rate signal, a switching optical signal and a power signal; The board controller includes a frequency modulation circuit, a light output adjustment circuit and a power adjustment circuit which are connected to each other; The laser generating circuit includes a seed pulse generating circuit and a gain circuit connected in sequence; The method comprises: Outputting a frequency modulation signal according to the re-frequency signal through the frequency modulation circuit; By means of the seed pulse generating circuit, when a trigger signal is received, a seed pulse and an index signal are output according to the pulse width modulation signal and the frequency modulation signal; Obtaining a light output phase compensation signal according to the switch light signal and the index signal through the light output adjustment circuit and outputting the signal; Outputting a power compensation signal according to the power signal and the index signal through the power regulation circuit; The seed pulse is compensated for by the gain circuit according to the light output phase compensation signal and the power compensation signal, and a laser pulse is output.

2. The high-stability fiber pulse MOPA laser control method according to claim 1, characterized in that: The light output adjustment circuit includes a light output control module, a light output duration control module and a light output phase control module connected in sequence; the light output adjustment circuit obtains and outputs a light output phase compensation signal according to the switch optical signal and the index signal, including: Obtaining a light output control signal according to the switch light signal through the light output control module; Outputting a pumping duration signal through the light emission duration control module according to the light emission control signal, the input frequency, the index signal and the trigger pulse; The light output phase compensation signal is outputted through the light output phase control module according to the pump duration signal and the input frequency.

3. The high-stability fiber pulse MOPA laser control method according to claim 2, characterized in that: The power regulation circuit includes a current intensity control module and a power control module connected in sequence; the power regulation circuit outputs a power compensation signal according to the power signal and the index signal, including: Outputting a current intensity signal and a current control signal according to the input frequency and the index signal through the current intensity control module; Performing gain control on the laser pulse according to the current control signal through the gain circuit; The power control module outputs the power compensation signal according to the current intensity signal.

4. The high-stability fiber pulse MOPA laser control method according to claim 1, characterized in that: The seed pulse generating circuit comprises a pulse generating module and a seed module connected in sequence, and the seed pulse generating circuit outputs a seed pulse and an index signal according to the pulse width modulation signal and the frequency modulation signal when receiving a trigger signal, including: The pulse generating module is triggered by the trigger signal and outputs a pulse signal and an index signal according to the pulse width modulation signal and the frequency modulation signal; The seed module outputs the seed pulse according to the pulse signal.

5. The high-stability fiber pulse MOPA laser control method according to claim 1, characterized in that: The frequency modulation circuit includes a frequency measurement module, a frequency generation module and a frequency phase control module connected in sequence, and outputting a frequency modulation signal according to the re-frequency signal through the frequency modulation circuit includes: The frequency measurement module measures the repetition frequency signal to obtain an input frequency; Outputting a trigger pulse through the frequency generating module according to the light-on signal and the input frequency, wherein the light-on signal is output by the light-out adjustment circuit according to the switch light signal; The frequency modulation signal is outputted through the frequency phase control module according to the trigger pulse, the input frequency and the index signal.

6. The high-stability fiber pulse MOPA laser control method according to claim 1, characterized in that: The gain circuit includes a pre-amplifier module and a main amplifier module connected in sequence, and the seed pulse is compensated by the gain circuit according to the output light phase compensation signal and the power compensation signal to output a laser pulse, including: Through the pre-amplifier module, the light emission duration of the seed pulse is controlled according to the light emission phase compensation signal and the current intensity signal, and an amplified signal is output; The main amplifier module performs phase compensation on the amplified signal according to the output light phase compensation signal and the power compensation signal to obtain and output the laser pulse.

7. The high-stability fiber pulse MOPA laser control method according to claim 1, characterized in that: The laser circuit further includes a clock circuit, and the clock circuit is connected to the control board. The method further includes: Generate an output clock signal according to the internal clock signal of the laser by the clock circuit; Clock synchronization is performed through the control board according to the output clock signal.

8. The high-stability fiber pulse MOPA laser control method according to claim 7, characterized in that: The method further comprises: The clock circuit receives the input clock signal of the control board, and the input clock signal is used to perform clock synchronization on the pulse width modulation signal, the repetition frequency signal, the switching optical signal and the power signal.

9. The high-stability fiber pulse MOPA laser control method according to claim 1, characterized in that: The laser circuit further comprises: a central processing unit, and the method further comprises: The central processor performs parameter configuration on the frequency modulation circuit, the light output adjustment circuit and the power adjustment circuit in the board controller.

10. A fiber pulse laser, characterized in that: Used to execute the high-stable fiber pulse MOPA laser control method as described in any one of claims 1-9.

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