A multi-mode seed source laser and power stabilization method

Abstract

The application discloses a multi-mode seed source laser and a power stabilization method, and the laser comprises a data processing module, an arbitrary waveform generator, a high-speed constant current source driving circuit, an optoelectronic acquisition module, a double-channel analog-digital acquisition module and a seed source laser; the data processing module comprises a microcontroller, a programmable logic device, a first PID control unit and a second PID control unit which are electrically connected with the microcontroller; the programmable logic device is electrically connected with the double-channel analog-digital acquisition module; signal output ends of the first and second PID control units are electrically connected with the arbitrary waveform generator; an output end of the arbitrary waveform generator is electrically connected with the high-speed constant current source driving circuit; and the high-speed constant current source driving circuit is electrically connected with the seed source laser. Through the double-independent PID closed loop architecture, the pulse light and the continuous light power can be independently detected and regulated in time, the substrate signal interference can be avoided, the high-resolution arbitrary waveform output is supported, and the stability and flexibility of the multi-mode laser output are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of laser source control technology, specifically to a multi-mode seed laser and a power stabilization method. Background Technology

[0002] With the continuous development of the precision industrial processing industry, various micro-etching, composite cladding, and fine drilling processes have placed increasingly stringent demands on the comprehensive performance of laser light sources. As the signal source of the MOPA laser system, the seed source laser's output laser waveform and energy characteristics are directly transmitted to the processing section after power amplification, making it a core front-end component that determines the workpiece processing and forming effect.

[0003] Existing seed lasers typically consist of a pump source, a gain medium, a resonant cavity, a pulse modulator, and a drive control circuit. The pump source injects energy into the gain medium under the action of the drive circuit. The light in the resonant cavity is amplified and output as continuous laser light, or pulsed laser light is generated by the pulse modulator. To achieve power stability, existing seed lasers generally employ a single-channel photoelectric acquisition circuit to split and detect the output light, and a single-channel power closed-loop controller adjusts the current of the constant current source drive circuit based on the detection signal feedback. Limited by traditional hardware architecture design, the drive circuit of existing seed lasers typically only has a single PID control channel. Whether outputting continuous or pulsed light, the same control algorithm and the same set of hardware links are used for regulation. When switching operating modes is required, the system can only switch the drive current configuration and control parameters as a whole, and cannot simultaneously activate two independent control loops within the same resonant cavity to independently calculate and coordinately regulate the continuous and pulsed light components. Therefore, traditional single-cavity seed lasers only support independent output in a single mode, either outputting continuous light alone or pulsed light alone, and cannot achieve simultaneous coexistence of pulsed and continuous light output within the same resonant cavity.

[0004] Meanwhile, traditional seed source lasers are only equipped with a single photoelectric detection path and a single PID closed-loop control structure. For continuous light output, the average power signal obtained by the photodetector after low-pass filtering is sufficient to meet the voltage regulation requirements. However, for pulsed light output, this acquisition architecture can only obtain the average power of the pulse train and cannot identify the peak power of a single pulse or the energy fluctuations between pulses. Furthermore, this single-path acquisition structure cannot provide feedback data for two independent control loops. Even with multi-mode lasers, the control architecture is only a single controller switching mode, rather than waveform synthesis after parallel operation by two controllers. If it is necessary to achieve superimposed output of pulsed and continuous light in a single path, this single-path acquisition structure cannot distinguish between the DC base component of continuous light and the instantaneous peak component of the pulse, and cannot separately identify the pulse peak fluctuations and continuous light amplitude fluctuations. Therefore, the traditional control system can only achieve a rough stability of the overall power and completely lacks the ability to independently decouple and adjust the power of pulsed light and continuous light, and cannot achieve the linkage and synchronous ratio adjustment of the power of the two modes. Even if the superposition of pulsed light and continuous light is barely achieved through external auxiliary means, the power of the other light will be passively shifted when the power parameter of any one of them is adjusted, and the stability and consistency of the power ratio of the two modes cannot be guaranteed.

[0005] To address the process requirements of precision thermal co-processing that simultaneously requires pulsed high-energy etching and continuous light preheating, those skilled in the art have adopted a multi-source laser output and beam combining technique. This involves configuring two or more independent light sources to generate pulsed and continuous light respectively, and then optically combining them to achieve dual-mode laser output. This traditional improvement scheme requires two independent drive circuits, two independent photoelectric acquisition feedback loops, and two independent control units. The overall equipment is large, hardware costs are high, system timing synchronization accuracy is poor, and the power of the two laser streams is difficult to precisely match. These inherent defects lead to an imbalance in the energy ratio of pulsed and continuous light when the laser is amplified and applied to the workpiece. Due to the nonlinear difference in the response of the amplification stage gain saturation characteristics to the pulse peak power and the continuous light substrate power, the energy ratio of pulsed and continuous light is easily disrupted during amplification. This results in poor consistency in processing effects between different batches and even within the same batch of workpieces, making it difficult to meet the current high-end industrial processing requirements for precise power matching and synchronous adjustment of the two light sources.

[0006] In view of this, how to overcome the shortcomings of the existing technology has become the subject of study and solution of this invention. Summary of the Invention

[0007] The purpose of this invention is to provide a multi-mode seed source laser and a power stabilization method.

[0008] To achieve the above objectives, on the one hand, the technical solution provided by the present invention is: a multi-mode seed source laser, comprising: a data processing module, an arbitrary waveform generator, a high-speed constant current source driving circuit, a photoelectric acquisition module, a dual-channel analog-to-digital acquisition module, and a seed source laser; The data processing module includes a microcontroller, a programmable logic device, a first PID control unit, and a second PID control unit. The microcontroller is electrically connected to the programmable logic device, the first PID control unit, and the second PID control unit, respectively. The programmable logic device is electrically connected to the dual-channel analog-to-digital acquisition module and is used to distribute the acquired digital feedback signal to the corresponding PID control unit via the microcontroller. Both the first PID control unit and the second PID control unit have built-in independent digital PID algorithms, and their signal output terminals are electrically connected to the arbitrary waveform generator; the output terminal of the arbitrary waveform generator is electrically connected to the high-speed constant current source drive circuit. The high-speed constant current source driving circuit is electrically connected to the seed source laser and is used to output a composite driving current containing a DC bias component and a pulse modulation component to drive the seed source laser to output continuous light alone, pulsed light alone, or pulsed and continuous light simultaneously. The photoelectric acquisition module includes a photodetector, a transimpedance amplifier, a peak hold circuit, and a filter circuit. The photodetector is used to acquire the laser signal output by the seed source laser, and the signal output terminal of the photodetector is electrically connected to the transimpedance amplifier. The output of the transimpedance amplifier is divided into two paths: one path is electrically connected to the peak hold circuit, and the other path is electrically connected to the filter circuit. The peak hold circuit is used to latch the peak voltage signal of the pulsed light, and the filter circuit is used to output a stable continuous optical voltage signal. The peak hold circuit and the filter circuit are electrically connected to the dual-channel analog-to-digital acquisition module, which converts the two analog voltage signals into corresponding digital feedback signals and transmits them to the programmable logic device.

[0009] In the above scheme, the microcontroller is used to receive external control signals, configure the working mode of the seed source laser, including pulse mode, continuous mode and pulse and continuous synchronous mode, input the preset power ratio parameters and target power parameters of the pulse light and continuous light of the seed source laser, and send working parameters and timing scheduling instructions to the first PID control unit and the second PID control unit.

[0010] The programmable logic device is used to output system synchronization timing signals and reads the digital feedback signals output by the dual-channel analog-to-digital acquisition module in a time-division manner through the SPI interface. The digital feedback signals are then transmitted to the microcontroller, which schedules and distributes them to the corresponding first PID control unit and second PID control unit. Both the first PID control unit and the second PID control unit have built-in digital PID algorithms, which can receive measured power data and target power parameters, and autonomously complete power deviation calculation and PID adjustment operation. The signal output terminals of the first PID control unit and the second PID control unit are electrically connected to an arbitrary waveform generator for outputting waveform adjustment control quantities. Through the overall architecture of dual-channel independent acquisition, dual PID control unit time-sharing closed loop, and multi-mode collaborative control, pulse, continuous, and pulse and continuous synchronous output can be realized, effectively solving the problem of difficult precise timing matching of the two beams and unstable power in existing traditional seed source lasers, thus improving processing consistency. At the same time, the pulse peak and continuous average power of this application can be independently controlled, effectively solving the problem of poor processing consistency caused by pulse peak drift due to relying solely on stable average power in the current industry, thus improving the stability of laser processing power ratio.

[0011] In a further technical solution, the first PID control unit incorporates a continuous light average power PID control algorithm, and the second PID control unit incorporates a pulse peak power PID control algorithm.

[0012] By adopting the above technical solution, the first PID control unit has a built-in continuous light average power PID control algorithm, and the second PID control unit has a built-in pulse peak power PID control algorithm. The parameters of the two algorithms are independent and do not interfere with each other, effectively avoiding the defect that a single control algorithm cannot simultaneously adapt to pulse instantaneous peak and continuous average stability. The first PID control unit is a continuous PID controller adapted to continuous light control, and the second PID control unit is a pulse PID controller adapted to pulse light control.

[0013] In a further technical solution, the high-speed constant current source driving circuit includes a high-bandwidth operational amplifier, an RF power transistor, and a sampling resistor. The input terminal of the high-bandwidth operational amplifier is electrically connected to the arbitrary waveform generator, and the output terminal of the high-bandwidth operational amplifier is electrically connected to the RF power transistor. The output terminal of the RF power transistor is electrically connected to the seed laser, the seed laser is electrically connected to the sampling resistor, and the output terminal of the sampling resistor is electrically connected to the high-bandwidth operational amplifier, forming a current negative feedback loop to calibrate the drive current output to the seed laser in real time.

[0014] By adopting the above technical solution, a current negative feedback adjustment circuit is formed by a high-bandwidth operational amplifier, an RF power transistor, and a sampling resistor, which can quickly respond to the switching of working modes and the dynamic adjustment requirements, thereby further improving the stability of laser output and the consistency of processing.

[0015] A further technical solution is that the dual-channel analog-to-digital acquisition module includes a high-precision analog-to-digital converter and a high-speed analog-to-digital converter. The high-precision analog-to-digital converter is electrically connected to the filter circuit and is used to acquire continuous optical power signals. The high-speed analog-to-digital converter is electrically connected to the peak hold circuit and is used to acquire pulsed optical peak power signals.

[0016] By adopting the above technical solution, a high-precision analog-to-digital converter acquires continuous optical power signals, and a high-speed analog-to-digital converter acquires pulsed optical peak power signals. Differentiated acquisition is performed based on the characteristics of the two laser signals, effectively solving the problems that single sampling and single-channel cannot balance speed and accuracy, and that the feedback data is inaccurate.

[0017] In a further technical solution, the sampling rate of the high-speed analog-to-digital converter is not less than 65MS / s.

[0018] By adopting the above technical solution, the sampling rate of the high-speed analog-to-digital converter is no less than 65MS / s, which is used to sample the pulse flat-top signal after the peak hold circuit is broadened multiple times. By accumulating and averaging, the accuracy of pulse peak power detection is improved. Pulse waveforms can be collected in high density, and instantaneous peaks can be captured completely, reducing the possibility of missed sampling and peak sampling distortion.

[0019] In a further technical solution, the photodetector is an avalanche diode.

[0020] By adopting the above technical solution, avalanche diodes have fast response speed and high bandwidth.

[0021] In a further technical solution, the transimpedance amplifier is a 100MHz transimpedance amplifier, which adopts a three-stage cascaded amplification mode to amplify the weak photocurrent signal output by the avalanche diode.

[0022] By adopting the above technical solution, 100MHz is used to adapt to high-speed narrow pulse signals. The three-stage cascaded amplification significantly amplifies the weak photocurrent output by the avalanche diode, thereby improving the stability of subsequent processing.

[0023] On the other hand, the technical solution provided by the present invention is: a power stabilization method for a multi-mode seed source laser, applied to the multi-mode seed source laser, the method comprising the following steps: Step 1: Configure the working mode of the seed laser through the microcontroller. The working modes include pulse mode, continuous mode, and pulse and continuous synchronous mode. Input the target power parameters for the corresponding working mode through the microcontroller. When the working mode is pulse and continuous synchronous mode, also input the preset power ratio parameters of pulse light and continuous light and send the parameters to the corresponding PID control unit. Step 2: The microcontroller generates the corresponding timing instructions according to the selected working mode and sends the timing instructions to the arbitrary waveform generator. The arbitrary waveform generator outputs the matching waveform signal. The high-speed constant current source drive circuit outputs the drive current according to the output waveform signal, driving the seed source laser to output the laser of the corresponding mode. Step 3: The laser light signal output by the seed source laser is acquired in real time by a photodetector. The light signal is converted and amplified into a voltage signal by a transimpedance amplifier and then divided into two signals. One signal is sent to the peak holding circuit to obtain the pulse peak voltage signal, and the other signal is sent to the filter circuit to obtain a stable continuous photovoltage signal. Step 4: The dual-channel analog-to-digital acquisition module acquires the pulse peak voltage signal and the continuous optical voltage signal respectively and converts them into digital signals, obtaining two digital signals and transmitting them to the programmable logic device. The programmable logic device reads the corresponding number of digital feedback signals according to the current working mode. In pulse and continuous synchronous mode, the two digital feedback signals are read in a time-division manner to distinguish the pulse peak power data and the continuous optical average power data, which are then transmitted to the microcontroller. The microcontroller sends the pulse peak power data to the second PID control unit and the continuous optical average power data to the first PID control unit. Step 5: The first PID control unit and the second PID control unit respectively receive the corresponding measured power data and preset target parameters, autonomously calculate the continuous optical power deviation and pulse peak power deviation, and generate the corresponding waveform adjustment correction data through the built-in digital PID algorithm. Step Six: Through unified scheduling using programmable logic devices, the first PID control unit and the second PID control unit operate independently or collaboratively according to the selected operating mode: In continuous mode, the first PID control unit calculates and outputs the continuous optical power adjustment amount independently; In pulse mode, the second PID control unit calculates and outputs the pulse peak power adjustment amount independently; In pulse and continuous synchronous mode, the two PID control units operate in parallel and output their respective adjustment correction data synchronously. The two adjustment correction data are combined into a single composite waveform signal by an arbitrary waveform generator. The composite waveform signal is converted into the corresponding mode's drive current by a high-speed constant current source drive circuit to stably output optical power.

[0024] By adopting the above technical solution, through working mode configuration and timing distribution, combined with dual-channel independent sampling and closed-loop calculation correction by dual PID control units, synchronous and controllable output of pulse and continuous processing can be achieved, effectively solving the problem of poor processing consistency caused by the mismatch of timing and power in traditional pulse and continuous processing.

[0025] In a further technical solution, in step four, the pulse peak voltage signal is sent to a high-speed analog-to-digital converter to complete data processing, and the continuous optical voltage signal is sent to a high-precision analog-to-digital converter to complete data processing.

[0026] By adopting the above technical solution and processing the signals separately, the mutual interference between the two signals is effectively reduced, ensuring that the pulse peak data and the continuous optical power data are independent and have high acquisition accuracy, thereby reducing subsequent processing deviations and improving data processing accuracy.

[0027] In a further technical solution, in step five, the microcontroller calls the corresponding closed-loop control algorithm according to the working mode and matches the corresponding PID control unit to complete the calculation and adjustment; When in pulse mode: the microcontroller starts the high-speed analog-to-digital converter, captures the peak power of the pulse in real time through the sliding average window, averages the peak power of multiple consecutive pulses, filters out random jitter of single pulses, compares the average value with the preset target peak power, calculates the correction amount through the pulse PID algorithm in the second PID control unit, adjusts the modulation current output by the arbitrary waveform generator, and realizes closed-loop stabilization of pulse power. When in continuous mode: the microcontroller starts the high-precision analog-to-digital converter, performs digital low-pass filtering on the acquired continuous optical voltage signal and calculates the continuous optical power value, compares the actual continuous optical power with the preset target power, calculates the correction amount through the continuous optical PID algorithm in the first PID control unit, adjusts the output waveform of the arbitrary waveform generator, and realizes the closed-loop stability of continuous optical power. When in pulse and continuous synchronous mode: the microcontroller, based on the synchronization timing provided by the programmable logic device, collects and latches the pulse peak power in conjunction with the peak hold circuit at the moment the pulse occurs, and then switches to the continuous optical power acquisition state, calling the corresponding algorithms of the first PID control unit and the second PID control unit in a time-division manner to synchronously correct the output waveforms corresponding to the pulse peak power and the continuous optical power, and maintain the stability of the dual-mode power ratio.

[0028] By adopting the above technical solutions, multiple working modes can be realized to meet existing processing needs and improve processing consistency.

[0029] Due to the application of the above-mentioned solution, the technical solution of this application has the following advantages and effects compared with the prior art: Significantly improved power stability: Through dual-channel independent acquisition and dual-PID closed-loop control, the long-term stability of pulse peak power and the stability of continuous optical power are significantly improved; compared with the traditional single-channel PID seed source solution, it effectively suppresses the problems of pulse peak drift and dual-mode power ratio imbalance.

[0030] Significant advantages in synchronization accuracy and cost: Compared with the dual-source beam combining scheme, this application adopts a single-path composite driving current to drive a single source. The timing synchronization of pulse and continuous light is uniformly controlled by the same arbitrary waveform generator, which significantly improves the synchronization accuracy. At the same time, it reduces the hardware configuration such as independent source light and optical beam combiner, reducing equipment cost and size, while avoiding engineering problems such as optical path alignment and beam combining loss.

[0031] Highly flexible control: Supports arbitrary waveform editing with a resolution of 200MSPS. Pulse repetition rate, peak power, continuous light substrate power, and their ratio can be independently and continuously adjusted to meet the different process requirements of various precision machining scenarios such as micro-etching, composite cladding, and fine drilling.

[0032] The architecture features synergistic gains: through the coordinated cooperation of dual-path decoupled acquisition, dual PID independent closed loop, and electrical waveform synthesis, independent and stable control of dual-mode power is achieved in a single resonant cavity, breaking through the technical bias in this field that a single cavity can only output in a single mode. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a multi-mode seed source laser system according to an embodiment of the present invention; Figure 2 This is a baseline waveform diagram of the photoelectric detection signal in the seed source laser off state in an embodiment of the present invention; Figure 3 This is a measured waveform of the output optical signal of the seed source laser in continuous mode in an embodiment of the present invention; Figure 4 This is a measured waveform of the output optical signal of the seed source laser in pulse mode in an embodiment of the present invention; Figure 5 This is a measured waveform of the output optical signal of the seed source laser in pulsed and continuous synchronous modes in an embodiment of the present invention. Figure 1 ; Figure 6 This is a measured waveform of the output optical signal of the seed source laser in pulsed and continuous synchronous modes in an embodiment of the present invention. Figure 2 ; Figure 7 This is a schematic diagram of a method for stabilizing the power of a multi-mode seed source laser according to an embodiment of the present invention. Detailed Implementation

[0034] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0035] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0036] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0037] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0038] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing this case.

[0039] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0040] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0041] This application aims to solve the problem that the existing MOPA seed source laser can only stabilize the average power and cannot synchronously adjust the pulse peak and continuous optical power, resulting in poor processing consistency.

[0042] See Figure 1 As shown, a multi-mode seed source laser includes: a data processing module, an arbitrary waveform generator, a high-speed constant current source driving circuit, a photoelectric acquisition module, a dual-channel analog-to-digital acquisition module, and a seed source laser; The data processing module includes a microcontroller, a programmable logic device (PLD), a first PID control unit, and a second PID control unit. The microcontroller is electrically connected to the PLD, the first PID control unit, and the second PID control unit. The microcontroller receives external control signals, configures the operating mode of the seed laser (including pulse mode, continuous mode, and pulse / continuous synchronous mode), inputs the preset power ratio parameters and target power parameters of the pulsed and continuous light from the seed laser, and sends operating parameters and timing instructions to the first and second PID control units. In the diagram, the microcontroller is an MCU, and the PLD is an FPGA.

[0043] The programmable logic device (PLD) is electrically connected to the dual-channel analog-to-digital (ADC) acquisition module, used to distribute the acquired digital feedback signals to the corresponding PID control units via the microcontroller. The PLD outputs system synchronization timing signals and reads the digital feedback signals from the dual-channel ADC through an SPI interface in a time-division multiplexing manner, transmitting the digital feedback signals to the microcontroller, which then schedules and distributes them to the corresponding first and second PID control units. Both the first and second PID control units have built-in digital PID algorithms, capable of receiving measured power data and target power parameters, autonomously performing power deviation calculations and PID adjustment operations. The signal output terminals of both the first and second PID control units are electrically connected to an arbitrary waveform generator for outputting waveform adjustment control quantities.

[0044] The output of the arbitrary waveform generator is electrically connected to a high-speed constant current source drive circuit. This high-speed constant current source drive circuit is electrically connected to the seed laser and outputs a composite drive current containing a DC bias component and a pulse modulation component to drive the seed laser to output continuous light, pulsed light, or both pulsed and continuous light simultaneously. The arbitrary waveform generator is represented in the diagram as a 200MSPS mode controller.

[0045] In this embodiment, the seed source laser is a butterfly-packaged semiconductor laser. Butterfly-packaged semiconductor lasers are characterized by fast response speed and high electro-optical conversion efficiency. Their output optical power is linearly related to the injected current. Therefore, by precisely controlling the high and low level amplitude ratio of the composite drive current, the ratio of continuous optical substrate power to pulse peak power can be independently adjusted. The output optical waveform of the semiconductor laser is consistent with the injected current waveform. Therefore, when the high-speed constant current source drive circuit outputs a composite drive current containing DC bias and pulse modulation components, the seed source laser directly outputs the corresponding composite optical waveform of the continuous optical substrate superimposed with the pulse peak, achieving single-cavity dual-mode coexistence output without the need for additional intracavity or extracavity modulation devices.

[0046] To verify the output characteristics of the three operating modes mentioned above, the output optical signal of the seed source laser was measured using a photoelectric acquisition module. The results are as follows: Figure 2 This is the baseline waveform of the photodetector signal with the seed source laser off. The horizontal axis time base is 1.00 μs / division, and the vertical axis scale is 50.0 mV / division. The waveform is a stable horizontal bright line, corresponding to the baseline state when the system has no output, and serves as the benchmark for comparing the waveforms of the three subsequent operating modes.

[0047] Figure 3 This is the measured waveform of the output optical signal from the seed source laser in continuous mode. The horizontal axis time base is 1.00 μs / division, and the vertical axis scale is 50.0 mV / division. The waveform is a stable horizontal bright line, corresponding to constant power output of continuous light.

[0048] Figure 4 This is the measured waveform of the output optical signal from the seed source laser in pulsed mode. The horizontal axis time base is 1.00 μs / division, and the vertical axis scale is 50.0 mV / division. The waveform is a periodic sharp pulse, with the pulse starting from the substrate.

[0049] Figure 5 This is a measured waveform of the output optical signal of the seed source laser in pulsed and continuous synchronous modes (high repetition rate condition). The horizontal axis time base is 1.00 μs / division, and the vertical axis scale is 50.0 mV / division. The bright line at the bottom of the waveform corresponds to the continuous optical substrate power, and the peak corresponds to the pulse peak power. Under this condition, the pulse interval is short, and the continuous optical substrate remains stable, making it suitable for high-speed processing scenarios that require high-frequency pulse superposition and preheating.

[0050] Figure 6 This is a measured waveform of the output optical signal from the seed source laser in pulsed and continuous synchronous modes (low repetition rate condition). The horizontal axis time base is 1.00 μs / division, and the vertical axis scale is 50.0 mV / division. The bright line at the bottom of the waveform corresponds to the continuous light substrate power, and the spike corresponds to the pulse peak power. Under this condition, the pulse interval is relatively long, and the continuous light substrate accounts for a higher proportion, which is suitable for composite processing scenarios that require strong preheating effects in conjunction with intermittent pulse etching.

[0051] The waveform data above are example data for this embodiment. In actual operation, the pulse repetition rate, pulse peak power, continuous optical substrate power, and the power ratio between the two can be flexibly adjusted according to specific processing requirements, and are not limited to the example values ​​above.

[0052] The photoelectric acquisition module includes a photodetector, a transimpedance amplifier, a peak hold circuit, and a filter circuit. The photodetector is used to acquire the laser signal output from the seed laser source, and its signal output terminal is electrically connected to the transimpedance amplifier. The output terminal of the transimpedance amplifier is divided into two paths: one is electrically connected to the peak hold circuit, and the other is electrically connected to the filter circuit. The peak hold circuit latches the peak voltage signal of the pulsed light, and the filter circuit outputs a stable continuous photovoltage signal. The peak hold circuit and the filter circuit are electrically connected to a dual-channel analog-to-digital (ADC) acquisition module, which converts the two analog voltage signals into corresponding digital feedback signals and transmits them to a programmable logic device. The photodetector is an avalanche diode. The transimpedance amplifier is a 100MHz transimpedance amplifier using a three-stage cascaded amplification mode to amplify the weak photocurrent signal output by the avalanche diode.

[0053] The dual-channel analog-to-digital (ADC) acquisition module includes a high-precision ADC and a high-speed ADC. The high-precision ADC is electrically connected to the filtering circuit and is used to acquire continuous optical power signals. The high-speed ADC is electrically connected to the peak hold circuit and is used to acquire pulsed optical peak power signals. The sampling rate of the high-speed ADC is no less than 65 MS / s, and it is used to sample the pulse flat-top signal after it has been broadened by the peak hold circuit multiple times, thereby improving the accuracy of pulse peak power detection through cumulative averaging.

[0054] The first PID control unit incorporates a continuous light average power PID control algorithm, and the second PID control unit incorporates a pulse peak power PID control algorithm. In this embodiment, the first PID control unit is a continuous PID controller adapted to continuous light modulation, and the second PID control unit is a pulse PID controller adapted to pulsed light modulation.

[0055] The high-speed constant current source drive circuit includes a high-bandwidth operational amplifier, an RF power transistor, and a sampling resistor. The input of the high-bandwidth operational amplifier is electrically connected to an arbitrary waveform generator, and the output of the high-bandwidth operational amplifier is electrically connected to the RF power transistor. The output of the RF power transistor is electrically connected to a seed laser, the seed laser is electrically connected to the sampling resistor, and the output of the sampling resistor is electrically connected to the high-bandwidth operational amplifier, forming a current negative feedback loop to calibrate the drive current output to the seed laser in real time.

[0056] The implementation principle of a multi-mode seed source laser in this embodiment is as follows: The data processing module includes a microcontroller (MCU), a programmable logic device (FPGA), a first PID control unit, and a second PID control unit. The first and second PID control units have built-in PID control algorithms (proportional integral derivative control algorithms).

[0057] Microcontrollers (MCUs) are used to receive control signals from the host computer or device to control the output current and waveform of the seed source; programmable logic devices (FPGAs) are used to synchronize the timing of each module and accurately acquire the voltage amplitude of pulse and continuous optical signals.

[0058] The microcontroller (MCU) first sets the operating mode of the seed laser source: continuous mode, pulsed mode, and pulsed and continuous synchronous mode. In continuous mode, the microcontroller enables a high-precision analog-to-digital converter (ADC); in pulsed mode, it enables a high-speed ADC; and in pulsed and continuous synchronous mode, an arbitrary waveform generator outputs a PWM waveform signal with an adjustable duty cycle. This waveform contains a low-level substrate component and a high-level pulse component: the low-level period corresponds to the continuous optical substrate power, and the high-level period superimposes the pulse modulation component onto the continuous optical substrate to form the pulse peak power. By independently adjusting the ratio of the high-level amplitude to the low-level amplitude, the pulse peak power and the continuous optical substrate power are independently controllable; by adjusting the PWM duty cycle, the pulse width and repetition rate are controlled.

[0059] At the start of pulse output, the microcontroller first activates the peak hold circuit to temporarily store the highest amplitude voltage, which is then repeatedly sampled by the high-speed analog-to-digital converter (ADC). Meanwhile, the microcontroller (MCU) controls the high-precision ADC to acquire the voltage already in continuous mode. After receiving the data from the high-precision ADC acquisition circuit, the MCU selects and calls the corresponding PID control unit based on the current operating mode: in continuous mode, it calls the first PID control unit alone; in pulse mode, it calls the second PID control unit alone; and in pulse and continuous synchronous mode, it calls both PID control units in parallel and outputs correction values ​​synchronously. The pulse PID controller and the continuous PID controller are adjusted in a time-division manner, and the results, calculated by the algorithm, control the actual output current of the high-speed constant current source drive circuit, achieving power stability under both pulse and continuous operating conditions.

[0060] In this embodiment, the arbitrary waveform generator can be a high-speed digital-to-analog converter with an update rate of 200MSPS, controlled by a programmable logic device (FPGA) via a parallel bus. It can achieve a voltage output signal with a resolution of 5ns adjustment, which is used to set the output current of the subsequent high-speed constant current source drive circuit.

[0061] High-speed constant current source drive circuit: The main components include a high-bandwidth operational amplifier, an RF power transistor, and a sampling resistor, forming a negative feedback adjustment circuit.

[0062] The photoelectric acquisition module consists of a 100MHz transimpedance amplifier, a peak hold circuit, a filter circuit, and an avalanche diode. First, the avalanche diode acquires the weak optical signal separated from the main output optical path. To improve the amplification factor and ensure high bandwidth, a three-stage cascaded amplification mode is adopted. The amplified signal includes both pulse and continuous optical signals, and the pulse duration is much shorter than the continuous operation time. Therefore, a programmable logic device (FPGA) is used for synchronous timing control. During the pulse current generation time, the peak hold circuit function is activated. The peak hold circuit tracks the peak voltage of the pulsed light in real time. If the peak value of the subsequent pulse is higher than the current latch value, it is automatically updated to the new value; otherwise, the original latch value remains unchanged. The hold time of the peak hold circuit can be dynamically adjusted according to the pulse repetition rate, not less than 1μs, ensuring that the high-speed analog-to-digital converter completes multiple sampling and averaging times, reserving sufficient time slots for continuous optical power acquisition. After the latch stabilizes, the FPGA controls the high-speed analog-to-digital converter to complete the acquisition. After acquisition, the FPGA sends a clear signal to reset the peak hold circuit, waiting for the next pulse peak acquisition. After the pulsed light acquisition signal ends, the programmable logic device (FPGA) controls the continuous light acquisition signal. The output signal of the photodetector is processed by the filter circuit and then enters the high-precision analog-to-digital converter of the continuous light.

[0063] The dual-channel analog-to-digital (ADC) acquisition module (also known as a high-precision ADC acquisition circuit) inputs pulsed light and continuous light into a high-speed ADC and a high-precision ADC, respectively. The high-speed ADC is a pulse ADC acquisition circuit with a sampling rate of not less than 65 MS / s, while the high-precision ADC is a continuous ADC acquisition circuit.

[0064] The seed source laser has three operating modes: pulsed mode, continuous mode, and pulsed and continuous synchronous mode. In pulsed mode, the microcontroller activates a high-speed analog-to-digital converter (ADC) to capture the peak power of the pulse in real time through a moving average window. The peak power of N consecutive pulses is averaged to filter out random jitter in single pulses; in this embodiment, the peak power of at least 20 pulses is averaged. The average value is compared with a preset target peak power, and a correction amount is calculated using a PID algorithm to adjust the modulation current output of the 200MSPS high-speed ADC, achieving closed-loop stabilization of the pulse power. In continuous mode, the microcontroller activates a high-precision ADC to acquire the output voltage of the photodetector and convert it into a continuous optical power value after digital low-pass filtering. When pulsed and continuous modes operate simultaneously, the microcontroller activates the high-speed ADC at the moment the pulse occurs, according to the FPGA's synchronization timing, to obtain the peak power of the pulse. The voltage value of this peak power is latched at the output of the peak hold circuit. The microcontroller switches to continuous mode, acquires the continuous optical power, and uses the PID processing algorithms of both modes in a time-division multiplexing manner to synchronously adjust the peak optical power and continuous optical power.

[0065] In summary, this laser features two independent optical signal acquisition lines that can separately detect the peak value of the pulsed light and the continuous light power, eliminating the interference of the continuous light signal on the detection of the pulse peak value and resulting in stronger output power stability. Combined with an arbitrary waveform generator, various output waveforms can be freely edited, and stable light control can be maintained regardless of the waveform. Relying on programmable logic devices to acquire power data from the two channels in a time-division manner, and using two independent PID units to perform closed-loop regulation of the pulsed and continuous light respectively, the control is flexible and can accurately match the different power ratio requirements of composite processing.

[0066] Reference Figure 7 As shown, this embodiment also discloses a power stabilization method for a multimode seed laser, applied to the aforementioned multimode seed laser. The method includes the following steps: Step 1: Configure the working mode of the seed laser through the microcontroller. The working modes include pulse mode, continuous mode, and pulse and continuous synchronous mode. Input the target power parameters for the corresponding working mode through the microcontroller. When the working mode is pulse and continuous synchronous mode, also input the preset power ratio parameters of pulse light and continuous light and send the parameters to the corresponding PID control unit. Step 2: The microcontroller generates the corresponding timing instructions according to the selected working mode and sends the timing instructions to the arbitrary waveform generator. The arbitrary waveform generator outputs the matching waveform signal. The high-speed constant current source drive circuit outputs the drive current according to the output waveform signal, driving the seed source laser to output the laser of the corresponding mode. Step 3: The laser light signal output by the seed source laser is acquired in real time by a photodetector. The light signal is converted and amplified into a voltage signal by a transimpedance amplifier and then divided into two signals. One signal is sent to the peak holding circuit to obtain the pulse peak voltage signal, and the other signal is sent to the filter circuit to obtain a stable continuous photovoltage signal. Step 4: The dual-channel analog-to-digital acquisition module acquires the pulse peak voltage signal and the continuous optical voltage signal respectively and converts them into digital signals, resulting in two digital signals which are transmitted to the programmable logic device (PLD). The PLD reads the corresponding number of digital feedback signals according to the current operating mode. In pulse and continuous synchronous mode, the two digital feedback signals are read in a time-division manner to distinguish the pulse peak power data and the continuous optical average power data, which are then transmitted to the microcontroller. The microcontroller sends the pulse peak power data to the second PID control unit and the continuous optical average power data to the first PID control unit. The pulse peak voltage signal is sent to a high-speed analog-to-digital converter for data processing, and the continuous optical voltage signal is sent to a high-precision analog-to-digital converter for data processing.

[0067] Step 5: The first PID control unit and the second PID control unit respectively receive the corresponding measured power data and preset target parameters, autonomously calculate the continuous optical power deviation and pulse peak power deviation, and generate the corresponding waveform adjustment correction data through the built-in digital PID algorithm; the microcontroller calls the corresponding closed-loop control algorithm according to the working mode and matches the corresponding PID control unit to complete the calculation and adjustment. When in pulse mode: the microcontroller starts the high-speed analog-to-digital converter, captures the peak power of the pulse in real time through the sliding average window, averages the peak power of multiple consecutive pulses, filters out random jitter of single pulses, compares the average value with the preset target peak power, calculates the correction amount through the pulse PID algorithm in the second PID control unit, adjusts the modulation current output by the arbitrary waveform generator, and realizes closed-loop stabilization of pulse power. When in continuous mode: the microcontroller starts the high-precision analog-to-digital converter, performs digital low-pass filtering on the acquired continuous optical voltage signal and calculates the continuous optical power value, compares the actual continuous optical power with the preset target power, calculates the correction amount through the continuous optical PID algorithm in the first PID control unit, adjusts the output waveform of the arbitrary waveform generator, and realizes the closed-loop stability of continuous optical power. When in pulse and continuous synchronous mode: the microcontroller, based on the synchronization timing provided by the programmable logic device, collects and latches the pulse peak power in conjunction with the peak hold circuit at the moment the pulse occurs, and then switches to the continuous optical power acquisition state, calling the corresponding algorithms of the first PID control unit and the second PID control unit in a time-division manner to synchronously correct the output waveforms corresponding to the pulse peak power and the continuous optical power, and maintain the stability of the dual-mode power ratio.

[0068] Step Six: Through unified scheduling using programmable logic devices, the first PID control unit and the second PID control unit operate independently or collaboratively according to the selected operating mode: In continuous mode, the first PID control unit calculates and outputs the continuous optical power adjustment amount independently; In pulse mode, the second PID control unit calculates and outputs the pulse peak power adjustment amount independently; In pulse and continuous synchronous mode, the two PID control units operate in parallel and output their respective adjustment correction data synchronously. The two adjustment correction data are combined into a single composite waveform signal by an arbitrary waveform generator. The composite waveform signal is converted into the corresponding mode's drive current by a high-speed constant current source drive circuit to stably output optical power.

[0069] By separately detecting the output power of pulsed and continuous light, the microcontroller's control algorithm calculates and adjusts the output current magnitude of pulsed and continuous light in a time-division manner, thereby improving the overall output power stability of the laser. In this method, the data processing module controls a 200MSPS arbitrary waveform generator to produce a control signal. The high-speed constant current source drive circuit outputs a synchronous current to drive the seed source laser according to the control signal. The high-bandwidth photoelectric acquisition module receives the optical signal from the seed source, converts the current into a voltage signal through a 100MHz transimpedance amplifier, a peak hold circuit maintains the voltage of the peak pulse, and a filter circuit obtains a smooth voltage for the continuous light. This voltage is then transmitted to a dual-channel high-precision ADC acquisition circuit. The data processing module reads the digital value from the ADC via the SPI interface and uses a digital PID algorithm to process the amplitude of the continuous and pulsed voltages in a time-division manner, adjusting the high-speed constant current source drive circuit to improve the stability of both pulsed and continuous laser outputs.

[0070] The photoelectric acquisition module of this application has two independent analog paths. One path is a peak hold circuit to acquire pulse peaks, and the other path is a filter circuit to acquire the average signal of continuous light. The two paths are respectively connected to a dual-channel analog-to-digital acquisition module. The continuous light substrate will not mix in pulse peaks, effectively reducing the interference of the continuous light substrate on pulse peak detection and improving power stability.

[0071] This application features an arbitrary waveform generator, supporting arbitrary waveform editing (200MSPS resolution) and ensuring stable power output under any waveform. Combined with dual independent PID control units for closed-loop regulation, real-time power correction can be performed separately for pulsed and continuous light, ensuring output stability. Pulsed and continuous light amplitudes can be detected independently. The transimpedance amplifier output is split into two paths: a peak hold circuit separately acquires the pulse peak voltage, and a filter circuit separately acquires the continuous stable voltage. These two analog signals are fed into a dual-channel analog-to-digital acquisition module, enabling separate sampling and detection of the two types of optical power.

[0072] The main control program collects optical power in two modes in a time-division manner. The programmable logic device outputs the system synchronization timing signal and reads the digital feedback signal output by the dual-channel analog-to-digital acquisition module in a time-division manner through the SPI interface. The digital feedback signal is then transmitted to the microcontroller, which schedules and distributes it to the corresponding first PID control unit and second PID control unit.

[0073] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A multi-mode seed source laser, characterized in that, include: Data processing module, arbitrary waveform generator, high-speed constant current source drive circuit, photoelectric acquisition module, dual-channel analog-to-digital acquisition module and seed source laser; The data processing module includes a microcontroller, a programmable logic device, a first PID control unit, and a second PID control unit. The microcontroller is electrically connected to the programmable logic device, the first PID control unit, and the second PID control unit, respectively. The programmable logic device is electrically connected to the dual-channel analog-to-digital acquisition module and is used to distribute the acquired digital feedback signal to the corresponding PID control unit via the microcontroller. Both the first PID control unit and the second PID control unit have built-in independent digital PID algorithms, and their signal output terminals are electrically connected to the arbitrary waveform generator; the output terminal of the arbitrary waveform generator is electrically connected to the high-speed constant current source drive circuit. The high-speed constant current source driving circuit is electrically connected to the seed source laser and is used to output a composite driving current containing a DC bias component and a pulse modulation component to drive the seed source laser to output continuous light alone, pulsed light alone, or pulsed and continuous light simultaneously. The photoelectric acquisition module includes a photodetector, a transimpedance amplifier, a peak hold circuit, and a filter circuit. The photodetector is used to acquire the laser signal output by the seed source laser, and the signal output terminal of the photodetector is electrically connected to the transimpedance amplifier. The output of the transimpedance amplifier is divided into two paths: one path is electrically connected to the peak hold circuit, and the other path is electrically connected to the filter circuit. The peak hold circuit is used to latch the peak voltage signal of the pulsed light, and the filter circuit is used to output a stable continuous optical voltage signal. The peak hold circuit and the filter circuit are electrically connected to the dual-channel analog-to-digital acquisition module, which converts the two analog voltage signals into corresponding digital feedback signals and transmits them to the programmable logic device.

2. The multimode seed source laser according to claim 1, characterized in that: The first PID control unit has a built-in continuous light average power PID control algorithm, and the second PID control unit has a built-in pulse peak power PID control algorithm.

3. A multi-mode seed source laser according to claim 1, characterized in that: The high-speed constant current source driving circuit includes a high-bandwidth operational amplifier, an RF power transistor, and a sampling resistor. The input terminal of the high-bandwidth operational amplifier is electrically connected to the arbitrary waveform generator, and the output terminal of the high-bandwidth operational amplifier is electrically connected to the RF power transistor. The output terminal of the RF power transistor is electrically connected to the seed laser, the seed laser is electrically connected to the sampling resistor, and the output terminal of the sampling resistor is electrically connected to the high-bandwidth operational amplifier, forming a current negative feedback loop to calibrate the drive current output to the seed laser in real time.

4. A multi-mode seed source laser according to claim 1, characterized in that: The dual-channel analog-to-digital acquisition module includes a high-precision analog-to-digital converter and a high-speed analog-to-digital converter. The high-precision analog-to-digital converter is electrically connected to the filter circuit and is used to acquire continuous optical power signals. The high-speed analog-to-digital converter is electrically connected to the peak hold circuit and is used to acquire pulsed optical peak power signals.

5. A multi-mode seed source laser according to claim 4, characterized in that: The sampling rate of the high-speed analog-to-digital converter is not less than 65 MS / s.

6. A multimode seed source laser according to claim 1, characterized in that: The photodetector is an avalanche diode.

7. A multimode seed source laser according to claim 6, characterized in that: The transimpedance amplifier is a 100MHz transimpedance amplifier, which adopts a three-stage cascaded amplification mode to amplify the weak photocurrent signal output by the avalanche diode.

8. A method for stabilizing the power of a multi-mode seed laser, characterized in that, The method, applied to the multimode seed source laser of any one of claims 1-7, comprises the following steps: Step 1: Configure the working mode of the seed laser through the microcontroller. The working modes include pulse mode, continuous mode, and pulse and continuous synchronous mode. Input the target power parameters for the corresponding working mode through the microcontroller. When the working mode is pulse and continuous synchronous mode, also input the preset power ratio parameters of pulse light and continuous light and send the parameters to the corresponding PID control unit. Step 2: The microcontroller generates the corresponding timing instructions according to the selected working mode and sends the timing instructions to the arbitrary waveform generator. The arbitrary waveform generator outputs the matching waveform signal. The high-speed constant current source drive circuit outputs the drive current according to the output waveform signal, driving the seed source laser to output the laser of the corresponding mode. Step 3: The laser light signal output by the seed source laser is acquired in real time by a photodetector. The light signal is converted and amplified into a voltage signal by a transimpedance amplifier and then divided into two signals. One signal is sent to the peak holding circuit to obtain the pulse peak voltage signal, and the other signal is sent to the filter circuit to obtain a stable continuous photovoltage signal. Step 4: The dual-channel analog-to-digital acquisition module acquires the pulse peak voltage signal and the continuous optical voltage signal respectively and converts them into digital signals, obtaining two digital signals and transmitting them to the programmable logic device. The programmable logic device reads the corresponding number of digital feedback signals according to the current working mode. In pulse and continuous synchronous mode, the two digital feedback signals are read in a time-division manner to distinguish the pulse peak power data and the continuous optical average power data, which are then transmitted to the microcontroller. The microcontroller sends the pulse peak power data to the second PID control unit and the continuous optical average power data to the first PID control unit. Step 5: The first PID control unit and the second PID control unit respectively receive the corresponding measured power data and preset target parameters, autonomously calculate the continuous optical power deviation and pulse peak power deviation, and generate the corresponding waveform adjustment correction data through the built-in digital PID algorithm. Step Six: Through unified scheduling using programmable logic devices, the first PID control unit and the second PID control unit operate independently or collaboratively according to the selected operating mode: In continuous mode, the first PID control unit calculates and outputs the continuous optical power adjustment amount independently; In pulse mode, the second PID control unit calculates and outputs the pulse peak power adjustment amount independently; In pulse and continuous synchronous mode, the two PID control units operate in parallel and output their respective adjustment correction data synchronously. The two adjustment correction data are combined into a single composite waveform signal by an arbitrary waveform generator. The composite waveform signal is converted into the corresponding mode's drive current by a high-speed constant current source drive circuit to stably output optical power.

9. The method for stabilizing the power of a multi-mode seed laser according to claim 8, characterized in that: In step four, the pulse peak voltage signal is sent to a high-speed analog-to-digital converter to complete data processing, and the continuous photovoltage signal is sent to a high-precision analog-to-digital converter to complete data processing.

10. The method for stabilizing the power of a multi-mode seed source laser according to claim 8, characterized in that: In step five, the microcontroller calls the corresponding closed-loop control algorithm according to the working mode and matches the corresponding PID control unit to complete the calculation and adjustment. When in pulse mode: the microcontroller starts the high-speed analog-to-digital converter, captures the peak power of the pulse in real time through the sliding average window, averages the peak power of multiple consecutive pulses, filters out random jitter of single pulses, compares the average value with the preset target peak power, calculates the correction amount through the pulse PID algorithm in the second PID control unit, adjusts the modulation current output by the arbitrary waveform generator, and realizes closed-loop stabilization of pulse power. When in continuous mode: the microcontroller starts the high-precision analog-to-digital converter, performs digital low-pass filtering on the acquired continuous optical voltage signal and calculates the continuous optical power value, compares the actual continuous optical power with the preset target power, calculates the correction amount through the continuous optical PID algorithm in the first PID control unit, adjusts the output waveform of the arbitrary waveform generator, and realizes the closed-loop stability of continuous optical power. When in pulse and continuous synchronous mode: the microcontroller, based on the synchronization timing provided by the programmable logic device, collects and latches the pulse peak power in conjunction with the peak hold circuit at the moment the pulse occurs, and then switches to the continuous optical power acquisition state, calling the corresponding algorithms of the first PID control unit and the second PID control unit in a time-division manner to synchronously correct the output waveforms corresponding to the pulse peak power and the continuous optical power, and maintain the stability of the dual-mode power ratio.

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