CN219643292U

CN219643292U - Multi-pump source disc laser pumping cavity structure

Info

Publication number: CN219643292U
Application number: CN202320356758.3U
Authority: CN
Inventors: 周煌
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-03-02
Filing date: 2023-03-02
Publication date: 2023-09-05
Anticipated expiration: 2033-03-02

Abstract

The utility model discloses a pumping cavity structure of a multi-pumping source disk laser, which comprises a near end and a far end, and is characterized by comprising the following components: the laser gain medium absorption spectrum laser comprises N groups of pumping laser beams, N groups of beam collimators, N groups of parabolic reflector groups, 1 laser gain medium and N groups of deflection optical prism groups, wherein N is more than or equal to 2, and the wavelengths of the pumping laser beams are all on the laser gain medium absorption spectrum; the laser gain medium comprises a medium reflecting surface, a plurality of reflecting curved surfaces are arranged on the parabolic reflecting mirror group, and the reflecting curved surfaces are all parabolic; the pumping laser beams are incident after passing through one beam collimator correspondingly, and are absorbed by the laser gain medium after multiple reflections to form pumping light spots. The beneficial effects of the utility model are as follows: the problem of asymmetric intensity distribution of the large-diameter pumping light spots is effectively solved, so that the finally obtained high-power pumping light spots are distributed in a flat-top light effect.

Description

Multi-pump source disc laser pumping cavity structure

Technical Field

The utility model belongs to the field of laser, and particularly relates to a pumping cavity structure of a multi-pumping-source disc laser.

Background

Since the disk laser utility model in 1993, the thickness of the adopted laser gain medium is only 100-300 microns, and the excellent radiating effect of the laser gain medium can be realized by combining the back jet cooling technology, so that extremely high laser output power, laser pulse energy and excellent beam quality are obtained. However, due to the small thickness of the laser gain medium, a special pump optical path design is required to make the pump laser pass through the laser gain medium multiple times to obtain a sufficiently high absorption rate. In order to enable the pump light to be uniformly absorbed by the laser gain medium, the designed pump light path needs to have the effect that a light spot formed by superposing the pump light on the laser gain medium is a flat-top light spot.

Patent EP 0632551B 1 discloses a pump light beam which is reflected back to the laser gain medium for multiple times by utilizing a plurality of pump light reflectors and auxiliary reflectors and adopting a spherical mirror to deflect the pump light beam, and finally, pump light spots with flat tops are formed by superposition. Ideally, the better the collimation of the pump beam, the closer the final pump spot is to the ideal flat-top spot. However, in practical use, after multiple reflections, the transmission distance of the pump light increases, and the pump light beam continuously diverges, so that the final pump light spot cannot form a flat-top light spot. And the laser gain medium has certain thermal deformation after being heated, which is equivalent to a lens with the focal length of f, thereby enhancing the divergence effect of the pumping beam. Meanwhile, on the premise that the absorption coefficient of the laser gain medium is unchanged, the power of the partial absorption of the pump light which is firstly incident into the laser gain medium is larger than the light power of the absorption of the pump light which is incident into the laser gain medium again after deflection and reflection. The light intensity distribution of the finally obtained pumping light spot is not an ideal flat-top light spot, but the light intensity distribution of the pumping light spot near the side of the first incident light spot is higher than that near the side of the last incident light spot. This phenomenon is more pronounced the larger the pump spot diameter. For example, when the spot diameter is larger than 10mm, a phenomenon that one side of the intensity distribution of the pumping spot is higher than the other side easily occurs. The pump light spot without the flat top can reduce the matching effect of the pump light spot and the laser mode in the laser, thereby reducing the parameters such as the quality, the output power and the like of the output laser beam.

Although various patents and academic articles, such as patent EP1252687B1, patent CN103688426B, doctor paper "pump optical system and resonator for disc laser" I SBN3-8316-0173-9, doctor paper "disc laser with kilowatt etc. radial power" I SBN3-89675-763, design various improved pump optical design structures, or use parabolic mirror to compensate the divergence angle of pump beam, or use telecentric imaging system to compensate the equivalent focal length caused by thermal deformation of laser gain medium, or use asymmetric biprism to improve the imaging effect of the telecentric imaging system, none of the above-mentioned problems of non-flat intensity distribution of large diameter pump light spots are effectively solved.

Summary of the utility model

The utility model aims to provide a multi-pump source disc laser pumping cavity structure which can solve or partially solve the problems.

In order to achieve the above purpose, the present utility model provides the following technical solutions:

a multi-pump source disc laser pumping chamber structure comprising a proximal end and a distal end, comprising: the laser gain medium absorption spectrum laser comprises N groups of pumping laser beams, N groups of beam collimators, N groups of parabolic reflector groups, 1 laser gain medium and N groups of deflection optical prism groups, wherein N is more than or equal to 2, and the wavelengths of the pumping laser beams are all on the laser gain medium absorption spectrum;

the laser gain medium comprises a medium reflecting surface, a plurality of reflecting curved surfaces are arranged on the parabolic reflecting mirror group, and the reflecting curved surfaces are all parabolic;

the pumping laser beams at the near end are respectively and correspondingly transmitted through a beam collimator and then are incident on the parabolic reflector group at the far end in an aligned manner so as to be reflected between the deflection optical prism group, the reflecting curved surface and the medium reflecting surface for multiple times and transmitted through the laser gain medium for multiple times so as to be absorbed by the laser gain medium and form pumping light spots;

the deflection optical prism groups are coaxial annular structures formed by a plurality of prism pairs, each prism pair comprises two prisms, and the two prisms are provided with reflection planes forming an included angle of 90 degrees with each other; the reflection planes of all the prism pairs are uniformly distributed annularly toward the distal end.

Preferably, the laser gain medium and the medium reflecting surface are both round; the parabolic reflector sets are of annular structures, and a plurality of reflecting curved surfaces are arranged on the parabolic reflector sets at equal intervals around the circumference of the parabolic reflector sets; the medium reflecting surface and the parabolic reflecting mirror group are coaxial, and the focuses of all reflecting curved surfaces on the parabolic reflecting mirror group are positioned on the medium reflecting surface; the laser gain medium is positioned between the medium reflecting surface and the parabolic reflector group.

Preferably, the reflective curved surfaces all have the same equivalent focal length.

Preferably, the deflection optical prism group includes a plane mirror or a pyramid reflector for returning the incident pumping laser beam along an original path.

Preferably, the laser gain medium comprises 2 groups of pumping laser beams, wherein the optical power of the 2 groups of pumping laser beams is the same, and the diameters of light spots formed on the laser gain medium are the same and coincide with each other on the laser gain medium; the incidence angle of the pumping laser beam at the input position on the inner ring on the laser gain medium is smaller than that of the pumping laser beam at the input position on the outer ring on the laser gain medium, and the beam collimator corresponding to the pumping laser beam at the input position on the inner ring has larger magnification.

Preferably, both the reflective curved surface and the reflective plane are coated with a first dielectric film having a high reflectivity for the pump laser beam.

Preferably, the thickness of the laser gain medium is 0.15-0.35 mm, and the laser gain medium comprises a front surface facing the parabolic reflector set and a rear surface facing away from the parabolic reflector set; the front surface is plated with a second dielectric film for anti-reflection of the pumping laser beam; the rear surface is plated with a third dielectric film having a high reflectivity for the pump laser beam to form the dielectric reflecting surface.

Preferably, the laser gain medium is fixed on a heat sink through a welding, gluing or bonding process, the other surface of the heat sink is contacted with jet cooling liquid to realize cooling of the laser gain medium, and the heat sink is made of tungsten copper, diamond, sapphire, silicon carbide or aluminum nitride ceramics.

Preferably, the pump laser beam has 12, 16 or 24 reflection areas on the parabolic mirror set, and the pump laser beam does not overlap between the spots on the reflection areas.

The beneficial effects of the utility model are as follows: the problem of asymmetric intensity distribution of the large-diameter pumping light spots is effectively solved, so that the finally obtained high-power pumping light spots are distributed in a flat-top light effect, the mode matching effect of the pumping laser and the laser modes in the resonator can be further improved, and the conversion efficiency of the laser and the beam quality of output laser are improved.

Drawings

FIG. 1 is a diagram of a pump cavity structure of a multi-pump-source disk laser according to a first embodiment of the present utility model;

FIG. 2 is a diagram of a pump cavity structure of a multi-pump disk laser according to a second embodiment;

FIG. 3 is a schematic elevational view of the first embodiment;

FIG. 4 is a schematic diagram showing the distribution of the reflection area of the pump laser beam on the hollow parabolic mirror according to the third embodiment;

FIG. 5 is a schematic diagram showing the distribution of the reflection area of the pump laser beam on the hollow parabolic mirror according to the fourth embodiment;

FIG. 6 is a schematic diagram of an optical deflection prism set corresponding to an external pumping laser beam according to the first embodiment;

FIG. 7 is a schematic diagram of an optical deflection prism set corresponding to an inner ring pump laser beam according to the first embodiment;

FIG. 8 is a simulated plot of the intensity distribution of pump spots formed by a prior art disk laser pump cavity;

FIG. 9 is a graph of two-dimensional intensity in the horizontal direction of a simulated plot of the intensity distribution of pump spots formed by a single pump source;

FIG. 10 is a simulated plot of the intensity distribution of pump spots formed by a disk laser pumping chamber employing a dual pump source;

FIG. 11 is a two-dimensional plot of intensity in the horizontal direction of a simulated plot of the intensity distribution of a pump spot formed using a dual pump source.

Detailed Description

The technical scheme of the patent is further described in detail below with reference to the specific embodiments.

In the description of the present utility model, it should be noted that the directions or positional relationships indicated by the terms "far", "near", "inner", "outer", "upper", "lower", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the apparatus or element to be referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

As shown in fig. 1 to 11, the present utility model discloses a multi-pump source disk laser pumping cavity structure.

Referring to fig. 1, 2, 6 and 7, a first embodiment of the present utility model is shown, which is a dual pump source disk laser pumping cavity structure. Comprising the following steps: 2 sets of pump laser beams, namely pump laser beam 8 and pump laser beam 9;2 sets of beam collimators, namely beam collimator 6 and beam collimator 7;2 groups of annular and coaxial parabolic reflector groups, namely a parabolic reflector group 1 and a parabolic reflector group 2;1 laser gain medium 3 of disc structure; 2 groups of deflection optical prism groups, namely a deflection optical prism group 4 and a deflection optical prism group 5.

The wavelengths of the 2 sets of pump laser beams are all on the absorption spectrum of the laser gain medium 3. The parabolic reflector group 1 and the parabolic reflector group 2 are provided with a plurality of reflecting curved surfaces (not labeled), and the reflecting curved surfaces are parabolic. The deflection optical prism groups are coaxial annular structures composed of a plurality of prism pairs, each prism pair comprises 2 prisms, and the 2 prisms are provided with reflection planes (not labeled) which form an included angle of 90 degrees with each other; the reflection planes of all prism pairs are uniformly distributed in a ring shape towards the far end.

Both the reflective curved surface and the reflective plane are coated with a first dielectric film of high reflectivity for the pump laser beam band.

After being collimated by the beam collimator 6, the pumping laser beam 8 is incident to the A1 position on the parabolic reflector 2 and then is reflected to be focused on the laser gain medium 3; the remaining pumping laser beam 8 after the absorbed part of the laser energy is reflected to the A2 position of the parabolic reflector 2 and then reflected again to the deflection optical prism group 4; the deflection optical prism group 4 is positioned on the outer ring of the pumping cavity structure and consists of a plurality of prism pairs, and each prism pair consists of two prisms P1 and P2 which form an included angle of 90 degrees with each other. The deflecting optical prism group 4 deflects the transmission direction of the pumping laser beam 8 by 180 degrees and then makes the pumping laser beam enter the position A3 through the parabolic reflector 2; and so on, the pumping laser beam 8 is repeatedly incident into the laser gain medium 3 under the action of the deflection optical prism group 4 and the parabolic reflector 2 positioned at the outer ring, reaches the plane reflector 10, is then reflected by the plane reflector, returns along the original light path, and is repeatedly incident into the laser gain medium 3 again; the final pump laser beam 8 is absorbed by the laser gain medium 3.

After being collimated by the beam collimator 7, the pumping laser beam 9 is incident to the A1 position on the parabolic reflector 1 and then is focused on the laser gain medium 3 after being reflected; the remaining pumping laser beam 9 after the absorption of part of the laser energy is reflected to the B2 of the parabolic reflector 1 and then reflected again to the deflection optical prism group 5; the deflection optical prism group 5 is positioned on the inner ring of the pumping cavity structure and consists of two prism pairs, and each prism consists of two prisms P3 and P4 or prisms P5 and P6 which form an included angle of 90 degrees with each other; the deflecting optical prism group 5 deflects the transmission direction of the pumping laser beam 9 by 180 degrees and then makes the pumping laser beam enter at the position B3 through the parabolic reflector 1; by analogy, the pumping laser beam 9 is repeatedly incident into the laser gain medium 3 under the action of the deflection optical prism group 4 and the parabolic reflector 1 positioned at the inner ring, then is incident into the pyramid reflector formed by the prism P3 and the prism P6, the beam transmission direction is deflected 180 degrees, returns along the original light path, and is repeatedly incident into the laser gain medium 3 again; the final pump laser beam 9 is absorbed by the laser gain medium.

The deflection optical prism group 4 positioned at the outer ring consists of a plurality of more than or equal to 3 prism pairs, and each prism pair consists of two prisms P1 and P2 which form an included angle of 90 degrees with each other; so that the optical path Cheng Huaban of the pump laser beam 8 is symmetrically distributed and the deflected beam is reflected only once between every two prisms at 90 ° to each other; this configuration can avoid the pump laser beam 8 crossing over the laser gain medium to be blocked by the inner ring of deflection optical prism groups 5.

The deflection optical prism group 5 positioned in the inner ring consists of two prism pairs, and each prism consists of two prisms P3 and P4 or P5 and P6 which form an included angle of 90 degrees with each other; the light path is distributed asymmetrically and the deflected light beam is reflected 2 or 3 times between different positions of each two prisms at 90 deg. angle to each other.

The two parabolic reflectors 1 and 2 are coaxial, and the equivalent focal lengths of the two parabolic reflectors can be the same or different, so long as the equivalent focal planes of the two parabolic reflectors are all located on the plane of the laser gain medium 3.

The wavelengths of the pumping laser beams 8 and 9 emitted by the two pumping light sources can be the same or different; when different wavelength pump sources are used, the wavelengths of both pump laser beam 8 and pump laser beam 9 must be in the laser gain medium absorption spectrum. The pump laser beam 8 and the pump laser beam 9 have the same optical power, and have the same spot diameter formed on the laser gain medium 3, and are symmetrically distributed with a common center line, overlapping on the laser gain medium 3.

The two groups of beam collimators 6 and 7 are not identical; and further, since the incident angle of the pump laser beam 9 at the inner ring on the laser gain medium 3 is smaller than the incident angle of the pump laser beam 8 at the outer ring on the laser gain medium 3, the beam collimator 7 should have a slightly larger magnification to ensure that the spot diameter of the pump laser beam 9 on the laser gain medium 3 is the same as the spot diameter of the pump laser beam 8 on the laser gain medium 3.

The thickness of the laser gain medium 3 is 0.15-0.35 mm, the surface facing the parabolic reflector 2 is a front surface, and the surface is a rear surface; the front surface of which is coated with a second dielectric film that is antireflective to the pump laser beams 8, 9 and the seed light (not shown); the rear surface is coated with a third dielectric film having a high reflectivity for the pump laser beams 8, 9 and the seed light.

The laser gain medium 3 is fixed on a heat sink (not shown) by welding, gluing or chemical bonding, and the other surface of the heat sink is contacted with jet cooling liquid to realize cooling of the laser gain medium 3. The heat sink can be made of tungsten copper CuW, diamond, sapphire, silicon carbide SiC, aluminum nitride AlN ceramic and other materials with high heat conductivity.

FIG. 8 is a simulated graph of the intensity distribution of a pump spot formed by a disk laser pumping chamber employing a single pump source, as can be seen, the intensity distribution is symmetrical up and down but asymmetrical left and right; wherein i ncoherent i rrad i ance represents incoherent irradiance; x coord i nate va l ue the X-axis coordinate value and Y coord i nate va l ue the Y-axis coordinate value.

FIG. 9 is a two-dimensional plot of the intensity distribution of a pump spot formed by a single pump source in the horizontal direction, as can be seen, with the intensity on the right side of the pump spot being higher than on the left side;

FIG. 10 is a simulated graph of the intensity distribution of a pump light spot formed by a disk laser pumping cavity with a dual pump source, and the graph shows that the intensity distribution is symmetrical at the center and has good flat top effect;

fig. 11 is a two-dimensional light intensity diagram in the horizontal direction of a simulation diagram of the intensity distribution of a pumping light spot formed by using a double pumping source, and the diagram shows that the right side intensity of the pumping light spot is the same as the left side intensity, and the flat top effect is good.

Therefore, the utility model skillfully applies the double pump source and the two deflection optical prism groups to generate two pump light spots, the intensity distribution between the two pump light spots is symmetrical and overlapped, the problem of asymmetrical intensity distribution of the large-diameter pump light spots is effectively solved, the finally obtained high-power pump light spots are distributed in a flat-top effect, the mode matching effect of the pump laser and the laser modes in the resonator can be further improved, and the conversion efficiency of the laser and the beam quality of output laser are improved.

Fig. 2 shows a two-embodiment, a two-pump source disk laser pump cavity structure with only one parabolic mirror, with its equivalent focal plane located in the plane of the laser gain medium 3.

Fig. 4 shows a third embodiment, in which the pump laser beam 8 located in the outer ring has 12 reflection areas on the parabolic mirror, denoted A1, A2, …, a12, respectively; the pump laser beam 9 located in the inner ring has 16 reflection areas on the parabolic mirror, denoted B1, B2, …, B16, respectively.

Fig. 5 shows a fourth embodiment, in which the pump laser beam 8 located in the outer ring has 24 reflection areas on the parabolic mirror, denoted A1, A2, …, a24, respectively; the pump laser beam 9 located in the inner ring has 16 reflection areas on the parabolic mirror, denoted B1, B2, …, B16, respectively.

The foregoing description is only illustrative of the present utility model and is not intended to limit the scope of the utility model, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present utility model.

Claims

1. A multi-pump source disc laser pumping chamber structure comprising a proximal end and a distal end, comprising: the laser gain medium absorption spectrum laser comprises N groups of pumping laser beams, N groups of beam collimators, N groups of parabolic reflector groups, 1 laser gain medium and N groups of deflection optical prism groups, wherein N is more than or equal to 2, and the wavelengths of the pumping laser beams are all on the laser gain medium absorption spectrum;

2. The multiple pump source disc laser pumping chamber structure of claim 1, wherein: the laser gain medium and the medium reflecting surface are both round; the parabolic reflector sets are of annular structures, and a plurality of reflecting curved surfaces are arranged on the parabolic reflector sets at equal intervals around the circumference of the parabolic reflector sets; the medium reflecting surface and the parabolic reflecting mirror group are coaxial, and the focuses of all reflecting curved surfaces on the parabolic reflecting mirror group are positioned on the medium reflecting surface; the laser gain medium is positioned between the medium reflecting surface and the parabolic reflector group.

3. The multiple pump source disc laser pumping chamber structure of claim 2, wherein: the reflective curved surfaces all have the same equivalent focal length.

4. A multiple pump source disc laser pumping chamber structure according to claim 3, characterized in that: the deflection optical prism group comprises a plane reflecting mirror or a pyramid reflector, and is used for returning the incident pumping laser beam along the original path.

5. A multiple pump source disc laser pumping chamber structure according to claim 3, characterized in that: the laser gain medium comprises 2 groups of pumping laser beams, wherein the optical power of the 2 groups of pumping laser beams is the same, and the diameters of light spots formed on the laser gain medium are the same and coincide with each other on the laser gain medium; the incidence angle of the pumping laser beam at the input position on the inner ring on the laser gain medium is smaller than that of the pumping laser beam at the input position on the outer ring on the laser gain medium, and the beam collimator corresponding to the pumping laser beam at the input position on the inner ring has larger magnification.

6. The multiple pump source disc laser pumping chamber structure of claim 5, wherein: the reflective curved surface and the reflective plane are both coated with a first dielectric film having a high reflectivity for the pump laser beam.

7. The multiple pump source disc laser pumping chamber structure of claim 6, wherein: the thickness of the laser gain medium is 0.15-0.35 mm, and the laser gain medium comprises a front surface facing the parabolic reflector group and a rear surface facing away from the parabolic reflector group; the front surface is plated with a second dielectric film for anti-reflection of the pumping laser beam; the rear surface is plated with a third dielectric film having a high reflectivity for the pump laser beam to form the dielectric reflecting surface.

8. The multiple pump source disc laser pumping chamber structure of claim 7, wherein: the laser gain medium is fixed on the heat sink through a welding, gluing or bonding process, the other surface of the heat sink is contacted with jet cooling liquid to realize cooling of the laser gain medium, and the heat sink is made of tungsten copper, diamond, sapphire, silicon carbide or aluminum nitride ceramics.

9. The multiple pump source disc laser pumping chamber structure of claim 1, wherein: the pump laser beam has 12, 16 or 24 reflection areas on the parabolic reflector set, and the pump laser beam is not overlapped between light spots on the reflection areas.