CN115621820A - Linear polarization output laser structure for effectively compensating thermal depolarization effect - Google Patents
Linear polarization output laser structure for effectively compensating thermal depolarization effect Download PDFInfo
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/0602—Crystal lasers or glass lasers
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
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- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08072—Thermal lensing or thermally induced birefringence; Compensation thereof
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
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- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
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Abstract
The invention discloses a linear polarization output laser structure for effectively compensating a thermal depolarization effect, which comprises a laser shell, a first full-reflection cavity plate, a laser power supply, a semiconductor pumping module, a laser bar, a polarizer, an output cavity plate, a second full-reflection cavity plate and a laser water cooling system, wherein the laser shell is provided with a first cavity plate; a main resonant cavity and a branch resonant cavity which are communicated are arranged in the laser shell; the first full-anti-cavity plate, the laser rod, the polarizer and the output cavity plate are sequentially arranged in the main resonant cavity from back to front, and the semiconductor pumping module is surrounded around the laser rod; and a second full-inverse-cavity sheet is arranged in the branch resonant cavity and is positioned at one side of the polarizer. The invention utilizes the self thermal induced birefringence effect of the laser rod to convert the linearly polarized light S light generated by the self thermal induced birefringence effect of the laser rod into the linearly polarized light P light again, thereby effectively reducing the intracavity loss caused by the thermal induced birefringence effect of the laser rod and improving the output power and efficiency of the linear polarization output laser.
Description
Technical Field
The invention relates to the technical field of lasers, in particular to a linear polarization output laser structure for effectively compensating a thermal depolarization effect.
Background
In the process of pumping the laser working substance by the solid laser, the laser working substance generates heat due to the absorption of pump radiation, and meanwhile, in order to ensure the stable and continuous work of the laser working substance, the laser working substance is required to be cooled, so that uneven temperature distribution is generated inside the laser working substance. The refractive index of the laser working substance is changed due to the change of temperature and stress, and the laser beam is distorted. The thermal effect occurring in the laser working substance is a thermal lens effect and a thermal birefringence effect. The thermotropic birefringence effect is that thermal stress is generated due to non-uniform temperature distribution in a laser working substance, and further the refractive index is changed through a photoelastic effect, so that an original isotropic material is changed into anisotropy, or the original birefringence characteristics of an anisotropic material are changed, namely, thermal stress birefringence is generated.
When the laser working substance is rod-shaped, the principal axes of induced birefringence are radial and tangential at each point in the rod cross-section, and the magnitude of birefringence is proportional to the square of the radius. Therefore, when the linearly polarized light enters and passes through different regions, the linearly polarized light is changed into light of different polarization states, so that the total polarization state of the light beam after passing through the entire rod-shaped laser working substance becomes very complicated, which is not favorable for the operation of the linearly polarized light. This can lead to thermal depolarization effects and reduced power. To reduce the power reduction, birefringence compensation is required to effectively compensate for the thermal depolarization effect.
The birefringence compensation is typically performed in order to obtain the same phase retardation for both radially and tangentially polarized light at each point in the cross-section of the rod. This can be compensated by rotating the polarized beam in the continuous path between two identical laser bars or in the same bar, i.e. exchanging the radial and tangential polarization components. The thermal depolarization effect is usually compensated by inserting a faraday rotator in the laser cavity. For example, a 90 ° quartz rotator is inserted between two identical laser bars of a laser cavity to achieve birefringence compensation for the laser. In a single rod laser cavity, a 45 ° faraday rotator between the rod and back mirror can compensate for the birefringence of the laser.
A faraday rotator is a magneto-optical device that uses the faraday effect to rotate the polarization state of light. The direction of the magnetic field is the same as or opposite to the propagation direction of the light beam, and the polarization direction of the light is continuously changed when the light passes through the medium. The magnetic field is usually generated by permanent magnets or ferromagnetic materials, and usually the magnetic field strength should be large enough so that a short medium can achieve a certain rotation angle. And the magnetic flux density should be kept as constant as possible as light passes through the medium, so that the spatial distribution of the rotation angle can be ensured to be uniform.
The faraday rotator should have high transparency in the spectral region of operation, high optical quality, but sometimes also requires a high damage threshold. In some specific wave bands, such as 3 μm laser wave band, there is no suitable material to make Faraday rotator with high damage threshold, which restricts the thermal depolarization compensation of the laser crystal thermal induced birefringence effect.
Disclosure of Invention
The invention aims to provide a linear polarization output laser structure for effectively compensating the thermal depolarization effect, which utilizes the self thermal birefringence effect of a laser rod to convert part of linearly polarized light S light generated by the self thermal birefringence effect of the laser rod into linearly polarized light P light again, thus effectively reducing the intra-cavity loss caused by the thermal birefringence effect of the laser rod and improving the output power and the efficiency of the linear polarization output laser.
In order to achieve the above object, the present invention provides a linear polarization output laser structure for effectively compensating thermal depolarization effect, comprising a laser housing, a laser rod and a laser power supply;
a main resonant cavity and a branch resonant cavity are arranged in the laser shell, and the branch resonant cavity is communicated with the main resonant cavity;
the laser device comprises a main resonant cavity, a semiconductor pump module, a laser power supply, a polarizer and an output cavity sheet, wherein the main resonant cavity is internally provided with the first full-inverse cavity sheet, the laser rod, the polarizer and the output cavity sheet in sequence, the semiconductor pump module is surrounded by the laser rod, the laser power supply is electrically connected with the semiconductor pump module to ensure that the laser rod and the semiconductor pump module are sufficiently cooled, the pressure of cooling liquid on the semiconductor pump module is less than the pressure which can be born by the semiconductor pump module, and the semiconductor pump module pumps the laser rod to ensure that the laser rod is thermally balanced;
the laser device comprises a main path resonant cavity, a branch resonant cavity and a laser, wherein a first full-reflection cavity sheet is arranged in the branch resonant cavity, the first full-reflection cavity sheet is arranged on one side of a polarizer, when the polarizer and the first full-reflection cavity sheet are arranged at the rear end of a laser rod, the polarization states of oscillation laser in the main path resonant cavity and the branch resonant cavity are linearly polarized light P and linearly polarized light S respectively, the oscillation laser outputs laser through a coupling output mirror of the laser, and the output laser is non-linearly polarized light.
Furthermore, the end faces of the front end and the rear end of the laser bar are respectively plated with antireflection films.
Furthermore, one surface of the second total reflection cavity plate facing the laser rod is plated with a total reflection film, one surface of the output cavity plate facing the front end of the laser rod is plated with a partial reflection film, and the other surface of the output cavity plate is plated with an anti-reflection film.
And the laser water cooling system is connected with the laser bar and the semiconductor pumping module through pipelines respectively to provide constant-temperature cooling liquid for the laser bar and the semiconductor pumping module.
Further, the cooling liquid is refractive index matching liquid.
Furthermore, a spiral cooling channel is arranged inside the laser rod along the length direction of the laser rod, and an inlet and an outlet are respectively arranged at two ends of the laser rod of the cooling channel.
Furthermore, a cooling water inlet and a cooling water outlet which are communicated with the laser rod and the semiconductor pumping module are arranged on the laser shell.
Further, the laser water cooling system comprises a water tank, a water cooler and a deionization purification filter;
the water inlet of the water cooler is connected with the water tank through a pipeline, the water outlet of the water cooler is connected with the water inlet of the deionization purification filter, the water outlet of the deionization purification filter is connected with the cooling water inlet arranged on the laser shell through a pipeline, and the cooling water outlet arranged on the laser shell is connected with the water tank.
Further, the water tank is arranged in a sealing mode, and the upper end of the water tank is provided with a ventilation valve.
Further, an air filtering device is arranged in the air vent valve.
Compared with the prior art, the invention has the beneficial effects that:
1. the laser structure of the invention utilizes the self thermal induced birefringence effect of the laser bar to convert the linearly polarized light S light generated by the self thermal induced birefringence effect of the laser bar into the linearly polarized light P light again, thus effectively reducing the intra-cavity loss caused by the laser bar thermal induced birefringence effect and improving the output power and efficiency of the linear polarization output laser.
2. According to the laser structure, the spiral cooling flow channel is arranged in the laser rod along the length direction of the laser rod, the cooling flow channel is provided with the inlet and the outlet at two ends of the laser rod respectively, the cooling medium is the refractive index matching liquid, and the refractive index of the refractive index matching liquid is the same as that of the laser rod. The refractive index matching liquid passes through the cooling flow channel of the laser rod, so that the internal and external temperature distribution of the laser rod is more uniform, the thermal stress of the laser rod is effectively reduced, the distortion of laser beams is further reduced, the generation of linearly polarized light is reduced, and the power of the laser is improved. And the refractive index matching liquid has the same refractive index as the laser rod, and when the refractive index matching liquid passes through the laser rod, the normal work of the laser rod cannot be influenced.
Drawings
FIG. 1 is a schematic diagram of a linearly polarized output laser for effectively compensating for thermal depolarization effects according to the present invention;
FIG. 2 is a schematic structural diagram of a laser water cooling system of the present invention;
FIG. 3 is a flow chart of a method for using a linearly polarized output laser for effectively compensating for thermal depolarization effects according to the present invention.
Reference numerals: 1. a first full-inverse cavity plate; 2. a laser power supply; 3. a semiconductor pump module; 4. a laser bar; 5. a polarizer; 6. an output cavity plate; 7. a second full-inverse cavity plate; 8. a laser water cooling system; 81. a water tank; 82. a water chiller; 83. a deionization purification filter; 84. and a ventilation valve.
Detailed Description
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The following further description is made with reference to the accompanying drawings and specific examples:
example 1
As shown in fig. 1, an embodiment of the present invention provides a linearly polarized output laser structure for effectively compensating thermal depolarization effect, including a laser housing, a laser rod 4 and a laser power supply 2;
a main resonant cavity and a branch resonant cavity are arranged in the laser shell, and the branch resonant cavity is communicated with the main resonant cavity;
the laser device comprises a main resonant cavity, and is characterized in that a first full-anti-cavity sheet 1, a laser rod 4, a polarizer 5 and an output cavity sheet 6 are sequentially arranged in the main resonant cavity, a semiconductor pumping module 3 is arranged around the laser rod 4, a laser power supply 2 is electrically connected with the semiconductor pumping module 3 to ensure that the laser rod 4 and the semiconductor pumping module 3 are sufficiently cooled, the pressure of cooling liquid on the semiconductor pumping module 3 is less than the pressure capable of being borne by the semiconductor pumping module 3, and the semiconductor pumping module 3 pumps the laser rod 4 to ensure that the laser rod 4 is thermally balanced;
the laser comprises a main resonant cavity and a branch resonant cavity, wherein a second full-reflection-cavity sheet 7 is arranged in the branch resonant cavity, the second full-reflection-cavity sheet 7 is positioned on one side of a polarizer 5, when the polarizer 5 and the second full-reflection-cavity sheet 7 are positioned at the rear end of a laser rod 4, the polarization states of oscillation laser in the main resonant cavity and the branch resonant cavity are linearly polarized light P and linearly polarized light S respectively, the oscillation laser outputs laser through a coupling output mirror of a laser, and the output laser is non-linearly polarized light. The linear polarization output laser structure utilizes the self thermal induced birefringence effect of the laser rod to partially convert the linearly polarized light S light generated by the self thermal induced birefringence effect of the laser rod into the linearly polarized light P light again, so that the intracavity loss caused by the self thermal induced birefringence effect of the laser rod can be effectively reduced, and the output power and the efficiency of the linear polarization output laser are improved.
Specifically, the laser structure comprises a laser shell, a first total reflection cavity plate 1, a laser power supply 2, a semiconductor pumping module 3, a laser rod 4, a polarizer 5, an output cavity plate 6, a second total reflection cavity plate 7 and a laser water cooling system 8. The laser shell is internally provided with a main resonant cavity and a branch resonant cavity which are communicated with each other. The first full-anti-cavity plate 1, the laser rod 4, the polarizer 5 and the output cavity plate 6 are sequentially arranged in the main resonant cavity from back to front, the semiconductor pumping module 3 is surrounded around the laser rod 4, the end faces of the front end and the rear end of the laser rod 4 are respectively plated with an antireflection film, the wave band of the antireflection film is matched with the wavelength of laser generated by the laser, such as a 3-micron laser wave band, specifically, the wave band can be 2.79 microns, 2.94 microns and the like, and the selection basis is that the wave band of the laser generated by the laser is matched. One surface of the output cavity plate 6 facing the front end of the laser rod 4 is coated with a partial reflection film, such as an 80% reflection film, a 60% reflection film and the like, and the other surface of the output cavity plate 6 is coated with an anti-reflection film. The laser power supply 2 is electrically connected with the semiconductor pumping module 3, and the laser power supply 2 supplies power to the semiconductor pumping module 3. A second full-cavity-reflecting sheet 7 is arranged in the branch resonant cavity, the second full-cavity-reflecting sheet 7 is positioned on one side of the polarizer 5, a full-reflection film is plated on one surface, facing the laser rod 4, of the second full-cavity-reflecting sheet 7, and the wave band of the full-reflection film is matched with the wavelength of laser generated by the laser.
As shown in fig. 1 and 2, the laser water cooling system 8 includes a water tank 81, a water chiller 82, and a deionization purification filter 83, and the laser power supply 2 may supply power to the water chiller 82 and the deionization purification filter 83. The laser shell is provided with a cooling water inlet leading to the laser rod 4 and the semiconductor pumping module 3, and the laser shell is also provided with a cooling water outlet. The water suction port of the water chiller 82 is connected with the water tank 81 through a pipeline, the water outlet of the water chiller 82 is connected with the water inlet of the deionization purification filter 83, the water outlet of the deionization purification filter 83 is connected with the cooling water inlet arranged on the laser shell through a pipeline, and the cooling water outlet arranged on the laser shell is connected with the water tank 81. The water cooler 82 sucks water in the water tank 81 and cools the water, and the control panel of the water cooler 82 is provided with the outlet water temperature of the water cooler 82, so that required constant-temperature cooling water can be obtained. The constant temperature cooling water discharged from the water outlet of the water chiller 82 is filtered by the deionization purification filter 83 and then enters the laser housing through the cooling water outlet arranged on the laser housing to cool the semiconductor pump module 3 and the laser rod 4. The water heated by the semiconductor pump module 3 and the laser rod 4 is returned to the water tank 81 through a cooling water outlet provided in the laser housing, and thus circulated. The deionizing purification filter 83 may make the cooling water entering the laser housing non-conductive. In order to prevent dust in the external environment from entering the water tank 81 and contaminating the water in the water tank 81, the water tank 81 is hermetically disposed, a vent valve 84 is disposed at an upper end of the water tank 81, and an air filtering component such as a screen or an air filtering device is disposed in the vent valve 84. According to the laser structure, the spiral cooling flow channel is arranged in the laser bar along the length direction of the laser bar, the cooling flow channel is respectively provided with the inlet and the outlet at two ends of the laser bar, the cooling medium is refractive index matching liquid, and the refractive index of the refractive index matching liquid is the same as that of the laser bar. The refractive index matching liquid passes through the cooling flow channel of the laser rod, so that the internal and external temperature distribution of the laser rod is more uniform, the thermal stress of the laser rod is effectively reduced, the distortion of laser beams is further reduced, the generation of linearly polarized light is reduced, and the power of the laser is improved. And the refractive index of the refractive index matching liquid is the same as that of the laser rod, and when the refractive index matching liquid passes through the laser rod, the normal work of the laser rod cannot be influenced.
The working principle of the invention is as follows: the laser power supply 2 powers a semiconductor pump module 3 to pump a laser rod 4, which then generates laser light in the resonant cavity. The polarizer 5 makes the laser oscillated and output in the main resonant cavity be linearly polarized light P. If the thermal birefringence effect in the laser rod 4 is not present, there is no problem of output power reduction due to the thermal depolarization effect. However, under practical conditions, laser light is reflected by the first full-reflection-cavity plate 1 at the rear end of the laser rod 4 and is affected by the thermal birefringence effect when passing through the laser rod 4, and at the front end of the laser rod 4, after passing through the polarizer 5, the linearly polarized light P is partially converted into linearly polarized light S. The linearly polarized light P is transmitted through the polarizer 5, continuously propagates in the main resonant cavity and is partially output after passing through the output cavity plate 6. The linearly polarized light S is reflected by the polarizer 5, enters the branch resonant cavity, is reflected by the second full-reflection-cavity sheet 7, enters the polarizer 5 again and enters the main resonant cavity. The linearly polarized light S continues to be transmitted in the main resonant cavity and passes through the laser rod 4 twice, and then is partially converted into linearly polarized light P by utilizing the thermotropic birefringence effect of the laser rod 4, and the linearly polarized light P is partially output after passing through the output cavity plate 6.
Therefore, the linearly polarized light output laser utilizes the self thermal induced birefringence effect of the laser rod 4 to partially convert the linearly polarized light S light generated by the self thermal induced birefringence effect of the laser rod 4 into the linearly polarized light P light again, so that the intracavity loss caused by the thermal induced birefringence effect of the laser rod 4 can be effectively reduced, and the output power and the efficiency of the linearly polarized output laser are improved.
In a 3-micron laser wave band, no proper material is used for manufacturing a Faraday rotator with a high damage threshold, so that the thermal depolarization compensation of the laser crystal thermal induced birefringence effect is restricted. The invention has no special requirements on materials, is suitable for thermal depolarization compensation of a laser with a laser band of 3 mu m, and is also suitable for thermal depolarization compensation of other lasers with laser bands which do not have suitable materials for manufacturing a Faraday rotator with a high damage threshold.
In the invention, the polarizer 5 and the second full-reflection-cavity sheet 7 are positioned at the front end of the laser rod 4, only the main-path resonant cavity outputs laser through the coupling output mirror of the laser, and the output laser is linearly polarized. When the polarizer 5 and the second full-reflection cavity plate 7 are located at the rear end of the laser rod 4, the polarization states of the oscillation laser in the main resonant cavity and the branch resonant cavity are linearly polarized light P and linearly polarized light S respectively, the oscillation laser outputs laser through the coupling output mirror of the laser, and the output laser is non-linearly polarized light.
Example 2
This example differs from example 1 in that: the first is that the cooling medium is different, the cooling medium of the embodiment 1 is water, the cooling medium of the embodiment is the refractive index matching liquid, and the refractive index of the refractive index matching liquid is the same as that of the laser rod 4. Secondly, in this embodiment, a spiral cooling channel is arranged inside the laser rod 4 along the length direction thereof, the cooling channel is respectively provided with an inlet and an outlet at two ends of the laser rod 4, and the refractive index matching liquid serving as a cooling medium passes through the cooling channel of the laser rod 4, so that the internal and external temperature distribution of the laser rod 4 is more uniform, the thermal stress of the laser rod 4 is effectively reduced, the distortion of a laser beam is further reduced, the generation of linearly polarized light S light is reduced, and the power of the laser is improved. And the refractive index of the refractive index matching liquid is the same as that of the laser rod 4, and when the refractive index matching liquid passes through the laser rod 4, the normal work of the laser rod 4 cannot be influenced.
Example 3
As shown in fig. 3, the present embodiment provides a method of using a laser for the lasers disclosed in embodiments 1 and 2. The method comprises the following steps:
s100, checking a laser, blowing off floating dust on the laser rod 4 and each cavity piece, dipping and wiping the surfaces of the laser rod 4 and each cavity piece by using paper wetted by acetone or ethanol, and wiping along the direction of the coating lines during wiping;
and S200, setting the water outlet temperature and the water outlet flow of the water chiller 82 according to the optimal working temperature of the laser rod 4. The laser bars 4 made of different materials have different optimal working temperatures, for example, the optimal working temperature of the laser bar 4 made of Nd: YAG crystal is 25 ℃. The water pump motor inside the water cooler 82 is a variable frequency motor, and the flow rate of the water cooler 82 is set, namely the rotating speed of the water pump motor is set. When the semiconductor pump module is arranged, the laser rod 4 and the semiconductor pump module 3 are considered, the laser rod 4 and the semiconductor pump module 3 are ensured to be sufficiently cooled, meanwhile, the pressure of the cooling liquid on the semiconductor pump module 3 cannot be damaged and exceed the pressure which can be born by the semiconductor pump module 3, and the semiconductor pump module 3 cannot be damaged;
s300, starting the water chiller 82 and the deionization purification filter, and conveying cooling liquid to the laser rod 4 and the semiconductor pumping module 3;
s400, starting the semiconductor pumping module 3, pumping the laser rod 4 by the semiconductor pumping module 3, and waiting for 4-6 minutes to enable the laser rod 4 to reach thermal equilibrium. After the laser rod 4 reaches thermal equilibrium, the laser can work normally;
and S500, after the work is finished, stopping the semiconductor pumping module 3, keeping the water chiller 82 to work for 2 minutes, and fully cooling the laser rod 4 and the semiconductor pumping module 3.
The present invention is not limited to the above-described preferred embodiments, but various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A linear polarization output laser structure for effectively compensating thermal depolarization effect is characterized by comprising a laser shell, a laser rod (4) and a laser power supply (2);
a main resonant cavity and a branch resonant cavity are arranged in the laser shell, and the branch resonant cavity is communicated with the main resonant cavity;
the laser device is characterized in that a first full-inverse cavity sheet (1), a laser rod (4), a polarizer (5) and an output cavity sheet (6) are sequentially arranged in the main resonant cavity, a semiconductor pumping module (3) is arranged around the laser rod (4), a laser power supply (2) is electrically connected with the semiconductor pumping module (3) to ensure that the laser rod (4) and the semiconductor pumping module (3) are sufficiently cooled, the pressure of cooling liquid on the semiconductor pumping module (3) is smaller than the pressure capable of being borne by the semiconductor pumping module (3), and the semiconductor pumping module (3) pumps the laser rod (4) to ensure that the laser rod (4) is thermally balanced;
be equipped with the whole anti-chamber piece of second (7) in the branch road resonant cavity, the whole anti-chamber piece of second (7) is located one side of polarizer (5), and when polarizer (5) and the whole anti-chamber piece of second (7) were located the rear end of laser rod (4), the polarization state of oscillating laser is linearly polarized light P light and linearly polarized light S light respectively in main road resonant cavity and the branch road resonant cavity, and all exports laser through the coupling output mirror of laser instrument, and the laser of output is non-linearly polarized light.
2. The structure of a linear polarization output laser for effectively compensating the thermal depolarization effect as claimed in claim 1, wherein the front and rear end faces of the laser rod (4) are coated with antireflection films respectively.
3. The structure of a linear polarization output laser for effectively compensating the thermal depolarization effect as claimed in claim 1, wherein a surface of the second total cavity plate (7) facing the laser rod (4) is coated with a total reflection film, a surface of the output cavity plate (6) facing the front end of the laser rod (4) is coated with a partial reflection film, and another surface of the output cavity plate (6) is coated with an anti-reflection film.
4. The linear polarization output laser structure for effectively compensating the thermal depolarization effect according to claim 1, further comprising a laser water cooling system (8), wherein the laser water cooling system (8) is respectively connected with the laser rod (4) and the semiconductor pump module (3) through pipelines to provide constant temperature cooling liquid for the laser rod (4) and the semiconductor pump module (3).
5. A linearly polarized output laser structure effective in compensating for the effects of thermal depolarization as recited in claim 4, wherein the cooling fluid is a refractive index matching fluid.
6. A linearly polarized output laser structure for efficiently compensating for thermal depolarization effects as set forth in claim 5, characterized in that the laser rod (4) is internally provided with a spiral cooling channel along the length direction thereof, and the cooling channel is provided with an inlet and an outlet at both ends of the laser rod (4), respectively.
7. A linearly polarized output laser structure with efficient compensation of thermal depolarization effects according to any of claims 1-6, characterized by the fact that the laser housing is provided with cooling water inlets and outlets to the laser rod (4) and the semiconductor pump module (3).
8. A linearly polarized output laser structure for effectively compensating the thermal depolarization effect according to claim 7, characterized in that the laser water cooling system (8) comprises a water tank (81), a water chiller (82) and a deionization purification filter (83);
the water inlet of the water cooler (82) is connected with the water tank (81) through a pipeline, the water outlet of the water cooler (82) is connected with the water inlet of the deionized purification filter (83), the water outlet of the deionized purification filter (83) is connected with the cooling water inlet arranged on the laser shell through a pipeline, and the cooling water outlet arranged on the laser shell is connected with the water tank (81).
9. A linearly polarized output laser structure with efficient compensation of thermal depolarization according to claim 6, characterized in that the water tank (81) is hermetically disposed, and the upper end of the water tank (81) is disposed with a gas permeation valve (84).
10. A linearly polarized output laser structure with efficient compensation of the effects of thermal depolarization according to claim 7, characterized in that an air filtering device is arranged in the ventilation valve (84).
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