JP3481553B2 - Solid slab laser equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser used in an oscillating device or an amplifying device and formed of a slab-shaped laser medium for generating a laser beam, and particularly, to a high quality and a high output. The present invention relates to a low-cost, high-performance solid-state slab laser device that can be easily realized.

[0002]

2. Description of the Related Art Laser light having a wavelength of 1 μm or less generated and oscillated by a solid-state laser using a solid laser medium has a relatively strong interaction with a substance and can be easily transmitted by an optical fiber. It is being widely used in the field of processing applications. Therefore, in order to improve the processing performance, there is a need for a laser beam having higher quality and higher output, in which the transverse mode is close to the fundamental mode and the condensing characteristics are excellent.

Conventionally, in this type of solid-state laser, high-intensity pumping light is applied to obtain high output. With high-intensity pumping light, a temperature distribution is generated inside the medium, and photothermal effects such as thermal lens effect and thermal birefringence effect are generally generated.Therefore, laser light is deflected or depolarized, and laser oscillation efficiency and beam The quality is poor. Therefore, in such a solid-state laser, stable high output cannot be obtained, and the quality of the output beam is also deteriorated.

Further, even if a high output can be realized by constructing a resonator in combination with a lens or the like so as to compensate for the thermal lens effect, the thermal lens effect changes when the excitation intensity is changed over a wide range. However, it is difficult to maintain stable output, and stable wide output variability cannot be obtained.

As a means for solving such a drawback, as shown in FIG. 7, a slab-shaped laser medium having a length L, a width W and a thickness T is used as a solid laser 100.
A solid-state slab laser has been devised in which the interior 1011 of the solid-state laser 1000 is totally reflected on both side surfaces 1012 and the laser light 1020 forms a zigzag optical path. In this slab laser, in the case of an ideal two-dimensional temperature distribution, the direction of the internal temperature gradient and the traveling direction of the laser light coincide with each other, so that the laser beam does not undergo the thermal lens effect.

Further, in the slab-shaped laser medium, the heat exhaust area can be increased by increasing the aspect ratio with respect to the dimension of the cross section perpendicular to the longitudinal direction .
It is possible to input higher power into the slab without thermal destruction of the slab . However , since the cross-sectional shape of the medium becomes a thinner rectangle, the lasing laser light contains higher-order transverse modes. So, resonance using slab laser
A circular aperture can be inserted inside the chamber to limit the oscillation mode to the fundamental mode or lower order mode oscillation. However, in such a configuration , the end portion of the slab-shaped laser medium deviates from the oscillation mode volume, so that the utilization efficiency of the injected pumping light is reduced. Therefore, only a part of the excited portion of the slab-shaped laser medium near the central portion contributes to laser oscillation / amplification. Therefore, the efficiency of the fundamental mode or low-order mode laser oscillation required to realize a high-quality laser beam is reduced, and a high output cannot be obtained even if the generated laser beam is of high quality. .
There is also a problem that the wavefront of laser light is disturbed by a three-dimensional temperature distribution or stress distribution generated near the input / output surface of the slab.

A laser device and a solid-state laser using a slab-shaped laser medium capable of solving the above-mentioned problems are disclosed in Japanese Patent Application Laid-Open No. Hei 4 (1999) -1998
No. 16397 and Japanese Patent Application Laid-Open No. 4-30484. These are solid-state slab lasers in which two slab-shaped laser media are arranged at intervals and oscillate a laser beam between them. In such a solid slab laser structure, the aspect ratio of the two slab media containing the laser medium can be increased, while the slab formed by including the transparent slab body or space sandwiched between the two slab media. Since there is a degree of freedom in setting the total cross-section thickness of the laser-shaped amplification medium in the same dimension as the diameter of the incident laser light, there is an advantage that the efficiency does not decrease even when oscillating the low-order mode laser light. is there.

FIG. 8 shows a laser device 1 having a composite slab structure disclosed in Japanese Patent Application Laid-Open No. 4-16397.
100 is shown. In this case, two relatively thin slab-shaped laser amplification media 1110 sandwich the transparent slab material 1111 at the center from both sides and fuse them together. In such a composite slab structure, since the laser amplification medium 1110 that absorbs the excitation light emitted from the outside of the laser amplification medium 1110 and generates heat is thin, it is easy to dissipate heat. The photothermal effect is hard to appear, and the thermal destruction of the slab is hard to occur.

However, in order to make a laser medium into a composite, it is necessary to adjust the refractive indexes of different laser medium materials to be fusion-bonded to each other so that residual stress does not remain on the boundary surface. For this reason, it is necessary not only to have the same optical refractive index of each material, but also to precisely control the compounding and fusion temperature of the materials so that their thermal expansion coefficients become the same. Therefore, it is complicated and extremely difficult to manufacture a composite slab having a size required for high output.
Further, even in the structure of the composite slab, there is a problem that the wavefront of the laser light is disturbed by the three-dimensional temperature distribution or stress distribution in the vicinity of the light input / output surface of the transparent slab medium in the central portion.

As a solid-state slab laser that can solve the above problems, there is a solid-state laser using two slab-shaped laser media disclosed in Japanese Patent Application Laid-Open No. 4-30484 shown in FIG. This solid-state laser excites the laser medium along the zigzag optical path of the oscillated laser beam 1220 formed inside the two laser mediums 1210 and the portion sandwiched between the two laser mediums 1210 by the resonator. Individual semiconductor lasers having directivity and high output power density are arranged and used as the pumping light source 1230.

[0011]

In the device using the conventional solid-state slab laser described above, the output light of the pumping semiconductor laser having a large individual output power density is incident on the laser medium along the zigzag optical path and the internal oscillation is generated. Laser light is being excited. However, since the pumping laser light passes through the laser medium for pumping only once, the efficiency of the pumping light being absorbed by the slab laser medium is low, so that there is a problem that a large output cannot be expected. When a plurality of pumping semiconductor lasers are provided in order to solve this problem, there arises a problem that economic efficiency is poor. Further, although it is necessary to cool the slab laser medium by using a plurality of pumping semiconductor lasers, the above structure does not disclose a forced cooling mechanism for the slab laser medium by a fluid or the like. There is a practical problem that it is impossible.

An object of the present invention is to solve the above problems and provide a low-cost and high-performance solid-state slab laser device which can stably realize high quality, high output, and output variability. is there.

[0013]

Solid slab according to the present invention
In the laser device, the generated laser light travels in the zigzag optical path.
To the longitudinal direction, and the plane perpendicular to this longitudinal direction
Intersection lines form parallel lines to form a central spaceShiPlaced opposite
Two slab-shaped laser media and the laser media
With a fixture to fix it in place, One-dimensional or two-dimensional array
Excitation Light Emitting Excitation Light with Arranged Luminescent Material
SourceAnd the laser medium is,The central spaceSandwich
soFacing each otherPlacedThe first optical thin film is coated
Inner surface,Opposite to the central spaceLocated inSecond
Coated with optical thin filmAnd as an excitation surface
Irradiated by the excitation light from the sideHas an outer surface,Previous
RecordExcitation light,Of the two slab-shaped laser mediaOuter surface
Irradiates the entire area ofPass throughThe slab-shaped lace
The inner surface of the fixture facing the central space side of the medium
Reflected,Inside the laser mediumLaser medium passes through multiple round trips
Uniform throughout the bodyexcitationSileThe light isThe slab shape
To the central space of the laser medium, fill the basic space
Or as a wave in a lower modeThe inner surface of the outer surface is
Total reflection by the second optical thin filmIncident at an angle
However, the inner surface is non-reflective due to the first optical thin film.
By transmitting, inside the outer surface, the slab
The laser medium and the central space
The zigzag optical path is formed.

The above structure is strong in order to obtain high output.
As even as possible along the slab surface when excited
In order to obtain a temperature distribution, A excitation light both of the two pieces of slab laser medium facing transmitted over the entire surface, so can be excited, which is arranged one-dimensionally or two-dimensionally suitable for this
An excitation light source having a ray-shaped emission line or emission surface can be used. Therefore, since it is not necessary to locally concentrate the output as the excitation light, it is possible to eliminate the need for a high-output laser light source for excitation, which has a large output power density and therefore is difficult to maintain a long life.

Further, in the solid-state slab laser device according to the present invention, it is preferable that an inner surface of a portion including the fixture and forming the central space is a mirror surface that reflects 90% or more of the excitation light. With such a mirror surface, the excitation light can be effectively utilized by confining the excitation light in the internal space of the fixture for fixing the laser medium.

Further, the fixture has an airtight member capable of transmitting laser light at each of an entrance and an exit of the laser light to hermetically form the central space, and the laser medium has a predetermined flow rate and atmospheric pressure. It is desirable to further include a gas introduction path for introducing a gas for correcting the shape of the above into the central space. By introducing such a gas, it is possible to prevent the shape of the laser medium from being deformed when the cooling fluid is passed through the outer wall surface of the laser medium.

The side surfaces of each of the two slab-shaped laser media include the longitudinal direction and are perpendicular to the parallel lines.
The line of intersection with the surface is a predetermined angle, or the end where laser light enters and exits in the central space formed by the two parallel slab-shaped laser media It is desirable to provide a prism that is arranged in the section and in which the optical axis of the laser light that enters and exits is parallel to the side surface of the laser medium. The direction of the laser beam can be adjusted by the prism.

Further, in one specific solid-state slab laser device according to the present invention, the laser medium is disposed so as to face each other with the central space interposed therebetween, and the inner surface coated with an optical thin film and the central space. Are located opposite to each other and have an outer surface which is irradiated with excitation light from the outside as an excitation surface, and the excitation light passes through the inner and outer surfaces of the two slab-shaped laser media to excite the inside of the laser medium. .

In this apparatus, a reflecting surface which is on the surface for emitting the excitation light and which reflects the excitation light coming through the two laser media except the excitation light source portion for emitting the excitation light, An inner wall surface surrounding the optical path of the excitation light between the reflection surface and the outer surface of the laser medium through which the excitation light is transmitted, the inner wall surface including the fixture and reflecting the internal excitation light, and the laser medium And a transparent member which is disposed with a predetermined gap and which transmits the excitation light, wherein the reflection surface and the inner wall surface form a light collection surface that collects the internal excitation light on the outer surface. Is desirable. As a result, the excitation light can be transmitted through the laser medium multiple times, and the laser medium can be effectively excited.

Further, in another solid-state slab laser device according to the present invention, the laser medium faces the central space, and the inner surface on which the first optical thin film is coated and the opposite surface to the central space. And an outer surface coated with the second optical thin film, and the excitation light is made perpendicular to the longitudinal direction from the end faces in the width direction of each of the two laser media and is incident parallel to the side surface of the laser media. Then, total internal reflection is repeated on both sides of each laser medium to excite the inside. In this way, since the pumping light is made incident on the entire inside of each of the two laser media, a normal output pumping light source having a structure suitable for this can be used. Therefore, it is possible to eliminate the need for a high-output laser light source for pumping, which has a large output power density as pumping light and thus is difficult to maintain a long life.

Further, it is desirable that the cooling fluid be caused to flow in a predetermined direction by using a gap formed between the transparent member and the outer surface or a gap contacting the outer surface of the laser medium as a fluid path. As a result, it is possible to efficiently cool the thin slab-shaped laser medium.

Further, in order to cool the laser medium from the inner side surface and control the temperature, a single or a fixing member for the laser medium may be provided in the laser traveling direction which is the longitudinal direction in the central space between the laser media or along the longitudinal direction. It is desirable to provide a plurality of gas introduction paths and discharge paths, and to flow the cooling gas perpendicularly to the longitudinal direction and parallel to the side surface of the slab-shaped laser medium.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing one mode of use of the slab-shaped laser medium used in the present invention.

In the solid-state slab laser in which the laser medium 10 shown in FIG. 1 is used, two laser mediums 10 have the same length L ₀ and the thickness d ₀ which are parallel to each other and have a length L in the longitudinal direction.
_The central space 1 is maintained at a position deviated by ₁ while maintaining an equal interval d 1.
1 is formed. Each of the two laser media 10 has an outer surface 12 and a central space 11 on the side opposite to the central space 11.
Has an inner side surface 13 facing each other.

As shown in the figure, the laser beam 20 formed by a beam having a diameter D is incident on the surface of the laser medium 10 with the optical axis of the laser beam placed in a plane perpendicular to the surface of the laser medium 10. Incident. Laser medium 1
The inner surface 13 of 0 has a non-reflection coating that does not reflect the incident laser light 20. On the other hand, the outer surface 12 totally reflects the incident laser light 20 to the inner side by the total reflection coating. The laser light incident from one end is emitted through an optical path having an angle symmetrical with the angle incident from the other end. Therefore, the displacement length L _{1 at} which the two laser media 10 are positioned is represented by the following mathematical formula 1.

[0027]

[Equation 1]

That is, the condition in which the beam of the laser light 20 is returned over the entire outer surface 12 of the laser medium 10 without any gap is that the laser light 20 having the beam diameter D is in a plane perpendicular to the surface of the laser medium 10. When the laser beam 20 is incident at an incident angle θ and the refractive index n of the slab-shaped laser medium 10 and the number of times the laser light 20 is folded back over the entire outer surface 12 without any gap are set to an arbitrary integer N of “1” or more, the beam diameter D And the total length L ₀ of the laser medium 10 is expressed by the following mathematical expressions 2 and 3, respectively.

[0029]

[Equation 2]

[Equation 3]

Here, when the slab medium is Nd: YAG crystal, since n = 1.82, d ₀ = 1.5 mm
And d ₁ = 5.3 mm, by choosing N = 3, L ₀ = 15 mm, incident angle θ = 70 degrees, and D =
It is possible to obtain 4.2 mm. Further, under such conditions, the widthwise dimension of the slab medium 10 can be matched with the beam diameter D of the laser light to achieve efficient amplification.

Next, the solid-state slab laser device according to the present invention will be described with reference to FIG. FIG. 2 is an explanatory cross-sectional view showing a cross-section when the longitudinal direction of the laser medium 110 is perpendicular to the paper surface as one embodiment of the present invention.

The solid-state slab laser device shown in FIG.
In the central portion, two laser mediums 110 having the shape shown in FIG. 1 and a structure in which the two laser mediums 110 are positioned substantially parallel to each other as shown in FIG. Fixture 1 forming a certain central space 111
40 and two transparent members 150 arranged along the outer side of the outer side surface of each of the two laser media 110 with a predetermined gap. Excitation light 130 that excites the laser medium 110 irradiates almost the entire outer surface of the laser medium 110 from the outside of the two transparent members 150 arranged outside the laser medium 110.

The fixture 140 uses the inner surface forming the central space 111 as a mirror surface 141 to confine the excitation light 130 in the central space 111 by reflection, and the excitation light 130 incident from the outside into the laser light 120 inside the laser medium 110. Of the laser beam 120 inside the laser medium 110 at the facing position again after being transmitted through the central space 111.
It can be used for excitation and emitted from the outer surface. In order to efficiently confine the excitation light 130, it is desirable that the mirror surface 141 reflect 90% or more of the excitation light.

Further, the fixing member 140 has a central space 111.
The central space 111 is hermetically formed by providing an airtight member capable of transmitting the laser light 120 at each of the entrance and the exit of the laser light 120 at both ends of the laser medium 120, and correcting the shape of the laser medium 110 at a predetermined flow rate and atmospheric pressure. A gas introduction path 142 for introducing the gas to be introduced into the central space 111 is provided. Further, a gap formed between the outer surface of the laser medium 110 and the transparent member 150 arranged on the outer side thereof is provided as a fluid passage 143 for flowing the cooling fluid in a predetermined direction.

Further, the fixture 140 is composed of two transparent members 1
A confinement portion 145 of the excitation light 130 that holds the excitation light source 131 that emits the excitation light 130 that irradiates almost the entire outer surface of the laser medium 110 from the outside of the laser medium 110 on the outer facing surface of the laser medium 110 is provided. The transparent member 150 occupies almost the entire area of the confinement portion 145.

The transparent member 150 transmits the excitation light 130 emitted from the excitation light source 131 and emits it from the transmission surface 151 facing the outer surface of the laser medium.

The transparent member 150 is coated with a metal thin film except for the portion of the excitation light source 131 which emits the excitation light 130, a reflection surface 152 which reflects the excitation light that has transmitted through the outer surface of the laser medium, and the reflection surface 152. An intermediate wall surface 153, which is a mirror surface formed around the optical path of the excitation light 130 between the surface 152 and the outer surface of the laser medium 110 and coated with a metal thin film to reflect the internal excitation light. The 152 and the intermediate wall surface 153 form a light condensing surface that condenses the internal excitation light 130 on the outer surface of the laser medium 110.

The central space 111 can be filled with air or a gas such as helium gas and sealed.
The slab-shaped laser medium 110 can be cooled by flowing a gas using the gas introduction path 142. Furthermore,
In the fluid path 143 formed between the outer surface of the laser medium 110 and the transparent member 150, a cooling fluid is provided in a direction perpendicular to the surface of the zigzag optical path of the laser light 120 and in the longitudinal direction or the width direction of the laser medium 110. The laser medium 110 is made to flow and cools. The slab-shaped laser medium 110 may be mechanically deformed by the pressure of the cooling fluid. However, when the laser medium 110 has a curvature, the gas pressure value inside the central space 111 is controlled. Can be externally adjusted to compensate for mechanical deformation.

Excitation light 13 emitted from the excitation light source 131
0 passes through the transparent member 150 and is incident on the laser medium 110 from almost the entire outer surface, which is the excitation surface, to excite the laser medium 110. Therefore, it is desirable that the outer surface of the laser medium 110 and the transmissive surface 151 of the transparent member 150 be non-reflective coating that does not reflect excitation light. In addition, the excitation light 130 emitted from the excitation light source 131
In order to efficiently reach the laser medium 110, the condensing surface formed by the reflecting surface 152 and the intermediate wall surface 153 of the transparent member 150 guides the excitation light 130. Further, the excitation light 130 transmitted through the laser medium 110 is confined in the central space 111 by the mirror surface 141 forming the central space 111, and is guided to the other laser medium 110.

Therefore, the excitation light 130 is transmitted from the one laser medium 110 through the central space 111 to the second laser medium 110 on the opposite side, and further, at the reflecting surface 152 of the transparent member 150 and the intermediate wall surface 153. The laser beam 120 is reflected by the condensing surface to be formed, folded back again, added to the excitation light 130 newly emitted from the excitation light source, and transmitted through the third laser medium 110 which is the second laser beam, and the laser beam 120 is pumped. can do.

As the excitation light 130, a one-dimensional semiconductor laser array can be used. Further, by arranging the two-dimensional semiconductor laser array at the position of the reflecting surface 152 which is a part of the light collecting surface, a higher excitation intensity can be obtained.

Next, a solid-state slab laser device according to the present invention, which is different from that shown in FIG. 2, will be described with reference to FIG. Figure 3
FIG. 4 is an explanatory transverse sectional view showing a transverse section when the longitudinal direction of the laser medium 110 is perpendicular to the paper surface, as an embodiment of the present invention.

The solid-state slab laser device shown in FIG. 3 differs from that of FIG. 2 in that instead of the transparent member 150 of FIG. 2, a predetermined gap is provided along the outside of the outer surface of each of the two laser media 110. That is, two transparent members 160 having a flat plate shape to be arranged are provided. Therefore,
The confinement portion 145, except for the portion of the excitation light source 131 that emits the excitation light 130, has a reflection surface 146 that reflects the excitation light that has come through the outer surface of the laser medium, and the reflection surface 146 and the excitation light 130 that are transmitted therethrough. An intermediate wall surface 147 that is a mirror surface that surrounds the optical path of the excitation light 130 with the surface of the transparent member 150 and that reflects the internal excitation light.
The reflection surface 146 and the intermediate wall surface 147 form a light condensing surface that condenses the internal excitation light 130 on the outer surface of the laser medium 110. That is, in order that the excitation light 130 emitted from the excitation light source 131 reaches the laser medium 110 efficiently, the reflection surface 146 of the confinement portion 145 and the intermediate wall surface 1
The light condensing surface formed by 47 guides the excitation light 130.

2 is the same as FIG. 2 except the above-mentioned differences, and the same reference numerals are given to the constituent elements and the description thereof will be omitted.

Next, a solid-state slab laser device different from that shown in FIG. 2 or 3 will be described with reference to FIG. Figure 4
As another embodiment of the present invention, the laser medium 21
It is an explanatory sectional view showing a transverse section when the longitudinal direction of 0 is perpendicular to the paper surface.

The solid-state slab laser device shown in FIG.
In the central portion, the two laser media 210 having the shape shown in FIG. 1 and the structure in which the two laser media 210 are positioned so as to face each other substantially in parallel as shown in FIG. Fixture 2 forming a certain central space 211
40 and 40. Excitation light 230 that excites the laser medium 210 irradiates substantially the entire area of both side surfaces that are narrow in the width direction perpendicular to the longitudinal direction of the slab-shaped laser medium 210.

Therefore, the pumping light 230 is totally reflected by the inner wall surface of the slab-shaped laser medium 210 and is confined inside, so that the laser medium 210 can be efficiently pumped. Further, it is preferable that the inner wall surface of the fixture 240 facing the central space 211 is a mirror surface 241, and the excitation light 230 leaking into the central space 211 is confined and guided to the laser medium 210 on the other side.

The central space 211 can be filled with a gas such as air or helium gas and sealed as in the description of FIG. 2. However, a slab-shaped laser medium is formed by flowing the gas through the gas introduction passage 242. 210 can be cooled.

Further, the fixture 240 has a fluid path 243 formed on the outer surface of each of the two slab-shaped laser media 210 in a direction perpendicular to the surface of the zigzag optical path of the laser light 220. A cooling fluid is flowed in the longitudinal direction or the width direction to cool the laser medium 210. The slab-shaped laser medium 21 is produced by the pressure of the cooling fluid.
0 may be mechanically deformed, but laser medium 2
When 10 has a curvature, the gas pressure value inside the central space 211 can be controlled and externally adjusted to compensate for mechanical deformation.

As the excitation light 230, a one-dimensional semiconductor laser array can be used as described above.

Next, a solid-state slab laser device having a laser medium arrangement different from that described above will be described with reference to FIG. FIG. 5 is a side view for explaining the side surface when the width direction of the laser medium 310 is perpendicular to the paper surface, as another embodiment according to the present invention.

The two slab-shaped laser media 310 shown in FIG. 5 are parallel to each other in the widthwise transverse section, but are parallel to each other in the longitudinal longitudinal section, in contrast to the above-mentioned elements arranged in parallel with each other and incorporated. It is arranged with an inclination of an angle θ ₁ .

Due to this inclination, the incident laser light 32
0 can reflect a number of times inside the slab-shaped laser medium 310 and the inner space 311 to form a zigzag optical path, and can return to the incident side. Two slab-shaped laser media 31
Since 0 has the inner space 311, it is easy to adjust the size of the tilt angle θ ₁ . Also, laser light 3
A total reflection mirror 312 and an output mirror 313 for the laser light 320 are provided for pumping, amplifying, and emitting 20.

Next, a solid-state slab laser device in which optical prisms are arranged at both ends of the above-mentioned two slab-shaped laser media will be described with reference to FIG.

As shown in FIG. 6, the prism 412 for closing the opening slope formed at the end of the central space 411 in the longitudinal direction of the two slab-shaped laser media 410 is
The laser medium 41 has the same cross-sectional shape as the central space 411, and the sloped surface on the side opposite to the central space 411 has a slab shape.
The beam of the laser light 420 that is incident parallel to the plane of 0 has an angle such that it can be reflected a number of times inside the prism 412, inside the laser medium 310, and inside space 311 to form a zigzag optical path. Therefore, the beam directions can be adjusted by disposing the prisms 412 at both ends of the central space 411 formed by the laser medium 410, that is, at the entrance and the exit of the laser light 420.

The solid-state slab laser device described with reference to FIGS. 2 to 6 employs two slab-shaped laser media as shown in FIG. Therefore, by adjusting the distance between the two slab-shaped media, that is, the thickness of the central space, it is possible to sufficiently secure the overlap of the mode volumes even in the oscillation of the laser light of the low-order mode. On the other hand, the thickness of each slab medium can be freely selected regardless of the mode diameter of the beam. Therefore, by increasing the aspect ratio of the slab medium, it is possible to improve the cooling efficiency of the slab and provide a high excitation input.

Further, since there is a hollow portion along the laser optical path, the slab alone is generated in the vicinity of the laser light input / output surface.
The turbulence of the laser light wavefront due to the dimensional temperature distribution and stress distribution, or the thermal birefringence in the zigzag optical path and the thermal lens effect do not occur except in the thin slab medium. Further, there is no problem that the wavefront of the laser light is disturbed by the three-dimensional temperature distribution or stress distribution generated near the laser light input / output surface of the slab itself. Therefore, it is possible to easily realize a device capable of stably outputting the same high-quality beam as in the case of a low pumping input even under a high pumping input.

Further, since the solid slab laser device according to the present invention has a structure that is mechanically assembled as compared with the composite slab type synthesized by high temperature fusion under precise temperature control, a slab-shaped laser medium having a long dimension is produced. Can be easily realized, and inexpensive and high-power laser light can be easily obtained.

[0059]

As described above, according to the present invention, it is possible to provide a low-cost and high-performance solid-state slab laser device that can easily realize high quality, high output, and stable output variability. .

First, because of the mechanically assembled structure, a long-sized slab medium can form a hollow solid-state slab laser with a space in between, thus making it easy to produce an inexpensive and high-power laser beam. Obtainable.

Secondly, the pumping efficiency of the slab medium can be maintained high because the pumping light is confined inside by providing a mirror surface around the slab medium or directly injecting so as to totally reflect the inside. Therefore, high output can be obtained at low cost.

Thirdly, since a structure in which the surface of the slab medium is directly cooled by a fluid can be easily realized, the slab medium operates stably without degrading the beam quality even with a high excitation input, and The output can be easily obtained at a low price.

[Brief description of drawings]

FIG. 1 is a side view showing one mode of use of a slab-shaped laser medium used in the present invention.

FIG. 2 is an explanatory transverse sectional view showing an embodiment of a sectional structure in the present invention.

FIG. 3 is an explanatory transverse sectional view showing an embodiment in a sectional structure different from that in FIG.

FIG. 4 is an explanatory transverse sectional view showing an embodiment in a sectional structure different from those in FIGS.

FIG. 5 is a side view showing one form of a slab-shaped laser medium arrangement different from that in FIGS. 2-4.

FIG. 6 is a side view showing an embodiment in which an optical prism is arranged at an end portion of the slab-shaped laser medium in FIG. 2-4.

FIG. 7 is a side view (A) and a plan view (B) when a conventional slab-shaped laser medium is a solid-state laser.

FIG. 8 is a side view for explaining a case where two conventional slab-shaped laser media have a composite structure.

FIG. 9 is a side view showing an example in which a space is provided between two conventional slab-shaped laser media.

[Explanation of symbols]

10, 110, 210, 310, 410 Laser medium 11, 111, 211, 411 Central space 12 Outer side 13 Inside surface 20, 120, 220, 320, 420 Laser light 130, 230 Excitation light 131,231 Excitation light source 140,240 Fixture 141, 241 Mirror surface 142, 242 gas introduction path 143, 243 fluid path 145 Confinement 146, 152 reflective surface 147,153 Intermediate wall surface 150, 160 Transparent member 151 transparent surface 311 Inside space 412 prism

Continued Front Page (72) Inventor Takeshi Yamane 5-7 Shiba 5-chome, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-4-30484 (JP, A) JP-A-9-92913 ( JP, A) JP 62-16588 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01S 3/00-3/30

Claims (5)

(57) [Claims] 1. A direction of laser light that occurs proceeds in a zigzag optical path as a lengthwise direction, two of intersection of the vertical plane are arranged opposite to form a central space in parallel with lines to the longitudinal direction A slab-shaped laser medium, a fixture for fixing the laser medium at a predetermined position, and a one-dimensional or two-dimensional arrangement
Excitation Light Emitting Excitation Light with Arranged Luminescent Material
And a source, said laser medium, distribution on opposite sides of said central portion space
An inner surface that is placed and coated with a first optical thin film ;
Located opposite to the center space, the second optical thin film coatings Rutotomoni, the excited from the outside as the excitation surface
And an outer surface which is irradiated by the electromotive light, the excitation light is within the outer of the two sheets of slab laser medium
Irradiates the entire surface and partially passes through the slab
-Inner surface of the fixture facing the central space side of the media
In reflected laser back and forth through the interior laser medium to multiplex
The entire inside of the medium is excited uniformly, and laser light is emitted to the central space of the slab-shaped laser medium,
As a wave of the fundamental mode or the lower mode that satisfies the whole
Total reflection by the second optical thin film on the inner surface of the outer surface Te
Thus, the slab-shaped laser medium and the central space are alternately arranged inside the outer side surface by being incident on the inner side surface and being transmitted without reflection by the first optical thin film on the inner side surface. A solid-state slab laser device, wherein the solid-state slab laser device passes through to form the zigzag optical path. 2. The solid slab according to claim 1, wherein an inner surface of the fixture facing the central space side of the slab-shaped laser medium is a mirror surface that reflects 90% or more of the excitation light. Laser device. 3. The fixing device according to claim 1, wherein the fixing member has an airtight member capable of transmitting laser light at each of an entrance and an exit of the laser light to hermetically form the central space, and a predetermined flow rate and The solid-state slab laser device further comprising a gas introduction path for introducing a gas for correcting the shape of the laser medium into the central space with atmospheric pressure. 4. The side surface of each of the two slab-shaped laser media according to claim 1, including the longitudinal direction,
A solid-state slab laser device characterized in that a line of intersection with a plane perpendicular to the parallel lines is arranged at a predetermined angle. 5. The metal thin film according to claim 1 , which is on a surface emitting the excitation light and reflects the excitation light coming through the two laser media except an excitation light source portion emitting the excitation light. And a metal thin film that surrounds the optical path of the excitation light between the reflection surface and the outer surface of the laser medium through which the excitation light passes and that reflects the internal excitation light. further comprising a coated intermediate wall, and the solid slab laser device characterized by forming a light collecting surface on which the reflecting surface and said intermediate wall is reflected condenses inside the excitation light to the outer surface.