CN201008074Y - Solid-state thin disk laser - Google Patents
Solid-state thin disk laser Download PDFInfo
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- CN201008074Y CN201008074Y CNU2006200488891U CN200620048889U CN201008074Y CN 201008074 Y CN201008074 Y CN 201008074Y CN U2006200488891 U CNU2006200488891 U CN U2006200488891U CN 200620048889 U CN200620048889 U CN 200620048889U CN 201008074 Y CN201008074 Y CN 201008074Y
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Abstract
The utility model relates to a solid thin slice laser, which comprises a plurality of modules, wherein every module comprises two parallel gain medium thin slices which are arranged in a certain gap, every module is provided with cooling device, pumping light beam (semiconductor pumping source) enters the surface of thin slice medium with a certain angle or parallel from two sides of the module, the left medium thin slice right side and the right medium thin slice left side are respectively adhered with two diamond thermal sinks, the two diamond thermal sinks are provided with a liquid cooling passage between each other to cool off the sinks. The cooling device of the utility model can realize cooling of the high power slice laser medium, which effectively increases deformation of the small medium thin slice at the same time of improving inner stress distribution.
Description
Technical Field
The utility model relates to a solid thin-film laser, especially a solid thin-film laser's structure.
Technical Field
In the development of high average power solid laser, the thermal effect of the laser medium has been a major factor restricting the improvement of laser energy and beam quality output by the laser. For a continuously operating laser, the temperature gradient caused by real-time cooling can lead to undesirable effects such as thermal lensing, stress birefringence, and thermal depolarization. To improve and mitigate the non-uniform thermal distribution in the lasing medium, a number of approaches are possible.
One is as follows: pumping is performed by Laser Diode (LD). The use of LD instead of a conventional flash lamp pumping solid laser medium can significantly reduce waste heat in the medium and has a higher lifetime and efficiency.
And the second step is as follows: changing the geometry of the lasing medium. The rod-shaped gain medium can generate serious thermal lens effect under high average power operation, and the limit of a cooling mode can also cause overlarge temperature gradient inside and outside the laser medium to cause explosion. And the plate-shaped and sheet-shaped laser medium is adopted, the area of the cooled surface can be increased, the heat flow in the medium can be approximately distributed in a one-dimensional mode, and the thermotropic effect is relieved to a great extent.
And the third step: by optimizing the pumping and laser emission directions to make the thermal gradient consistent with the laser transmission direction, the influence of thermal distortion on the beam quality can be reduced, for example, a Z-shaped light path is adopted in a slab laser, and the cylindrical focusing phenomenon in a slab can be further eliminated.
In the existing solutions, a thin-film laser (generally, the diameter/thickness =10 to 50: 1) becomes a better technical approach for realizing high-power and high-beam-quality laser output due to the advantages of excellent performance in reducing thermal lens effect and thermal stress birefringence, easy scaling and amplification, and the like. In the process of developing a thin-slice laser, the more key technologies are as follows: how to realize the uniformity of pumping light and the effective management of the internal waste heat of the dielectric thin sheet. The two technologies are the key points for realizing uniform distribution of heat flow and reducing the thermotropic effect, namely reducing the stress in the medium and avoiding the breakage of the medium.
Analysis of the maximum heat power that can be absorbed by a single-sided cooled sheet medium can be calculated from the following equation [1] ：
P max ＝3RbS/l(1)
Wherein: r is a thermal shock parameter of a cooled medium, b is a safety factor, S is the area of a pumping region, and 1 is the thickness of the medium.
When the average pumping power is P, the thermal power generated by the medium absorbing the pumping optical power is as follows:
Q＝η ∞ η a ηP (2)
wherein: eta ∞ Is the coupling efficiency of the system, eta a And the absorption efficiency of the medium to the pumping light, eta is the heat generation ratio of the medium, and P is the maximum average power output by the pumping source.
For cooling the thin sheet medium, the existing method is to weld the thin sheet medium on a heat sink with high cooling efficiency for heat dissipation, so the heat dissipation capability of the heat sink is an important guarantee for realizing rapid heat dissipation.
Among the solid substances known on earth, diamond material is known to have the highest thermal conductivity at room temperature and good electrical insulation, and it is also a relatively ideal heat sink material in terms of cooling of electronic devices. The diamond material is transparent in an optical band, can be in close contact with a laser medium, has very little influence on the absorption and pumping energy of the laser medium, and the advantages determine the potential application of the diamond material in a cooling structure of a thin-slice laser. Chou et al propose a sandwich wafer laser structure that achieves good cooling effect by using diamond wafers for heat dissipation [ SPIE,2004, 5448:550-560], wanlegonger et al studied the cooling effect of diamond cooling schemes and other schemes under the condition of cooling side pumping laser medium, and the results showed that the diamond cooling schemes are superior to those of sapphire, composite medium and the like [ optical science, 2005, 25 (6): 829-834].
Disclosure of Invention
The utility model aims at providing a solid thin slice laser, the utility model discloses solid thin slice laser structure should be able to realize the thin slice working medium effective cooling under the high average power laser output, can alleviate the temperature gradient in the thin slice, improves its inside stress distribution, reduces the deformation of thin slice medium.
To achieve the above object, the technical solution of the present invention is as follows:
a solid state thin chip laser comprised of a plurality of modules, wherein each module is comprised of: the two sheets of the left sheet laser medium and the right sheet laser medium are identical in size and performance and are arranged in parallel at intervals; the first diamond heat sink is attached to the inner side of the left sheet laser medium and the second diamond heat sink is attached to the inner side of the right sheet laser medium; a cooling medium channel is formed by the first diamond heat sink, the second diamond heat sink, the upper end sealing device and the lower end sealing device together, a cooling medium inlet is formed in the upper end sealing device, a cooling medium outlet is formed in the lower end sealing device, and a right pumping source and a left pumping source which are parallel or incident at a certain angle are respectively arranged on the outer sides of the left sheet laser medium and the right sheet laser medium.
The slice laser medium is Yb: YAG crystal or Nd: YAG crystal slice.
The cooling medium is water or gas.
The following describes the simulation calculation results of the structure of the present invention using the finite element analysis software ANSYS.
Because the geometry and the bearing load of the studied object have symmetry, 1/4 part of the left sheet medium 4 is selected to carry out numerical simulation of the temperature field and the thermal stress field (see figure 1). The origin of the coordinate system is chosen as the center of the circle of the sheet. Assuming that light emitted by the pumping source is incident along the direction of the z axis after passing through the coupling system, the light intensity is uniformly distributed on an x-y plane. Only a part of pumping light energy absorbed by the medium is converted into laser output energy, and the rest most of energy is converted into heat after being absorbed by the medium, so that the function of the energy can be equivalent to a virtual internal heat source q existing in the medium v It can be expressed as:
wherein: alpha is the absorption coefficient (m) -1 ) Q is the thermal power (W) generated by the absorption of the pumping optical power by the medium, and A is the effective pumping area (m) 2 ) B is the thickness of a single lamina, thus q v In the thickness direction of the sheet is a variable which varies with the coordinate z, the result of the simulation being: internal heat source q of single sheet v See fig. 2.
And the diamond with a certain thickness is bonded on the inner sides of the two parallel thin-sheet laser media, and a channel with a certain size is formed between the two diamond sheet heat sinks. The heat generated in the medium can be conducted away by the adjacent diamonds, while the cooling medium 5 circulating between the two diamond plates can simultaneously evacuate the heat conducted away by the diamonds.
YAG thin slice along the temperature distribution of thickness direction by laser diode array pumping Nd, wherein curve 1 corresponds to the situation when the non-pumping face is directly water-cooled, and curve 2 corresponds to the situation of adopting the cooling method of the utility model. Known by the numerical simulation result, adopt the utility model discloses a cooling structure and cooling method can effectively reduce the temperature of thin slice medium, simultaneously, make the stress distribution in the medium more even.
The utility model has the advantages that: double-slice laser medium and double-diamond-slice heat sink are adopted, and cooling medium circulates in a cooling channel formed by the diamond heat sink. The diamond can effectively conduct the waste heat in the slice laser medium, and the cooling medium in the side channel can timely evacuate the heat conducted by the diamond, so that the heat exchange efficiency is high. Meanwhile, the diamond has a thermal expansion coefficient lower than that of the laser medium, and compared with a heat sink with a thermal expansion coefficient higher than that of the laser medium, such as copper, the diamond is beneficial to reducing the deformation of the laser medium. Adopt outside this the utility model discloses a structure that two thin slice laser medium and diamond piece are heat sink, when obtaining good cooling effect, easily realize the scaling of modularization and power and enlarge.
Drawings
FIG. 1 is a schematic diagram of the modeling of numerical simulation of the temperature field and the thermal stress field of the structure of the present invention by using finite element analysis software
FIG. 2 is a schematic diagram of the distribution of heat sources in a single slice of the present invention
YAG wafer temperature profile in the thickness direction pumped by a laser diode array
FIG. 4 is a schematic diagram of the solid laser structure with double thin-slice laser medium and diamond heat sink
FIG. 5 is a partial cross-sectional view (Y-Z cross section) of the cooling structure of the present invention
In the figure: 1 is the lateral surface of left thin slice laser medium, 2 is first diamond heat sink, 3 is the interior cooling surface of first diamond heat sink, 4 is left thin slice laser medium, 5 is cooling medium, 6 is second diamond heat sink, 7 is right thin slice laser medium, 8 is right pump power, 9 is left pump power, 10 is upper end sealing device, 11 is the cooling medium entry, 12 is the cooling medium passageway, 13 is lower extreme sealing device, 14 is the cooling medium export.
Detailed Description
The method of the present invention will be described in detail with reference to the accompanying drawings and examples.
Referring to fig. 4 and 5, fig. 4 is a schematic general diagram of a dual-slice laser medium and diamond heat-sink solid-state laser structure according to the present invention, and fig. 5 is a schematic partial sectional view of an embodiment of a cooling structure according to the present invention. As shown in fig. 4, the solid-state thin-film laser of the present invention is composed of a plurality of modules, wherein each module comprises:
1) The laser medium comprises a left sheet laser medium 4 and a right sheet laser medium 7 which are identical in size and performance and are arranged in parallel at intervals. A thin plate of Yb: YAG crystal or Nd: YAG crystal may be chosen, or other laser medium suitable for use as a thin-plate laser. And a right pumping source 8 and a left pumping source 9 which are parallel or incident at a certain angle are respectively arranged at the outer sides of the left sheet laser medium 4 and the right sheet laser medium 7.
2) Two pieces of diamond heat sinks are respectively combined with the first diamond heat sink 2 at the inner side of the left sheet laser medium 4 and the second diamond heat sink 6 at the inner side of the right sheet laser medium 7. The first diamond heat sink 2 and the second diamond heat sink 6, together with the upper end sealing device 10 and the lower end sealing device 13, form a channel 12 for the cooling medium 5.
3) With the aid of an upper end seal 10 and a lower end seal 13, and the laser medium and diamond described above are assembled into a module, the cooling medium inlet 11 being on the upper end seal 10 and the cooling medium outlet 14 being on the lower end seal 13.
The specific structural parameters in this embodiment are: YAG slices are Nd of phi 13mm multiplied by 1mm in the slice laser media 4 and 7, the sizes of the diamond heat sinks 2 and 6 are phi 14mm multiplied by 0.5mm, the width of a cooling channel is 1mm, the cooling medium 5 is water of 15 ℃, the flow rate is 7.5m/s, and the pumping source 8 and the pumping source 9 are laser diode arrays with the average output power of about 450W respectively. And assuming an effective pumping aperture of phi 13mm and an ambient temperature of 15 ℃.
By selecting 1/4 of the whole structure as a research object, simulation is carried out by utilizing a thermal-structure coupling module of finite element analysis software ANSYS, and the steady-state temperature field distribution in the sheet medium and the diamond heat sink is obtained. From the results, it is understood that the temperature difference in the sheet laser medium of the laser of this example is about 16 ℃ and the maximum temperature rise of the entire sheet laser medium is about 44 ℃ in the steady-state operation. Since diamond has excellent thermal conductivity, its inside maintains a uniform temperature distribution. Fig. 3 is not adopted the utility model discloses cooling structure and adoption the utility model discloses cooling structure's temperature distribution curve, wherein curve 1 is not adopted the utility model discloses cooling structure's temperature distribution curve, and curve 2 is adopted the utility model discloses cooling structure's temperature distribution curve can see, the utility model discloses a cooling structure has better cooling effect. Meanwhile, experiments show that the uniformity of the stress field distribution in the thin-sheet laser medium is improved and the deformation is reduced.
Claims (4)
1. A solid state thin film laser, wherein the laser is comprised of a plurality of modules, wherein each module is comprised of: the two sheets of the left sheet laser medium (4) and the right sheet laser medium (7) are identical in size and performance and are arranged in parallel at intervals; a first diamond heat sink (2) and a second diamond heat sink (6) which are respectively attached to the inner sides of the left sheet laser medium (4) and the right sheet laser medium (7); a cooling medium channel (12) is formed by a first diamond heat sink (2), a second diamond heat sink (6), an upper end sealing device (10) and a lower end sealing device (13) together, a cooling medium inlet (11) is formed in the upper end sealing device (10), a cooling medium outlet (14) is formed in the lower end sealing device (13), and a right pumping source (8) and a left pumping source (9) which are parallel or incident at a certain angle are respectively arranged on the outer sides of a left sheet laser medium (4) and a right sheet laser medium (7).
2. The solid-state thin-chip laser device of claim 1, wherein the thin-chip laser medium is a Yb: YAG crystal or Nd: YAG crystal thin chip.
3. The solid-state thin-sheet laser device as claimed in claim 1, wherein the cooling medium is water or gas.
4. The solid state thin film laser according to any one of claims 1 to 3, wherein said pump source is a laser diode array.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2006200488891U CN201008074Y (en) | 2006-12-13 | 2006-12-13 | Solid-state thin disk laser |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2006200488891U CN201008074Y (en) | 2006-12-13 | 2006-12-13 | Solid-state thin disk laser |
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| CN201008074Y true CN201008074Y (en) | 2008-01-16 |
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| CNU2006200488891U Expired - Fee Related CN201008074Y (en) | 2006-12-13 | 2006-12-13 | Solid-state thin disk laser |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104659641A (en) * | 2015-02-13 | 2015-05-27 | 合肥大族科瑞达激光设备有限公司 | Four-way holmium laser with four-cavity space |
| CN107534263A (en) * | 2015-04-22 | 2018-01-02 | 相干公司 | water cooling carbon dioxide laser |
| CN110086070A (en) * | 2019-05-19 | 2019-08-02 | 北京工业大学 | A kind of high pumping absorbs, the novel sheet laser structure of high-power output |
| CN110459938A (en) * | 2019-07-23 | 2019-11-15 | 中国电子科技集团公司第十一研究所 | A kind of encapsulation of laser crystal and cooling structure |
-
2006
- 2006-12-13 CN CNU2006200488891U patent/CN201008074Y/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104659641A (en) * | 2015-02-13 | 2015-05-27 | 合肥大族科瑞达激光设备有限公司 | Four-way holmium laser with four-cavity space |
| CN107534263A (en) * | 2015-04-22 | 2018-01-02 | 相干公司 | water cooling carbon dioxide laser |
| CN107534263B (en) * | 2015-04-22 | 2021-08-10 | 相干公司 | Water-cooled carbon dioxide laser |
| CN110086070A (en) * | 2019-05-19 | 2019-08-02 | 北京工业大学 | A kind of high pumping absorbs, the novel sheet laser structure of high-power output |
| CN110459938A (en) * | 2019-07-23 | 2019-11-15 | 中国电子科技集团公司第十一研究所 | A kind of encapsulation of laser crystal and cooling structure |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080116 Termination date: 20111213 |