Irregular pulse train laser emission control system and method

Abstract

The invention relates to the technical field of laser, and provides an irregular pulse train laser emission control system and method.The irregular pulse train laser emission control system and method are characterized in that two electro-optical crystals in a seed optical oscillation cavity and an optical parametric oscillation cavity are subjected to coordinated control; the two electro-optical crystals are respectively used for obtaining pulse string seed laser and mid-infrared pulse string parameter laser, adjustment is carried out according to the starting time of the two electro-optical crystals in a plurality of time sequences, pulse string seed laser output with different time intervals is obtained, and then irregular mid-infrared pulse string parameter laser output is obtained. Therefore, the technical problem that the pulse interval generated by the pulse string laser system in the prior art is usually fixed and is easy to reconnaissance and identification is solved, quicker and more efficient irregular pulse string operation is provided, the starting time of the laser system is shortened, and the reconnaissance resistance of the output laser signal is improved.

Description

Technical Field

[0001] The present invention generally relates to the field of laser technology, and in particular to an irregular pulse train laser emission control system and method. Background Art

[0002] Laser technology has a wide range of applications in many fields, including communications, medical treatment, material processing and military. The laser is the core component of the laser system, and its performance directly affects the performance of the entire system.

[0003] In some applications, it is necessary to emit multiple pulses of laser in a very short time to achieve a specific goal. For example, in military applications, a pulsed laser system that starts and emits quickly can be used to excite a specific target or perform target identification. In addition, in the medical field, pulsed lasers can accurately cut biological tissues and perform various minimally invasive surgeries. Therefore, pulsed lasers have broad application prospects.

[0004] Conventional laser systems are usually subject to some limitations, making it difficult to achieve rapid start-up of pulse train operations. Some of these problems include: conventional laser systems require a certain amount of time to start and stabilize, which results in a start-up time delay between pulses, limiting the speed and efficiency of pulse train operations; conventional pulse train laser systems output pulse train frequencies of the kHz order, making it difficult to achieve MHz-level pulse train output; conventional pulse train laser systems generate pulse intervals that are usually fixed and easily identified by reconnaissance.

[0005] Therefore, it is necessary to develop an irregular pulse train laser emission control system to overcome the problems of startup time delay and easy reconnaissance and identification of traditional laser systems, provide faster and more efficient irregular pulse train operation, reduce the startup time of the laser system, and improve the anti-reconnaissance ability of the output laser signal. Summary of the invention

[0006] Refer to the following Figures 1 to 4 An irregular pulse train laser emission control system provided by an embodiment of the present invention is described below. Figure 1 As shown, an irregular pulse train laser emission control system includes a seed light oscillation optical path, an optical parametric oscillation optical path and an emission control device 16, wherein:

[0007] The seed light oscillation optical path includes a pump source 1, a transmission optical fiber 2, a coupling lens tube 3, a first cavity mirror 4, a laser crystal 5, a first electro-optical crystal 6, a first polarizer 7, and a second cavity mirror 8; wherein,

[0008] The pump source 1 is connected to the coupling lens barrel 3 through the transmission optical fiber 2, and the first cavity mirror 4, the laser crystal 5, the first electro-optical crystal 6, the first polarizer 7, and the second cavity mirror 8 are sequentially arranged along the optical path behind the coupling lens barrel 3;

[0009] The first polarizer 7 can transmit the P-polarized laser light while reflecting the S-polarized laser light, or the first polarizer 7 can transmit the S-polarized laser light while reflecting the P-polarized laser light;

[0010] The first polarizer 7 is arranged at 45° along the light path direction to change the propagation direction of the light path;

[0011] The second cavity mirror 8 is arranged in the reflection direction of the first polarizer 7;

[0012] The optical parametric oscillator light path is arranged in the transmission direction of the first polarizer 7 so that the seed light generated by the seed light oscillator light path can enter the optical parametric oscillator light path;

[0013] The optical parametric oscillator optical path includes a third cavity mirror 9, a MgO:PPLN crystal 10, a fourth cavity mirror 11, a fifth cavity mirror 12, a second electro-optical crystal 13, a sixth cavity mirror 14, and a second polarizer 15; wherein,

[0014] The third cavity mirror 9 is arranged in the transmission direction of the first polarizer 7;

[0015] The MgO:PPLN crystal 10, the fourth cavity mirror 11, the fifth cavity mirror 12, the second electro-optical crystal 13, the second polarizer 15, and the sixth cavity mirror 14 are arranged in sequence along the optical path behind the third cavity mirror 9;

[0016] The third cavity mirror 9, the fourth cavity mirror 11, the fifth cavity mirror 12, and the sixth cavity mirror 14 form an eight-shaped optical parametric oscillator cavity;

[0017] The MgO:PPLN crystal 10 is arranged between the third cavity mirror 9 and the fourth cavity mirror 11;

[0018] The second electro-optical crystal 13 and the second polarizer 15 are arranged between the fifth cavity mirror 12 and the sixth cavity mirror 14;

[0019] The second polarizer 15 can transmit the P-polarized laser light while reflecting the S-polarized laser light, or the second polarizer 15 can transmit the S-polarized laser light while reflecting the P-polarized laser light;

[0020] The second polarizer 15 and the second electro-optical crystal 13 are arranged at 45 degrees along the optical path direction, and are used to emit the mid-infrared parametric light;

[0021] The upper end surface of the first electro-optical crystal 6 and the upper end surface of the second electro-optical crystal 13 are both attached to the metal plate, and the lower end surface of the first electro-optical crystal 6 and the lower end surface of the second electro-optical crystal 13 are both grounded;

[0022] The emission control device 16 includes a processor 16-1, a delay controller 16-2, a first high voltage module 16-3, and a second high voltage module 16-4; wherein,

[0023] The processor 16-1 is electrically connected to the delay controller 16-2, and the delay controller 16-2 is electrically connected to the pump source 1, the first high-voltage module 16-3 and the second high-voltage module 16-4 respectively;

[0024] The first high-voltage module 16 - 3 is electrically connected to the upper end surface of the first electro-optical crystal 6 , and the second high-voltage module 16 - 4 is electrically connected to the upper end surface of the second electro-optical crystal 13 .

[0025] In one embodiment, the pump source 1 is an 808nm pulse pump source, the laser crystal 5 is an a-axis cut Nd:YVO4 crystal, the polarization period of the MgO:PPLN crystal 10 is 29.8μm, the first electro-optical crystal 6 is an RTP electro-optical crystal, and the second electro-optical crystal 13 is an LN crystal.

[0026] In one embodiment, the first cavity mirror 4 is coated with a 1064nm total reflection film, the second cavity mirror 8 is coated with a 1064nm total reflection film, the third cavity mirror 9 is coated with a 1064nm anti-reflection film and a 2.7-4.5μm total reflection film, and the fourth cavity mirror 11, the fifth cavity mirror 12 and the sixth cavity mirror 14 are all coated with a 2.7-4.5μm total reflection film.

[0027] According to another aspect of the present invention, a method for controlling the emission of an irregular pulse train laser is disclosed, which uses the above-mentioned irregular pulse train laser emission control system, and the control method comprises:

[0028] Set the time sequence of the delay controller 16-2 to 0-t1, t1-t2, t2-t3;

[0029] In the time sequence of 0-t1, the processor 16-1 in the emission control device 16 controls the delay controller 16-2 to turn on the pump source 1, and the pump source 1 emits pump light through the transmission optical fiber 2 and enters the coupling lens barrel 3;

[0030] The pump light enters the first cavity mirror 4 through the coupling lens barrel 3 and then enters the laser crystal 5;

[0031] The seed light emitted by the laser crystal 5 after being excited is P-type linearly polarized light. The polarization state of the seed light does not change after passing through the first electro-optical crystal 6. At this time, the seed light can be transmitted out of the seed light oscillation cavity through the first polarizer 7.

[0032] At time t', the emission control device 16 controls the delay controller 16-2 through the processor 16-1 to turn on the first high-voltage module 16-3, and the first high-voltage module 16-3 provides a 1 / 2 wavelength voltage to both ends of the first electro-optical crystal 6;

[0033] Among them, 0 <t’<t1;

[0034] The seed light becomes S-type linear polarized light after passing through the first electro-optical crystal 6. At this time, the seed light cannot be transmitted through the first polarizer 7, but is reflected by the first polarizer 7 and then transmitted to the second cavity mirror 8;

[0035] After the seed light is reflected by the second cavity mirror 8, it oscillates in the seed light oscillation cavity, and the number of photons is accumulated in the seed light oscillation cavity;

[0036] At time t1, the number of photons in the cavity reaches a maximum value, and the emission control device 16 controls the delay controller 16-2 through the processor 16-1 to turn off the first high-voltage module 16-3, so that the voltage across the first electro-optical crystal 6 is 0. At this time, the seed light is P-type linearly polarized light, and the seed light can be transmitted out of the seed light oscillation cavity through the first polarizer 7;

[0037] The seed light enters the optical parametric oscillator cavity, undergoes nonlinear frequency conversion through the MgO:PPLN crystal 10, and obtains 3.8 μm mid-infrared parametric light, which is P-type linearly polarized light. At this time, the mid-infrared parametric light can pass through the second polarizer 15;

[0038] Repeating the operation in the time sequence 0-t1 in the time sequence t1-t2 to obtain a plurality of seed lights, and allowing the seed lights to accumulate in the optical parametric oscillator cavity;

[0039] In the time sequence t2-t3, when the second high-voltage module 16-4 is not turned on, the mid-infrared parametric light is a P-type linearly polarized light, and at this time, the mid-infrared parametric light cannot be reflected by the second polarizer 15;

[0040] At time t'', the emission control device 16 controls the delay controller 16-2 through the processor 16-1 to turn on the second high-voltage module 16-4, and the second high-voltage module 16-4 provides a 1 / 2 wavelength voltage to both ends of the second electro-optical crystal 13;

[0041] Among them, t2 <t’’<t3;

[0042] The mid-infrared parametric light becomes S-type linear polarized light after passing through the second electro-optical crystal 13. At this time, the mid-infrared parametric light cannot be transmitted through the second polarizer 15, but is reflected by the second polarizer 15 and then emitted, thereby obtaining a mid-infrared pulse train parametric laser output;

[0043] Adjust the values ​​of t1, t2 and t3 to change the 0-t1 time sequence, the t1-t2 time sequence and the t2-t3 time sequence, thereby changing the pulse train time interval;

[0044] The values ​​of t' and t'' are adjusted to change the opening time of the first high-voltage module 16-3 and the second high-voltage module 16-4 to obtain irregular mid-infrared pulse train parametric laser output.

[0045] like Figure 3 The figure shows the time domain diagram of seed light output, where Figure 3 (a) is a waveform timing diagram of pump source 1. In the time sequence of 0-t1, the pump source 1 emits pump light; Figure 3 (b) is a timing diagram of the voltage across the first electro-optical crystal 6, Figure 3 (c) is a seed light pulse timing diagram, with the first high voltage module 16-3 turned on at time t', a seed light pulse sequence is output. In the t1-t2 time sequence, the process in the 0-t1 time sequence is repeated to obtain a pulse train seed laser output.

[0046] like Figure 4 The figure shows the time domain schematic diagram of mid-infrared parametric light output. Figure 4 (a) is a timing diagram of the voltage across the second electro-optical crystal 13, Figure 4 (b) is a mid-infrared pulse timing diagram. In the time sequence t2-t3, as the second high-voltage module 16-4 is turned on at time t'', an irregular mid-infrared pulse train parametric laser is output.

[0047] Beneficial Effects

[0048] The present invention coordinates and controls two electro-optic crystals in a seed light oscillator cavity and an optical parametric oscillator cavity respectively. First, a plurality of time sequences are set through a delay controller to obtain a pulse train seed laser and a mid-infrared pulse train parametric laser respectively. In the plurality of time sequences, the opening time of the two electro-optic crystals is adjusted to obtain a pulse train seed laser output with different time intervals, and then obtain an irregular mid-infrared pulse train parametric light laser output. This overcomes the technical problem in the prior art that the pulse interval generated by a pulse train laser system is usually fixed and easily detected and identified, provides a faster and more efficient irregular pulse train operation, reduces the startup time of the laser system, and improves the anti-detection property of the output laser signal.

[0049] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and other features, advantages and aspects of the embodiments of the present invention will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

[0051] Figure 1 It is a schematic diagram of an irregular pulse train laser emission system;

[0052] Figure 2 It is a schematic diagram of a launch control device for an irregular pulse train laser launch system;

[0053] Figure 3 This is a schematic diagram of the seed light output time domain;

[0054] Figure 4 This is a time domain schematic diagram of mid-infrared parametric light output;

[0055] In the figure, the structural components indicated by the reference numerals are:

[0056] 1. Pump source; 2. Transmission optical fiber; 3. Coupling lens barrel; 4. First cavity mirror; 5. Laser crystal; 6. First electro-optic crystal; 7. First polarizer; 8. Second cavity mirror; 9. Third cavity mirror; 10. MgO:PPLN crystal; 11. Fourth cavity mirror; 12. Fifth cavity mirror; 13. Second electro-optic crystal; 14. Sixth cavity mirror; 15. Second polarizer; 16. Launch control device; 16-1. Processor; 16-2. Delay controller; 16-3. First high-voltage module; 16-4. Second high-voltage module. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] In addition, the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean that A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0059] Refer to the following Figures 1 to 4 An irregular pulse train laser emission control system provided by an embodiment of the present invention is described below. Figure 1 As shown, an irregular pulse train laser emission control system includes a seed light oscillation optical path, an optical parametric oscillation optical path and an emission control device 16, wherein:

[0060] The seed light oscillation optical path includes a pump source 1, a transmission optical fiber 2, a coupling lens tube 3, a first cavity mirror 4, a laser crystal 5, a first electro-optical crystal 6, a first polarizer 7, and a second cavity mirror 8; wherein,

[0061] The pump source 1 is connected to the coupling lens barrel 3 through the transmission optical fiber 2, and the first cavity mirror 4, the laser crystal 5, the first electro-optical crystal 6, the first polarizer 7, and the second cavity mirror 8 are sequentially arranged along the optical path behind the coupling lens barrel 3;

[0062] The first polarizer 7 can transmit the P-polarized laser light while reflecting the S-polarized laser light, or the first polarizer 7 can transmit the S-polarized laser light while reflecting the P-polarized laser light;

[0063] The first polarizer 7 is arranged at 45° along the light path direction to change the propagation direction of the light path;

[0064] The second cavity mirror 8 is arranged in the reflection direction of the first polarizer 7;

[0065] The optical parametric oscillator light path is arranged in the transmission direction of the first polarizer 7 so that the seed light generated by the seed light oscillator light path can enter the optical parametric oscillator light path;

[0066] The optical parametric oscillator optical path includes a third cavity mirror 9, a MgO:PPLN crystal 10, a fourth cavity mirror 11, a fifth cavity mirror 12, a second electro-optical crystal 13, a sixth cavity mirror 14, and a second polarizer 15; wherein,

[0067] The third cavity mirror 9 is arranged in the transmission direction of the first polarizer 7;

[0068] The MgO:PPLN crystal 10, the fourth cavity mirror 11, the fifth cavity mirror 12, the second electro-optical crystal 13, the second polarizer 15, and the sixth cavity mirror 14 are arranged in sequence along the optical path behind the third cavity mirror 9;

[0069] The third cavity mirror 9, the fourth cavity mirror 11, the fifth cavity mirror 12, and the sixth cavity mirror 14 form an eight-shaped optical parametric oscillator cavity;

[0070] The MgO:PPLN crystal 10 is arranged between the third cavity mirror 9 and the fourth cavity mirror 11;

[0071] The second electro-optical crystal 13 and the second polarizer 15 are arranged between the fifth cavity mirror 12 and the sixth cavity mirror 14;

[0072] The second polarizer 15 can transmit the P-polarized laser light while reflecting the S-polarized laser light, or the second polarizer 15 can transmit the S-polarized laser light while reflecting the P-polarized laser light;

[0073] The second polarizer 15 and the second electro-optical crystal 13 are arranged at 45 degrees along the optical path direction, and are used to emit the mid-infrared parametric light;

[0074] The upper end surface of the first electro-optical crystal 6 and the upper end surface of the second electro-optical crystal 13 are both attached to the metal plate, and the lower end surface of the first electro-optical crystal 6 and the lower end surface of the second electro-optical crystal 13 are both grounded;

[0075] The emission control device 16 includes a processor 16-1, a delay controller 16-2, a first high voltage module 16-3, and a second high voltage module 16-4; wherein,

[0076] The processor 16-1 is electrically connected to the delay controller 16-2, and the delay controller 16-2 is electrically connected to the pump source 1, the first high-voltage module 16-3 and the second high-voltage module 16-4 respectively;

[0077] The first high-voltage module 16 - 3 is electrically connected to the upper end surface of the first electro-optical crystal 6 , and the second high-voltage module 16 - 4 is electrically connected to the upper end surface of the second electro-optical crystal 13 .

[0078] In one embodiment, the pump source 1 is an 808nm pulse pump source, the laser crystal 5 is an a-axis cut Nd:YVO4 crystal, the polarization period of the MgO:PPLN crystal 10 is 29.8μm, the first electro-optical crystal 6 is an RTP electro-optical crystal, and the second electro-optical crystal 13 is an LN crystal.

[0079] In one embodiment, the first cavity mirror 4 is coated with a 1064nm total reflection film, the second cavity mirror 8 is coated with a 1064nm total reflection film, the third cavity mirror 9 is coated with a 1064nm anti-reflection film and a 2.7-4.5μm total reflection film, and the fourth cavity mirror 11, the fifth cavity mirror 12 and the sixth cavity mirror 14 are all coated with a 2.7-4.5μm total reflection film.

[0080] According to another aspect of the present invention, a method for controlling the emission of an irregular pulse train laser is disclosed, which uses the above-mentioned irregular pulse train laser emission control system, and the control method comprises:

[0081] Set the time sequence of the delay controller 16-2 to 0-t1, t1-t2, t2-t3;

[0082] In the time sequence of 0-t1, the processor 16-1 in the emission control device 16 controls the delay controller 16-2 to turn on the pump source 1, and the pump source 1 emits pump light through the transmission optical fiber 2 and enters the coupling lens barrel 3;

[0083] The pump light enters the first cavity mirror 4 through the coupling lens barrel 3 and then enters the laser crystal 5;

[0084] The seed light emitted by the laser crystal 5 after being excited is P-type linearly polarized light. The polarization state of the seed light does not change after passing through the first electro-optical crystal 6. At this time, the seed light can be transmitted out of the seed light oscillation cavity through the first polarizer 7.

[0085] At time t', the emission control device 16 controls the delay controller 16-2 through the processor 16-1 to turn on the first high-voltage module 16-3, and the first high-voltage module 16-3 provides a 1 / 2 wavelength voltage to both ends of the first electro-optical crystal 6;

[0086] Among them, 0 <t’<t1;

[0087] The seed light becomes S-type linear polarized light after passing through the first electro-optical crystal 6. At this time, the seed light cannot be transmitted through the first polarizer 7, but is reflected by the first polarizer 7 and then transmitted to the second cavity mirror 8;

[0088] After the seed light is reflected by the second cavity mirror 8, it oscillates in the seed light oscillation cavity, and the number of photons is accumulated in the seed light oscillation cavity;

[0089] At time t1, the number of photons in the cavity reaches a maximum value, and the emission control device 16 controls the delay controller 16-2 through the processor 16-1 to turn off the first high-voltage module 16-3, so that the voltage across the first electro-optical crystal 6 is 0. At this time, the seed light is P-type linearly polarized light, and the seed light can be transmitted out of the seed light oscillation cavity through the first polarizer 7;

[0090] The seed light enters the optical parametric oscillator cavity, undergoes nonlinear frequency conversion through the MgO:PPLN crystal 10, and obtains 3.8 μm mid-infrared parametric light, which is P-type linearly polarized light. At this time, the mid-infrared parametric light can pass through the second polarizer 15;

[0091] Repeating the operation in the time sequence 0-t1 in the time sequence t1-t2 to obtain a plurality of seed lights, and allowing the seed lights to accumulate in the optical parametric oscillator cavity;

[0092] In the time sequence t2-t3, when the second high-voltage module 16-4 is not turned on, the mid-infrared parametric light is a P-type linearly polarized light, and at this time, the mid-infrared parametric light cannot be reflected by the second polarizer 15;

[0093] At time t'', the emission control device 16 controls the delay controller 16-2 through the processor 16-1 to turn on the second high-voltage module 16-4, and the second high-voltage module 16-4 provides a 1 / 2 wavelength voltage to both ends of the second electro-optical crystal 13;

[0094] Among them, t2 <t’’<t3;

[0095] The mid-infrared parametric light becomes S-type linear polarized light after passing through the second electro-optical crystal 13. At this time, the mid-infrared parametric light cannot be transmitted through the second polarizer 15, but is reflected by the second polarizer 15 and then emitted, thereby obtaining a mid-infrared pulse train parametric laser output;

[0096] Adjust the values ​​of t1, t2 and t3 to change the 0-t1 time sequence, the t1-t2 time sequence and the t2-t3 time sequence, thereby changing the pulse train time interval;

[0097] The values ​​of t' and t'' are adjusted to change the opening time of the first high-voltage module 16-3 and the second high-voltage module 16-4 to obtain irregular mid-infrared pulse train parametric laser output.

[0098] like Figure 3The figure shows the time domain diagram of seed light output, where Figure 3 (a) is a waveform timing diagram of pump source 1. In the time sequence of 0-t1, the pump source 1 emits pump light; Figure 3 (b) is a timing diagram of the voltage across the first electro-optical crystal 6, Figure 3 (c) is a seed light pulse timing diagram, with the first high voltage module 16-3 turned on at time t', a seed light pulse sequence is output. In the t1-t2 time sequence, the process in the 0-t1 time sequence is repeated to obtain a pulse train seed laser output.

[0099] like Figure 4 The figure shows the time domain schematic diagram of mid-infrared parametric light output. Figure 4 (a) is a timing diagram of the voltage across the second electro-optical crystal 13, Figure 4 (b) is a mid-infrared pulse timing diagram. In the time sequence t2-t3, as the second high-voltage module 16-4 is turned on at time t'', an irregular mid-infrared pulse train parametric laser is output.

[0100] In the description of this specification, the terms "connection", "installation", "fixation" and the like should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific state.

[0101] In the description of this specification, the description of the terms "one embodiment", "some embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An irregular pulse train laser emission control system, comprising a seed light oscillation optical path, an optical parametric oscillation optical path and an emission control device (16), wherein: The seed light oscillation optical path comprises a pump source (1), a transmission optical fiber (2), a coupling lens barrel (3), a first cavity mirror (4), a laser crystal (5), a first electro-optical crystal (6), a first polarizer (7), and a second cavity mirror (8); wherein: The pump source (1) is connected to the coupling lens barrel (3) via the transmission optical fiber (2); the first cavity mirror (4), the laser crystal (5), the first electro-optic crystal (6), the first polarizer (7), and the second cavity mirror (8) are sequentially arranged along the optical path behind the coupling lens barrel (3); The first polarizer (7) is capable of transmitting P-polarized laser light while reflecting S-polarized laser light, or the first polarizer (7) is capable of transmitting S-polarized laser light while reflecting P-polarized laser light; The first polarizer (7) is arranged at 45° along the light path direction, and is used to change the propagation direction of the light path; The second cavity mirror (8) is arranged in the reflection direction of the first polarizer (7); The optical parametric oscillator light path is arranged in the transmission direction of the first polarizer (7) so that the seed light generated by the seed light oscillation light path can enter the optical parametric oscillator light path; The optical parametric oscillator optical path comprises a third cavity mirror (9), a MgO:PPLN crystal (10), a fourth cavity mirror (11), a fifth cavity mirror (12), a second electro-optical crystal (13), a sixth cavity mirror (14), and a second polarizer (15); wherein: The third cavity mirror (9) is arranged in the transmission direction of the first polarizing plate (7); The MgO:PPLN crystal (10), the fourth cavity mirror (11), the fifth cavity mirror (12), the second electro-optical crystal (13), the second polarizer (15), and the sixth cavity mirror (14) are sequentially arranged along the optical path behind the third cavity mirror (9); The third cavity mirror (9), the fourth cavity mirror (11), the fifth cavity mirror (12), and the sixth cavity mirror (14) form an eight-shaped optical parametric oscillator cavity; The MgO:PPLN crystal (10) is arranged between the third cavity mirror (9) and the fourth cavity mirror (11); The second electro-optical crystal (13) and the second polarizer (15) are arranged between the fifth cavity mirror (12) and the sixth cavity mirror (14); The second polarizer (15) is capable of transmitting P-polarized laser light while reflecting S-polarized laser light, or the second polarizer (15) is capable of transmitting S-polarized laser light while reflecting P-polarized laser light; The second polarizer (15) and the second electro-optical crystal (13) are arranged at 45 degrees along the optical path direction, and are used to emit mid-infrared parametric light; The upper end surface of the first electro-optical crystal (6) and the upper end surface of the second electro-optical crystal (13) are both bonded to the metal electrode plate, and the lower end surface of the first electro-optical crystal (6) and the lower end surface of the second electro-optical crystal (13) are both grounded; The emission control device (16) comprises a processor (16-1), a delay controller (16-2), a first high-voltage module (16-3), and a second high-voltage module (16-4); wherein: The processor (16-1) is electrically connected to the delay controller (16-2), and the delay controller (16-2) is electrically connected to the pump source (1), the first high-voltage module (16-3), and the second high-voltage module (16-4) respectively; The first high-voltage module (16-3) is electrically connected to an upper end surface of the first electro-optical crystal (6), and the second high-voltage module (16-4) is electrically connected to an upper end surface of the second electro-optical crystal (13).

2. The irregular pulse train laser emission control system according to claim 1, characterized in that: The pump source (1) is an 808 nm pulse pump source, the laser crystal (5) is an a-axis cut Nd:YVO4 crystal, the polarization period of the MgO:PPLN crystal (10) is 29.8 μm, the first electro-optical crystal (6) is an RTP electro-optical crystal, and the second electro-optical crystal (13) is an LN crystal.

3. The irregular pulse train laser emission control system according to claim 1, characterized in that: The first cavity mirror (4) is coated with a 1064nm total reflection film, the second cavity mirror (8) is coated with a 1064nm total reflection film, the third cavity mirror (9) is coated with a 1064nm anti-reflection film and a 2.7-4.5μm total reflection film, and the fourth cavity mirror (11), the fifth cavity mirror (12) and the sixth cavity mirror (14) are all coated with a 2.7-4.5μm total reflection film.

4. An irregular pulse train laser emission control method, using an irregular pulse train laser emission control system as claimed in any one of claims 1 to 3, comprising: Setting the time sequence of the delay controller (16-2) to 0-t1, t1-t2, t2-t3; In the time sequence 0-t1, the processor (16-1) in the emission control device (16) controls the delay controller (16-2) to turn on the pump source (1), and the pump source (1) emits pump light through the transmission optical fiber (2) and enters the coupling lens barrel (3); The pump light passes through the coupling lens barrel (3), enters the first cavity mirror (4), and then enters the laser crystal (5); The seed light emitted by the laser crystal (5) after being excited is P-type linearly polarized light, and the polarization state of the seed light does not change after passing through the first electro-optical crystal (6). At this time, the seed light can be transmitted out of the seed light oscillation cavity through the first polarizer (7); At time t', the emission control device (16) controls the delay controller (16-2) through the processor (16-1) to turn on the first high-voltage module (16-3), and the first high-voltage module (16-3) provides a 1 / 2 wavelength voltage to both ends of the first electro-optical crystal (6); Among them, 0 <t’<t1; After the seed light passes through the first electro-optical crystal (6), it becomes S-type linear polarized light. At this time, the seed light cannot be transmitted through the first polarizer (7), but is reflected by the first polarizer (7) and then transmitted to the second cavity mirror (8); After the seed light is reflected by the second cavity mirror (8), it oscillates in the seed light oscillation cavity, and the number of photons is accumulated in the seed light oscillation cavity; At time t1, the number of photons in the cavity reaches a maximum value, and the emission control device (16) controls the delay controller (16-2) through the processor (16-1) to turn off the first high-voltage module (16-3), so that the voltage across the first electro-optical crystal (6) is 0. At this time, the seed light is P-type linearly polarized light, and the seed light can be transmitted out of the seed light oscillation cavity through the first polarizer (7); The seed light enters the optical parametric oscillator cavity, undergoes nonlinear frequency conversion through the MgO:PPLN crystal (10), and obtains 3.8 μm mid-infrared parametric light, wherein the mid-infrared parametric light is P-type linearly polarized light, and at this time, the mid-infrared parametric light can pass through the second polarizer (15); Repeating the operation in the time sequence 0-t1 in the time sequence t1-t2 to obtain a plurality of seed lights, and allowing the seed lights to accumulate in the optical parametric oscillator cavity; In the time sequence t2-t3, when the second high-voltage module (16-4) is not turned on, the mid-infrared parametric light is P-type linearly polarized light, and at this time, the mid-infrared parametric light cannot be reflected by the second polarizer (15); At time t'', the emission control device (16) controls the delay controller (16-2) through the processor (16-1) to turn on the second high-voltage module (16-4), and the second high-voltage module (16-4) provides a 1 / 2 wavelength voltage to both ends of the second electro-optical crystal (13); Among them, t2 <t’’<t3; The mid-infrared parametric light is converted into S-type linear polarized light after passing through the second electro-optical crystal (13). At this time, the mid-infrared parametric light cannot be transmitted through the second polarizer (15), but is reflected by the second polarizer (15) and then emitted, thereby obtaining a mid-infrared pulse train parametric laser output; Adjust the values ​​of t1, t2 and t3 to change the 0-t1 time sequence, the t1-t2 time sequence and the t2-t3 time sequence, thereby changing the pulse train time interval; The values ​​of t' and t'' are adjusted to change the opening time of the first high-voltage module (16-3) and the second high-voltage module (16-4) to obtain irregular mid-infrared pulse train parametric laser output.

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