CN103887699A - Large-power pulse air-flow chemical laser apparatus - Google Patents

Abstract

The invention discloses a large-power pulse air-flow chemical laser apparatus. The apparatus is successively provided with a flat concave reflector, an electro-optical adjusting Q crystal, a polarizer, a flat concave output coupling mirror, a planar holophote, a telescope system, an optical isolation system, a flat concave back-cavity mirror, an activation medium gain region, a scraper mirror and a flat convex front-cavity mirror along the advancing direction of output laser. According to the utility model, the laser gain medium in the same gain region is utilized, and through electro-optical adjusting Q pulse laser amplification, large-power pulse oxygen-iodine chemical pulse output can be obtained. Besides, the large-power pulse air-flow chemical laser apparatus has the advantages of compact structure, high energy, high repetition frequency, narrow pulse width, high efficiency, good light beam quality and the like, thereby being widely applied to such fields as laser material processing, underwater operation, mining industry exploitation and the like.

Description

High-power pulsed gas flow chemical laser device

technical field

The invention belongs to the field of chemical laser devices, in particular to an electro-optic Q-switched laser unsteady cavity amplified pulse gas flow chemical laser.

Background technique

Pneumatic chemical lasers have the advantages of high power, high efficiency, low-loss optical fiber transmission, and better atmospheric transmission window, and are widely used in industrial, medical, scientific research and other fields. Current high-power oxygen-iodine lasers usually operate in continuous wave, which causes plasma and nonlinear effects to be formed on the surface of the material when the laser interacts with the material, which affects the penetration depth and speed of the laser. If the laser can operate at high repetition rate and high peak power with low average power loss, it can produce new effects such as reducing the thickness of the plasma screen generated when the laser interacts with the material, weakening thermal radiation deposition, etc. Its work efficiency can be increased dozens of times,

At present, the methods to realize gas flow chemical laser pulse output mainly include: optically induced pulse, electrically induced pulse, resonant cavity loss modulation and gain modulation, etc. In photo-induced and electrically induced pulsed chemical lasers, it is difficult to obtain high-energy, high-repetition-frequency pulsed laser output by using these two methods because it is difficult to achieve high repetition rate, large-volume uniform glow discharge and light irradiation. The output of pulsed laser can be realized by modulating the resonant cavity loss. In high-power chemical lasers, due to their large aperture and high power density in the cavity, only mechanical modulation can be used, but the modulation depth of this method is Very low, and will greatly reduce the average power of the output laser. Another method is to modulate the gain of the active medium, such as using an external strong magnetic field to modulate the gain of the active medium, but the device to realize this modulation is very large, and each work can only obtain a repetition frequency of the order of Hz hundreds of laser pulses.

Contents of the invention

The object of the present invention is to overcome the above-mentioned shortcomings, and provide a high-power pulsed gas flow chemical laser device, which can realize the output of pulsed laser light without excessive loss of average power, and has a compact structure, high output pulse energy, and high repetition rate. Frequency, narrow pulse width, high efficiency, excellent beam quality and other characteristics.

For realizing the purpose of the present invention, concrete technical solution is:

A high-power pulsed gas flow chemical laser device, including a laser oscillator and an amplifier, is characterized in that a plano-concave reflector, an electro-optic Q-switched crystal, a polarizer, a plano-concave output coupling mirror, and a planar full Mirrors, telescope systems, optical isolation systems, plano-concave rear cavity mirrors, active medium gain regions, scraper mirrors, plano-convex front cavity mirrors. The plano-concave mirror, electro-optic Q-switching crystal, polarizer, and plano-concave output coupling mirror constitute a laser oscillator; the plano-concave rear cavity mirror, scraper mirror, and plano-convex front cavity mirror constitute a laser amplifier.

The working process of the laser device of the present invention is as follows: the gain regions of the laser oscillator and the amplifier are located in the gain region of the active medium. The gain region of the laser oscillator is located downstream of the gain region of the active medium. When the reaction medium undergoes a chemical reaction, stimulated fluorescence radiation is generated. After the Q switch is turned on, the radiated fluorescence oscillates and amplifies in the resonant cavity to form stable oscillating light. The oscillating light enters the telescope system through the total reflection mirror to expand the beam. After passing through the optical isolation system, it enters the laser amplifier through the plano-concave rear cavity mirror for amplification. The optical isolation system is used to isolate the oscillating light reflected from the amplifier. The laser amplified in the unstable cavity amplifier is coupled out by the scraper mirror.

The telescope system is composed of a plano-concave mirror and a plano-convex mirror, which are respectively coated with an anti-reflection film.

The optical isolation system is composed of a Faraday rotator and a 1/2 wave plate.

The electro-optic Q-switching crystal is a β-barium borate crystal with a low 1/4 wave voltage value and can operate at a high repetition rate

The amplifier is an unstable cavity multi-pass amplifier.

A small circular hole is bored in the center of the plano-concave rear cavity mirror.

The laser device of the present invention utilizes the laser gain medium in the same gain region to amplify the electro-optical Q-switched pulse laser to obtain high-power pulse oxygen-iodine chemical laser output, and has the advantages of compact structure, high energy, high repetition frequency, narrow pulse width and high efficiency. , excellent beam quality and other characteristics, can be widely used in laser material processing, underwater operations and mining and other fields.

The present invention has the following advantages:

1. The pulsed oxygen iodine chemical laser adopts laser amplification technology, uses the pulse Q-switched laser generated by the laser oscillator to control the amplifier, and adopts an unstable cavity structure to obtain pulsed laser with high energy and excellent beam quality.

2. The laser oscillator and the amplifier use the same activation medium, and the amplification medium and the output signal have the same energy level structure, which can realize resonance amplification, and the whole device is relatively compact.

3. Using the electro-optic Q-switching method to obtain pulsed oscillating light, the pulse width of the output laser is narrow, the modulation depth is deep, and the peak power is high, which greatly improves the application space of pulsed chemical lasers.

4. Choose β barium borate crystal as the electro-optic Q-switching crystal, the required 1/4 wave voltage is lower, thus reducing the requirement of driving power, and can obtain high repetition frequency operation.

Description of drawings

Fig. 1 is a schematic structural diagram of a pulsed oxygen-iodine chemical laser device of the present invention.

Detailed ways

As shown in the accompanying drawings, the structure of the pulsed oxygen iodine chemical laser of the present invention comprises:

A high-power pulsed gas flow chemical laser device, including a laser oscillator and a laser amplifier,

The laser amplifier consists of a plano-concave rear cavity mirror 9, a scraper mirror 11, a plano-convex front cavity mirror 12, and an active medium gain region 10 located on the optical path between the plano-concave rear cavity mirror 9 and the scraper mirror 11. ;

The laser oscillator includes a coaxial plano-concave mirror 1 and a plano-concave output coupling mirror 4, which are sequentially arranged between the plano-concave mirror 1 and the plano-concave output coupling mirror 4, an electro-optic Q-switching crystal 2, and a polarizer 3; The concave mirror 1 , the electro-optic Q-switching crystal 2 , the polarizer 3 , and the plano-concave output coupling mirror 4 are on the same optical axis; the optical path between the plano-concave output coupling mirror 4 and the polarizer 3 passes through the active dielectric gain region 10 .

Along the forward direction of the output laser, there are plano-concave reflector 1, electro-optic Q-switching crystal 2, polarizer 3, plano-concave output coupling mirror 4, plane total reflection mirror 5, plane total reflection mirror 6, telescope system 7, optical isolation System 8, plano-concave rear cavity reflector 9, scraper mirror 11, plano-convex front cavity reflector 12.

A circular small hole is bored in the center of the flat-concave rear cavity reflector of the laser amplifier, and the pulsed oscillating light enters the amplifier through the small hole to be amplified.

The gain area of the laser oscillator and the amplifier are both located in the lasing area of the nozzle, the gain area of the laser oscillator is located downstream of the gain area of the active medium, and the gain area of the amplifier is located upstream of the gain area of the active medium.

The telescope system is composed of a plano-concave lens and a plano-convex lens arranged in sequence along the advancing direction of the output laser, and are respectively coated with an anti-reflection film.

The optical isolation system is composed of a Faraday rotator and a 1/2 wave plate arranged in sequence along the advancing direction of the output laser.

The electro-optic Q-switching crystal is β barium borate crystal, its 1/4 wave voltage value is low, and it can operate at a high repetition rate.

Laser generation and transmission path: The active medium located in the active medium gain region 10 produced by chemical reaction emits natural light. When the electro-optic Q-switching crystal 2 is applied with a 1/4 wave voltage, the natural light located downstream of the active medium gain region 10 passes through. After the polarizer 3, it becomes linearly polarized light along the optical axis of the laser oscillator, passes through the electro-optic Q-switched crystal 2, is reflected by the plano-concave mirror 1, and then passes through the electro-optic Q-switched crystal 2 again, and the vibration direction of the linearly polarized light changes by π /2, at this time, it cannot pass through the polarizer 3, and laser oscillation cannot be formed. Due to external excitation, the number of upper-level particles increases rapidly. When the 1/4 wave voltage on the electro-optic Q-switched crystal is suddenly removed, the beam can freely pass through the resonator, and the resonator is in a high-Q state at this time, thereby generating laser pulses. The laser pulse is emitted by the plano-concave output coupling mirror 4, and after being reflected by the plane total reflection mirror 5 and the plane total reflection mirror 6, it enters the telescope system 7 for beam expansion, and the beam expanded laser pulse is unidirectionally isolated by the optical isolation system 8 , enter the laser amplifier through the circular bore in the center of the laser amplifier plano-concave rear cavity mirror 9, pass through the scraper mirror 11 by activating the gain medium upstream of the medium gain region 10, and pass through the plano-concave rear cavity reflector 9, plano-convex front cavity The reflection mirror 12 performs feedback oscillation amplification, and finally is coupled out by the scraper mirror 11 to obtain high-power pulsed laser light.

The laser oscillator includes a coaxial plano-concave mirror 1 and a plano-concave output coupling mirror 4, and between the plano-concave mirror 1 and the plano-concave output coupling mirror 4, an electro-optic Q-switching crystal 2, a polarizer 3, and a plano-concave Reflector 1 , electro-optic Q-switching crystal 2 , polarizer 3 , and plano-concave output coupling mirror 4 are on the same optical axis;

Along the forward direction of the output laser, there are plano-concave reflector 1, electro-optic Q-switching crystal 2, polarizer 3, plano-concave output coupling mirror 4, plane total reflection mirror 5, plane total reflection mirror 6, telescope system 7, optical isolation System 8, plano-concave rear cavity reflector 9, scraper mirror 11, plano-convex front cavity reflector 12.

A circular small hole is bored in the center of the flat-concave rear cavity reflector of the laser amplifier, and the pulsed oscillating light enters the amplifier through the small hole to be amplified.

The chemical reaction medium undergoes a chemical reaction at the outlet of the supersonic nozzle to produce excited particles. The laser oscillator is located downstream of the gain region of the active medium, and its gain is much smaller than that of the amplifier upstream of the nozzle lasing region. In the laser oscillator, the stimulated fluorescence radiation is generated due to the chemical reaction. At this time, the Q switch works. At this time, the loss in the cavity of the laser oscillator is much greater than the gain, and there is no laser oscillation output, and a large number of energy level reversal particles accumulate on the laser. When the Q switch is turned on, a large number of inversion particles transition from the upper energy level of the laser to the lower energy level, and the radiated fluorescence oscillates and amplifies instantaneously in the resonant cavity, forming oscillating light with extremely high peak power and stability. The oscillating light enters the telescope system through the total reflection mirror. The telescope system is composed of a plano-concave lens coated with an anti-reflection coating and a plano-convex lens coated with an anti-reflection coating, which are used to expand the beam and compress the divergence angle. The shaped oscillating light enters an optical isolation system composed of a Faraday rotator and a 1/2 wave plate. The optical isolation system is used to isolate the oscillating light reflected from the amplifier. The one-way isolated oscillating light enters the amplifier through the circular bore of the flat-concave rear cavity mirror of the laser amplifier for amplification. The amplifier adopts an unstable cavity structure in order to obtain laser with high beam quality. The pulsed oscillating light makes multiple round trips in the amplifier. After amplification, it is coupled and output by the scraper mirror to obtain a high-power pulsed laser.

The invention can realize the output of pulsed gas flow chemical laser without excessive loss of average power, and has the characteristics of compact structure, high output pulse energy, high repetition frequency, narrow pulse width, high efficiency, excellent beam quality and the like. The invention can also be applied to oxygen-iodine laser, HF/DF laser, pneumatic _CO2 laser and other systems.

Claims (7)

1. A high-power pulsed gas flow chemical laser device, comprising a laser oscillator and a laser amplifier, characterized in that: A plano-concave mirror (1), an electro-optic Q-switched crystal (2), a polarizer (3), a plano-concave output coupling mirror (4), a planar total reflection mirror (5), and a planar full Reflector (6), telescope system (7), optical isolation system (8), plano-concave rear cavity reflector (9), scraper mirror (11), plano-convex front cavity reflector (12); The optical path between the plano-concave output coupling mirror (4) and the polarizer (3), and the optical path between the plano-concave rear cavity mirror (9) and the scraper mirror (11) pass through the active medium gain region (10); A circular small hole is bored in the center of the flat-concave rear cavity reflector of the laser amplifier, and the pulsed oscillating light enters the amplifier through the small hole to be amplified. 2. The high-power pulsed gas flow chemical laser device according to claim 1, characterized in that: comprising a laser oscillator and a laser amplifier, The laser amplifier consists of a plano-concave rear cavity mirror (9), a scraper mirror (11), a plano-convex front cavity mirror (12), and a plano-concave back cavity mirror (9) and a scraper mirror (11) arranged in sequence. The active medium gain region (10) on the optical path constitutes; The laser oscillator includes a coaxial plano-concave mirror (1) and a plano-concave output coupling mirror (4), and an electro-optic Q-switching crystal ( 2), polarizer (3), plano-concave mirror (1), electro-optic Q-switching crystal (2), polarizer (3), and plano-concave output coupling mirror (4) are on the same optical axis; plano-concave output The optical path between the coupling mirror (4) and the polarizer (3) passes through the active medium gain region (10). 3. according to the described high-power pulsed gas flow chemical laser device of claim 1, it is characterized in that: the gain zone of laser oscillator and amplifier is jointly located in the lasing region of nozzle, and the gain zone of laser oscillator is positioned at the active medium gain zone Downstream, the amplifier gain region is located upstream of the active medium gain region. 4. The high-power pulsed gas flow chemical laser device according to claim 1, characterized in that: the telescope system is composed of a plano-concave lens and a plano-convex lens arranged in sequence along the advancing direction of the output laser, and are respectively coated with an anti-reflection film. 5. The high-power pulsed gas flow chemical laser device according to claim 1, characterized in that: the optical isolation system is composed of a Faraday rotator and a 1/2 wave plate arranged in sequence along the advancing direction of the output laser. 6. The high-power pulsed gas flow chemical laser device according to claim 1, characterized in that: the electro-optic Q-switched crystal is β-barium borate crystal, whose 1/4 wave voltage value is low, and can operate at a high repetition rate. 7. The high-power pulsed gas flow chemical laser device according to claim 1, characterized in that: said laser amplifier is an unstable cavity multi-pass amplifier.

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