阅读说明：本技术 单纵模与非单纵模双脉冲激光交替调q输出方法及激光器 (Single longitudinal mode and non-single longitudinal mode double-pulse laser alternate Q-switching output method and laser ) 是由 董渊 刘宇 李述涛 王超 金光勇 于 2019-05-09 设计创作，主要内容包括：本发明公开了一种单纵模与非单纵模双脉冲激光交替调Q输出方法及激光器,该激光器包括：激光输出镜、电光调Q晶体、起偏器、45°反射镜、第一激光增益介质、第一激光全反射镜、第一耦合透镜组、第一光纤、第一泵浦源、四分之一波片、第二激光增益介质、第二激光全反射镜、第二耦合透镜组、第二光纤和第二泵浦源,当电光调Q晶体迅速加压时,所述激光器输出非单纵模激光,当电光调Q晶体阶跃式退压时,所述激光器输出单纵模激光。本发明不仅能够输出双脉冲激光,而且所输出的脉冲序列从时间上来看为单纵模与非单纵模交替输出的。(The invention discloses a single longitudinal mode and non-single longitudinal mode double-pulse laser alternative Q-switched output method and a laser, wherein the laser comprises: the laser comprises a laser output mirror, an electro-optic Q-switched crystal, a polarizer, a 45-degree reflector, a first laser gain medium, a first laser holophote, a first coupling lens group, a first optical fiber, a first pumping source, a quarter-wave plate, a second laser gain medium, a second laser holophote, a second coupling lens group, a second optical fiber and a second pumping source. The invention can not only output double-pulse laser, but also output pulse sequence which is alternately output by a single longitudinal mode and a non-single longitudinal mode in terms of time.)

1. A single longitudinal mode and non-single longitudinal mode double-pulse laser alternative Q-switched output laser, characterized in that the laser comprises: laser output mirror, electro-optic Q-switched crystal, polarizer, 45 degree speculum, first laser gain medium, first laser holophote, first coupling lens group, first optic fibre, first pumping source, quarter wave plate, second laser gain medium, second laser holophote, second coupling lens group, second optic fibre and second pumping source, wherein:

the first pump source is arranged on one side of the first coupling lens group, the first optical fiber is used for connecting the first pump source and the first coupling lens group, and the first coupling lens group is used for coupling light emitted by the first pump source into the first laser gain medium;

the second pump source is arranged behind the second coupling lens group, the second optical fiber is used for connecting the second pump source and the second coupling lens group, and the second coupling lens group is used for coupling light emitted by the second pump source into a second laser gain medium;

the first laser holophote, the first laser gain medium, the 45-degree reflector, the polarizer, the electro-optic Q-switched crystal and the laser output mirror form a first path of laser resonant cavity;

the second laser holophote, the second laser gain medium, the quarter-wave plate, the 45-degree reflector, the polarizer, the electro-optic Q-switched crystal and the laser output mirror form a second laser resonant cavity;

the first path of laser resonant cavity and the second path of laser resonant cavity are arranged at a position of the 45-degree reflector in a 90-degree mode;

when the electro-optic Q-switched crystal is rapidly pressurized, the laser outputs non-single longitudinal mode laser, when the electro-optic Q-switched crystal is stepped to be decompressed, the laser outputs single longitudinal mode laser, rapid pressurization and stepped decompression are periodically carried out on the electro-optic Q-switched crystal, and the laser alternately outputs single longitudinal mode and non-single longitudinal mode double-pulse laser.

2. The laser device according to claim 1, wherein the first laser total reflection mirror is disposed at the other side of the first coupling lens group; the second laser total reflection mirror is arranged in front of the second coupling lens group.

3. The laser device according to claim 1, wherein the first laser gain medium is disposed on a side of the first total laser reflection mirror away from the first coupling lens group; the second laser gain medium is arranged on one side, far away from the second coupling lens group, of the second laser total reflector.

4. The laser of claim 1, wherein the quarter-wave plate and the 45 ° reflector are sequentially disposed on a side of the second laser gain medium away from the second laser total reflection mirror, and the quarter-wave plate is disposed between the second laser gain medium and the 45 ° reflector.

5. The laser of claim 1, wherein the quarter wave plate is placed perpendicular to the 45 ° mirror.

6. The laser of claim 1, wherein the 45 ° reflector, the polarizer, the electro-optically Q-switched crystal and the laser output mirror are sequentially disposed on a side of the first laser gain medium away from the first laser total reflection mirror.

7. The laser of claim 1, wherein the first pump source and the second pump source are both semiconductor pump sources.

8. The laser of claim 1, further comprising a Q-switched drive module coupled to the electro-optic Q-switched crystal for applying a Q-switched drive signal to the electro-optic Q-switched crystal.

9. The laser of claim 8, wherein the Q-switched driving signal generated by the Q-switched driving module is a step-up high voltage signal.

10. A single longitudinal mode and non-single longitudinal mode double pulse laser alternating Q-switched output method, applied to the laser device as claimed in any one of claims 1 to 9, wherein the method comprises:

applying quarter preset wavelength voltage to the electro-optical Q-switched crystal;

the first pump source performs pulse pumping on the first laser gain medium, the first path of laser resonant cavity is in a high loss state, the first laser gain medium is in a population inversion state, when the inversion population of the first laser gain medium reaches the maximum, the electro-optic Q-switched crystal is in step-back pressure, the voltage applied to the electro-optic Q-switched crystal becomes zero, and single longitudinal mode laser with preset wavelength is output;

the second pump source performs pulse pumping on the second laser gain medium, the voltage applied to the electro-optic Q-switched crystal is zero, the second laser resonant cavity is in a high-loss state, the second laser gain medium is in a population inversion state, when the inversion population of the second laser gain medium reaches the maximum, a quarter of preset wavelength voltage value is rapidly applied to the electro-optic Q-switched crystal, and the preset wavelength non-single longitudinal mode laser is output;

the rapid pressurizing and step-type decompressing states of the electro-optic Q-switching crystal are periodically repeated, and single-longitudinal-mode and non-single-longitudinal-mode double-pulse lasers which are alternately Q-switched and output are obtained.

Technical Field

The invention relates to the field of solid lasers, in particular to a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switching output method and a laser.

Background

The double-pulse laser has very wide requirements in the aspects of laser ranging, environment monitoring, laser remote sensing and laser radar. Compared with the single longitudinal mode pulse laser, the non-single longitudinal mode pulse laser has wider line width, but can often obtain larger pulse energy output, and the non-single longitudinal mode pulse laser can realize ultra-long distance detection in the technical field. The single longitudinal mode pulse laser has a narrow line width, is a detection light source for ultrahigh-precision and ultrahigh-sensitivity detection, and the narrower the line width of the laser, the higher the measurement precision. However, since extra elements are required to be inserted into the laser resonant cavity for obtaining the laser resonant cavity, the output capacity of the laser resonant cavity is often lower than that of a non-single longitudinal mode pulse laser. Therefore, when the double-pulse laser is non-single longitudinal mode pulse laser and single longitudinal mode pulse laser, the ultra-long distance coarse detection and the short-distance high-precision detection can be realized in the technical fields of laser ranging, environment monitoring, laser remote sensing, laser radar and the like. At present, the publicly reported double-pulse laser mainly takes non-single longitudinal mode double-pulse laser output as a main part, wherein one known technology related to the invention is disclosed by Lifeng et al (Lifeng, Wangjuntao, Yinsu, etc.. electro-optical Q-switched double-pulse output Nd: YAG all-solid-state laser [ J ]. Chinese laser, 2012, 39 (08): 27-31.), and the adopted structure is shown in FIG. 1. In fig. 1, 101 is a laser resonator total reflection mirror, 102 is a Q switch, 103 is a quarter-wave plate, 104 is a polarizer, 105 is an LD pump source, 106 is a focusing coupling system, 107 is a mirror coated with pumping light anti-reflection and laser high reflection, 108 is Nd: YAG laser crystal 109 is a laser resonator output mirror. However, the known technology has the following three disadvantages: firstly, the output double-pulse laser is all non-single longitudinal mode, and the known technical scheme can not obtain the double-pulse laser alternative output of single longitudinal mode pulse laser and non-single longitudinal mode pulse laser; secondly, when each pair of Q-switched crystals applies a high-voltage signal, only one Q-switched pulse laser output can be obtained, so that the Q-switched crystals can be subjected to larger pressure under the condition of high repetition frequency operation; thirdly, the known technical scheme is to obtain the output of the double-pulse laser by adopting the technology of one-time pumping and two-time Q-switching, and the two-pulse laser consumes the number of inversion particles generated by one-time pumping, so that the double-pulse laser with larger energy is difficult to obtain.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switching output method and a laser.

According to an aspect of the present invention, a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switched output laser is provided, the laser includes:

laser output mirror, electro-optic Q-switched crystal, polarizer, 45 degree speculum, first laser gain medium, first laser holophote, first coupling lens group, first optic fibre, first pumping source, quarter wave plate, second laser gain medium, second laser holophote, second coupling lens group, second optic fibre and second pumping source, wherein:

the first pump source is arranged on one side of the first coupling lens group, the first optical fiber is used for connecting the first pump source and the first coupling lens group, and the first coupling lens group is used for coupling light emitted by the first pump source into the first laser gain medium;

the second pump source is arranged behind the second coupling lens group, the second optical fiber is used for connecting the second pump source and the second coupling lens group, and the second coupling lens group is used for coupling light emitted by the second pump source into a second laser gain medium;

the first laser holophote, the first laser gain medium, the 45-degree reflector, the polarizer, the electro-optic Q-switched crystal and the laser output mirror form a first path of laser resonant cavity;

the second laser holophote, the second laser gain medium, the quarter-wave plate, the 45-degree reflector, the polarizer, the electro-optic Q-switched crystal and the laser output mirror form a second laser resonant cavity;

the first path of laser resonant cavity and the second path of laser resonant cavity are arranged at a position of the 45-degree reflector in a 90-degree mode.

When the electro-optic Q-switched crystal is rapidly pressurized, the laser outputs non-single longitudinal mode laser, when the electro-optic Q-switched crystal is stepped to be decompressed, the laser outputs single longitudinal mode laser, rapid pressurization and stepped decompression are periodically carried out on the electro-optic Q-switched crystal, and the laser alternately outputs single longitudinal mode and non-single longitudinal mode double-pulse laser.

Optionally, the first laser total reflection mirror is arranged on the other side of the first coupling lens group; the second laser total reflection mirror is arranged in front of the second coupling lens group.

Optionally, the first laser gain medium is disposed on a side of the first laser total reflection mirror away from the first coupling lens group; the second laser gain medium is arranged on one side, far away from the second coupling lens group, of the second laser total reflector.

Optionally, the quarter-wave plate and the 45 ° reflector are sequentially disposed on a side of the second laser gain medium away from the second laser total reflection mirror, and the quarter-wave plate is disposed between the second laser gain medium and the 45 ° reflector.

Optionally, the quarter wave plate is placed perpendicular to the 45 ° mirror.

Optionally, the 45 ° reflector, the polarizer, the electro-optical Q-switched crystal, and the laser output mirror are sequentially disposed on a side of the first laser gain medium away from the first laser total reflection mirror.

Optionally, the first pump source and the second pump source are both semiconductor pump sources.

Optionally, the laser further includes a Q-switched driving module, and the Q-switched driving module is connected to the electro-optical Q-switched crystal and is configured to apply a Q-switched driving signal to the electro-optical Q-switched crystal.

Optionally, the Q-switched driving signal generated by the Q-switched driving module is a step-type high-voltage signal.

According to another aspect of the present invention, a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switched output method is provided, which is applied to the laser as described above, and the method includes:

applying quarter preset wavelength voltage to the electro-optical Q-switched crystal;

the first pump source performs pulse pumping on the first laser gain medium, the first path of laser resonant cavity is in a high loss state, the first laser gain medium is in a population inversion state, when the inversion population of the first laser gain medium reaches the maximum, the electro-optic Q-switched crystal is in step-back pressure, the voltage applied to the electro-optic Q-switched crystal becomes zero, and single longitudinal mode laser with preset wavelength is output;

the second pump source performs pulse pumping on the second laser gain medium, the voltage applied to the electro-optic Q-switched crystal is zero, the second laser resonant cavity is in a high-loss state, the second laser gain medium is in a population inversion state, when the inversion population of the second laser gain medium reaches the maximum, a quarter of preset wavelength voltage value is rapidly applied to the electro-optic Q-switched crystal, and the preset wavelength non-single longitudinal mode laser is output;

the rapid pressurizing and step-type decompressing states of the electro-optic Q-switching crystal are periodically repeated, and single-longitudinal-mode and non-single-longitudinal-mode double-pulse lasers which are alternately Q-switched and output are obtained.

The invention provides a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switching output method and a laser. Moreover, the laser adopts a mode that a double-pump source alternatively pumps double laser gain media, and the two laser gain media work in turn, so that the heat effect of the laser can be greatly reduced under the condition of high pump power. In addition, under the condition that a Q-switched pulse signal is applied to the electro-optical Q-switched crystal once, single longitudinal mode and non-single longitudinal mode double-pulse laser output can be realized, and an effective way is provided for alternate output of high-repetition-frequency single longitudinal mode and non-single longitudinal mode laser.

Drawings

FIG. 1 is a schematic diagram of a prior art double pulse laser;

FIG. 2 is a schematic diagram of a single longitudinal mode and non-single longitudinal mode double-pulse laser alternative Q-switched output laser according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the timing of driving signals and the timing of forming a laser according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a pulse sequence of a single longitudinal mode and a non-single longitudinal mode double pulse laser alternatively Q-switched output laser according to an embodiment of the present invention;

fig. 5 is a flowchart of a method for alternately adjusting Q-switched output by a single longitudinal mode and a non-single longitudinal mode double-pulse laser according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.

Fig. 2 is a schematic structural diagram of a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switched output laser according to an embodiment of the present invention, as shown in fig. 2, the laser includes: the laser gain control device comprises a laser output mirror 1, an electro-optical Q-switched crystal 3, a polarizer 4, a 45-degree reflector 5, a first laser gain medium 6, a first laser holophote 7, a first coupling lens group 8, a first optical fiber 9, a first pumping source 10, a quarter wave plate 11, a second laser gain medium 12, a second laser holophote 13, a second coupling lens group 14, a second optical fiber 15 and a second pumping source 16, wherein:

the first pump source 10 is arranged at one side of the first coupling lens group 8, and the first pump source 10 and the first coupling lens group 8 are connected by using the first optical fiber 9, and the first coupling lens group 8 is used for coupling light emitted by the first pump source 9 into the first laser gain medium 6;

the second pump source 16 is disposed behind the second coupling lens group 14, and the second pump source 16 and the second coupling lens group 14 are connected by using the second optical fiber 15, and the second coupling lens group 14 is configured to couple light emitted by the second pump source 16 into the second laser gain medium 12;

the first laser holophote 7, the first laser gain medium 6, the 45-degree reflector 5, the polarizer 4, the electro-optic Q-switched crystal 3 and the laser output mirror 1 form a first path of laser resonant cavity;

the second laser holophote 13, the second laser gain medium 12, the quarter-wave plate 11, the 45-degree reflector 5, the polarizer 4, the electro-optic Q-switched crystal 3 and the laser output mirror 1 form a second path of laser resonant cavity;

the first path of laser resonant cavity and the second path of laser resonant cavity are arranged at a position of the 45-degree reflector 5 at an angle of 90 degrees.

In this embodiment, the two resonators in which the electro-optical Q-switching crystal 3 is located share one laser output mirror 1, and the purpose is to realize coaxial laser output, to output single longitudinal mode laser light when the electro-optical Q-switching crystal 3 is stepped back, and to output non-single longitudinal mode laser light when the electro-optical Q-switching crystal 3 is rapidly pressurized. Wherein, the square wave voltage is applied when the pressure is rapidly applied, and the rising time and the falling time are both less than 10 nanoseconds.

In one embodiment of the present invention, the first laser total reflection mirror 7 is disposed at the other side of the first coupling lens group 8; the second laser total reflection mirror 13 is arranged in front of the second coupling lens group 14.

In one embodiment of the present invention, the first laser gain medium 6 is disposed on a side of the first laser total reflection mirror 7 away from the first coupling lens group 8; the second laser gain medium 12 is disposed on a side of the second laser total reflection mirror 13 away from the second coupling lens group 14.

In one embodiment of the present invention, the quarter-wave plate 11 and the 45 ° mirror 5 are sequentially disposed on a side of the second laser gain medium 12 away from the second laser total reflection mirror 13, and the quarter-wave plate 11 is disposed between the second laser gain medium 12 and the 45 ° mirror 5.

In one embodiment of the present invention, the quarter-wave plate 11 is placed perpendicular to the 45 ° mirror 5.

In one embodiment of the invention, the 45 ° reflector 5, the polarizer 4, the electro-optical Q-switched crystal 3 and the laser output mirror 1 are sequentially disposed on a side of the first laser gain medium 6 away from the first laser total reflection mirror 7.

In one embodiment of the present invention, the first pump source 10 and the second pump source 16 are both semiconductor pump sources.

In an embodiment of the present invention, the crystal used in the electro-optical Q-switched crystal 3 is LN, KD × P, KDP, LiNbO₃Isoelectric optical crystal.

In an embodiment of the present invention, the laser further includes a Q-switching driving module 2, and the Q-switching driving module 2 is connected to the electro-optical Q-switching crystal 3 and configured to apply a Q-switching driving signal to the electro-optical Q-switching crystal 3.

In an embodiment of the present invention, the Q-switched driving signal generated by the Q-switched driving module 2 is a step-type high-voltage signal, and the falling edge thereof is in a dual-step form, as shown in fig. 3The rising edge of the Q-switched drive signal is shown in a rapid rising manner, and the falling edge is in the form of a step signal, and the main purpose is to obtain lambda with relatively high pulse energy in the rising edge stage of the Q-switched drive signal₁The laser output with narrow wavelength and pulse width and non-single longitudinal mode is obtained by using pre-laser technology in the falling stage of Q-switched drive signal₁And outputting the single longitudinal mode pulse laser of the wavelength laser. The working process of the pre-laser technology can be divided into the following three stages in terms of time sequence:

a. seed light formation stage

Unlike the general Q-switched technique, the signal generator used in the pre-lasing technique is a two-step signal generator that generates a periodic stepped voltage signal that varies with time. In a high voltage state, the Q-switching loss in the cavity is high, and the inside of the laser is subjected to reversed particle accumulation; during the process of regulating high voltage to low voltage, the Q loss in the cavity is changed from high to low. At this time, the partially inverted particle transitions from a high energy level to a low energy level and generates a photon to form seed light.

b. Mode competition phase

When a low voltage is applied to the Q-switched crystal, the intra-cavity losses are low. And the low voltage duration is prolonged, the seed light carries out a natural mode selection process due to the existence of gain and loss difference values among different modes. Meanwhile, because the single-pass gain of the central mode is slightly larger than that of the adjacent mode, and the single-pass loss of the central mode is slightly smaller than that of the adjacent mode, the adjacent mode gradually disappears along with the increase of the duration time along with the continuation of the mode competition process, and finally single longitudinal mode seed light only with the central mode is formed.

c. Output process

When the Q-switch is fully opened, a large number of the inverted particles transition from a high energy level to a low energy level and a giant pulse laser is formed. The intensity level of the single longitudinal mode seed light is far larger than that of noise, so that the seed light can replace the noise as initial oscillation starting noise of the laser, and the seed light can amplify the seed light and inhibit other modes again to form the single longitudinal mode pulse laser.

The invention provides a single longitudinal mode and non-single longitudinal mode double-pulse laser alternative Q-switched output laserThe method is realized on the basis of effectively combining the principle of the voltage relief type electro-optical Q-switching with the principle of the voltage pressurization type electro-optical Q-switching. That is, when the electro-optical Q-switched crystal 3 is stepped to be decompressed, lambda can be realized₁The single longitudinal mode laser Q-switched output with the wavelength can be realized when the electro-optic Q-switched crystal 3 is rapidly pressurized, and the single longitudinal mode and the non-single longitudinal mode double pulse laser Q-switched pulse with the same wavelength can be alternately output by periodically rapidly pressurizing and step-type decompressing the electro-optic Q-switched crystal 3.

Specifically, the specific working principle of the single longitudinal mode and non-single longitudinal mode double-pulse laser alternate Q-switched output laser is as follows: when a quarter of the preset lambda is applied to the electro-optically Q-switched crystal 3₁During the wavelength voltage, the first pump source 10 of the first laser gain medium 6 performs a pulsed pumping of the first laser gain medium 6 due to λ₁Wavelength laser is changed into linearly polarized light through the polarizer 4, under the action of an external electric field, the linearly polarized light passes through the electro-optic Q-switched crystal 3 twice in a reciprocating manner, the polarization direction of the original linearly polarized light is deflected by 90 degrees, the polarization direction of the polarizer 4 is orthogonal to the transmission direction of the polarizer and is reflected out of the first path of laser resonant cavity, and oscillation cannot be formed in the first path of laser resonant cavity, so that the first path of laser resonant cavity is in a high-loss state, and the first laser gain medium 7 is in a population inversion (energy storage) state; at this time, the second pump source 16 of the second laser gain medium 12 is in an intermittent state. When the population of the first laser gain medium 6 reaches a maximum inversion, the voltage applied to the electro-optically Q-switched crystal 3 is reduced by a fraction in the phase A of FIG. 3, i.e., when the electro-optically Q-switched crystal 3 is stepped back, in which phase λ is formed₁Seed light of wavelength laser is subjected to sufficient mode competition to form lambda₁Wavelength single longitudinal mode seed laser. At λ₁After the wavelength single longitudinal mode seed laser is formed, the voltage drop applied to the electro-optically Q-switched crystal 3 is zero, lambda₁The wavelength single longitudinal mode seed laser is amplified to finally form lambda₁And outputting the wavelength single longitudinal mode laser.

At the next instant, the second pump source 16 of the second laser gain medium 12 pulse pumps the second laser gain medium 12, the first laser gain medium 6Is in an intermittent state and the voltage applied to the electro-optically Q-switched crystal 3 is zero. At the second laser wavelength lambda₁The polarization direction of the polarized light passing through the electro-optical Q-switched crystal 3 back and forth is rotated by 90 degrees under the action of the quarter-wave plate 11, so that the polarization direction at the polarizer 4 is orthogonal to the transmission direction thereof, and the resonant cavity of the second laser gain medium 12 is in a high-loss state, and the second laser gain medium 12 is in a population inversion (energy storage) state. When the number of inversion particles of the second laser gain medium 12 reaches the maximum, the stored energy reaches the peak value, and a quarter lambda is rapidly applied to the electro-optical Q-switched crystal 3₁The wavelength voltage value is in the B-phase of FIG. 3, where λ₁The wavelength laser has the lowest intra-cavity loss, and the intra-cavity laser gain is rapidly amplified, so that giant pulse laser output with narrower pulse width can be obtained, namely Q-switched output of non-single longitudinal mode laser with the same wavelength is formed.

By repeating the steps, a single longitudinal mode and non-single longitudinal mode double-pulse laser alternating Q-switched output sequence shown in FIG. 4 can be obtained, wherein s in FIG. 4 represents single longitudinal mode laser, and m represents non-single longitudinal mode laser.

In an embodiment of the present invention, the first laser gain medium 6 is Nd: YAG crystal with size of 4X 50mm³Plating 1064nm antireflection film (T is more than 99%) at two ends; the second laser gain medium 12 is Nd: YVO₄Crystals of phi 4X 50mm in size³And the two ends are plated with anti-reflection films with the thickness of 1064nm (T is more than 99%). The first laser total reflector 7 is a flat-concave mirror, a 1064nm high-reflectivity film (R is more than 99%) is plated on the concave surface of the first laser total reflector, the second laser total reflector 13 is a flat-concave mirror, a 1064nm high-reflectivity film (R is more than 99%) is plated on the concave surface of the second laser total reflector, the laser output mirror 1 is a flat-flat mirror, a 1064nm partial-transmittance film is plated on one surface close to the cavity, the transmittance of 1064nm laser is 6%, and an anti-reflection film of 1064nm laser is plated on the outer side of the laser output mirror. The polarizer 4 is plated with a 1064nm laser Brewster angle antireflection film, the 1064nm laser transmittance is higher than 98%, the corresponding wavelength of the quarter-wave plate 11 is 1064nm, and two light transmission surfaces are plated with 1064nm antireflection films (T is more than 98%). The first pump source 10 of the first laser gain medium 6 and the second pump source 16 of the second laser gain medium 12 are both stripe arrays composed of 808nm laser diodes.The timing of the driving signals applied to the first pump source 10, the second pump source 16 and the Q-switched driving module 2 is shown in fig. 3. Wherein, V₁Waveform V for exciting the first pump source 10₂Waveform V for exciting second pump source 16_QIs a voltage waveform applied to the electro-optically Q-switched crystal 3. For the laser configuration shown in fig. 2, the first wavelength λ is generated when the laser is decompressed₁Outputting the Q-switched single longitudinal mode pulse laser, and generating a second path of wavelength lambda when pressurizing₁And (5) Q-switched non-single longitudinal mode pulse laser output. From the whole time sequence, the pulse sequence of the single longitudinal mode and the non-single longitudinal mode double-pulse laser alternating Q-switched output as shown in figure 4 is generated.

According to another aspect of the present invention, there is also provided a single longitudinal mode and non-single longitudinal mode double pulse laser alternating Q-switched output method, as shown in fig. 5, the method includes steps S501-S504:

in step S501, a quarter-preset wavelength voltage is applied to the electro-optically Q-switched crystal 3;

in step S502, the first pump source 10 performs pulse pumping on the first laser gain medium 6, the first path of laser resonant cavity is in a high loss state, the first laser gain medium 6 is in a population inversion state, when the inversion population of the first laser gain medium 6 reaches a maximum, the electro-optic Q-switched crystal 3 is in step-back, the voltage applied to the electro-optic Q-switched crystal 3 becomes zero, and a single longitudinal mode laser with a preset wavelength is output;

in step S503, the second pump source 16 performs pulse pumping on the second laser gain medium 12, the voltage applied to the electro-optically modulated Q crystal 3 is zero, the second laser resonant cavity is in a high loss state, the second laser gain medium 12 is in a population inversion state, and when the population inversion of the second laser gain medium 12 reaches a maximum, a quarter of a preset wavelength voltage value is rapidly applied to the electro-optically modulated Q crystal 3, and a preset wavelength non-single longitudinal mode laser is output;

in step S504, the electro-optic Q-switched crystal 3 is periodically repeated to rapidly pressurize and step-back the pressure state, so as to obtain a single-longitudinal-mode and non-single-longitudinal-mode double-pulse laser with alternately-switched Q output.

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.