阅读说明：本技术 脉冲输出可调的声光调q固体激光器及脉冲激光产生方法 (Pulse output adjustable acousto-optic Q-switched solid laser and pulse laser generation method ) 是由 林学春 王红洋 张志研 余海军 董智勇 赵树森 于 2021-07-02 设计创作，主要内容包括：一种脉冲输出可调的声光调Q固体激光器及脉冲激光产生方法,该声光调Q固体激光器包括：振荡级模块,用于被泵浦持续产生激光；可编程信号发生器,用于产生模拟信号；声光Q驱动器,用于接收所述可编程信号发生器产生的模拟信号,产生台阶状的射频信号；声光Q开关,用于接收所述声光Q驱动器产生的射频信号,并基于所述射频信号对所述振荡级模块产生的连续激光进行调制,使其转变为脉冲激光。(An acousto-optic Q-switched solid laser with adjustable pulse output and a pulse laser generation method are provided, the acousto-optic Q-switched solid laser comprises: the oscillating stage module is used for being pumped to continuously generate laser; a programmable signal generator for generating an analog signal; the acousto-optic Q driver is used for receiving the analog signal generated by the programmable signal generator and generating a step-shaped radio frequency signal; and the acousto-optic Q switch is used for receiving the radio-frequency signal generated by the acousto-optic Q driver and modulating the continuous laser generated by the oscillating stage module based on the radio-frequency signal so as to convert the continuous laser into pulse laser.)

1. An acousto-optic Q-switched solid state laser with adjustable pulse output, comprising:

the oscillation stage module is used for continuously generating laser;

a programmable signal generator for generating an analog signal;

the acousto-optic Q driver is used for receiving the analog signal generated by the programmable signal generator and generating a step-shaped radio frequency signal;

and the acousto-optic Q switch is used for receiving the radio-frequency signal generated by the acousto-optic Q driver and modulating the laser generated by the oscillating stage module based on the radio-frequency signal so as to convert the laser into pulse laser.

2. An acousto-optic Q-switched solid state laser as claimed in claim 1,

the work frequency of the acousto-optic Q-switch driver is 50MHZ, and the falling time of electric pulses is less than or equal to 120 ns.

3. The acousto-optic Q-switched solid state laser of claim 1, wherein the acousto-optic Q-switched solid state laser further comprises a total reflection mirror and a laser output mirror, respectively disposed at two sides of the oscillating stage module and symmetrically arranged in a collinear manner; forming a resonant cavity between the total reflection lens and the laser output lens;

the acousto-optic Q switch is positioned between the oscillating stage module and the laser output lens or between the oscillating stage module and the total reflection lens, and pulse laser generated by modulation of the acousto-optic Q switch is output through the laser output lens after oscillating in the resonant cavity.

4. An acousto-optic Q-switched solid state laser according to claim 3, wherein said laser output lens has a laser transmittance of 40% -70%.

5. An acousto-optic Q-switched solid state laser according to claim 3, wherein said cavity length is 400 mm.

6. The acousto-optic Q-switched solid state laser of claim 3, wherein the acousto-optic Q-switched solid state laser further comprises:

and the beam expander lens group is used for expanding and shaping the pulse laser output by the laser output lens.

7. The acousto-optic Q-switched solid state laser of claim 6, wherein the acousto-optic Q-switched solid state laser further comprises:

the hard optical path transmission collimation output lens group is used for carrying out hard optical path transmission on the laser output by the beam expander lens group after beam expansion and shaping; or

And the optical fiber transmission coupling lens group is used for coupling the expanded and shaped laser output by the beam expander lens group to an optical fiber for transmission.

8. The acousto-optic Q-switched solid state laser of claim 1, wherein the acousto-optic Q-switched solid state laser further comprises:

and the driving power supply is used for providing pumping current for the oscillating stage module, and the driving power supply adjusts the pumping power of the oscillating stage module by adjusting the pumping current so as to adjust the power of the laser generated by the oscillating stage module.

9. A method of generating pulsed laser light using the acousto-optic Q-switched solid state laser of any one of claims 1-8, comprising:

generating laser by using an oscillating stage module;

generating an analog signal using a programmable signal generator;

receiving the analog signal by using an acousto-optic Q driver, enabling the analog signal to generate a step-shaped radio frequency signal, and enabling the radio frequency signal generated by the acousto-optic Q driver to act on an acousto-optic Q switch;

converting the electric energy of the step-shaped radio frequency signal into ultrasonic energy corresponding to different step heights and different durations by utilizing a piezoelectric transducer in the acousto-optic Q switch;

and modulating the diffraction efficiency of the acousto-optic crystal to laser by using the acousto-optic crystal in the acousto-optic Q switch according to the intensity of ultrasonic energy, thereby modulating the laser generated by the oscillation level module and converting the laser into pulse laser with adjustable sub-pulse energy, number and interval.

10. The method of claim 9, wherein the method further comprises providing a pumping current to the oscillating stage module using a driving power supply to adjust a power of the laser light generated by the oscillating stage module;

the intensity of each step of the step-shaped radio frequency signal is adjusted at any time according to the size of the pumping current, and the length of each step is synchronous with the interval time of the required sub-pulse.

Technical Field

The invention relates to the field of building of solid lasers and radio frequency signal modulation methods of acousto-optic Q-switch drivers, in particular to an acousto-optic Q-switching solid laser with adjustable pulse output and a pulse laser generation method.

Background

The double-pulse laser has important application prospect in the technical field of laser-induced breakdown spectroscopy, and can enhance the spectral intensity of the generated plasma, prolong the light-emitting time and improve the detection precision. Meanwhile, the laser cleaning system has important application in the laser medical field such as tumor treatment, calculus and gastrolith removal and the like, but reports of applying double-pulse laser in the laser cleaning field are not seen at present, and the main reasons are that a common single-pulse solid laser for cleaning is not suitable for optical fiber transmission under high energy, damages an optical mirror surface and the like, and a related double-pulse laser output system is complex in structure, and cannot realize double-pulse or multi-pulse solid laser output with high power and high repetition frequency parameters and the like. Therefore, there is a need for optimization of lasers.

The related double-pulse solid laser has the following defects: in the scheme of adopting an electro-optical Q-switching switch device to change the electro-optical effect in crystals or liquid to regulate and control output double-pulse laser, the mode needs thousands of volts of working voltage when controlling high-power laser, and simultaneously an 1/4 wave plate is needed to form a laser resonant cavity with stable oscillation starting, so that the improvement of the average power of the laser of the resonant cavity is greatly reduced by using the 1/4 wave plate; in the scheme of outputting double-pulse laser by adopting two resonant cavities, a plurality of pulses cannot be output, if multi-pulse output is realized, the number of the resonant cavities needs to be increased, and the complexity of a system is increased; neither of the two aforementioned schemes can achieve a double-pulse or multi-pulse solid-state laser output with both high power (hectowatt) and high repetition rate (kHz) parameters.

Disclosure of Invention

It is therefore an objective of the claimed invention to provide an acousto-optic Q-switched solid-state laser with adjustable pulse output and a method for generating pulsed laser, so as to at least partially solve at least one of the above-mentioned problems.

In order to achieve the above object, as a first aspect of the present invention, there is provided an acousto-optic Q-switched solid-state laser whose pulse output is controllable, comprising: the oscillation stage module is used for continuously generating laser; a programmable signal generator for generating an analog signal; the acousto-optic Q driver is used for receiving the analog signal generated by the programmable signal generator and generating a step-shaped radio frequency signal; and the acousto-optic Q switch is used for receiving the radio-frequency signal generated by the acousto-optic Q driver and modulating the laser generated by the oscillating stage module based on the radio-frequency signal so as to convert the laser into pulsed light.

As a second aspect of the present invention, there is provided a method of generating pulsed laser light with an acousto-optic Q-switched solid state laser as described above, comprising: generating laser by using an oscillating stage module; generating an analog signal using a programmable signal generator; receiving an analog signal by using an acousto-optic Q driver to enable the analog signal to generate a step-shaped radio frequency signal; applying the radio-frequency signal generated by the acousto-optic Q driver to an acousto-optic Q switch; converting the electric energy of the step-shaped radio frequency signal into ultrasonic energy corresponding to different step heights and different durations by utilizing a piezoelectric transducer in the acousto-optic Q switch; and modulating the diffraction efficiency of the acousto-optic crystal to laser by using the acousto-optic crystal in the acousto-optic Q switch according to the intensity of ultrasonic energy, thereby modulating the laser generated by the oscillation level module and converting the laser into pulse light with adjustable sub-pulse number, energy proportion and interval time.

According to the technical scheme, the acousto-optic Q-switched solid laser with adjustable pulse output and the pulse laser generating method have one or part of the following beneficial effects:

the acousto-optic Q-switched solid laser with adjustable pulse output provided by the invention has the advantages that the analog signal generated by the programmable signal generator is applied to the acousto-optic Q driver, the acousto-optic Q driver generates a step-shaped radio frequency signal and transmits the same to the acousto-optic Q switch, the acousto-optic Q switch modulates the laser generated by the oscillating stage module after receiving the step-shaped radio frequency signal, the laser is converted into pulse light, the number of pulses, the energy proportion and the sub-pulse interval of the pulse light can be adjusted and controlled, and the acousto-optic Q-switched solid laser can output the pulse laser, the number of the sub-pulses, the energy proportion and the sub-pulse interval of the pulse laser can be adjusted and controlled.

Based on the adjustability of the pulse laser output by the acousto-optic Q-switched solid laser, the output of double-pulse or multi-pulse solid laser with high power and high repetition frequency parameters can be realized at the same time, the input energy can be increased by multiple times on the premise of a certain damage threshold of an optical lens or an optical fiber section, and the problem of large energy damage in laser cleaning application is effectively solved.

Drawings

FIG. 1 is a schematic diagram of an acousto-optic Q-switched solid state laser according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the acousto-optic Q-switched solid state laser output double pulses in an embodiment of the present invention;

FIG. 3 is a comparison of waveforms of RF signals tested and hypothetical RF signals in an embodiment of the present invention, where (a) is a waveform of a hypothetical RF signal and (b) is a waveform of a RF signal tested;

fig. 4 is a waveform diagram of a double pulse laser implemented in an embodiment of the present invention.

Description of the reference numerals

1 total reflection lens

2 oscillating stage module

3 acousto-optic Q switch

4 laser output lens

5 light beam expander lens group

6 hard light path transmission collimation output lens group

7 acousto-optic Q switch driver

8 programmable signal generator

9 drive power supply

Detailed Description

In the implementation process of the invention, the solid laser generates double-pulse or multi-pulse laser by optimizing the structure of the solid laser, and the problems that the existing solid laser for laser cleaning is not suitable for optical fiber transmission under high energy, damages an optical mirror surface and the like can be effectively solved.

Therefore, the invention creatively provides an acousto-optic Q-switched solid laser with adjustable pulse output and a pulse light generation method, and aims to optimize the solid laser, so that laser of the solid laser can generate pulse light after being modulated by an acousto-optic Q switch, and then the pulse laser is resonantly output.

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

According to an embodiment of the present invention, there is provided an acousto-optic Q-switched solid-state laser with controllable pulse output, including: the oscillation stage module is used for continuously generating laser; a programmable signal generator for generating an analog signal; the acousto-optic Q driver is used for receiving the analog signal generated by the programmable signal generator and generating a step-shaped radio frequency signal; and the acousto-optic Q switch is used for receiving the radio-frequency signal generated by the acousto-optic Q driver and modulating the laser generated by the oscillating stage module based on the radio-frequency signal so as to convert the laser into pulse laser.

It is understood that the acousto-optic Q-switch is composed primarily of a piezoelectric transducer, an acousto-optic crystal (typically a fused silica body), and a sound absorbing material. Generally, a piezoelectric transducer is used to convert the electrical energy of a radio frequency signal into ultrasonic energy, and the ultrasonic energy is applied to an acousto-optic crystal to cause the refractive index of the acousto-optic crystal to change periodically, so as to diffract incident light. In the invention, the acousto-optic Q-switch driver capable of receiving the input of the analog signal is selected, so that the acousto-optic Q-switch driver can output the step-shaped radio frequency signal after receiving the specific analog modulation signal, the intensity of the radio frequency signal influences the ultrasonic power applied to the acousto-optic crystal by the piezoelectric transducer in the acousto-optic Q-switch, further influences the diffraction efficiency of the acousto-optic crystal on the laser, further influences the diffraction capability of the acousto-optic Q-switch, and further can realize the output of double pulse light or multi-pulse light under the modulation of the step-shaped radio frequency signal. That is to say, the intensity of the Bragg diffraction light can be controlled by controlling the intensity of the radio frequency signal, two or more pulse outputs can be carried out in one pumping period, and the sub-pulse interval can be adjusted by adjusting the step width of the radio frequency signal. The adjustable energy proportion of the sub-pulse can be realized by adjusting the step height proportion of the radio frequency signal. The repetition frequency of the laser is more than 1kHz-20kHz, the sub-pulse interval is 500ns-10us, and the power can reach more than 100W.

According to an embodiment of the present invention, the oscillating stage module may select, but is not limited to, 4mm × 160mm nd: a module of YAG crystal bars.

According to the embodiment of the invention, the working frequency of the acousto-optic Q-switch driver is 50MHZ, and the falling time of the electric pulse is less than or equal to 120 ns. The acousto-optic Q switch driver with the working frequency as high as possible is selected, so that the acousto-optic Q switch driver can output a plurality of step-shaped radio-frequency signals and simultaneously ensure the turn-off of an optical path, and the higher the working frequency is, the stronger the turn-off capability of the acousto-optic Q switch can be, so that the acousto-optic Q switch driver with the working frequency of 50MHz is selected.

According to the embodiment of the invention, the acousto-optic Q-switched solid laser further comprises a total reflection lens and a laser output lens which are respectively arranged on two sides of the oscillating stage module and are symmetrically arranged in a collinear manner; a resonant cavity is formed between the total reflection lens and the laser output lens; the acousto-optic Q switch is positioned between the oscillating stage module and the laser output lens or between the oscillating stage module and the total reflection lens, and pulse laser generated by the acousto-optic Q switch is output through the laser output lens after oscillating in the resonant cavity. The length of the resonant cavity is 400nm, and the resonant cavity with the length is stable and high in conversion rate. The reflectance of the total reflection mirror for light having a wavelength of 1064nm was 100%.

According to the embodiment of the invention, the laser transmittance of the laser output lens is 40-70%.

According to an embodiment of the present invention, the acousto-optic Q-switched solid state laser further includes: and the beam expander lens group is used for expanding and shaping the pulse laser output by the laser output lens. The beam expanding lens module can be selected according to actual requirements but is not limited to 1 consisting of spherical mirrors with f being-50 mm and f being 100 mm: 2 a beam expanding system.

According to an embodiment of the present invention, the acousto-optic Q-switched solid state laser further includes: the hard optical path transmission collimation output lens group is used for carrying out hard optical path transmission on the laser which is output by the beam expander lens group and subjected to beam expansion and shaping; or the optical fiber transmission coupling lens group is used for coupling the expanded and shaped laser output by the beam expander lens group to the optical fiber for transmission.

According to an embodiment of the present invention, the acousto-optic Q-switched solid state laser further includes: the driving power supply is used for providing pumping current for the oscillating stage module so as to adjust the power of the laser generated by the oscillating stage module; the driving power supply adjusts the pumping power of the oscillating stage module by adjusting the pumping current of the oscillating stage module, so that the laser output power of the oscillating stage module can be adjusted.

According to an embodiment of the present invention, there is also provided a method of generating pulsed laser light with an acousto-optic Q-switched solid state laser as described above, including: generating laser by using an oscillating stage module; generating an analog signal using a programmable signal generator; receiving the analog signal by using an acousto-optic Q driver, enabling the analog signal to generate a step-shaped radio frequency signal, and enabling the radio frequency signal generated by the acousto-optic Q driver to act on an acousto-optic Q switch; converting the electric energy of the step-shaped radio frequency signal into ultrasonic energy corresponding to different step heights and different durations by utilizing a piezoelectric transducer in the acousto-optic Q switch; and modulating the diffraction efficiency of the acousto-optic crystal to laser by using the acousto-optic crystal in the acousto-optic Q switch according to the intensity of ultrasonic energy, thereby modulating the laser generated by the oscillation level module and converting the laser into pulse laser with adjustable sub-pulse energy, number and interval.

According to an embodiment of the present invention, the method for generating pulsed laser further includes providing a pumping current to the oscillating stage module by using a driving power supply, so as to adjust the power of the laser generated by the oscillating stage module.

According to the embodiment of the invention, the strength of the step-shaped radio frequency signal is adjusted at any time according to the magnitude of the pumping current, and the length of each step is synchronous with the interval time of the required sub-pulse.

The technical solution of the present invention will be described in detail below with reference to specific examples. It should be noted that the following specific examples are only for illustration and are not intended to limit the invention.

Example 1

The principle of generating multi-pulse laser light by the acousto-optic Q-switched solid-state laser of the present invention is described below with reference to FIGS. 1 and 2.

Fig. 1 is a schematic structural diagram of an acousto-optic Q-switched solid-state laser in an embodiment of the invention. As shown in fig. 1, the acousto-optic Q-switched solid-state laser includes:

the oscillating stage module 2 is used for continuously generating laser; a programmable signal generator 8 for generating an analog signal; the acousto-optic Q driver 7 is used for receiving the analog signal generated by the programmable signal generator 8 and generating a step-shaped radio frequency signal; the acousto-optic Q switch 3 is used for receiving the radio frequency signal generated by the acousto-optic Q driver 7 and modulating the laser generated by the oscillating stage module 2 based on the radio frequency signal so as to convert the laser into pulse laser; and the driving power supply 9 is used for providing pumping current for the oscillating stage module 2 so as to adjust the power of the laser generated by the oscillating stage module 2, and the driving power supply 9 adjusts the pumping power of the oscillating stage module by adjusting the pumping current so as to adjust the power of the laser generated by the oscillating stage module. The acousto-optic Q-switched solid laser also comprises a total reflection lens 1 and a laser output lens 4 which are respectively arranged at two sides of the oscillating stage module 2 and are symmetrically arranged in a collinear way; a resonant cavity is formed between the total reflection lens 1 and the laser output lens 4; the acousto-optic Q switch 3 is positioned between the oscillating stage module 2 and the laser output lens 4 and is close to the oscillating stage module 2 as much as possible, so that the light path can be completely cut off by the fine adjustment angle of the acousto-optic Q switch 3; pulse laser generated by the modulation of the acousto-optic Q switch is output through the laser output lens after oscillating in the resonant cavity. The acousto-optic Q-switched solid state laser further comprises: the beam expander lens group 5 is used for expanding and shaping the pulse laser output by the laser output lens; and a hard optical path transmission collimation output lens group 6, which is used for carrying out hard optical path transmission on the expanded and shaped laser output by the beam expander lens group 5. Fig. 2 is a schematic diagram of the acousto-optic Q-switched solid state laser outputting double pulses in an embodiment of the invention. The working principle of the acousto-optic Q switch is as follows: through the radio frequency signal who applys the high level, acousto-optic crystal's diffraction efficiency is higher in the acousto-optic Q switch 3, and acousto-optic Q switch 3 is turn-offed to resonant cavity laser this moment, simultaneously, because acousto-optic Q switch 3's acousto-optic crystal's diffraction effect, increases the diffraction loss of resonant cavity, because Laser Diode (LD) in the oscillating stage module is to the Nd: the YAG crystal rod is continuously pumped and therefore a large number of inversion populations accumulate in the oscillating stage module 2. If the applied radio frequency signal is cut off at the moment, the acousto-optic crystal returns to a high-transmissivity state, the acousto-optic crystal in the acousto-optic Q switch 3 does not diffract the laser any more, so that the diffraction loss is reduced, the number of reversed particles can jump to a low energy level, and a pulse laser is output in the resonant cavity instantly.

As shown in fig. 2, at the first step of the rf signal, the acousto-optic crystal of the acousto-optic Q-switch 3 has a higher diffraction efficiency, i.e., a higher diffraction loss, and the resonant cavity is in a low Q state. When the intensity of the applied radio frequency signal is partially weakened, namely the radio frequency signal is reduced to a second step, the diffraction efficiency is reduced, and a pulse is output instantaneously in the resonant cavity; and then, in the step duration of the second radio frequency signal, the LD of the oscillation level module 2 continuously pumps to continuously accumulate the number of inversion particles, and when the intensity of the radio frequency signal is reduced again, the diffraction efficiency is reduced along with the accumulation of the number of inversion particles to form a second pulse, so that two pulse outputs in one period are completed. By analogy, the control method can be utilized to design that the multi-step radio frequency signal output influences the diffraction of the acousto-optic Q switch 3 on the laser, and further obtain multi-pulse.

The programmable signal generator 8 inputs a suitable analog modulation signal into the acousto-optic Q-switch driver 7, and outputs a radio frequency signal corresponding to a step shape, as shown in fig. 2, the width of a first step in the radio frequency signal represents the inverse particle count accumulation time in the resonant cavity, the width of a second and subsequent steps determines the time interval for generating the sub-pulse, and the wider the step width, the longer the time interval for generating the sub-pulse. The sub-pulse interval range of 500ns-10us can be realized by adjusting the step width. The first step voltage value of the radio frequency signal output by the acousto-optic Q driver is 3V, the second step voltage range is 1.5-2.5V, and the second step width range is 500ns-10 us. The energy ratio between the sub-pulses can be adjusted by adjusting the height ratio of each step of the radio frequency signal. The energy ratio of the sub-pulses can be adjusted within the range of 1: 1-1: 0.7 by adjusting the step height of the radio frequency signal.

Fig. 3 is a comparison of waveforms of rf signals tested and those envisioned in an embodiment of the present invention. As shown in fig. 3, the waveform of the rf signal tested is highly similar to that of the rf signal under consideration, and the rf signal is implemented at a frequency of 10 kHz.

Fig. 4 is a waveform diagram of a double-pulse laser implemented in an embodiment of the present invention, where the left diagram shows that the laser outputs a pulse laser with a repetition rate of 5kHz, and the right diagram shows a partially amplified pulse, and it can be seen that the sub-pulse interval of the output double-pulse laser is about 500 ns. As can be seen from fig. 4, the acousto-optic Q-switched solid-state laser with controllable pulse output of the present invention can generate double-pulse laser light, and the pulse width of the single-pulse laser light is 70 ns. The invention can theoretically improve the input energy by multiple times on the premise of a certain damage threshold of the optical lens or the optical fiber section, and effectively solves the problem of large energy damage in laser cleaning application.

Therefore, the acousto-optic Q-switched solid laser can regulate and control the number of sub-pulses, the energy ratio and the sub-pulse interval.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.