JP3149922B2 - Solid slab laser equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid-state slab laser device, and more particularly to a solid-state slab laser device in which a laser beam forms a zigzag optical path in a slab laser crystal.

[0002]

2. Description of the Related Art As a conventional solid slab laser device, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 1-270375. FIG. 12 is a schematic perspective view showing a schematic configuration of a conventional solid slab laser device. In FIG. 12, a slab laser crystal 601 has an end face 6 inclined with respect to an optical axis 611.
07, 608, and a cross section orthogonal to the optical axis 611 is a rectangular slab-shaped crystal, and the optically smooth surfaces 603, 6
04. The slab laser crystal 60 on the optical axis
A resonator is constituted by the output mirror 621 and the high reflection mirror 622 provided on both sides of 1.

Next, the operation of laser light oscillation of a conventional solid slab laser device will be described. Slab laser crystal 60
Numeral 1 is excited by an external light source (not shown) through optical smooth surfaces 603 and 604, and generates a laser beam by a resonator including an output mirror 621 and a high reflection mirror 622. The laser light reciprocates between the output mirror 621 and the high reflection mirror 622, and a part of the laser light passes through the output mirror 621 and is extracted as an output. The optical path 612 of the laser light coincides with the optical axis 611 outside the slab laser crystal 601. In the slab laser crystal 601, the end face 6 inclined with respect to the optical axis 611
Since the laser light is refracted by entering and exiting the laser beams 07 and 608 and has an angle that makes total reflection on the optically smooth surfaces 603 and 604, the laser beam follows a zigzag path as shown in FIG. Follow. Laser light is slab laser crystal 6
01, a plane formed by a zigzag path when passing through
13 is known as the P plane. A plane 614 that includes the optical axis 611 and is perpendicular to the P plane 613 is S
Also known as a plane.

Generally, the width w of the laser beam measured in the S plane 614 of the slab laser crystal 601 and the P plane 61
The ratio to the thickness t of the laser beam measured in 3 is 2 or more. Therefore, it is stable in the P plane 613 and the S plane 6
By constructing a resonator that is unstable in 14, a laser beam with a good convergence having a cross section adapted to the rectangular cross section of the slab laser crystal 601 is efficiently obtained.

[0005]

A first problem of the above-mentioned prior art is that the beam cross section of the laser output light of the solid-state slab laser device is bad. The reason is that the P plane and S
This is because the resonators having different conditions with respect to the plane have different cross-sectional widths of the output beam between the S plane and the P plane.

A second problem is that the beam divergence angles of the laser output light of the solid-state slab laser device are not uniform in the vertical and horizontal directions. The reason is that the laser oscillation conditions are different in each plane because the resonators are similarly configured under different conditions with respect to the P plane and the S plane.

It is an object of the present invention to provide a solid-state slab laser device in which the aspect ratio of the cross-sectional shape and the divergence angle of the laser output light is made uniform and isotropic.

[0008]

According to the present invention, there is provided a solid-state slab laser device comprising: a resonator using an axially symmetric mirror for oscillating laser light; and a laser arranged in series in the resonator to excite the laser light. is the a two slab laser crystal of the same shape, the laser beam proceeds while maintaining a light path of zigzag within each slab laser crystal, and scan
Love laser crystals have a cross-sectional shape that approximates the length of the short and long sides
The planes containing the zigzag optical paths of the two slab laser crystals intersect at an angle of 90 ° C., and the two parallel long sides form a cross section.
Laser light forms a zigzag optical path by repeating total reflection
Has formed .

A half-wave plate may be arranged between two slab laser crystals arranged in series in the resonator.

[0010] slab laser crystal is cross-sectional shape may be square, input and output end faces of the laser beam of the slab laser crystals, perpendicular to the plane including the optical path of the zigzag in the slab laser crystal and laser beam Preferably intersect obliquely with two parallel surfaces that repeat total reflection.

According to another aspect of the present invention, there is provided a resonator including an output mirror for oscillating a laser beam, a high reflection mirror, and a beam turning device, and a slab laser arranged in the resonator to excite the laser beam. And crystals. The beam turning device changes the traveling direction of the incident laser light.
Invert, translate the position, and move the laser beam
By emitted by rotating 90 degrees around, has an optical mechanism folding is reflected in a U-shape to each other the two laser beams in parallel to input and output, a slab laser crystal cross
Rectangular shape with long side twice or slightly shorter than short side
More than twice, forming a long side in cross section
Zigzag light by repeating total reflection of laser light between surfaces
A channel is formed, and one end face is arranged so as to straddle two laser light input / output positions of the beam turning device, and one end face of the slab laser crystal corresponds to one laser light. An output mirror is provided, and a high-reflection mirror is provided corresponding to another laser beam.

In one of the two laser light paths between the slab laser crystal and the beam turning device, two laser light paths are provided.
A quarter wave plate may be arranged, and a quarter wave plate may be arranged on both of the two laser light paths.

[0013]

Further, the input / output end face of the laser beam of the slab laser crystal is inclined and intersects two parallel planes which are perpendicular to the zigzag optical path in the slab laser crystal and form long sides. Is preferred.

In the solid-state slab laser device of the present invention, the laser light path in the resonator passes through the slab laser crystal twice. Further, the zigzag direction of the first pass through the slab laser crystal is the u direction and the zigzag direction of the second pass through the crystal is the v direction with respect to the orthogonal axes u and v on the sectional plane of the laser beam. As the mirrors constituting the resonator, axially symmetric mirrors having the same conditions in both the u and v directions are used.

Since the laser beam takes a zigzag optical path in both u and v directions while passing through the slab laser crystal twice in the resonator, the condition of the resonator in the slab laser crystal is the same in both u and v directions. Since the mirrors constituting the resonator are also axially symmetric, the resonator conditions are equal in both u and v directions. From the above, the laser output light has the same cross-sectional shape and the same aspect ratio of the divergence angle.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a solid-state slab laser device according to a first embodiment of the present invention,
FIG. 2 is a schematic plan view of the solid-state slab laser device according to the first embodiment of the present invention. 1 and 2, the optical axis 1
The first slab laser crystal 101 and the second slab laser crystal 102 arranged in series with respect to 11 have a square cross section or a rectangular shape whose short side and long side are similar in length. End face 10 inclined with respect to
7, 108 and 109 and 110, and optically smooth surfaces 103, 104 and 105 and 106 parallel to the optical axis 111.

Further, in the first slab laser crystal 101 and the second slab laser crystal 102, the planes including the zigzag laser light paths 112 cross each other at an angle of 90 degrees. The first slab laser crystal 1
01 and an output mirror 121 and a high reflection mirror 122 provided on both sides of the optical axis 111 of the second slab laser crystal 102.
Form a resonator.

Next, the operation of laser light oscillation will be described. The first slab laser crystal 101 and the second slab laser crystal 102 are excited by an external light source (not shown) through optically smooth surfaces 103, 104 and 105, 106, and resonate from an output mirror 121 and a high reflection mirror 122. A laser beam is generated by the device.

The laser light reciprocates between the output mirror 121 and the high reflection mirror 122, and a part of the laser light passes through the output mirror 121 and is extracted as an output. The laser beam path 112 coincides with the optical axis 111 outside the first slab laser crystal 101 and the second slab laser crystal 102.

In the first slab laser crystal 101, laser light is refracted by entering and exiting end surfaces 107 and 108 inclined with respect to the optical axis 111, and the optically smooth surfaces 103 and 10 are refracted.
4, the laser beam follows a zigzag path in the y-direction as shown in FIG.

The laser light emitted from the first slab laser crystal 101 has a special optical mechanism because the cross-sectional shape of the second slab laser crystal 102 is a square or a rectangle whose short side and long side are similar in length. Even without passing through, it is incident on the end face of the second slab laser crystal 102. The same applies to laser light in the opposite direction.

In the second slab laser crystal 102, the laser light is refracted by entering and exiting the end faces 109 and 110 inclined with respect to the optical axis 111, and the optically smooth surfaces 105 and 10 are refracted.
6, the laser beam follows a zigzag path in the x direction as shown in FIG. For this reason, since the laser beam path 112 takes a zigzag path in both the x and y directions, the resonator conditions are equal in both the x and y directions, and the cross-sectional shape and the aspect ratio of the divergence angle of the laser output light are also equal.

FIG. 3 is a schematic side view of a solid-state slab laser device according to a second embodiment of the present invention, and FIG. 4 is a schematic plan view of a solid-state slab laser device according to a second embodiment of the present invention. It is. 3 and 4, the first slab laser crystal 201 and the second slab laser crystal 202 arranged in series with respect to the optical axis 211 have a square cross section or a short side and a long side having an approximate length. End faces 207, 208 and 2 which are rectangular and respectively inclined with respect to the optical axis 211
09, 210 and the optically smooth surface 20 parallel to the optical axis 211.
3,204 and 205,206.

Further, in the first slab laser crystal 201 and the second slab laser crystal 202, the planes including the zigzag laser light paths 212 cross each other at an angle of 90 degrees. The half-wave plate 223 includes the first slab laser crystal 201 and the second slab laser crystal 20.
2 are arranged. The optical axis 211 of the first slab laser crystal 201 and the second slab laser crystal 202
Output mirror 121, high reflection mirror 1 provided on both sides of
22 constitutes a resonator.

The first embodiment refers to a half-wave plate 2
The same applies except that 23 is disposed between the first slab laser crystal 201 and the second slab laser crystal 202.

Next, the operation of laser light oscillation different from that of the first embodiment will be described. First slab laser crystal 2
01 and end face 20 of second slab laser crystal 202
7, 208 and 209, 210 are inclined with respect to the optical axis 211, so that the laser beam path 212 is refracted here.
Therefore, the transmittance at the end face is equal to that of the first slab laser crystal 2.
01 is high when the direction of S-polarized light of the laser beam is the x direction,
In the second slab laser crystal 202, it becomes higher when the direction of the S-polarized light of the laser beam is the y-direction. In the first slab laser crystal 201, the S-polarized light having the high transmittance in the x direction in the x direction is converted into the y direction by the half-wave plate 223, so that the second slab laser crystal 202 has High transmittance is obtained. For this reason, since loss can be reduced in both the first slab laser crystal 201 and the second slab laser crystal 202, high-power laser light can be obtained.

FIG. 5 is a schematic side view of a solid-state slab laser device according to a third embodiment of the present invention, and FIG. 6 is a schematic plan view of a solid-state slab laser device according to a third embodiment of the present invention. It is. 5 and 6, the slab laser crystal 30
1 has a rectangular cross section and a long side that is twice or slightly more than twice a short side, is orthogonal to two parallel surfaces forming the long side, and intersects obliquely with respect to the optical axis 311. End surfaces 307 and 308 and an optically smooth surface 3 parallel to the optical axis 311
03, 304.

The output mirror 321, the high reflection mirror 322 and the beam turning device 324 form a resonator having a substantially U-shape. The slab laser crystal 301 includes the beam turning device 324, the output mirror 321, and the high reflection mirror 322. The laser beam path 312 passes through the slab laser crystal 301 twice during one pass through the resonator.

FIG. 7 is a schematic perspective view showing an optical path of the beam turning device 324 according to the third embodiment of the present invention. The beam turning device 324 includes the turning mirror 32
5 to 328, and are arranged as shown so as to form an optical path as described later.

Next, the operation of laser light oscillation will be described. The slab laser crystal 301 has an optically smooth surface 303,
The laser light is excited by an external light source (not shown) through 304, and laser light is generated by a resonator including an output mirror 321, a high reflection mirror 322, and a beam turning device 324. Laser light is output mirror 321, high reflection mirror 322
The laser beam reciprocates in a substantially U-shaped resonator including the beam turning device 324, and a part of the light passes through the output mirror 321 and is taken out as an output.

In the slab laser crystal 301, a laser beam path 312 passing twice through the crystal is refracted by entering and exiting end surfaces 307 and 308 inclined with respect to the optical axis 312, and is refracted by optically smooth surfaces 303 and 304. In this case, the laser beam is reciprocated in both directions because the angle is such that total reflection occurs.
Follow a zigzag path in the y-direction as shown in FIG. In the beam turning device 324, as shown in FIG.
The traveling direction is sequentially changed to + x, + y, -y + by 5-328.
The light is emitted after being deflected to z and + z and the position is also shifted in the + x direction. At this time, if the orthogonal axes on the sectional plane of the laser beam are u and v, the u-axis of the incident laser beam is in the same direction as the y-axis of the resonator in FIGS. Is in the same direction as the x-axis. From these, a slab laser crystal 301 through which laser light passes twice
In the first pass, the u direction can be used as the zigzag route in the u direction during the first pass, and the v direction can be used as the zigzag route in the second pass.
The resonator conditions are equal in both the u and v directions, and the cross-sectional shape and the aspect ratio of the divergence angle of the laser output light are also equal.

FIG. 8 is a schematic side view of a solid-state slab laser device according to a fourth embodiment of the present invention, and FIG. 9 is a schematic plan view of a solid-state slab laser device according to a fourth embodiment of the present invention. It is. 8 and 9, a slab laser crystal 40
Reference numeral 1 denotes end faces 407 and 408 which are rectangular in cross section and whose long side exceeds twice or slightly twice the short side, and which are inclined with respect to the optical axis 411;
03,404.

The half-wave plate 423 is arranged between the slab laser crystal 401 and the beam turning device 424 so that only one of the two laser light paths passes. The output mirror 421, the high reflection mirrors 422, 2
The quarter-wave plate 423 and the beam turning device 424 form a resonator having a substantially U-shape, and the laser light path 412 passes through the slab laser crystal 401 twice during one pass through the resonator.

A beam folding device is provided except that a half-wave plate 423 is arranged between the slab laser crystal 401 and the beam folding device 424 so that only one of the two laser light paths passes. Third including the configuration of 424
This is the same as the embodiment.

Next, an operation of laser light oscillation different from the third embodiment will be described. Since the end faces 407 and 408 of the slab laser crystal 401 are inclined with respect to the optical axis 411, the laser light path 412 is refracted here. Therefore, the transmittance at the end face of the slab laser crystal 401 increases when the direction of S-polarized laser light is in the x direction. The laser light having high transmittance in the x direction after passing through the first slab laser crystal 401 has the S polarization direction rotated in the y direction by the beam folding device 424, but the S wavelength is again rotated by the half-wave plate 423. Since the polarization direction is returned to the x direction, a high transmittance can be obtained even in the second pass of the slab laser crystal. For this reason, when the slab laser crystal 401 passes twice, it is possible to reduce the loss in both, so that
High output laser light can be obtained.

FIG. 10 is a schematic side view of a solid-state slab laser device according to a fifth embodiment of the present invention, and FIG. 11 is a schematic plan view of a solid-state slab laser device according to a fifth embodiment of the present invention. It is. 10 and 11, the slab laser crystal 501 has a rectangular cross section and a long side that is twice or slightly more than twice the short side, and has end faces 507 and 508 inclined with respect to the optical axis 511; Optical smooth surfaces 503 and 504 parallel to 501 are provided.

The quarter-wave plate 533 is arranged between the slab laser crystal 501 and the beam turning device 524 so that both of the two laser light paths pass. The output mirror 521, the high-reflection mirror 522, the quarter-wave plate 533, and the beam turning device 524 generally form
A resonator having a V-shape is formed, and the laser beam path 512 has two slab laser crystals 501 in one pass through the resonator.
Pass twice.

The structure of the beam turning device 524 is the same as that of the beam turning device 524 except that the quarter-wave plate 533 is disposed between the slab laser crystal 501 and the beam turning device 524 so that both of the two laser light paths pass therethrough. This is the same as in the third embodiment.

Next, the operation of laser light oscillation different from that of the third embodiment will be described. Since the end faces 507 and 508 of the slab laser crystal 501 are inclined with respect to the optical axis 511, the laser beam path 512 is refracted here. For this reason, the transmittance at the end faces 507 and 508 depends on the slab laser crystal 501.
In this case, when the direction of the S-polarized light of the laser beam is the x direction, it becomes higher.
The laser beam whose S-polarized light having high transmittance is in the x-direction in the first pass through the slab laser crystal 1 is converted into a beam turning device 524.
Is rotated by 90 degrees, but is corrected by the quarter-wave plate 533 that passes twice, so that the second slab laser crystal 50 under the high transmittance condition that the S polarization direction is the x direction is used.
1 can be passed. For this reason, the loss can be reduced both at the time of two passes of the slab laser crystal 501, and a high output laser beam can be obtained.

[0041]

As described above, the first effect of the solid-state slab laser device of the present invention is that the aspect ratio of the beam cross-sectional intensity distribution of the laser output light is made uniform and isotropic.

The reason is that the laser beam path in the resonator is made to pass through the slab laser crystal twice, and the first zigzag of the slab laser crystal passing through the slab laser crystal with respect to the orthogonal axes u and v on the sectional plane of the laser beam. This is because the direction was set to the u direction, and the zigzag direction at the second pass of the crystal was set to the v direction, so that the resonator conditions were the same for both u and v directions.

The second effect is that the aspect ratio of the beam divergence angle of the laser output light is made uniform and isotropic.

The reason is that the laser beam path in the resonator is made to pass through the slab laser crystal twice, and the first zigzag of the laser beam passing through the slab laser crystal with respect to the orthogonal axes u and v on the sectional plane of the laser beam. This is because the direction was set to the u direction, and the zigzag direction at the second pass of the crystal was set to the v direction, so that the resonator conditions were the same for both u and v directions.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a solid-state slab laser device according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of the solid-state slab laser device according to the first embodiment of the present invention.

FIG. 3 is a schematic side view of a solid-state slab laser device according to a second embodiment of the present invention.

FIG. 4 is a schematic plan view of a solid-state slab laser device according to a second embodiment of the present invention.

FIG. 5 is a schematic side view of a solid-state slab laser device according to a third embodiment of the present invention.

FIG. 6 is a schematic plan view of a solid-state slab laser device according to a third embodiment of the present invention.

FIG. 7 is a schematic perspective view showing an optical path of a beam folding device according to a third embodiment of the present invention.

FIG. 8 is a schematic side view of a solid-state slab laser device according to a fourth embodiment of the present invention.

FIG. 9 is a schematic plan view of a solid-state slab laser device according to a fourth embodiment of the present invention.

FIG. 10 is a schematic side view of a solid-state slab laser device according to a fifth embodiment of the present invention.

FIG. 11 is a schematic plan view of a solid-state slab laser device according to a fifth embodiment of the present invention.

FIG. 12 is a schematic perspective view showing a schematic configuration of a conventional solid slab laser device.

[Explanation of symbols]

101, 102, 201, 202, 301, 401, 5
01,601 Slab laser crystal 103-106,203-206,303,304,4
03,404,503,504,603,604 Optically smooth surface 107-110,207-210,307,308,4
07, 408, 507, 508, 607, 608 End faces 111, 211, 311, 411, 511, 611
Optical axis 112, 212, 312, 412, 512, 612
Laser optical paths 130, 230, 330, 430, 530 Planes orthogonal to the optical axis 121, 221, 321, 421, 521, 621
Output mirror 122,222,322,422,522,622
High reflection mirrors 223, 423 Half-wave plate 324, 424, 524 Beam turning device 325-328 Turning mirror 331 Slab laser crystal crystal passing laser beam Orthogonal axis u, v direction 332 on laser beam cross section plane in first pass The orthogonal axes u and v on the laser beam cross section plane of the second pass of the laser beam passing through the laser crystal 533 Quarter-wave plate 613 P plane 614 S plane

Claims (8)

(57) [Claims] 1. A resonator using an axially symmetric mirror for oscillating laser light, and two identically shaped slab laser crystals arranged in series in the resonator and each of which is excited with laser light. In each of the slab laser crystals, a laser beam travels while taking a zigzag optical path, and the slab laser crystal has a sectional shape having a short side and a long side.
Each of the two slab laser crystals has a rectangular shape, and the planes containing the zigzag optical paths are 90 ° C.
Angle intersect with, parallel forms the long side in cross-section
The laser beam repeats total reflection on the two surfaces
Solid slab laser characterized that you form an optical path of sag. 2. The two resonators arranged in series in the resonator.
2. The solid-state slab laser device according to claim 1, wherein a half-wave plate is arranged between the slab laser crystals. 3. The solid according to claim 1, wherein the slab laser crystal has a square cross section, and forms a zigzag optical path by repeating total reflection of laser light on two predetermined parallel surfaces. Slab laser device. 4. The input / output end face of the laser beam of the slab laser crystal is inclined to two parallel planes which are orthogonal to a plane including a zigzag optical path in the slab laser crystal and where the laser beam repeats total reflection. The solid-state slab laser device according to claim 1 or 2, wherein the solid slab laser device intersects. 5. A resonator comprising: an output mirror for oscillating laser light; a high reflection mirror; and a beam turning device; and a slab laser crystal disposed in the resonator and excited by the laser light. The beam folding device reverses the direction of travel of the incident laser light and translates the position in parallel.
And rotate the laser beam 90 degrees about the optical axis.
The slab laser crystal has an optical mechanism in which two laser beams that enter and exit in parallel are reflected in a U-shape and turned back by emitting, and the slab laser crystal has a rectangular cross section.
The long side exceeds twice or slightly twice the short side, and the cross section
The laser light between the two parallel surfaces forming the long side
A zigzag optical path is formed by repeating total reflection,
An output mirror corresponding to one laser light is arranged on one end face side of the slab laser crystal so as to face one end face across the two laser light input / output positions of the beam turning device. A solid slab laser device, wherein a high reflection mirror is arranged corresponding to another laser beam. 6. The half-wave plate according to claim 5 , wherein a half-wave plate is disposed in one of two laser light paths between the slab laser crystal and the beam turning device. Solid slab laser device. 7. The solid-state slab laser device according to claim 5 , wherein a quarter-wave plate is disposed in both of the two laser light paths between the slab laser crystal and the beam turning device. 8. A laser beam input / output end face of the slab laser crystal is inclined and intersects two parallel planes which are perpendicular to a zigzag optical path in the slab laser crystal and form long sides. The solid-state slab laser device according to any one of claims 5 to 7 , wherein: