Device, method and system for suppressing ringing effect of electro-optical crystal based on acousto-optic modulator

Abstract

The invention discloses a device, method and system for inhibiting the ringing effect of an electro-optical crystal based on an acousto-optic modulator, and belongs to the field of light modulation. The device comprises an electro-optical crystal, an electro-optical crystal driving control unit, an acousto-optic modulator and an acousto-optic modulator driving control unit, the electro-optical crystal driving control unit applies voltage to two ends of the electro-optical crystal; the electro-optical crystal outputs an effective optical signal when the applied voltage is stable, and outputs a ringing effect optical signal when the voltage is reduced; when the electro-optical crystal outputs an effective optical signal, the acousto-optic modulator driving control unit generates a signal which is not provided for the acousto-optic modulator; when the electro-optical crystal generates a ringing effect, the acousto-optic modulator driving control unit provides a driving signal for the acousto-optic modulator, and the acousto-optic modulator generates sound waves, so that an incident light signal is diffracted, and a ringing effect light signal is suppressed. Through the gating function of the acousto-optic modulator, the ringing light signal is suppressed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical modulation, and more particularly relates to a device, method and system for suppressing ringing effect of an electro-optic crystal based on an acousto-optic modulator. BACKGROUND

[0002] An electro-optic crystal (such as , KTP, etc.) occupies a pivotal position in the field of modern optoelectronic technology due to its unique electro-optic effect. In particular, in the field of high-speed optical modulation, an electro-optic modulator (EOM) is widely used as a key device in fiber-optic communication, laser radar, microwave photonics and other cutting-edge technologies. By applying an external electric field, the refractive index of the electro-optic crystal changes, thereby accurately controlling the phase, amplitude, polarization and other parameters of the light wave, providing technical support for high-speed and high-capacity information transmission.

[0003] With the increase of modulation rate and driving power, the ringing effect of the electro-optic crystal gradually becomes a problem that cannot be ignored. When a rapidly changing step voltage is applied to the electro-optic crystal, the output light intensity should ideally reach a stable value immediately. However, in reality, the output light intensity after the step change often shows a series of rapid oscillations, a dithered waveform, and then gradually decays to a stable state. This oscillation phenomenon is called ringing effect. The generation of ringing effect is the result of the coupling of multiple factors. On the one hand, the piezoelectric effect of the electro-optic crystal plays a key role. The crystal will deform under the action of the electric field, but this deformation is not instantaneous, but has a response time. The rapid change of the voltage will excite the mechanical vibration of the atoms or molecules inside the crystal. These vibrations propagate and reflect in the form of sound waves in the crystal, forming a standing wave, which in turn periodically changes the refractive index of the crystal and modulates the light passing through the crystal. On the other hand, there are inevitably parasitic inductance and parasitic capacitance in the actual circuit, which together with the crystal capacitance form a resonant circuit. When a step voltage is applied, the resonant circuit will oscillate, further exacerbating the ringing phenomenon of the light intensity. When the electro-optic crystal is used for cavity emptying and regenerative amplification, the ringing effect will bring many adverse consequences. In terms of energy loss, it will reduce the energy used for effective operation and cause device wear and tear, accelerating the aging and wear of the crystal and related components. In terms of time-domain waveform, it will cause pulse distortion, making the ideal pulse oscillate, fluctuate or trail, and also cause time jitter, affecting applications that require high time accuracy. When running at high repetition rate, the ringing effect limits the response of the crystal to high-frequency driving signals, reduces system stability, and makes it difficult to continuously and stably operate at high repetition rate. Moreover, it prolongs the time period, reduces work efficiency, and makes the electro-optic crystal unable to meet the requirements of some fast repetitive operation scenarios, severely limiting its application in related fields.

[0004] At present, the main methods for inhibiting the ringing effect of electro-optic crystal include optimizing the circuit structure design of electro-optic crystal, using filter for signal processing, etc., but these methods have certain limitations, for example, the circuit structure design optimization is difficult, the filter design process is complex, and additional signal distortion may be introduced. Therefore, it is of important practical significance to design a kind of efficient and simple device for inhibiting the ringing effect of electro-optic crystal. SUMMARY

[0005] In view of the defects of the related art, the purpose of the present application is to provide a device, method and system for inhibiting the ringing effect of electro-optic crystal based on acousto-optic modulator, aiming to solve the problems of complex circuit structure, high design difficulty and poor inhibition effect of the existing devices for inhibiting the ringing effect of electro-optic crystal.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a device for inhibiting the ringing effect of electro-optic crystal based on acousto-optic modulator, comprising: an electro-optic crystal, an electro-optic crystal driving control unit, an acousto-optic modulator and an acousto-optic modulator driving control unit. The electro-optic crystal driving control unit is used to apply voltage across the electro-optic crystal; the electro-optic crystal is used to output valid optical signal when the voltage is stable, and produce ringing effect and output ringing effect optical signal when the voltage is in the process of decaying; The acousto-optic modulator driving control unit is used to generate different control signals to control the operation of the acousto-optic modulator; when the electro-optic crystal outputs valid optical signal, the control signal generated by the acousto-optic modulator driving control unit is low level, and no driving signal is provided to the acousto-optic modulator; when the electro-optic crystal produces ringing effect, the control signal generated by the acousto-optic modulator driving control unit is high level, and driving signal is provided to the acousto-optic modulator; The acousto-optic modulator is used to generate sound wave when receiving driving signal, so that the incident ringing effect optical signal is diffracted and deviates from the path of resonant cavity, and cannot form stable oscillation, thereby inhibiting the ringing effect optical signal.

[0007] Optionally, the electro-optic crystal is a Q-switch.

[0008] Optionally, the electro-optic crystal driving control unit comprises a direct current power supply, a driving circuit and a signal generator. The direct current power supply is used to provide the required direct current voltage for the electro-optic crystal; The driving circuit is used to generate and adjust the voltage signal applied across the electro-optic crystal; The signal generator is used to control the voltage signal generated by the driving circuit to have a preset frequency and a preset waveform.

[0009] Optionally, the acousto-optic modulator comprises a piezoelectric crystal and an acousto-optic crystal. The piezoelectric crystal is used for converting an input driving signal into an ultrasonic wave to drive the acousto-optic crystal to work; and the acousto-optic crystal is used for modulating a light signal by using an acousto-optic effect to cause diffraction of the passing light signal.

[0010] Optionally, the acousto-optic modulator further comprises a sound absorption device.

[0011] Optionally, the acousto-optic modulator comprises a 0th order horizontal exit working mode and a 1st order horizontal exit working mode.

[0012] Optionally, the acousto-optic modulator driving control unit comprises a radio frequency signal source, a power amplifier, a direct current power supply and a control circuit. The radio frequency signal source is used for providing a radio frequency signal for the acousto-optic modulator. The power amplifier is used for enhancing the power of the radio frequency signal to effectively drive the acousto-optic modulator to work. The direct current power supply is used for providing a stable direct current power supply for the acousto-optic modulator. The control circuit is used for adjusting and controlling the frequency and amplitude of the radio frequency signal generated by the radio frequency signal source.

[0013] In a second aspect, the application further provides a method for suppressing a ringing effect of an electro-optic crystal based on an acousto-optic modulator, applied to the device of any one of the first aspect, comprising: controlling the electro-optic crystal driving control unit to generate a first preset driving signal, and controlling the acousto-optic modulator driving control unit to generate a second driving signal according to the first preset driving signal; controlling the electro-optic crystal to start working at a preset time based on the first preset driving signal to modulate an input laser to output a periodic light signal composed of an effective light signal and a ringing effect light signal; controlling the acousto-optic modulator to generate an acoustic wave to cause the incident ringing effect light signal to diffract and deviate from the path of the resonant cavity to suppress the ringing effect light signal based on the second preset driving signal when the electro-optic crystal outputs the ringing light signal.

[0014] Optionally, the diffraction efficiency of the acousto-optic modulator is set to 100%.

[0015] In a third aspect, the application further provides a device for suppressing a ringing effect of an electro-optic crystal based on an acousto-optic modulator, comprising: a controller and the device of any one of the first aspect. The controller is used for executing the method of any one of the second aspect.

[0016] Compared with the prior art, the above technical scheme conceived by the application can achieve the following beneficial effects: 1. This invention provides a device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator. The optical signal modulated by the electro-optic crystal contains a ringing optical signal caused by the ringing effect. Since the acousto-optic modulator has a gating function, it is activated when the ringing effect occurs according to the parameters of the ringing effect generated by the electro-optic crystal, generating sound waves that diffract the incident ringing optical signal, causing it to deviate from the resonant cavity path. This increases the loss within the resonant cavity, making it impossible to form a stable oscillation, thereby suppressing the ringing optical signal and eliminating the ringing optical signal in the output optical signal. At the same time, there is no need to change the circuit structure, thus significantly improving the modulation accuracy of the electro-optic crystal for laser and the system performance.

[0017] 2. This invention provides a device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator. During the signal processing stage, a first preset driving signal is generated by the electro-optic crystal drive control unit, and a corresponding second driving signal is generated by the acousto-optic modulator drive control unit. This precisely controls the gating time of the acousto-optic modulator. Compared with traditional methods of adjusting circuit parameters and filters, this method can suppress the ringing effect more directly and effectively without changing the circuit structure or introducing filters that may cause signal distortion. It has higher accuracy and lower signal loss, and is easier to implement in real-time. Furthermore, it can adapt to different electro-optic crystals and operating conditions, exhibiting better versatility. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator, provided as an embodiment of the present invention, wherein the acousto-optic modulator is a level 0 horizontal emitter; Figure 2 A timing diagram for the application of a device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator provided in an embodiment of the present invention, wherein the acousto-optic modulator is a level 0 horizontal emitter; Figure 3 The diagram shows a device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator, which is used to eliminate the ringing effect of electro-optic crystals in a regenerative amplifier. The acousto-optic modulator is a level 0 horizontal emitter. Figure 4 The diagram shows a device for suppressing electro-optic crystal ringing effect based on an acousto-optic modulator, provided in an embodiment of the present invention, applied to eliminate the electro-optic crystal ringing effect in a cavity-reversed Q-type laser. The acousto-optic modulator is a 0th-order horizontal emitter. In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is an electro-optic crystal; 2 is an electro-optic crystal driving control unit; 3 is an acousto-optic modulator; 4 is an acousto-optic modulator driving control unit; 5 is an isolator, 6 is a first λ / 2 wave plate, 7 is a pulse selector, 8 is a first thin film polarizer, 9 is a Faraday rotator, 10 is a second λ / 2 wave plate, 11 is a second thin film polarizer, 12 is a λ / 4 wave plate, 13 is a first total reflection mirror, 14 is a second total reflection mirror, 15 is a gain medium, and 16 is a third total reflection mirror. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0020] The content involved in the above embodiments will be described below in combination with a preferred embodiment.

[0021] As shown in FIG. 1, a device for suppressing the ringing effect of an electro-optic crystal based on an acousto-optic modulator includes an electro-optic crystal 1, an electro-optic crystal driving control unit 2, an acousto-optic modulator 3, and an acousto-optic modulator driving control unit 4. Figure 1 The electro-optic crystal driving control unit 2 is connected to both ends of the electro-optic crystal 1. The electro-optic crystal driving control unit 2 is used to control the voltage applied to the electro-optic crystal 1. The electro-optic crystal 1 is used to change the propagation characteristics of laser in the crystal to modulate the optical signal. When the applied voltage is stable, the effective optical signal is output. When the applied voltage is in the process of being removed, the ringing effect occurs inside the electro-optic crystal 1, and the ringing effect optical signal is output. The acousto-optic modulator driving control unit 4 is connected to both ends of the acousto-optic modulator 3. The acousto-optic modulator driving control unit 4 is used to generate different control signals to control the operation of the acousto-optic modulator 3. When the electro-optic crystal 1 outputs the effective optical signal, the control signal generated by the acousto-optic modulator driving control unit 4 is low, and no driving signal is provided to the acousto-optic modulator 3. When the electro-optic crystal 1 has the ringing effect, the control signal generated by the acousto-optic modulator driving control unit 4 is high, and a driving signal is provided to the acousto-optic modulator 3. The acousto-optic modulator 3 is used to generate sound waves when receiving the driving signal, so that the incident ringing effect optical signal is diffracted and deviates from the path of the resonant cavity, and cannot form stable oscillation, thereby suppressing the ringing effect optical signal.

[0022] ​The basic working principle of the acousto-optic modulator is described as follows: the core components of the acousto-optic modulator include an acousto-optic crystal and a piezoelectric transducer. When the drive circuit loads a radio frequency electrical signal to the transducer, the transducer converts the electrical signal into an ultrasonic wave through the piezoelectric effect and forms a stable acoustic field in the acousto-optic crystal. At this time, the incident light beam interacts with the acoustic field, Bragg diffraction occurs, and first-order diffraction light is generated, the intensity of which is linearly related to the acoustic power. By controlling the amplitude or switch of the drive signal, the intensity or existence state of the acoustic field can be adjusted, and then the first-order diffraction light can be selectively made to appear or disappear, so as to realize the regulation and control of the loss in the resonant cavity.

[0023] As shown in Figure 1 , the electro-optic crystal drive control unit 2 generates different control signals to accurately control the working state of the electro-optic crystal 1; specifically, the starting time and duration of the effective optical signal generated by the electro-optic crystal 1 can be controlled, as well as the period of the effective optical signal and the ringing effect optical signal. The acousto-optic modulator drive control unit 4 generates different radio frequency signals to accurately control the acousto-optic modulator 3; specifically, when the electro-optic crystal 1 has a ringing effect, the control signal generated by the acousto-optic modulator drive control unit 4 is high level, and the drive signal is provided to the acousto-optic modulator 3; the acousto-optic modulator 3 generates an acoustic wave to make the incident ringing effect optical signal diffract and deviate from the resonant cavity path, so that it cannot form stable oscillation, thereby suppressing the ringing effect optical signal. The acousto-optic modulator eliminates the ringing effect of the electro-optic crystal 1 by increasing the loss in the resonant cavity through the gating function of the optical signal it has.

[0024] In the present scheme, an acousto-optic modulator 3 is combined at the output end of the electro-optic crystal 1. Since the acousto-optic modulator has a gating function, according to the parameters of the ringing effect generated by the electro-optic crystal, the acousto-optic modulator is started to work when the ringing effect is generated, an acoustic wave is generated to make the incident ringing effect optical signal diffract and deviate from the resonant cavity path, the loss in the resonant cavity is increased, and stable oscillation cannot be formed, thereby suppressing the ringing effect optical signal. The ringing optical signal in the output optical signal is eliminated, thereby significantly improving the modulation precision of the electro-optic crystal on the laser and the system performance. The present scheme solves the problems of complex circuit structure, large design difficulty and poor suppression effect of the existing circuit for suppressing the ringing effect of the electro-optic crystal, and realizes accurate and effective suppression of the ringing effect without changing the circuit structure or introducing a filter that may cause signal distortion. Not only does it have a relatively simple circuit structure, but also has higher precision and lower signal loss, and is easier to realize real-time control. In addition, it can adapt to different electro-optic crystals and working conditions, and has better universality.

[0025] Optionally, the electro-optic crystal 1 is a Q-switch.

[0026] Optionally, the electro-optic crystal drive control unit 2 includes a direct current power supply, a drive circuit and a signal generator. The direct current power supply is used to provide the required direct current voltage for the electro-optical crystal; The driving circuit is used to generate and adjust the voltage signal size applied to the electro-optical crystal; The signal generator is used to control the voltage signal generated by the driving circuit to have a preset frequency and a preset waveform.

[0027] The electro-optical crystal driving control unit 2 generates an electrical signal with a preset frequency, a preset waveform and a preset size, so as to accurately control the electro-optical crystal 1.

[0028] Optionally, the acousto-optic modulator 3 includes a 0-level horizontal exit working mode and a 1-level horizontal exit working mode.

[0029] When the acousto-optic modulator 3 is in the 0-level horizontal exit working mode, the 0-level diffraction path of the acousto-optic modulator 3 is the same as the light path of the output light signal of the electro-optical crystal 1; when the electro-optical crystal 1 outputs an effective light signal, the control signal is low, the acousto-optic modulator driving control unit 4 does not provide a driving signal to the acousto-optic modulator 3, and the acousto-optic modulator 3 does not work, so the loss is small, the light path is open, and the effective light signal passes through the acousto-optic modulator 3 and is directly output; when the electro-optical crystal 1 outputs a ringing effect light signal, the control signal is high, the acousto-optic modulator driving control unit 4 provides a driving signal to the acousto-optic modulator 3, at this time the acousto-optic modulator 3 works and generates a sound wave, which diffracts the ringing effect light signal and makes it deviate from the resonant cavity path, the resonant cavity has a large loss, the ringing light signal cannot form stable oscillation, and the ringing light signal is suppressed. When the ringing effect in the electro-optical crystal disappears, the control signal is low, the light wave does not diffract, the resonant cavity has a small loss, and the resonant cavity starts to store energy. Repeating the above process, the gating of the effective signal can be realized, and the ringing effect can be successfully suppressed.

[0030] When the acousto-optic modulator 3 is in a first-order horizontal exit mode, specifically, the first-order diffraction path of the acousto-optic modulator 3 is the same as the light path of the output light signal of the electro-optic crystal 1; when the electro-optic crystal 1 outputs an effective light signal, the control signal generated by the acousto-optic modulator driving control unit 4 is high, the acousto-optic modulator 3 works, generates sound waves, and the light waves are diffracted, so that the loss is small, the light path is opened, the effective light signal is diffracted, and the effective light signal deviates from the original light path to the deflection path of the acousto-optic modulator 3 and is output through the acousto-optic modulator 3; when the electro-optic crystal 1 outputs a ringing effect light signal, the control signal is low, the acousto-optic modulator driving control unit 4 does not provide a driving signal to the acousto-optic modulator 3, at this time the acousto-optic modulator 3 does not work, does not generate sound waves, and the light waves are not diffracted, and the light waves deviate from the resonant cavity path, the loss in the resonant cavity is large, the ringing light signal cannot form stable oscillation, and the ringing light signal is suppressed. When the ringing effect in the electro-optic crystal disappears (i.e., the next effective signal is output by the electro-optic crystal), the control signal is high, the light waves are diffracted, the loss in the resonant cavity is small, and the resonant cavity starts to store energy. Repeating the above process, the effective signal is selected and the ringing effect is successfully suppressed.

[0031] Optionally, the acousto-optic modulator 3 further comprises a sound absorption device.

[0032] Optionally, the acousto-optic modulator driving control unit 4 comprises a radio frequency signal source, a power amplifier, a direct current power supply and a control circuit. The radio frequency signal source is used to provide a radio frequency signal for the acousto-optic modulator. The power amplifier is used to enhance the power of the radio frequency signal, so that the acousto-optic modulator 3 works effectively. The direct current power supply is used to provide a stable direct current power supply for the acousto-optic modulator. The control circuit is used to adjust and control the frequency and amplitude of the radio frequency signal generated by the radio frequency signal source.

[0033] The acousto-optic modulator driving control unit 4 generates a radio frequency signal with a preset frequency and a preset amplitude to accurately drive the acousto-optic modulator 3 to work, so that the acousto-optic modulator 3 cooperates with the working state of the electro-optic crystal 1 to accurately suppress the ringing effect light signal generated by the electro-optic crystal 1.

[0034] On the basis of the above embodiment, the application further provides a method for suppressing the ringing effect of an electro-optic crystal based on an acousto-optic modulator, which is applied to the device described in any one of the above embodiments and comprises the following steps. The electro-optic crystal driving control unit generates a first preset driving signal, and the acousto-optic modulator driving control unit generates a second driving signal according to the first preset driving signal; The electro-optic crystal is controlled to start working at a preset time based on the first preset driving signal, modulates the input laser, and outputs a periodic light signal composed of an effective light signal and a ringing effect light signal. The acousto-optic modulator is controlled based on the second preset driving signal to generate sound waves when the electric-optical crystal outputs the ringing light signal, so that the incident ringing effect light signal is diffracted and deviated from the resonant cavity path, and the ringing effect light signal is suppressed.

[0035] The working time of the acousto-optic modulator covers the time period during which the electric-optical crystal generates the ringing effect light signal, so that the ringing effect light signal is effectively suppressed.

[0036] Further, the diffraction efficiency of the acousto-optic modulator is set to 100%, so that the efficiency of suppressing the ringing effect light signal is improved.

[0037] On the basis of the above-mentioned embodiments, the application further provides a device for suppressing ringing effect of an electric-optical crystal based on an acousto-optic modulator, comprising a controller and the device according to any one of the above-mentioned embodiments. The controller is used to execute the method described above.

[0038] In a specific embodiment, the device for suppressing ringing effect of an electric-optical crystal based on an acousto-optic modulator is applied to eliminate the ringing effect of an electric-optical crystal in a regenerative amplifier, and the device comprises an electric-optical crystal 1, an electric-optical crystal driving control unit 2, an acousto-optic modulator 3, an acousto-optic modulator driving control unit 4, an isolator 5, a first λ / 2 wave plate 6, a pulse selector 7, a first thin film polarizer 8, a Faraday rotator 9, a second λ / 2 wave plate 10, a second thin film polarizer 11, a λ / 4 wave plate 12, a first total reflection mirror 13, a second total reflection mirror 14, a gain medium 15 and a third total reflection mirror 16. In the device, the acousto-optic modulator 3 is horizontally out of 0 level and has a diffraction efficiency of 100%. The electric-optical crystal 1, the electric-optical crystal driving control unit 2, the acousto-optic modulator 3, the acousto-optic modulator driving control unit 4, the λ / 4 wave plate 12, the first total reflection mirror 13, the second total reflection mirror 14, the gain medium 15 and the third total reflection mirror 16 constitute a regenerative amplifier resonant cavity.

[0039] The specific working process comprises: The seed laser after the isolator 5, its polarization state will change (screening S polarization state light), the first λ / 2 half-wave plate 6 changes its polarization direction, the seed light after the pulse selector 7 is p polarized light (horizontal polarization), the p polarized light will pass through the first film polarizer 8, after the Faraday rotator 9 and the second λ / 2 half-wave plate 10, the polarization state is not changed, then it will be transmitted by the second film polarizer 11, into the regenerative amplifier resonant cavity. The fast axis direction of the λ / 4 wave plate 12 and the horizontal polarized light are at an angle of 45 degrees, at this time, the electro-optic crystal driving control unit 2 is in the state of no pressure, the electro-optic crystal 1 does not work, and the polarization state of the light is not changed, the signal of the acousto-optic modulator driving control unit 4 is low, the acousto-optic modulator 3 does not work, and the light does not diffract. The p light passes through the first full mirror 13, passes through the λ / 4 wave plate 12 twice, and the polarization state is rotated by 90 degrees, becoming s light (vertical polarization). The s light is reflected by the second film polarizer 11, then reflected by the second full mirror 14, obtains gain at the gain medium 15, then reflected by the third full mirror 16, and after multiple reflections, returns to the second film polarizer 11 again, at this time, the electro-optic crystal driving control unit 2 applies a quarter-wave voltage to the electro-optic crystal 1, so that the electro-optic crystal 1 and the λ / 4 wave plate 12 cancel out, and the polarization state of the light is not changed as a whole, so that the s light is locked in the regenerative amplifier resonant cavity and is amplified all the time.

[0040] After a predetermined number of times, the high voltage loaded on the electro-optic crystal 1 is removed, the s light oscillating in the cavity becomes p light again after passing through the λ / 4 wave plate twice, passes through the second film polarizer 11, becomes s light after passing through the Faraday rotator 9 and the second λ / 2 wave plate 10, and is reflected again after passing through the first film polarizer 8. The amplified light is output.

[0041] When the regenerative amplifier completes the laser output, the electro-optic crystal 1 needs to be de-energized for the energy storage stage of the next cycle. When the voltage is removed, the electro-optic effect in the crystal does not stop immediately, and the ringing effect is generated. At this time, the acousto-optic modulator 3 starts to work, the ringing light signal is diffracted by 1 order, the diffracted light deviates from the resonant cavity path, and the loss in the resonant cavity is greatly increased. In the high loss state, stable laser oscillation cannot be formed in the cavity, so that the ringing effect is effectively suppressed. When the ringing effect ends, the acousto-optic modulator driving control unit 4 returns to low, the acousto-optic modulator 3 does not work, the light does not diffract, and the energy storage is restarted.

[0042] In a specific embodiment, the device for suppressing the ringing effect of an electro-optic crystal based on an acousto-optic modulator is applied to eliminate the ringing effect of an electro-optic crystal in a Q-switched cavity dumped laser. The device comprises an electro-optic crystal 1, an electro-optic crystal driving control unit 2, an acousto-optic modulator 3, an acousto-optic modulator driving control unit 4, a thin film polarizer 8, a λ / 4 wave plate 12, a first total reflection mirror 13, a second total reflection mirror 14, and a gain medium 15. In the device, the acousto-optic modulator 3 is a 0th order horizontal exit and has a diffraction efficiency of 100%.

[0043] The specific working process includes: The p-polarized light can pass through the thin film polarizer 8. At this time, the electro-optic crystal driving control unit 2 is in an unpressurized state, the electro-optic crystal 1 does not work, the polarization state of the light is not changed, the acousto-optic modulator driving control unit 4 controls the signal to be low, the acousto-optic modulator 3 does not work, and the light does not diffract. The fast axis direction of the λ / 4 wave plate 12 and the horizontal polarized light are at an angle of 45 degrees, and the light path is not changed. The p-light passes through the second total reflection mirror 14 twice through the λ / 4 wave plate 12, the polarization state is rotated by 90 degrees, and becomes s-light (vertical polarization). The s-light is reflected by the thin film polarizer 8, obtains gain at the gain medium 15, and then is reflected by the first total reflection mirror 13. After reflection, it returns to the thin film polarizer 8. At this time, the electro-optic crystal driving control unit 2 applies a quarter-wave voltage to the electro-optic crystal 1, so that the electro-optic crystal 1 and the λ / 4 wave plate 12 cancel each other out, and the polarization state of the light as a whole is not changed, so that the s-light is locked in the resonant cavity and is amplified all the time. After a certain number of amplifications, the high voltage applied to the electro-optic crystal 1 is removed, the s-light oscillating in the cavity becomes p-light again after passing through the λ / 4 wave plate twice, and the laser is output through the thin film polarizer 8.

[0044] When the cavity dumped laser completes the laser output, the electro-optic crystal needs to be de-energized to enter the next energy storage stage. When the voltage is removed, the electro-optic effect in the crystal does not stop immediately, and the ringing effect is generated. At this time, the acousto-optic modulator 3 starts to work, and the ringing light signal is diffracted by 1st order, and the diffracted light deviates from the resonant cavity path, greatly increasing the loss in the resonant cavity. In the high loss state, stable laser oscillation cannot be formed in the cavity, so that the ringing effect is effectively suppressed. When the ringing effect ends, the acousto-optic modulator driving control unit 4 returns to low, the acousto-optic modulator 3 does not work, the light does not diffract, and the energy storage is restarted.

[0045] In the above embodiment, the input light signal The electro-optically modulated light signal containing the ringing effect can be considered as an ideal modulated signal such as a pulse signal, which is superimposed with the ringing light signal which is usually an attenuated oscillation, and can be represented by the following equation

[0046] For the electro-optic crystal, the acousto-optic modulator and the input optical signal, we have:

[0047] where, is the modulation period of the electro-optic crystal, the acousto-optic modulator, is the effective signal duration, is the ringing light signal duration, is also the effective signal duration of the acousto-optic modulator.

[0048] For the acousto-optic modulator, the diffraction efficiency can be expressed as:

[0049] where, is the acousto-optic interaction length, is the ultrasonic power, is the quality factor of the acousto-optic material, which is expressed as , is the refractive index of the medium, is the photoelastic coefficient, is the medium density, is the propagation speed of the ultrasonic wave in the medium, is the wavelength of the light wave in the medium.

[0050] The device is designed to meet , the diffraction efficiency When diffraction occurs, the incident light energy is completely converted into first-order diffraction light energy.

[0051] In the above embodiment applied to eliminate the electro-optic crystal ringing effect in the regenerative amplifier, based on the zero-order diffraction direction of the light path configuration and the 100% diffraction efficiency parameter setting, the output end presents the bistable working characteristics: the effective signal state of complete retention of optical energy (100% transmission) or the extinction state of complete suppression of the ringing light signal (0% transmission), thereby realizing the dual-mode switching of the optical field. Therefore, the transfer function of the acousto-optic modulator can be simplified as the gating function , which can be expressed as:

[0052] When , at this time the input light is the effective signal, the acousto-optic modulator does not work, and the light path passes through; , the electro-optic crystal produces a ringing effect, the acousto-optic modulator works, the diffracted light deviates from the path of the resonant cavity, greatly increasing the loss in the resonant cavity. In the high loss state, the cavity cannot form stable laser oscillation, and the ringing part is suppressed.

[0053] Thus, the acousto-optic modulator modulates the system output after the acousto-optic modulator is:

[0054] That is, the suppression of the ringing effect can be achieved.

[0055] It is to be understood that the above-described embodiments are merely illustrative of the principles of the application and that numerous and various modifications can be made by those skilled in the art without departing from the spirit and scope of the present application.

Claims

1. A device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator, characterized in that, The device comprises: an electro-optic crystal, an electro-optic crystal driving control unit, an acousto-optic modulator and an acousto-optic modulator driving control unit; the electro-optic crystal driving control unit is used to apply a voltage across the electro-optic crystal; the electro-optic crystal is used to output an effective optical signal when the voltage is stable; the voltage is in a voltage withdrawal process, and a ringing effect is generated to output a ringing effect optical signal; the acousto-optic modulator driving control unit is used to generate different control signals to control the operation of the acousto-optic modulator; when the electro-optic crystal outputs an effective optical signal, the control signal generated by the acousto-optic modulator driving control unit is at a low level, and no driving signal is provided to the acousto-optic modulator; when the electro-optic crystal generates a ringing effect, the control signal generated by the acousto-optic modulator driving control unit is at a high level, and a driving signal is provided to the acousto-optic modulator; the acousto-optic modulator is used to generate a sound wave when receiving the driving signal, so that the incident ringing effect optical signal is diffracted and deviates from the path of the resonant cavity, and cannot form stable oscillation, thereby suppressing the ringing effect optical signal.

2. The apparatus of claim 1, wherein, The electro-optic crystal is a Q-switch.

3. The apparatus of claim 1, wherein, The electro-optic crystal driving control unit comprises a direct current power supply, a driving circuit and a signal generator; the direct current power supply is used to provide the required direct current voltage for the electro-optic crystal; the driving circuit is used to generate and adjust the voltage signal applied across the electro-optic crystal; the signal generator is used to control the voltage signal generated by the driving circuit to have a preset frequency and a preset waveform.

4. The apparatus of claim 1, wherein, The acousto-optic modulator comprises a piezoelectric crystal and an acousto-optic crystal; the piezoelectric crystal is used to convert the input driving signal into an ultrasonic wave to drive the acousto-optic crystal to work; the acousto-optic crystal is used to modulate the optical signal by using the acousto-optic effect to cause the passing optical signal to be diffracted.

5. The apparatus of claim 1, wherein, The acousto-optic modulator further comprises a sound absorption device.

6. The apparatus of claim 1, wherein, The acousto-optic modulator comprises a 0-level horizontal exit working mode and a 1-level horizontal exit working mode.

7. The apparatus of claim 1, wherein, The acousto-optic modulator driving control unit comprises a radio frequency signal source, a power amplifier, a direct current power supply and a control circuit; the radio frequency signal source is used to provide a radio frequency signal for the acousto-optic modulator; the power amplifier is used to enhance the power of the radio frequency signal to effectively drive the acousto-optic modulator to work; the direct current power supply is used to provide a stable direct current power supply for the acousto-optic modulator; the control circuit is used to adjust and control the frequency and amplitude of the radio frequency signal generated by the radio frequency signal source.

8. A method for suppressing the ringing effect of an electro-optic crystal based on an acousto-optic modulator, applied to the device according to any one of claims 1 to 7, characterized in that, The device comprises: controlling the electro-optic crystal driving control unit to generate a first preset driving signal, and controlling the acousto-optic modulator driving control unit to generate a second driving signal based on the first preset driving signal; controlling the electro-optic crystal to start working at a preset time based on the first preset driving signal to modulate the input laser and output a periodic optical signal composed of an effective optical signal and a ringing effect optical signal; controlling the acousto-optic modulator to generate a sound wave based on the second preset driving signal when the electro-optic crystal outputs a ringing optical signal, so that the incident ringing effect optical signal is diffracted and deviates from the path of the resonant cavity, thereby suppressing the ringing effect optical signal.

9. The method of claim 8, wherein, The diffraction efficiency of the acousto-optic modulator is set to 100%.

10. A device for suppressing the ringing effect of electro-optic crystals based on an acousto-optic modulator, characterized in that, The device comprises: a controller and the device of any one of claims 1-7. The controller is configured to perform the method of claim 8 or 9.

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