Laser power stabilizing method based on acousto-optic modulator

Abstract

The invention belongs to the technical field of quantum sensing and precision measurement. The invention provides a laser power stabilizing method based on an acousto-optic modulator. The embodiment of the invention is based on optical power conservation, that is, the power of the laser entering the AOM is the sum of the power of the emitted 0-level light beam and the power of the emitted 1-level light beam. Laser power control is carried out by using laser source power and 0-level or 1-level light beams, that is, real-time measurement is carried out on light source input power and 1-level light beams of an acousto-optic modulator, outer ring light beam power is represented through difference, and a control target value is adjusted through a PID controller, so that the difference value between the laser source power and the light beams participating in control is stable; an outer ring light beam is ingeniously participated in a feedback control loop through a numerical method, fluctuation noise of a laser light source can be effectively restrained, and therefore the long-term stability of laser power is effectively improved.

Description

Technical Field

[0001] The disclosed embodiments 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, laser plays an indispensable role as an important component, and the stability of laser power also has an important impact on the final output of the sensor. For example, in atomic magnetometers, the drift of laser power will cause the frequency deviation of the output oscillation signal, thereby affecting the resolution and stability of magnetic field measurement; in the application of atomic clocks, the drift of laser power reduces the medium- and long-term stability of atomic clocks; in gravitational wave detection, the stability of laser power will directly couple to the measurement results of the interferometer, resulting in a reduction in the detection effect. At present, the research results on the actuators that can change the intensity of diffracted light through liquid crystal variable phase retarders, electro-optic modulators, acousto-optic modulators, and magneto-optic modulators, and the research results on the stable control of laser power combined with feedback control technology are increasing day by day.

[0003] The problem with the prior art is that when using an acousto-optic modulator, only the 0th or 1st order 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 suppressed together, 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 the temperature fluctuation of the AOM, resulting in poor medium- and long-term stability. Summary of the invention

[0004] In order to avoid the shortcomings of the prior art, the present invention provides a laser power stabilization method based on an acousto-optic modulator, which is used to solve the problem in the prior art that when using an acousto-optic modulator, only the 0th or 1st level beam is split and then feedback control is performed, and the control loop will suppress any interference, resulting in insufficient long-term stability of the outer ring beam.

[0005] According to a first aspect of an embodiment of the present disclosure, a laser power stabilization method based on an acousto-optic modulator is provided, the method comprising: The laser beam is divided into a forward beam and a sampling beam according to a preset ratio n by using a beam splitter; Setting parameters of a power controller and using the power controller to generate an amplitude modulated high frequency sinusoidal signal; 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; 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 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; 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.

[0006] 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).

[0007] Furthermore, the method further comprises: The angle between the forward light beam and the AOM is adjusted so that the forward light beam enters the AOM at a Bragg angle.

[0008] Furthermore, the power of the 1st-order diffraction light is P1, the power of the 0th-order diffraction light is P0, and PL=P0+P1+δ, where δ is the loss in the optical path.

[0009] Further, 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 comprises: If the 1st-order diffraction light is used as the inner ring light beam, the 0th-order diffraction light is the outer ring light beam; If the 0th order diffraction light is taken as the inner ring light beam, the 1st order diffraction light is the outer ring light beam; The inner ring beam is used for power control, and the outer ring beam is used for output application.

[0010] Further, the step 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 comprises: Inputting the inner ring light beam into the first photodetector, and 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, and 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.

[0011] Further, 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; According to the second digital signal, the power Ps of the sampling beam is obtained, and according to the power Ps of the sampling beam, the power PL of the forward beam is obtained; 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 is used as the inner ring light beam, the PID control target value is P0=PL-Pol-δ; when the 1st order diffracted light is used 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.

[0012] 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: 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 using the amplitude-modulated high-frequency sinusoidal signal to control the diffraction efficiency of the laser beam in the acousto-optic modulator 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 controls the acousto-optic modulator after adjusting the amplitude of the high-frequency sinusoidal wave signal according to the analog signal to output the stable outer ring light beam.

[0013] 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: 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 according to the power of the sampling beam; 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.

[0014] The technical solution provided by the embodiments of the present disclosure may have the following beneficial effects: 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 0th-order diffraction light and the 1st-order diffraction light with a small spacing are emitted. The direction is changed and the optical path is expanded using a right-angle beam splitter 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 directly obtained from the laser device, the sampling beam splitter is omitted, and the laser light source directly enters the acousto-optic modulator. The 0th-order diffraction light and the 1st-order diffraction light with a small spacing are directed 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 converted into analog to digital. 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

[0015] The accompanying drawings herein are incorporated into the specification 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 accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0016] 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; Figure 2 A specific flow chart showing a laser power stabilization method based on an acousto-optic modulator in an exemplary embodiment of the present disclosure; Figure 3 A diagram showing the effect of light source disturbance suppression in an exemplary embodiment of the present disclosure is shown; Figure 4 A diagram showing the effect of improving long-term stability in an exemplary embodiment of the present disclosure; Figure 5 A diagram showing the steps of another method for stabilizing laser power based on an AOM in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to 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.

[0018] In addition, the accompanying drawings are only schematic illustrations of the embodiments of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated descriptions will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0019] 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.

[0020] 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; Step S102: setting the parameters of the power controller, and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal; Step S103: inputting the forward light beam into an acousto-optic modulator, and using the amplitude modulated high-frequency sinusoidal signal to control the diffraction efficiency of the forward light beam in the acousto-optic modulator to obtain first-order diffracted light and zero-order diffracted light; 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; Step S105: sequentially inputting the inner ring light beam into the first photodetector and the first analog-to-digital converter for processing to obtain a first digital signal, and sequentially inputting the sampling light beam into the second photodetector and the second analog-to-digital converter for processing to obtain a second digital signal; 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; 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.

[0021] Through the above-mentioned laser power stabilization method based on acousto-optic modulator, when the power of the laser beam cannot be directly obtained, based on the principle of power conservation, the power of the incident laser beam of the acousto-optic modulator is sampled in real time, and the 0th-order diffraction light and the 1st-order diffraction light with a small spacing are emitted. The direction is changed and the optical path is expanded using a right-angle beam splitter prism. 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 directly obtained from the laser device, the beam splitter for sampling 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.

[0022] Next, 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.

[0023] 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.

[0024] Among them, the laser light source is used to generate the laser beam of the frequency required for experimental research and application; A beam splitter is 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. The beam splitter is not limited to polarization, non-polarization beam splitters and prisms. an acousto-optic modulator for continuously controlling the intensity of the light beam by adjusting the diffraction rate of the light according to the amplitude of the driving signal of the power controller; A right-angle beam splitter is used to separate the 0th and 1st order lights with a small spacing so that a photodetector can be placed in it to sample it; 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; A first analog-to-digital converter, used to convert the electrical signal of the first photodetector into a digital signal; A second photodetector, used for converting the sampled laser light source signal into an electrical signal; a second analog-to-digital converter, used to convert the electrical signal of the second photodetector into a digital signal; A PID controller is used to analyze and filter the voltage signals of the first photodetector and the second photodetector and use the difference (i.e., the power of the outer loop) as the target value of the PID control; A digital-to-analog converter, used for converting a digital error signal received from a digital PID into an analog signal for controlling a power controller; A power controller is used to generate a high-frequency sinusoidal signal with a continuously changing amplitude to continuously control the diffraction efficiency of the AOM; 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.

[0025] The specific steps of the laser power stabilization method based on acousto-optic modulator are: Use laser light sources to generate light sources with the frequencies required for research or applications; The laser beam is split into two perpendicular beams according to the ratio n (sampling beam: forward beam ∈ (0.01-0.5)) by a beam splitter, one of which is used for sampling. The sampling power is set as Ps. The laser power PL=Ps / n entering the AOM is calculated by the splitting ratio. 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 adjusts the first-order diffracted light in the outgoing light beam; The 0th and 1st order light beams with narrow spacing are separated by the triangular prism right angle beam splitter. Their powers are set as P0 and P1 respectively. One of them is used as control and the other is used as the outer ring light beam. According to the characteristics of AOM, PL=P0+P1+δ, where δ is the loss of the light beam after passing through AOM and air.

[0026] The PID controller is parameterized to stabilize the control beam. The control beam is used as a feedback link, a fixed target value is set, and the parameters are adjusted to ensure that the PID controller has a good dynamic response and the beam power is stable.

[0027] 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).

[0028] This application is based on the conservation of optical power, that is, the laser power entering the AOM is the sum of the power of the emitted level 0 beam and level 1 beam. The laser power is controlled using the laser light source power and the level 0 or 1 beam, that is, the input power of the light source 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.

[0029] 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; The laser beam is split into two perpendicular beams in the ratio of n=10:90 (sampling beam: forward beam) by a beam splitter, of which 10% is used for sampling and 90% of the power enters the AOM for further processing. The laser power entering the AOM is calculated by the splitting ratio, PL=Ps / n=9Ps; Apply voltage to the power controller, such as applying 1 / 2 voltage of the full scale, 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 adjusts the first-order diffracted light in the outgoing light beam. Under this voltage, the 0th-order light beam and the 1st-order light beam basically show the phenomenon of equal brightness. Use a right-angle beam splitter to separate the narrowly spaced 0th and 1st order beams, assuming their powers are P0 and P1 respectively, and select one of them 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. 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 adjusted using the Ziegler-Nichols tuning method until the level 1 beam can be stable and have a good dynamic response. Set the expected value POL=M of the 0th order light beam (outer ring light beam), 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 1st order light fixed control to the variable target value control, and start the PID controller.

[0030] When the power of the laser light source increases, the PID controlled level 1 optical power target value P1 increases accordingly, and vice versa, thus ensuring that the outer ring beam power POL remains unchanged, thereby suppressing light source fluctuations.

[0031] like Figure 3 As shown in Figure , this is a diagram showing the effect of light source disturbance suppression. Figure 4 The figure shows the effect of long-term stability improvement.

[0032] It can be seen that for the first time, one of the 0th and 1st order light beams emitted by the AOM is fully involved in the control; the outer ring light beam is characterized by the difference between the laser source power and the control light beam, which is equivalent to the outer ring light 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 0th and 1st order light beams and increase the optical path, so that the two light 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 light beam.

[0033] 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.

[0034] Step S201: setting the parameters of the power controller, and using the power controller to generate an amplitude modulated high-frequency sinusoidal signal; Step S202: inputting the laser beam into an acousto-optic modulator, and using the amplitude modulated high-frequency sinusoidal signal to control the diffraction efficiency of the laser beam in the acousto-optic modulator to obtain first-order diffracted light and zero-order diffracted light; 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; 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 light beam 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; 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; Step S206: input the analog signal into the power controller, and the power controller controls the acousto-optic modulator after adjusting the amplitude of the high-frequency sinusoidal wave signal according to the analog signal to output the stable outer ring light beam.

[0035] 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: 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 proportional 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, a PID control target value is set, and a digital error signal is generated according to the PID control target value.

[0036] Through the above-mentioned laser power stabilization method based on acousto-optic modulator, when the power of the laser beam cannot be directly obtained, based on the principle of power conservation, the power of the incident laser beam of the acousto-optic modulator is sampled in real time, and the 0th-order diffraction light and the 1st-order diffraction light with a small spacing are emitted. The direction is changed and the optical path is expanded using a right-angle beam splitter prism. 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 directly obtained from the laser device, the beam splitter for sampling 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.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, 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 "multiple" is two or more, unless otherwise clearly and specifically defined.

[0038] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0039] 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 modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A laser power stabilization method based on an acousto-optic modulator, characterized in that: The method includes: The laser beam is divided into a forward beam and a sampling beam according to a preset ratio n by using a beam splitter; Setting parameters of a power controller and using the power controller to generate an amplitude modulated high frequency sinusoidal signal; 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; 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 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; 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 stabilization method based on an acousto-optic modulator according to claim 1, characterized in that: 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).

3. The laser power stabilization method based on an acousto-optic modulator according to claim 2, characterized in that: The method further includes: The angle between the forward light beam and the AOM is adjusted so that the forward light beam enters the AOM at a Bragg angle.

4. The laser power stabilization method based on an acousto-optic modulator according to claim 3, characterized in that: The power of the 1st order diffraction light is P1, the power of the 0th order diffraction light is P0, and PL=P0+P1+δ, where δ is the loss in the optical path.

5. The laser power stabilization method based on an acousto-optic modulator according to claim 4, characterized in that: 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 comprises: If the 1st-order diffraction light is used as the inner ring light beam, the 0th-order diffraction light is the outer ring light beam; If the 0th order diffraction light is taken as the inner ring light beam, the 1st order diffraction light is the outer ring light beam; The inner ring beam is used for power control, and the outer ring beam is used for output application.

6. The laser power stabilization method based on an acousto-optic modulator according to claim 5, 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, and 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, and 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.

7. The laser power stabilization method based on an acousto-optic modulator according to claim 6, 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 comprises: Obtaining the power of the inner ring light beam according to the first digital signal; According to the second digital signal, the power Ps of the sampling beam is obtained, and according to the power Ps of the sampling beam, the power PL of the forward beam is obtained; 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 is used as the inner ring light beam, the PID control target value is P0=PL-Pol-δ; when the 1st order diffracted light is used 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.

8. A laser power stabilization method based on an acousto-optic modulator, 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 using the amplitude-modulated high-frequency sinusoidal signal to control the diffraction efficiency of the laser beam in the acousto-optic modulator 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 controls the acousto-optic modulator after adjusting the amplitude of the high-frequency sinusoidal wave signal according to the analog signal to output the stable outer ring light beam.

9. The laser power stabilization method based on an acousto-optic modulator according to claim 8, 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 according to the power of the sampling beam; 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.

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