CN201113206Y - Conduction Cooled Laser Master Oscillator Power Amplifier - Google Patents

Abstract

A power amplifier of main laser oscillation with conduction cooling features that the central laser slab is used to transmit along zigzag optical path, and the variable-reflectivity convex output unit and concave back cavity mirror are used to form an unstable resonator along the length direction of gain. The laser medium of the amplifier adopts a rectangular slab, both sides of the rectangular slab are pumped, and the upper large side and the lower large side are conducted and cooled. The utility model discloses can enough improve the light beam quality, can realize high-efficient high pulse energy laser output again to compact structure has, simple and stable characteristics.

Description

Conduction Cooled Laser Master Oscillator Power Amplifier

technical field

The utility model relates to a laser, in particular to a conduction-cooled laser main oscillation power amplifier. It can realize high efficiency, high beam quality and high pulse energy laser output.

Background technique

Achieving conduction cooling with high beam quality, high pulse energy, and high-efficiency laser output has become an important technical indicator for the development of space lasers in recent years, and it is also an important driving force for the development of space lasers. Several common pumping methods in the past are as follows:

Side-pumped rod laser media and stable resonators. The traditional side-pumped rod-shaped laser medium operates at high average power. Due to severe thermal lens and thermally induced birefringence, the output laser is distorted, and it is difficult to obtain high beam quality laser output.

The side pumping goes straight through the plate-shaped laser medium and the stable cavity and the unstable cavity, uniform pumping and uniform cooling. The plate-shaped laser medium presents a one-dimensional distribution in the thickness direction, but there is still a thermal effect when operating at high power. It is difficult to get high beam quality output.

The side-pump cuts the Braust angle "zigzag" optical path to transmit the plate-shaped laser medium and the unstable, stable, and prism resonant cavity. The plate-shaped laser medium transmitted by the "zigzag" optical path can eliminate the first-order thermal focusing along the thickness direction through the average temperature, and improve the beam quality. However, when using a stable resonator, due to its small mode volume, the laser cannot be fully utilized. Medium, so high-efficiency output cannot be obtained. Although the traditional unstable resonator can obtain a large mode volume, the output is a ring laser beam. Although the prism resonator can improve the alignment misalignment, because it is a linear cavity, it cannot obtain high beam quality laser output.

In short, it is difficult to obtain high beam quality, high efficiency, high pulse energy or high average power output in the above methods.

Contents of the invention

The purpose of this utility model is to improve the deficiencies of the above-mentioned prior art, and to provide a conduction-cooled laser main oscillation power amplifier. And has the characteristics of compact structure, simple and stable.

The technical solution of the utility model is as follows:

A conduction-cooled laser main oscillation power amplifier is composed of an oscillator and an amplifier: the composition of the oscillator includes a slab gain medium whose end face is cut into a Brewster angle, and in the length direction of the slab gain medium, One end is an output convex mirror with variable reflectivity, and the other end is a polarizer, a Q switch, a quarter-wave plate, and a concave rear cavity mirror in turn. The slab gain medium has a cylindrical lens and a laser diode array on one side, and a laser diode array on the other side. Bonded with a bridge-type oxygen-free copper heat sink;

The composition of the amplifier includes a rectangular magnifying slat, a Faraday isolator and a polarizer are arranged on the incident light path of the Brewster angle at one end of the rectangular magnifying slat, and a third plane reflector and a quadrant are arranged on the returning light path. One wave plate, on the other end of the rectangular magnifying slab is provided with the first plane reflector and the second plane reflector that the optical path turns back, and the two sides of the rectangular magnifying slab are respectively provided with the second laser diode array and the second laser diode array;

The laser output from the oscillator enters the rectangular amplifying slab at the Brewster angle through the Faraday isolator and polarizer of the amplifier, and after being reflected by the first plane reflector and the second plane reflector after exiting , and then enter the rectangular amplifying slab at the Brewster angle, the laser output from the rectangular amplifying slab is reflected by the quarter-wave plate and the third mirror, and returns along the original optical path, and finally the laser is coupled out from the polarizer, Realize four-way amplification;

The upper and lower two large surfaces of the rectangular amplifier slats are fixed by indium and copper metal clamping devices, and the gain medium of the slats, the rectangular amplifying slats and the laser diode array emit excess heat through the metal clamps located in the The heat pipe of the holding device is exhausted.

The slab gain medium is a slab-shaped laser crystal cut into Brewster's angle.

The reflectivity radial distribution of the variable reflectivity output mirror is Gaussian distribution, or super Gaussian distribution.

The polarizer, the Q switch and the quarter wave plate form a Q switch device.

The laser diode array is a single-layer linear array, and its fast axis is arranged along the length direction of the laser slabs, and the cylindrical lens is a plano-convex structure.

The rectangular enlarged slats are laser crystal rectangular slats.

The reflectivity of the plane mirror is greater than 99.9%.

Advantage of the utility model:

In the utility model, the conduction cooling is adopted to avoid the pollution of the total reflection surface of the laser slab due to the convective cooling, and has higher heat transfer efficiency, so it is more suitable for space application.

In the utility model, the resonant cavity adopts an unstable cavity with a variable reflectivity output coupler, which can simultaneously obtain a large mode volume and a high beam quality laser output, thereby improving the laser output efficiency.

In the utility model, the laser medium adopts a "zigzag" optical path cut into Brewster's angle to transmit the laser slats to eliminate the first-order thermal focus, stress birefringence and depolarization effects in the "zigzag", thereby improving the beam quality .

In the utility model, the zigzag optical path transmission of the laser in the amplifier realizes four-pass amplification, which has the advantages of high pump extraction efficiency and good beam quality.

Description of drawings

Fig. 1 is the structural representation of the oscillator of the embodiment of the conduction-cooled laser main oscillation power amplifier of the present invention

Fig. 2 is the schematic structural view of the amplifier of the embodiment of the conduction-cooled laser main oscillation power amplifier of the present invention

Fig. 3 is the amplifier assembly schematic diagram of embodiment of the conduction cooled laser main oscillation power amplifier of the present invention

Detailed ways

The utility model will be further described below in conjunction with the embodiments and accompanying drawings, and the protection scope of the utility model should not be limited with this.

First please refer to Fig. 1, Fig. 2 and Fig. 3, which are schematic diagrams of the structure of the oscillator and the amplifier of the embodiment of the conduction-cooled laser main oscillation power amplifier of the present invention. It can be seen from the figure that the conduction-cooled laser main oscillation power amplifier of the present invention is composed of an oscillator and an amplifier:

The composition of the oscillator includes a slab laser crystal 2 whose end face is cut into a Brewster angle. In the length direction of the slab laser crystal 2, one end is an output convex mirror 1 with variable reflectivity, and the other end is a polarizing mirror 1 in turn. plate 3, Q switch 4, quarter-wave plate 5 and concave rear cavity mirror 6, one side of the slab laser crystal 2 is a cylindrical lens 7 and a laser diode array 8, and the other side is connected with a bridge-type oxygen-free copper heat sink 9 glued together;

The composition of described amplifier comprises a rectangular amplifying slat 11, on the incident optical path of the Brewster angle at one end of this rectangular amplifying slat 11, Faraday isolator 19 and polarizer 10 are arranged, on the return optical path there is a third Plane reflector 15 and quarter wave plate 14, the first plane reflector 12 and the second plane reflector 13 that light path turns back are provided at the other end of this rectangular magnifying slat 11, two of this rectangular magnifying slat 11 A second laser diode array 16 and a second laser diode array 17 are respectively provided on the sides;

The laser output from the oscillator enters the rectangular magnifying slab 11 at the Brewster angle through the Faraday isolator 19 and the polarizer 10 of the amplifier, and passes through the first plane mirror 12 and the second mirror 12 after exiting. After being reflected by the plane reflector 13, it enters the rectangular magnifying slat 11 at the Brewster angle, and the laser light is output from the rectangular magnifying slat 11 and then reflected by the quarter-wave plate 14 and the third reflector 15 along the original The optical path returns, and finally the laser is coupled out from the polarizer 10 to realize four-pass amplification.

The upper and lower two large surfaces of the rectangular enlarged slat 11 are fixed by a metal clamping device 18, and the excess heat emitted by the lath laser crystal 2, the rectangular enlarged slat 11 and the laser diode array 8, 16, 17 passes through the The heat pipe 20 discharges.

The reflectivity radial distribution of the variable reflectivity output mirror 1 is a Gaussian distribution, or a super-Gaussian distribution.

The polarizer 3, the Q switch 4 and the quarter wave plate 5 form a Q switch device.

The first laser diode array 8 is a single-layer linear array, its fast axis is arranged along the length direction of the laser slabs, and the cylindrical lens 7 is a plano-convex structure.

The rectangular magnifying strip 11 is a laser crystal rectangular strip.

The reflectivity of the plane mirrors 12, 13, 15 is greater than 99.9%.

The laser diode array (8) is a single-layer linear array, and its fast axis is arranged along the length direction of the strips. The converging cylindrical lens 7 is a plano-convex structure. After converging and compressing, the pump light is relatively uniform in the width direction of the laser medium. The laser output from the oscillator passes through the Faraday isolator 19, the polarizer 10, and enters the rectangular amplifier slab 11 at Brewster's angle. After exiting, it is reflected by the first plane mirror 12 and the second plane mirror 13, and again about the optical axis Symmetrically, it enters the rectangular laser slab 11 at the Brewster angle, and after outputting from the laser slab 11, passes through the quarter-wave plate 14 and the third plane mirror 15 and returns along the original optical path. Finally, the laser is coupled out from the polarizer 10 to realize four-pass amplification. In the conduction-cooled amplifier, the amplifier slat 11 is a rectangular slat, and the material is crystal.

In this embodiment, the laser dielectric pumping surface of the oscillator is coated with an anti-reflection film for the pump light and an anti-reflection film for the output laser to increase the absorption of the pump light and prevent parasitic oscillation, and the cooling surface is coated with an anti-reflection film for the output laser. anti-reflection coating and silicon dioxide protective coating. The area array laser diode array is arranged along the fast axis direction. After being compressed by the lens, the pump beam is compressed from the original 10mm to 4mm along the width of the laser medium. The pump light intensity is relatively uniform, and the pump power density is improved at the same time. . The pump light passes through the laser medium twice, which increases the absorption of the pump light and improves the laser output efficiency. The laser medium is connected with a tungsten-copper alloy with the same thermal expansion coefficient through a high thermal conductivity adhesive. Mounted on a bridge-type heat sink, the heat generated by the laser diode array and the laser medium is finally transferred to the evaporation end of the heat pipe through conduction cooling, and taken away by the cooling water at the cold end of the heat pipe, simulating the radiation plate in space applications. Compared with convection cooling, conduction cooling has the advantages of simple structure, reduced vibration, mechanical stability, simple structure, protection of laser medium total reflection surface, reduced vibration, and energy saving. The resonant cavity consists of a concave rear cavity mirror 6 and a variable reflectivity output mirror 1 to form an unstable resonant cavity, which increases the mode volume and beam quality. By suppressing the oscillation of high-order modes, the near-diffraction fundamental mode laser output can be obtained, which increases the laser extraction efficiency.

The slab laser amplifier adopts a rectangular structure for easy processing and manufacture. The pump surface is coated with a 2-3 micron silicon dioxide protective film and a 1064nm anti-reflection film. The upper and lower cooling surfaces are roughened to reduce the occurrence of parasitic vibrations.

Double-sided pumping increases the pumping power, and the four-way transmission of the zigzag optical path improves the beam quality and extraction efficiency. Proved by trial. The laser system has compact structure, high beam quality, high efficiency and high pulse energy laser output.

Claims (7)

1, a kind of laser master oscillator power amplifier that conducts cooling is made of oscillator and amplifier, it is characterized in that:

The composition of described oscillator, comprise that both ends of the surface are cut into the lath gain media (2) of Brewster's angle, on this lath gain media (2) length direction, one end is the output convex mirror (1) of reflectivity-variable, the other end is polarizer (3), Q switching (4), quarter-wave plate (5) and concave surface Effect of Back-Cavity Mirror (6) successively, these lath gain media (2) one sides are post lens (7) and first diode laser matrix (8), and another side and bridge-type oxygen-free copper heat sink (9) bond together;

The formation of described amplifier, comprise that a rectangle amplifies lath (11), amplify at this rectangle on the input path of Brewster's angle of an end of lath (11) faraday isolator (19) and polarizer (10) are arranged successively, return the 3rd plane mirror (15) and quarter-wave plate (14) are arranged on the light path, the other end that amplifies lath (11) at this rectangle is provided with first plane mirror (12) and second plane mirror (13) that light path is turned back, constitute a four-range multiplication system, the both sides that this rectangle amplifies lath (11) are respectively equipped with second diode laser matrix (16) and the 3rd diode laser matrix (17);

The laser of described oscillator output enters described rectangle amplification lath (11) through the faraday isolator (19) and the polarizer (10) of described amplifier with Brewster's angle, after the outgoing through after the reflection of first plane mirror (12) and second plane mirror (13), enter rectangle with Brewster's angle again and amplify lath (11), laser returns along original optical path through quarter-wave plate (14) and the 3rd plane mirror (15) reflection back after rectangle amplifies lath (11) output, last laser realizes that from polarizer (10) coupling output quadruple pass amplifies;

Two big faces up and down of described rectangle amplifier lath (11) are fixing by indium and copper metal clamping device (18), and described lath gain media (2), rectangle amplify lath (11) and diode laser matrix (8,16,17) sends unnecessary heat by being positioned at heat pipe (20) discharge of described metal clamping device (18).

2, the laser master oscillator power amplifier of conduction cooling according to claim 1 is characterized in that described lath gain media (2) is the laser crystal that is cut into the lath-shaped of Brewster's angle.

3, the laser master oscillator power amplifier of conduction cooling according to claim 1 is characterized in that described variable reflectivity outgoing mirror (1) is that the reflectivity radial distribution is the gaussian-shape distribution, or the lens of super gaussian-shape distribution.

4, the laser master oscillator power amplifier of conduction cooling according to claim 1 is characterized in that described polarizer (3), Q-switch (4) and quarter-wave plate (5) composition Q-modulating device.

5, the laser master oscillator power amplifier of conduction cooling according to claim 1, it is characterized in that described diode laser matrix (8) is linear array, its fast axle is arranged along the length direction of lath gain media (2), and described post lens (7) are the plano-convex structure.

6, the laser master oscillator power amplifier of conduction cooling according to claim 1 is characterized in that it is the laser crystal rectangular strip that described rectangle amplifies lath (11).

7, according to the laser master oscillator power amplifier of each described conduction cooling of claim 1 to 6, the reflectivity that it is characterized in that described plane mirror (12,13,15) is greater than 99.9%.

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