CN213753435U

CN213753435U - Er-based large-energy 2940 nanometer pulse disc laser

Info

Publication number: CN213753435U
Application number: CN202022886513.0U
Authority: CN
Inventors: 李刚; 刘锐; 公发全; 李想; 贾勇; 戴隆辉; 雷希音; 邓淞文; 金玉奇
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2020-12-03
Filing date: 2020-12-03
Publication date: 2021-07-20
Anticipated expiration: 2030-12-03

Abstract

The utility model relates to a disc laser technical field, in particular to big energy 2940 nanometer pulse disc laser based on Er. The multi-stroke pump cavity is internally provided with a disc crystal, a plano-concave aspheric reflector and a plurality of groups of prism groups, the plano-concave aspheric reflector is of an annular structure with a central hole, and the plano-concave aspheric reflector is used for receiving and focusing pump light emitted by the pump source; the disc crystal is arranged at the focusing center of the plano-concave aspheric reflector and used for pumping pump light and generating laser beams; the multiple groups of prism groups are circumferentially arranged around the disc crystal and used for secondary angle conversion of the pump light and incidence on the plano-concave aspheric surface reflector again in the form of parallel light. The utility model discloses effectively reduced the thermal lens effect of crystal, to high quantum loss gain medium Er³⁺The doped crystal has good heat dissipation effect, and can obtain higher-power pumping.

Description

Er-based large-energy 2940 nanometer pulse disc laser

Technical Field

The utility model relates to a disc laser technical field, in particular to big energy 2940 nanometer pulse disc laser based on Er.

Background

The laser with the wavelength of 2.94 microns is in a near infrared band, has extremely high instantaneous temperature, is positioned near a 3um absorption peak of water, and has strong absorption effect on the band due to water molecules because the laser with the wavelength of 2.94 microns is just positioned near the absorption peak (3 microns) of the water. In addition, more than 70 percent of the biological cells are water, and the penetration depth of Er laser in the biological cell tissue is shallow, so that the laser with the wave band of 2.94 mu m can avoid damaging other molecular bonds in the cells and has great thermal damage like the laser generated by a carbon dioxide laser, and the laser has little mechanical damage and thermal damage to the human body. Therefore, the Er-YAG laser is becoming an important research direction and hot spot in medical fields such as plastic surgery. The Er laser is an ideal scalpel in medicine, so the Er laser has wide prospect in the fields of biology, medicine and the like; meanwhile, the 2.94 μm laser can also be used as a pumping light source of an optical parametric oscillator to obtain tunable mid-infrared laser of 3-12 μm.

At present, Er is caused³⁺The pumping source of the laser generally adopts a wavelength near 970nm for pumping, the quantum loss of the pumping source reaches 67 percent, and the pumping source is wasted in the form of heat. A rod-like Er is generally used; YAG is used as a gain medium, and a diode laser with the wavelength of 970nm is used as a pumping source to realize Q-switched laser pulse. However, the Er and YAG can not realize high repetition frequency operation due to the extremely large heat generated during operation, usually only a few Hz to dozens Hz, and can not meet the current medical and industrial requirements. Meanwhile, due to the severe thermal lens effect of the high-power laser, the quality of laser beams generated by the high-power laser is poor, and the fields of precision machining, precision medical treatment and the like are difficult to perform.

SUMMERY OF THE UTILITY MODEL

In view of the above, an object of the present invention is to provide a large energy 2940nm pulse disk laser based on Er to reduce the thermal lens problem brought by Er pumping rod-shaped gain medium, so that it can obtain higher energy pulse laser output.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a large-energy 2940 nanometer pulse disc laser based on Er comprises a pumping source, a collimation homogenization system, a multi-stroke pumping cavity and a resonant cavity which are sequentially arranged along a light path, wherein a disc crystal, a plano-concave aspheric reflector and a plurality of groups of prism groups are arranged in the multi-stroke pumping cavity, the plano-concave aspheric reflector is of an annular structure with a central through hole, and the plano-concave aspheric reflector is used for receiving pumping light emitted by the pumping source and focusing; the disc crystal is arranged at the focusing center of the plano-concave aspheric reflector and used for pumping pump light and generating laser beams; the multiple groups of prism groups are circumferentially arranged around the disc crystal and used for secondary angle conversion of the pump light and incidence on the plano-concave aspheric mirror again in the form of parallel light.

The back of the disc crystal is provided with a heat sink.

The front side of the disc crystal is plated with an antireflection film, the rear side of the disc crystal is plated with a reflecting film, the antireflection film is used for improving the transmittance of pump light, and the reflecting film is used for improving the reflectivity of the residual pump light.

The thickness of the disc crystal is 50-200 um.

Each group of prism group all includes two prisms, and two prisms are relative to the horizontal plane symmetry setting to two prisms mutually perpendicular.

The number of the prism groups is at least five.

The collimation and homogenization system comprises a homogenization rod and a collimation lens which are sequentially arranged along a light path.

The laser comprises a resonant cavity, and is characterized in that a Q-switch, an F-P etalon, a reflector and an output coupling mirror are arranged in the resonant cavity, wherein the Q-switch, the F-P etalon and the reflector are sequentially arranged along a light path, and the output coupling mirror is arranged at a laser output port of the resonant cavity and used for outputting laser pulses.

The resonant cavity corresponds to the central through hole of the plano-concave aspheric reflector.

The pumping source adopts a diode with the wavelength of 970 +/-10 nm.

The utility model has the advantages and beneficial effects that:

1. the utility model reduces the thickness of Er-YAG crystal to 50-200um, so that the waste heat of the crystal is radiated along a single axial direction, the thermal lens effect of the crystal is effectively reduced, and the high quantum loss gain medium Er is realized³⁺The doped crystal has good heat dissipation effect, can obtain a pump with higher power, and further expands the application of 2940 nanometers in the fields of medical treatment and radio and television countermeasure.

2. The utility model discloses an utilize each other to become 90 degrees's speculum group and an aspheric surface speculum, constitute the pumping structure of many strokes, solved the puzzlement that prism angle calculated in traditional pumping mode, in processing, only need make the prism in pairs can, replaced traditional pumping mode, the processing difficulty of four prism group diverse has further reduced the cost and the design degree of difficulty of laser instrument.

3. The utility model discloses an introduce the intracavity with the F-P etalon, can realize 2940nm wavelength narrow linewidth output, expand its application.

4. The utility model adopts the disc technology to compress the thickness of the Er: YAG gain medium, thereby improving the diameter-thickness ratio (50-100:1), leading the heat flow direction to only follow one-dimensional direction, greatly improving the heat exchange efficiency, and simultaneously utilizing an acousto-optic Q-switching device or an electro-optic Q-switching device, such as RTP and TeO₂The Q-switched crystal can realize the output of large-energy kHz pulse laser, greatly improves the processing efficiency of 2940 nanometer laser, and further widens the application fields of the Q-switched crystal in medical treatment, industry and national defense.

Drawings

Fig. 1 is a schematic structural diagram of an Er-based large-energy 2940nm pulsed disk laser according to an embodiment of the present invention.

In the figure: 1 is a pumping source, 2 is a collimation and homogenization system, 21 is a homogenization rod, 22 is a collimation lens, 3 is a disc crystal, 4 is a multi-stroke pumping cavity, 5 is a resonant cavity, 6 is a heat sink, 7 is a prism group, 8 is a plano-concave aspheric reflector, 9 is a Q-switch, 10 is an F-P etalon, 11 is a reflector and 12 is an output coupling mirror.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, the utility model provides a big energy 2940 nanometer pulse disc laser based on Er, include pump source 1, collimation homogenization system 2, multi-stroke pump chamber 4 and resonant cavity 5 that lay in proper order along the light path, wherein be equipped with disc crystal 3, plano-concave aspheric mirror 8 and multiunit prism group 7 in the multi-stroke pump chamber 4, plano-concave aspheric mirror 8 is the annular structure who has central through-hole, plano-concave aspheric mirror 8 is used for receiving the pump light of pump source 1 transmission and focuses on; the disc crystal 3 is arranged at the focusing center position of the plano-concave aspheric reflector 8 and used for pumping pump light and generating laser beams; the multiple sets of prism sets 7 are circumferentially arranged around the disc crystal 3 for secondary angle conversion of the pump light and are incident again on the plano-concave aspheric mirror 8 in the form of parallel light.

In the embodiment of the present invention, the pumping source 1 employs a diode with a wavelength of 970 ± 10 nm. The collimation and homogenization system 2 comprises a homogenization rod 21 and a collimation lens 22 which are sequentially arranged along a light path, wherein the homogenization rod 21 adopts a polygonal rod or an SI type optical fiber and is made of quartz, sapphire and the like.

In the embodiment of the present invention, the front side of the disc crystal 3 is plated with an anti-reflection film, the rear side is plated with a reflection film, the anti-reflection film is used to improve the transmittance of the pump light, and the reflection film is used to improve the reflectance of the remaining pump light. Specifically, the disc crystal 3 adopts Er-YAG material with 50% doping concentration as the gain medium, and the thickness range is 50-200 um.

On the basis of the above embodiment, the back of the disc crystal 3 is provided with a heat sink 6 for back cooling. In this embodiment, the concave surface of the plano-concave aspheric reflector 8 faces the direction of the disc crystal 3, the disc crystal 3 is located at the focusing center of the plano-concave aspheric reflector 8, the front surface of the disc crystal is used for pumping pump light, and the back surface of the disc crystal is welded on the metal heat sink and used for back cooling; the central through hole of the plano-concave aspheric mirror 8 allows the pump light to pass through, and the ring band at the periphery is used as a reflecting end mirror to form a resonant cavity with the rear surface of the gain medium (the disc crystal 3).

The embodiment of the utility model provides an in, every group prism group 7 all includes two prisms, and two prisms set up for the horizontal plane symmetry to two prism mutually perpendicular. Specifically, the number of the prism groups 7 is at least five or more, and the prism groups are distributed in a circumferential array with the crystal focus point as the axis, and the function of the prism groups can realize a 24, 48, 72-stroke pumping structure, so that one beam of pumping light passes through the gain medium for multiple times, and finally the residual reflected light is reflected back to the LD (diode) through the reflecting prism.

In the embodiment of the present invention, the multi-stroke pumping cavity 4 adopts a multi-stroke pumping structure, so that a beam of pumping light is absorbed by the disc crystal 3 for 24 times. The principle is that pump light is collimated by a collimation homogenizing system 2 and then enters a plano-concave aspheric mirror 8, and is focused by the plano-concave aspheric mirror 8, and then a disc crystal 3 obtains first cycle of pump light absorption; the parallel light reflected by the plano-concave aspheric surface reflector 8 enters the prism group 7 to complete the light path turning, the light is separated and then enters the plano-concave aspheric surface reflector 8 with a through hole in the center, and the light is continuously focused on the disc crystal 3 to complete the first round of stroke pumping. And the rest pump light is emitted to the plano-concave aspheric reflector 8 with a through hole in the center as parallel light, the process is repeated, the second round of crystal pump light absorption process is completed, and the 24-time pump process is realized in a repeated way.

The embodiment of the utility model provides an in, be equipped with transfer Q switch 9, F-P etalon 10, speculum 11 and output coupling mirror 12 in the resonant cavity 5, wherein transfer Q switch 9, F-P etalon 10 and speculum 11 and set gradually along the light path, output coupling mirror 12 sets up in resonant cavity 5's laser output port position department for the pulse output of laser.

The resonant cavity 5 corresponds to the central through hole of the plano-concave aspheric mirror 8. The reflective film on the back surface of the disc crystal 3, the Q-switch 9, the output coupling mirror 12, the F-P etalon 10 and the reflective mirror 11 form a resonant cavity 5, and the pulse output of the laser is realized by controlling the time of the Q-switch 9. Specifically, the crystal selected by the Q-switch 9 is an RTP crystal and an antimony oxide crystal.

The utility model processes the gain medium to the thickness of 50-200um, and works in a way of single-side pumping and back cooling, thereby greatly solving the problem of thermal lens effect of the crystal, being beneficial to realizing high-power continuous output of Er: YAG crystal, and greatly solving the influence of high quantum loss waste heat caused by 970nm pumping on the device. After the two rounds of pump light absorption, the disc crystal 3 generates stimulated spontaneous emission, and the stimulated spontaneous emission is amplified and output through the resonant cavity 5. The resonant cavity can be changed into straight, V and Z-shaped cavities by changing the position and direction of the output coupling mirror 12, so that the output characteristics of the laser are changed differently, and multimode or fundamental transverse mode output is obtained.

The utility model discloses multi-stroke pumping disc laser, it utilizes multiunit speculum and parabolic mirror, through reasonable in design's reflection configuration, has realized multi-stroke pumping structure. And through the paraboloid center hole, through adopting a plurality of pairs of prism groups, the problem of the design angle of the prism in the existing multi-stroke pumping structure is greatly simplified, the multi-stroke pumping structure can be realized only by carrying out circumferential arrangement, and meanwhile, the distance between the prism and the aspherical mirror is reduced, so that the system is more compact, and the miniaturization is favorably realized. Meanwhile, RTP and antimony oxide are used as Q-switched crystals in the resonant cavity, so that Q-switched laser output is realized, and wavelength selection is performed by using an F-P etalon.

The utility model discloses a many strokes pumping thin-film laser, because disc crystal 3's thickness only 200um for its heat conduction direction only along one-dimensional z axle transmission, through utilizing 24 strokes pumping structure, make the absorption of doping concentration 50% Er: YAG laser reach more than 98%, thereby further solved 2940 nanometer when continuous operation output too low technical difficulty. In addition, the output of high-energy Q-switched laser can be realized through a reasonably designed cavity structure, so that the application requirements of the mid-infrared laser on industry and medical treatment are met.

The above description is only for the embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, extension, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.

Claims

1. A high-energy 2940 nanometer pulse disc laser based on Er is characterized by comprising a pumping source (1), a collimation homogenization system (2), a multi-stroke pumping cavity (4) and a resonant cavity (5) which are sequentially arranged along a light path, wherein a disc crystal (3), a plano-concave aspheric mirror (8) and a plurality of groups of prism groups (7) are arranged in the multi-stroke pumping cavity (4), the plano-concave aspheric mirror (8) is of an annular structure with a central through hole, and the plano-concave aspheric mirror (8) is used for receiving pumping light emitted by the pumping source (1) and focusing; the disc crystal (3) is arranged at the focusing center of the plano-concave aspheric reflector (8) and is used for pumping pump light and generating laser beams; the multiple groups of prism groups (7) are arranged around the disc crystal (3) along the circumferential direction, are used for secondary angle conversion of the pump light and are incident on the plano-concave aspheric surface reflector (8) again in the form of parallel light.

2. The Er-based large energy 2940nm pulsed disc laser according to claim 1, characterized in that the back of the disc crystal (3) is provided with a heat sink (6).

3. The Er-based large energy 2940nm pulse disc laser according to claim 2, wherein the front side of the disc crystal (3) is coated with an anti-reflection film for improving the transmittance of the pump light, and the rear side is coated with a reflection film for improving the reflectance of the remaining pump light.

4. The Er-based large energy 2940nm pulsed disc laser according to claim 3, characterized in that the disc crystal (3) has a thickness of 50-200 um.

5. The Er-based large energy 2940nm pulsed disc laser according to claim 1, characterized in that each set of prism groups (7) comprises two prisms, which are symmetrically arranged with respect to the horizontal plane and are perpendicular to each other.

6. The Er-based large energy 2940nm pulsed disc laser according to claim 1, characterized in that the number of prism groups (7) is at least five.

7. The Er-based large energy 2940nm pulsed disc laser according to claim 1, characterized in that the collimation homogenization system (2) comprises a homogenization rod (21) and a collimation lens (22) arranged in sequence along the light path.

8. The Er-based large-energy 2940 nanometer pulse disc laser device according to claim 1, wherein a Q-switch (9), an F-P etalon (10), a reflector (11) and an output coupling mirror (12) are arranged in the resonant cavity (5), wherein the Q-switch (9), the F-P etalon (10) and the reflector (11) are sequentially arranged along a light path, and the output coupling mirror (12) is arranged at a laser output port of the resonant cavity (5) and used for outputting laser pulses.

9. The Er-based large energy 2940nm pulsed disc laser according to claim 1, characterized in that the resonant cavity (5) corresponds to the central through hole of the plano-concave aspheric mirror (8).

10. The Er-based large energy 2940nm pulsed disc laser according to claim 1, characterized in that the pump source (1) employs diodes with a wavelength of 970 ± 10 nm.