A laser power stabilization method based on acousto-optic modulator

Abstract

The present application belongs to the field of quantum sensing and precision measurement technology. The present application provides a laser power stabilization method based on an acousto-optic modulator. The disclosed embodiment is based on the conservation of optical power, that is, the laser power entering the AOM is the sum of the powers of the emitted level 0 beam and level 1 beam. Laser power control is performed using the laser light source power, level 0 or level 1 beam, that is, the light source input power and the level 1 beam of the acousto-optic modulator are measured in real time, the outer ring beam power is characterized by difference, and the control target value is adjusted by the PID controller to stabilize the difference between the laser source power and the beam involved in the control. The outer ring beam is cleverly involved in the feedback control loop through numerical methods, which can effectively suppress the fluctuation noise of the laser light source, thereby effectively improving the long-term stability of the laser power.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of quantum sensing and precision measurement technology, and in particular to a laser power stabilization method based on an acousto-optic modulator. Background Art

[0002] In the research and application of quantum sensing, lasers, as important components, play an indispensable role, and the stability of laser power also has a significant impact on the sensor's final output. For example, in atomic magnetometers, laser power drift can cause frequency deviations in the output oscillation signal, thereby affecting the resolution and stability of magnetic field measurements. In atomic clock applications, laser power drift reduces the medium- and long-term stability of atomic clocks. In gravitational wave detection, laser power stability is directly coupled to the interferometer's measurement results, resulting in a reduction in detection effectiveness. Currently, research results are increasing on actuators that can change the intensity of diffracted light, such as liquid crystal variable phase retarders, electro-optic modulators, acousto-optic modulators, and magneto-optical modulators, combined with feedback control technology to achieve stable laser power control.

[0003] The problem with the existing technology is that when using an acousto-optic modulator, only level 0 or level 1 beam splitting is used for feedback control. The control loop will suppress any interference. Therefore, only the noise that causes common interference to the outer ring beam and the inner ring beam can be jointly suppressed, such as the drift of the laser source power. Suppressing non-common interference will cause the outer ring beam power to shift accordingly, such as the change in the PBS splitting ratio caused by AOM temperature fluctuations, resulting in poor medium- and long-term stability. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a laser power stabilization method based on an acousto-optic modulator (AOM). This method addresses the problem in the prior art of insufficient long-term stability of the outer ring beam caused by feedback control after only using level 0 or level 1 beam splitting when using an AOM. This problem is caused by the control loop suppressing any interference.

[0005] According to a first aspect of an embodiment of the present disclosure, a method for stabilizing laser power based on an acousto-optic modulator is provided, the method comprising:

[0006] A beam splitter is used to split the laser beam into a forward beam and a sampling beam according to a preset ratio n;

[0007] Setting parameters of a power controller and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal;

[0008] Inputting the forward light beam into an acousto-optic modulator, and controlling the diffraction efficiency of the forward light beam in the acousto-optic modulator using the amplitude-modulated high-frequency sinusoidal signal to obtain first-order diffracted light and zero-order diffracted light;

[0009] Separating the first-order diffracted light and the zero-order diffracted light by a right-angle beam splitter, and determining an inner ring light beam and an outer ring light beam according to the first-order diffracted light and the zero-order diffracted light;

[0010] The inner ring light beam is sequentially input into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and the sampling light beam is sequentially input into a second photodetector and a second analog-to-digital converter for processing to obtain a second digital signal;

[0011] Inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal;

[0012] The analog signal is input into the power controller, and the power controller adjusts the acousto-optic modulator according to the analog signal to output the stable outer ring light beam.

[0013] Furthermore, the power of the sampling beam is Ps, the power of the forward beam is PL=Ps / n, and the sampling beam: the forward beam∈(0.01-0.5), that is, n∈(0.01-0.5).

[0014] Furthermore, the method further comprises:

[0015] The angle between the forward light beam and the acousto-optic modulator is adjusted so that the forward light beam enters the acousto-optic modulator at a Bragg angle.

[0016] Furthermore, the power of the first-order diffracted light is P1, the power of the zero-order diffracted light is P0, and PL=P0+P1+δ, where δ is the loss in the optical path.

[0017] Furthermore, the step of separating the first-order diffracted light and the zero-order diffracted light by a right-angle beam splitter, and determining the inner ring light beam and the outer ring light beam according to the first-order diffracted light and the zero-order diffracted light includes:

[0018] If the 1st-order diffraction light is taken as the inner ring light beam, the 0th-order diffraction light is the outer ring light beam;

[0019] If the 0th-order diffracted light is taken as the inner ring light beam, the 1st-order diffracted light is taken as the outer ring light beam;

[0020] The inner ring beam is used for power control, and the outer ring beam is used for output application.

[0021] Furthermore, the steps of sequentially inputting the inner ring light beam into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and sequentially inputting the sampling light beam into a second photodetector and a second analog-to-digital converter for processing to obtain a second digital signal include:

[0022] Inputting the inner ring light beam into the first photodetector, wherein the first photodetector converts the inner ring light beam into a first electrical signal;

[0023] Inputting the first electrical signal into the first analog-to-digital converter, so that the first analog-to-digital converter converts the first electrical signal into the first digital signal;

[0024] Inputting the sampling light beam into the second photodetector, the second photodetector converting the sampling light beam into a second electrical signal;

[0025] The second electrical signal is input into the second analog-to-digital converter, and the second analog-to-digital converter converts the second electrical signal into the second digital signal.

[0026] Furthermore, the step of inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal includes:

[0027] obtaining the power of the inner ring light beam according to the first digital signal;

[0028] Obtaining the power Ps of the sampling beam according to the second digital signal, and obtaining the power PL of the forward beam according to the power Ps of the sampling beam;

[0029] The PID control target value Pol is set according to the power of the inner ring light beam and the power PL of the forward light beam, and the digital error signal is generated according to the PID control target value; wherein, when the 0th-order diffracted light serves as the inner ring light beam, the PID control target value is P0=PL-Pol-δ; when the 1st-order diffracted light serves as the inner ring light beam, the PID control target value is P1=PL-Pol-δ;

[0030] The digital error signal is input to the digital-to-analog converter, and the digital-to-analog converter converts the digital error signal into the analog signal.

[0031] According to a second aspect of an embodiment of the present disclosure, a method for stabilizing laser power based on an acousto-optic modulator is provided, the method comprising:

[0032] Setting parameters of a power controller and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal;

[0033] Inputting the laser beam into an acousto-optic modulator, and controlling the diffraction efficiency of the laser beam in the acousto-optic modulator using the amplitude-modulated high-frequency sinusoidal signal to obtain first-order diffracted light and zero-order diffracted light;

[0034] Separating the first-order diffracted light and the zero-order diffracted light by a right-angle beam splitter, and determining an inner ring light beam and an outer ring light beam according to the first-order diffracted light and the zero-order diffracted light;

[0035] The inner ring light beam is sequentially input into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and the laser light beam is sampled by a proportional beam splitter and sequentially input into a signal conditioning unit and a second analog-to-digital converter for processing to obtain a second digital signal; wherein the signal conditioning unit is used to obtain the power of the laser light beam;

[0036] Inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal;

[0037] The analog signal is input into the power controller, and the power controller adjusts the amplitude of the high-frequency sine wave signal according to the analog signal and controls the acousto-optic modulator to output the stable outer ring light beam.

[0038] Furthermore, the step of inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal includes:

[0039] obtaining the power of the inner ring light beam according to the first digital signal;

[0040] Using a fixed-ratio beam splitter to obtain the power of the sampling beam, and obtaining the power of the forward beam according to the power of the sampling beam;

[0041] The PID control target value is set according to the power of the inner ring light beam and the power of the forward light beam, and the digital error signal is generated according to the PID control target value.

[0042] The technical solutions provided by the embodiments of the present disclosure may have the following beneficial effects:

[0043] In the embodiments of the present disclosure, through the above-mentioned laser power stabilization method based on the acousto-optic modulator, when the power of the laser beam cannot be directly obtained, the power of the incident laser beam of the acousto-optic modulator is sampled in real time based on the principle of power conservation, and the direction and optical path of the emitted 0th-order diffraction light and 1st-order diffraction light with a very small spacing are changed using a right-angle diffraction prism, and the inner ring light beam participating in the control is also sampled in real time and analog-to-digital conversion is performed. The difference between the laser beam power and the inner ring light beam is the outer ring light beam power. In the PID controller, after specifying the outer ring light beam power, the inner ring light beam power target value is adjusted in real time by calculation to offset the power fluctuation noise of the light source. In principle, the purpose of the outer ring light beam being able to participate in the control without being blocked is achieved, so that the stability is greatly improved. When the electrical signal representing the laser beam power can be obtained directly from the laser device, the sampling beam splitter is omitted, and the laser light source directly enters the acousto-optic modulator. The emitted 0th-order diffraction light and 1st-order diffraction light with a small spacing are redirected and the optical path is expanded using a right-angle beam splitter prism. The inner ring light beam involved in the control is also sampled in real time and analog-to-digital converted. The difference between the laser beam power and the inner ring light beam is the outer ring light beam power. In the PID controller, after specifying the outer ring light beam power, the inner ring light beam power target value is adjusted in real time through calculation to offset the power fluctuation noise of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0045] Figure 1 A diagram showing the steps of a laser power stabilization method based on an acousto-optic modulator in an exemplary embodiment of the present disclosure;

[0046] Figure 2 A specific flow chart showing a method for stabilizing laser power based on an acousto-optic modulator in an exemplary embodiment of the present disclosure is provided;

[0047] Figure 3 A diagram showing the light source disturbance suppression effect in an exemplary embodiment of the present disclosure is shown;

[0048] Figure 4 A diagram showing the effect of improving long-term stability in an exemplary embodiment of the present disclosure;

[0049] Figure 5 A diagram showing the steps of another laser power stabilization method based on an acousto-optic modulator in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0050] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0051] In addition, the accompanying drawings are merely schematic illustrations of embodiments of the present disclosure and are not necessarily drawn to scale. Like reference numerals in the figures represent like or similar parts, and thus repeated descriptions thereof will be omitted. Some of the blocks shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically separate entities.

[0052] This example embodiment provides a laser power stabilization method based on an acousto-optic modulator. Figure 1 As shown in , the laser power stabilization method based on the acousto-optic modulator may include: steps S101 to S107.

[0053] Step S101: using a beam splitter to split the laser beam into a forward beam and a sampling beam according to a preset ratio n;

[0054] Step S102: setting parameters of a power controller, and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal;

[0055] Step S103: inputting the forward light beam into an acousto-optic modulator, and controlling the diffraction efficiency of the forward light beam in the acousto-optic modulator using the amplitude-modulated high-frequency sinusoidal signal to obtain first-order diffracted light and zero-order diffracted light;

[0056] Step S104: using a right-angle beam splitter to separate the first-order diffracted light and the zero-order diffracted light, and determining an inner ring light beam and an outer ring light beam according to the first-order diffracted light and the zero-order diffracted light;

[0057] Step S105: sequentially inputting the inner ring light beam into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and sequentially inputting the sampling light beam into a second photodetector and a second analog-to-digital converter for processing to obtain a second digital signal;

[0058] Step S106: inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal;

[0059] Step S107: inputting the analog signal into the power controller, and the power controller adjusts the acousto-optic modulator according to the analog signal to output the stable outer ring light beam.

[0060] Through the above-mentioned laser power stabilization method based on the acousto-optic modulator, when the power of the laser beam cannot be directly obtained, the power of the incident laser beam of the acousto-optic modulator is sampled in real time based on the principle of power conservation. The 0th-order diffraction light and the 1st-order diffraction light with a small spacing are emitted using a right-angle beam splitter to change the direction and expand the optical path. The inner ring beam participating in the control is also sampled in real time and analog-to-digital conversion is performed. The difference between the laser beam power and the inner ring beam is the outer ring beam power. In the PID controller, after specifying the outer ring beam power, the inner ring beam power target value is adjusted in real time through calculation to offset the power fluctuation noise of the light source. In principle, the purpose of allowing the outer ring beam to participate in the control without being blocked is achieved, so that the stability is greatly improved. When the electrical signal representing the laser beam power can be obtained directly from the laser device, the sampling beam splitter is omitted, and the laser light source directly enters the acousto-optic modulator. The inner ring beam involved in the control is also sampled in real time and converted into analog to digital. The difference between the laser beam power and the inner ring beam is the outer ring beam power. In the PID controller, after specifying the outer ring beam power, the inner ring beam power target value is adjusted in real time through calculation to offset the power fluctuation noise of the light source.

[0061] Below, we will refer to Figures 1 to 4 Each step of the above-mentioned laser power stabilization method based on an acousto-optic modulator in this exemplary embodiment is described in more detail.

[0062] In one embodiment, Figure 2 As shown, the device used in the method includes: 1. a laser light source; 2. a beam splitter; 3. an acousto-optic modulator (AOM); 4. a right-angle beam splitter; 5. a first photodetector (PD1); 6. a first analog-to-digital converter (ADC1); 7. a PID controller; 8. a digital-to-analog converter (DAC); 9. a power controller; 10. a second photodetector (PD2); 11. a second analog-to-digital converter (ADC2); and 12. a signal conditioning unit.

[0063] Among them, the laser light source is used to generate the laser beam of the frequency required for experimental research and application;

[0064] Beam splitters are used to sample the input power of the source. If an electrical signal representing the power can be directly obtained from the laser source, it can be omitted. Beam splitters are not limited to polarizing and non-polarizing beam splitters and prisms.

[0065] an acousto-optic modulator for continuously controlling the intensity of the light beam by adjusting the diffraction index of the light according to the amplitude of the driving signal from the power controller;

[0066] A right-angle beam splitter is used to separate the 0th and 1st order lights, which are closely spaced, so that a photodetector can be placed therein to sample them;

[0067] The first photoelectric detector is used to convert the inner ring light intensity control signal (either level 0 or level 1) into an electrical signal;

[0068] a first analog-to-digital converter, configured to convert the electrical signal of the first photodetector into a digital signal;

[0069] a second photodetector, configured to convert the sampled laser light source signal into an electrical signal;

[0070] a second analog-to-digital converter, configured to convert the electrical signal of the second photodetector into a digital signal;

[0071] A PID controller is configured to analyze and filter the voltage signals of the first photodetector and the second photodetector and use the difference between them (i.e., the outer loop power) as the target value for PID control;

[0072] A digital-to-analog converter, configured to convert a digital error signal received from the digital PID into an analog signal for controlling the power controller;

[0073] The power controller is used to generate a high-frequency sinusoidal signal with continuously varying amplitude to continuously control the diffraction efficiency of the AOM;

[0074] The signal conditioning unit is used to replace the function of the second photodetector when there is an electrical signal representing the laser power on the laser controller.

[0075] The specific steps of the laser power stabilization method based on acousto-optic modulator are as follows:

[0076] Use laser light sources to generate light sources with frequencies required for research or applications;

[0077] The laser beam is split into two perpendicular beams by a beam splitter according to the ratio n (sampling beam: forward beam ∈ (0.01-0.5)). One beam is used for sampling. The sampling power is set to Ps. The laser power entering the AOM is calculated by the splitting ratio as PL = Ps / n.

[0078] Apply voltage to the power controller to adjust the angle between the incident light beam and the AOM so that the light beam enters the AOM at the Bragg angle and the first-order diffracted light is adjusted in the outgoing light beam.

[0079] The narrowly spaced 0th and 1st order beams are separated by a triangular prism with a right-angle beam splitter. Their powers are set as P0 and P1 respectively. One beam is selected for control, and the other is used as the outer ring beam. According to the characteristics of AOM, PL=P0+P1+δ, where δ is the loss of the beam after passing through the AOM and air.

[0080] The PID controller is tuned to stabilize the control beam. Using the control beam as a feedback link, a fixed target value is set. Tuning parameters ensures the PID controller has good dynamic response and stabilizes the beam power.

[0081] Set the laser power Pol of the outer ring beam (P0 or P1) so that the target value of PID control P0 = PL - Pol - δ (i.e., the level 0 beam is used for control and the level 1 beam is used for application) or Pol = PL - P0 - δ (i.e., the level 1 beam is the inner ring beam and the level 0 beam is the outer ring beam).

[0082] This application is based on the conservation of optical power, that is, the laser power entering the AOM is the sum of the powers of the outgoing level 0 and level 1 beams. Laser power control is performed using the laser light source power and the level 0 or 1 beam. That is, the light source input power and the level 1 beam of the acousto-optic modulator are measured in real time, and the outer ring beam power is characterized by difference. The control target value is adjusted by the PID controller to stabilize the difference between the laser source power and the beam involved in the control. The outer ring beam is cleverly involved in the feedback control loop through numerical methods, which can effectively suppress the fluctuation noise of the laser light source, thereby effectively improving the long-term stability of the laser power.

[0083] In a specific embodiment, a laser light source is used to generate a light source of a frequency required for research or application, such as a laser source with a wavelength of 795 nm in an atomic magnetometer experiment;

[0084] The laser beam is split into two perpendicular beams in the ratio n=10:90 (sampling beam: forward beam) by a beam splitter. 10% of the beam is used for sampling, and 90% of the power enters the AOM for further processing. The laser power entering the AOM is calculated based on the splitting ratio: PL=Ps / n=9Ps.

[0085] Apply a voltage to the power controller, such as applying 1 / 2 of the full-scale voltage, and adjust the angle between the incident light beam and the AOM so that the light beam enters the AOM at the Bragg angle and the first-order diffracted light is adjusted in the outgoing light beam. At this voltage, the 0th-order and 1st-order light beams are basically equal in brightness.

[0086] Use a right-angle beam splitter to separate the narrowly spaced 0th and 1st order beams. Let their powers be P0 and P1, respectively. Select one beam as the inner ring beam and the other as the outer ring beam. According to the characteristics of AOM, PL = P0 + P1 + δ, where δ is the loss in the optical path.

[0087] Assuming that the level 1 beam is used as the inner loop control and the level 0 beam is used as the outer loop, the level 1 beam is used as the feedback quantity to form a closed-loop control with the PID controller, power controller and AOM. The target value of the level 1 beam power is set, and the proportional, integral and differential parameters of the PID are tuned using the Ziegler-Nichols tuning method until the level 1 beam can be stable and has good dynamic response.

[0088] Set the expected value POL of the 0th-order beam (outer ring beam) to M, introduce the laser source power PL and the 1st-order diffraction light power P1 of the AOM into the digital PID, and set the target value P1 of the PID control to PL-M-δ. That is, the PID controller is converted from the fixed control of the 1st-order light to the variable target value control, and the PID controller is started.

[0089] When the laser light source power increases, the PID control level 1 optical power target value P1 increases accordingly, and vice versa, so as to ensure that the outer ring beam power POL remains unchanged, thereby suppressing the light source fluctuation.

[0090] like Figure 3 As shown in the figure, it is the light source disturbance suppression effect diagram. Figure 4 The figure shows the effect of long-term stability improvement.

[0091] It can be seen that for the first time, one of the level 0 and level 1 beams emitted by the AOM is fully involved in the control; the outer ring beam is characterized by the difference between the laser source power and the control beam, which is equivalent to the outer ring beam directly participating in the control and has a very high noise suppression ratio; a right-angle reflection prism is used to change the direction of the level 0 and level 1 beams and increase the optical path, so that the two beams emitted by the AOM can be detected simultaneously in the test bench environment; a digital PID controller with a variable target value is used to stabilize the long-term stability of the outer ring beam.

[0092] This exemplary embodiment also provides a laser power stabilization method based on an acousto-optic modulator. Figure 5 As shown in , the laser power stabilization method based on the acousto-optic modulator may include: steps S201 to S206.

[0093] Step S201: setting parameters of a power controller, and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal;

[0094] Step S202: inputting the laser beam into an acousto-optic modulator, and controlling the diffraction efficiency of the laser beam in the acousto-optic modulator using the amplitude-modulated high-frequency sinusoidal signal to obtain first-order diffracted light and zero-order diffracted light;

[0095] Step S203: using a right-angle beam splitter to separate the first-order diffracted light and the zero-order diffracted light, and determining an inner ring light beam and an outer ring light beam according to the first-order diffracted light and the zero-order diffracted light;

[0096] Step S204: sequentially inputting the inner ring light beam into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal; sampling the laser light beam using a proportional beam splitter and sequentially inputting the sampling signal into a signal conditioning unit and a second analog-to-digital converter for processing to obtain a second digital signal; wherein the signal conditioning unit is used to obtain the power of the laser light beam;

[0097] Step S205: inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal;

[0098] Step S206: Input the analog signal into the power controller. The power controller adjusts the amplitude of the high-frequency sinusoidal wave signal according to the analog signal and controls the acousto-optic modulator to output the stable outer ring light beam.

[0099] In one embodiment, the step of inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal includes:

[0100] According to the first digital signal, the power of the inner ring beam is obtained; the power of the laser beam is obtained by using a fixed-proportion beam splitter, and the power of the forward beam is obtained according to the power of the laser beam; according to the power of the inner ring beam and the power of the forward beam, the PID control target value is set, and according to the PID control target value, a digital error signal is generated.

[0101] Through the above-mentioned laser power stabilization method based on the acousto-optic modulator, when the power of the laser beam cannot be directly obtained, the power of the incident laser beam of the acousto-optic modulator is sampled in real time based on the principle of power conservation. The 0th-order diffraction light and the 1st-order diffraction light with a small spacing are emitted using a right-angle beam splitter to change the direction and expand the optical path. The inner ring beam participating in the control is also sampled in real time and analog-to-digital conversion is performed. The difference between the laser beam power and the inner ring beam is the outer ring beam power. In the PID controller, after specifying the outer ring beam power, the inner ring beam power target value is adjusted in real time through calculation to offset the power fluctuation noise of the light source. In principle, the purpose of allowing the outer ring beam to participate in the control without being blocked is achieved, so that the stability is greatly improved. When the electrical signal representing the laser beam power can be obtained directly from the laser device, the sampling beam splitter is omitted, and the laser light source directly enters the acousto-optic modulator. The inner ring beam involved in the control is also sampled in real time and converted into analog to digital. The difference between the laser beam power and the inner ring beam is the outer ring beam power. In the PID controller, after specifying the outer ring beam power, the inner ring beam power target value is adjusted in real time through calculation to offset the power fluctuation noise of the light source.

[0102] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0103] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean 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 disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0104] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A laser power digital control method based on the power conservation principle, characterized in that: The method includes: A beam splitter is used to split the laser beam into a forward beam and a sampling beam according to a preset ratio n; Setting parameters of a power controller and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal; Adjusting the angle between the forward light beam and the acousto-optic modulator (AOM), allowing the forward light beam to enter the AOM at a Bragg angle, and controlling the diffraction efficiency of the forward light beam in the AOM using the amplitude-modulated high-frequency sinusoidal signal to obtain first-order diffracted light and zero-order diffracted light; The first-order diffracted light and the zero-order diffracted light are separated by a right-angle beam splitter, and an inner ring beam and an outer ring beam are determined based on the first-order diffracted light and the zero-order diffracted light. Specifically, if the first-order diffracted light is used as the inner ring beam, the zero-order diffracted light is used as the outer ring beam; if the zero-order diffracted light is used as the inner ring beam, the first-order diffracted light is used as the outer ring beam. The inner ring beam and the sampling beam are used for power control, and the outer ring beam is used for output applications. The inner ring light beam is sequentially input into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and the sampling light beam is sequentially input into a second photodetector and a second analog-to-digital converter for processing to obtain a second digital signal; the power of the sampling light beam is Ps, and the power of the forward light beam is PL=Ps / n, and the sampling light beam: the forward light beam∈(0.01-0.5), that is, n∈(0.01-0.5); Inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal; The analog signal is input into the power controller, and the power controller adjusts the acousto-optic modulator according to the analog signal to output the stable outer ring light beam.

2. The laser power digital control method based on the power conservation principle according to claim 1, characterized in that: The power of the first-order diffracted light is P1, the power of the zero-order diffracted light is P0, and PL=P0+P1+δ, where δ is the loss in the optical path.

3. The laser power digital control method based on the power conservation principle according to claim 2, characterized in that: The steps of sequentially inputting the inner ring light beam into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and sequentially inputting the sampling light beam into a second photodetector and a second analog-to-digital converter for processing to obtain a second digital signal include: Inputting the inner ring light beam into the first photodetector, wherein the first photodetector converts the inner ring light beam into a first electrical signal; Inputting the first electrical signal into the first analog-to-digital converter, so that the first analog-to-digital converter converts the first electrical signal into the first digital signal; Inputting the sampling light beam into the second photodetector, the second photodetector converting the sampling light beam into a second electrical signal; The second electrical signal is input into the second analog-to-digital converter, and the second analog-to-digital converter converts the second electrical signal into the second digital signal.

4. The laser power digital control method based on the power conservation principle according to claim 3, characterized in that: The step of inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal includes: obtaining the power of the inner ring light beam according to the first digital signal; Obtaining the power Ps of the sampling beam according to the second digital signal, and obtaining the power PL of the forward beam according to the power Ps of the sampling beam; A PID control target value Pol is set according to the power of the inner ring light beam and the power PL of the forward light beam, and the digital error signal is generated according to the PID control target value; wherein, when the 0th-order diffracted light serves as the inner ring light beam, the PID control target value is P0=PL-Pol-δ; when the 1st-order diffracted light serves as the inner ring light beam, the PID control target value is P1=PL-Pol-δ; The digital error signal is input to the digital-to-analog converter, and the digital-to-analog converter converts the digital error signal into the analog signal.

5. A laser power digital control method based on the power conservation principle, characterized in that: The method includes: Setting parameters of a power controller and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal; Inputting the laser beam into an acousto-optic modulator, and controlling the diffraction efficiency of the laser beam in the acousto-optic modulator using the amplitude-modulated high-frequency sinusoidal signal to obtain first-order diffracted light and zero-order diffracted light; Separating the first-order diffracted light and the zero-order diffracted light by a right-angle beam splitter, and determining an inner ring light beam and an outer ring light beam according to the first-order diffracted light and the zero-order diffracted light; The inner ring light beam is sequentially input into a first photodetector and a first analog-to-digital converter for processing to obtain a first digital signal, and the laser light beam is sampled by a proportional beam splitter and sequentially input into a signal conditioning unit and a second analog-to-digital converter for processing to obtain a second digital signal; wherein the signal conditioning unit is used to obtain the power of the laser light beam; Inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal, and inputting the digital error signal into a digital-to-analog converter to generate an analog signal; The analog signal is input into the power controller, and the power controller adjusts the amplitude of the high-frequency sine wave signal according to the analog signal and controls the acousto-optic modulator to output the stable outer ring light beam.

6. The laser power digital control method based on the power conservation principle according to claim 5, characterized in that: The step of inputting the first digital signal and the second digital signal into a PID controller for analysis and filtering to obtain a digital error signal includes: obtaining the power of the inner ring light beam according to the first digital signal; Using a fixed-ratio beam splitter to obtain the power of the sampling beam, and obtaining the power of the forward beam based on the power of the sampling beam; A PID control target value is set according to the power of the inner ring light beam and the power of the forward light beam, and the digital error signal is generated according to the PID control target value.

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