CN210957265U - End-pump multi-pass slab laser amplifier - Google Patents

Abstract

The utility model discloses an end-pump multi-pass slab laser amplifier, which comprises a pumping semiconductor laser, a laser shaping light path, a slab laser crystal, a laser reflection light path and a heat sink; a pumping semiconductor laser is respectively arranged below two ends of the slab laser crystal, a laser shaping light path is arranged between the slab laser crystal and the pumping semiconductor laser, and the pumping semiconductor laser and the laser shaping light path are coaxially arranged; laser reflection light paths are respectively arranged above two ends of the slab laser crystal; the upper surface and the lower surface of the slab laser crystal are respectively fixed with a heat sink. The utility model discloses a mode that two-sided end pump and multipass were enlargied is applicable to the commonality MOPA technique that different wavelength laser enlargied, on the basis that improves system efficiency and light beam quality, reduces system structure size simultaneously, improves the reliability, and lath amplifier simple structure and compactness are easily assembled and integrated for system's volume and weight reduce, are convenient for engineer and productization.

Description

An end-pumped multi-pass slab laser amplifier

technical field

The utility model relates to the field of solid-state lasers, in particular to an end-pump multi-pass slab laser amplifier.

Background technique

High-power and high-energy lasers are widely used in national defense, scientific research, industry, medical and other fields. Using lasers for long-term scientific research has gradually become an important tool for solving various engineering and scientific problems. High power and high energy is an important development direction of laser technology, and the depth and breadth of research and application are continuously expanded. As the core technology of high-power lasers, master oscillator power amplification (MOPA) has attracted a lot of attention. The laser amplifier is based on the principle of stimulated radiation, and the input laser is used to obtain laser energy amplification by single or multiple passes through the gain medium in the amplifier. Laser amplifiers at high power will inevitably face the problems of heat accumulation and thermal distortion, which seriously restrict the improvement of laser power and beam quality.

At present, laser amplifiers can be divided into side pump amplification, end pump amplification, slab amplification and other technologies according to the shape of the gain medium. Side-pump amplification and end-pump amplification are the most commonly used techniques in laser amplifiers. The end-pump amplification is such that the pumping direction is the same as the propagation direction of the incident laser, which has the outstanding advantages of uniform pumping and good beam quality. However, due to the use of end-face pumping, the cross-section of the crystal is small, and the allowable pumping energy is limited, that is, the laser amplification power is limited, and it is mostly used in medium and low power. The pumping light of the side-pumping amplification technology is perpendicular to the propagation direction of the laser, and the crystal side-pumping is used. The crystal has a larger side area and can be loaded with more pump energy. However, in the case of high-power pumping, the heat accumulation in the crystal can easily cause thermal depolarization, resulting in a decrease in system efficiency. At the same time, the optical efficiency of the side pump module is low, and more pumping energy is required. Moreover, the laser crystal and the concentrating cavity are in contact with the cooling water, and the crystal and the concentrating cavity are easily polluted and thus affect the laser power, so the maintenance of the side pump amplifier module will be poor. Combining the advantages of the side pump module and the end pump module, the slat amplification technology utilizes the Zig-zag transmission characteristics of the slat crystal to fully extract the laser gain energy. In particular, the thermal effects of the zigzag-propagating Zig-zag slab crystals can cancel each other out, and the light-to-optical conversion efficiency is high, which is especially suitable for side pumping output large energy and end pumping output high beam quality and high power.

At present, a laser amplifier is needed to realize the common MOPA technology of laser amplification of different wavelengths by combining the slab crystal and end pumping technology. At the same time, the size of the system in the existing equipment is large, which is difficult to install or integrate. Make improvements.

Utility model content

Technical purpose: In view of the lack of a common MOPA technology laser amplifier that combines slab crystal and end-pumping technology and is suitable for laser amplification of different wavelengths in the prior art, the utility model discloses an end-pumped multi-pass slab laser The amplifier is suitable for the common MOPA technology of laser amplification of different wavelengths. On the basis of improving the system efficiency and beam quality, the system structure size is reduced and the reliability is improved.

Technical scheme: The utility model discloses an end-pumped multi-pass slat laser amplifier, which includes a pumping semiconductor laser, a laser shaping optical path, a slat laser crystal, a laser reflection optical path and a heat sink; There is a pumping semiconductor laser, a laser shaping optical path is arranged between the slat laser crystal and the pumping semiconductor laser, and the pumping semiconductor laser and the laser shaping optical path are coaxially arranged; the two ends of the slat laser crystal are respectively provided with laser reflection optical paths; The upper and lower large surfaces of the laser crystal are respectively fixed with heat sinks.

Preferably, the laser shaping optical circuit is used to condense the pump beam emitted by the pump semiconductor laser, and the laser shaping optical circuit includes a first pump coupling lens and a second pump coupling lens, the first pump coupling lens and the third pump coupling lens. The two pump coupling lenses are all cylindrical lenses.

Preferably, the direction of the cylindrical generatrix of the first pump coupling lens is perpendicular to the direction of the fast axis of the pump beam, which is used to couple the pump beam in the fast axis direction, and the direction of the cylindrical generatrix of the second pump coupling lens is parallel to the direction of the pump beam. The fast axis direction of the pump beam is used to couple and narrow the pump beam in the slow axis direction.

Preferably, the pumping semiconductor laser is a semiconductor laser array, and the array structure is a conduction-cooled stack or a water-cooled vertical stack.

Preferably, the laser reflection optical path is used to reflect the laser beams emitted from the end faces of the two sides of the slab laser crystal back to the slab laser crystal, and the laser reflection optical path includes a first reflection mirror and a second reflection mirror, the first reflection mirror and the second reflection mirror The surface of the reflective lens is coated with a highly reflective film; the first reflective lens reflects the laser beam emitted from the slat laser crystal back to the slat laser crystal, and after output, the second reflective lens reflects it back to the slat laser crystal again, and the laser Output from one end of the slab laser crystal through the slab laser crystal multiple times.

Preferably. The reflection angle range of the first reflection lens and the second reflection lens in the laser reflection optical path is [20°, 30°].

Preferably, the shape of the slab laser crystal is a trapezoid or a parallelogram.

Preferably, the slab laser crystal adopts Nd: YAG crystal or Nd: YVO4 crystal.

Preferably, the bottom surface of the slab laser crystal is coated with a pump laser antireflection film; the end face of the slab laser crystal is coated with a laser antireflection film; the upper and lower surfaces of the slab laser crystal are coated with a SiO2 evanescent film.

Preferably, the upper and lower surfaces of the strip laser crystal are respectively welded or crimped to fix the heat sink.

Beneficial effects:

(1), the present utility model realizes a kind of end-pump multi-pass slat laser amplifier, adopts the mode of double-sided end-pump and multi-pass amplification, is suitable for the common MOPA technology of different wavelength laser amplification, in improving system efficiency and beam quality On the basis, the structure size of the system is reduced and the reliability is improved at the same time. The structure of the slat amplifier is simple and compact, and it is easy to assemble and integrate, which reduces the volume and weight of the system, and facilitates engineering and productization;

(2), the laser shaping light path of the present utility model adopts a plurality of cylindrical lenses, and adopts the cylinder to shape the slow axis and the fast axis of the pump light respectively, so that the pump light can be effectively incident on the interior of the slab laser crystal;

(3), in the utility model, the upper and lower large surfaces of the lath laser crystal in contact with the heat sink are plated with SiO Evanescent film, improves the reflectivity of incident laser light;

(4) The slat laser crystal adopts a conduction cooling structure, and the cooling water does not have direct contact with the crystal, which prevents the crystal from being polluted by water and greatly improves the reliability of the device.

Description of drawings

Figure 1 is a schematic diagram of the overall structure of the utility model.

Detailed ways

The present utility model will be further explained and described below in conjunction with the accompanying drawings.

As shown in FIG. 1 , the utility model discloses an end-pumped multi-pass slab laser amplifier, comprising a pumping semiconductor laser 1 , a laser shaping optical path 2 , a slab laser crystal 3 , a laser reflection optical path 4 and a heat sink 5 ; The slab laser crystal 3, the laser reflection optical path 4 and the heat sink 5 constitute a slab amplifier.

The two ends of the slab laser crystal 3 are respectively provided with a pumping semiconductor laser 1. The pumping semiconductor laser 1 is a semiconductor laser array. The wavelength is selected according to the crystal material, such as 808nm, 880nm, etc. The specific model can be FL-VS300-Nx1-100xN -808-Y, or FL-GS05-Nx1-100xN-808(Q), the array structure is a conduction cooling stack or a water-cooling vertical stack; the pump semiconductor laser 1 has high pump energy, and uses end faces at both ends The pumping method ensures pumping uniformity. The working mode of the pumped semiconductor laser 1 is continuous or pulsed, and if it is a pulsed working mode, the modulation of laser power, pulse width, timing and repetition frequency is realized by the driving power supply. The slat laser crystal 3 is cooled by conduction and heat dissipation, and the cooling water is not in direct contact with the crystal, which prevents the crystal from being polluted by water and greatly improves the reliability of the device.

A laser shaping optical circuit 2 is arranged between the slab laser crystal 3 and the pumping semiconductor laser 1, and the pumping semiconductor laser 1 and the laser shaping optical circuit 2 are coaxially arranged; the laser shaping optical circuit 2 is used for the pumping beam emitted by the pumping semiconductor laser 1 For beam reduction, the laser shaping optical circuit 2 includes a first pump coupling lens 21 and a second pump coupling lens 22, and both the first pump coupling lens 21 and the second pump coupling lens 22 use cylindrical lenses; The direction of the cylindrical generatrix of the lens 21 is perpendicular to the direction of the fast axis of the pump beam, and is used to couple and reduce the pump beam in the direction of the fast axis. The direction of the cylindrical generatrix of the second pump coupling lens 22 is parallel to the direction of the fast axis of the pump beam, and is used for Coupling and condensing the pump beam in the slow axis direction. The cylinder is used to shape the slow axis and fast axis of the pump light respectively, so that the pump light can be effectively incident into the interior of the slab laser crystal.

The two ends of the slat laser crystal 3 are respectively provided with a laser reflection optical path 4; the laser reflection optical path 4 is used to reflect the laser beams emitted from the end faces on both sides of the slat laser crystal 3 back to the slat laser crystal 3, and the laser reflection optical path 4 includes a first The reflective mirror 41 and the second mirror 42, the surfaces of the first mirror 41 and the second mirror 42 are coated with a high-reflection film to provide laser reflectivity; the first mirror 41 will The laser beam is reflected back to the slat laser crystal 3 , and then reflected back to the slat laser crystal 3 by the second reflecting mirror 42 after outputting. The laser reflection optical path 4 enables the laser to pass through the slab laser crystal multiple times to achieve high gain amplification. In the laser reflection optical path 4, the reflection angle range of the first reflection mirror 41 and the second reflection mirror 42 is [20°, 30°], and the mirror surfaces of the first reflection mirror 41 and the second reflection mirror 42 are coated with a high-reflection film.

The shape of the slab laser crystal 3 is trapezoid or parallelogram, and the sharp corner of the crystal is cut at 45° to reflect the pump light. The slab laser crystal 3 adopts neodymium-doped yttrium aluminum garnet Nd: YAG crystal or neodymium-doped yttrium vanadate Nd: YVO4 crystal. The bottom surface of the slat laser crystal 3 is coated with a pump laser anti-reflection film, such as 808nm anti-reflection film; the end face of the slat laser crystal 3 is coated with a laser anti-reflection film, such as a 1064 nm anti-reflection film; the upper and lower sides of the slat laser crystal 3 are large The surface is coated with SiO2 evanescent film to improve the reflectivity of incident laser light. The upper and lower large surfaces of the slab laser crystal 3 are respectively fixed to the heat sink 5 by welding or crimping, so as to fully dissipate heat.

The working principle of the present invention is as follows: the pumping semiconductor lasers 1 on both sides of the slat laser crystal 3 emit pumping light respectively, and the fast axis and slow axis directions of the pumping light are coupled and condensed through the laser shaping optical path 2, respectively. The laser beam processed by the shaping optical path 2 is incident on both end faces of the slab laser crystal 3, and is reflected into the slab laser crystal 3 by the end faces. The laser beam emitted from one end of the slab laser crystal 3 is reflected back to the slab by the corresponding laser reflection optical path 4. The strip laser crystal 3, the laser beam passes through the strip laser crystal 3 for many times to achieve high gain amplification and then output from the end face of the strip laser crystal 3.

The technical solution realizes an end-pumped multi-pass slab laser amplifier, which adopts the method of double-sided end-pump and multi-pass amplification, and is suitable for the common MOPA technology of laser amplification of different wavelengths. On the basis of improving system efficiency and beam quality, at the same time To reduce the size of the system structure and improve the reliability, the slat amplifier has a simple and compact structure, and is easy to assemble and integrate, which reduces the volume and weight of the system, and facilitates engineering and productization.

The above is only the preferred embodiment of the present utility model, it should be pointed out that: for those skilled in the art, without departing from the principle of the present utility model, several improvements and modifications can also be made. These improvements and Retouching should also be regarded as the protection scope of the present invention.

Claims (10)

1. An end-pumped multi-pass slat laser amplifier, characterized in that: comprising a pumped semiconductor laser (1), a laser shaping optical path (2), a slat laser crystal (3), a laser reflection optical path (4) and a heat sink (5); a pumping semiconductor laser (1) is respectively provided below both ends of the slab laser crystal (3), and a laser shaping optical path (2) is arranged between the slab laser crystal (3) and the pumping semiconductor laser (1). ), the pumping semiconductor laser (1) is arranged coaxially with the laser shaping optical path (2); the two ends of the slab laser crystal (3) are respectively provided with a laser reflection optical path (4); The heat sinks (5) are respectively fixed on the upper and lower large surfaces. 2. An end-pumped multi-pass slab laser amplifier according to claim 1, characterized in that: the laser shaping light path (2) is used for beam-shrinking the pump beam emitted by the pump semiconductor laser (1) , the laser shaping light path (2) includes a first pump coupling lens (21) and a second pump coupling lens (22), and both the first pump coupling lens (21) and the second pump coupling lens (22) are cylindrical lens. 3. A kind of end-pump multi-pass slab laser amplifier according to claim 2, it is characterized in that: the cylindrical generatrix direction of described first pump coupling lens (21) is perpendicular to the pump beam fast axis direction, is used for pairing The pump beam in the fast axis direction is coupled and condensed, and the cylindrical generatrix direction of the second pump coupling lens (22) is parallel to the fast axis direction of the pump beam for coupling and condensed the pump beam in the slow axis direction. 4. An end-pumped multi-pass slat laser amplifier according to claim 1, characterized in that: the laser reflection optical path (4) is used to reflect the laser beams emitted from the end faces on both sides of the slat laser crystal (3) The back-slab laser crystal (3), the laser reflection optical path (4) includes a first reflecting lens (41) and a second reflecting lens (42), and the surfaces of the first reflecting lens (41) and the second reflecting lens (42) are plated There is a high-reflection film; the first reflecting lens (41) reflects the laser beam emitted from the slat laser crystal (3) back to the slat laser crystal (3), and is reflected again by the second reflecting lens (42) after outputting Returning to the slab laser crystal (3), the laser passes through the slab laser crystal (3) for many times and is output from one end of the slab laser crystal (3). 5. The end-pumped multi-pass slat laser amplifier according to claim 4, characterized in that: the reflection of the first reflection mirror (41) and the second reflection mirror (42) in the laser reflection optical path (4) The angle range is [20°, 30°]. 6. An end-pumped multi-pass slab laser amplifier according to claim 1, characterized in that: the pumped semiconductor laser (1) is a semiconductor laser array, and the array structure is a conduction cooling stack or a water-cooled vertical stack . 7. The end-pumped multi-pass slab laser amplifier according to claim 1, characterized in that: the shape of the slab laser crystal (3) is a trapezoid or a parallelogram. 8 . The end-pumped multi-pass slab laser amplifier according to claim 1 , wherein the slab laser crystal ( 3 ) adopts Nd: YAG crystal or Nd: YV04 crystal. 9 . 9. An end-pumped multi-pass slab laser amplifier according to claim 1, characterized in that: the bottom surface of the slab laser crystal (3) is coated with a pump laser antireflection film; the slab laser crystal (3) ) is coated with a laser anti-reflection film; the upper and lower surfaces of the slab laser crystal (3) are coated with a SiO2 evanescent film. 10 . The end-pumped multi-pass slat laser amplifier according to claim 1 , wherein the upper and lower surfaces of the slat laser crystal ( 3 ) are respectively fixed to the heat sink ( 5 ) by welding or crimping. 11 . .

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