JPH03224282A - Solid-state laser device excited by semiconductor laser - Google Patents

Abstract

PURPOSE:To sharply increase the laser gain part of an excited solid-state laser medium by providing a diffraction grating which makes the light emitted from a laser to incident to the solid-state laser medium after diffracting the light to the direction in which a laser resonator mode is formed. CONSTITUTION:Zero-th order diffracted light 29 is propagated through a solid-state laser medium 22 while the light 29 is subject to such absorption that the intensity of the light is exponentially attenuated in a direction nearly perpendicular to the optical axis 6 and forms an excitation area. First-order light 30 advances in the direction at an angle (=0 deg.) expressed by the formula from the normal of a diffraction grating 24. The pitch (d) of the grating 24 is set so that the angle theta can approach 90 deg.. When the pitch (d) is set in such way, the diffracted light 30 is reflected by a plane 25 after the light 30 is propagated through the medium 22 while the light 30 is subject to such absorption that the intensity of the light 30 is exponentially attenuated in a direction almost parallel to the optical axis 6 and is again propagated through the medium 22, with the light 30 again being subject to the same absorption. Finally, the light 30 forms the excitation area. Then first-order diffracted light 31 advances in a direction which is almost symmetrical to the direction of the light 30 about the normal of the grating 24 and forms the excitation area after the light 31 is propagated through the medium 22, reflected by a plane 26, and again propagated through the medium 22.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solid-state laser device that excites a solid-state laser medium using a semiconductor laser, and particularly relates to means for guiding excitation light from the semiconductor laser to a solid-state sheath medium. .

[Conventional technology]

FIG. 14 is a block diagram of a semiconductor laser-excited solid-state laser device disclosed, for example, in U.S. Pat. No. 3,624,545 issued in 1971. A large number of semiconductor laser arrays are arranged in an array. 3 is a reflector tube;
4 is a high reflection mirror, 5 is an output coupling mirror, 6 is an optical axis of a laser resonator formed from the high reflection mirror 4 and the output coupling mirror 5, and 7 is a laser resonator mode. This is a so-called side view in which the light emitted from the semiconductor laser array 2, which is formed by arranging a large number of semiconductor lasers with an emission spectrum that almost matches the absorption spectrum I of the solid-state laser medium 1, is used to excite the solid-state Rayleigh medium rt. This is an optically excited solid-state ray IJ' device.

The emitted light from the semiconductor laser array 2 enters the solid-state laser medium 1 from the side surface almost perpendicular to the optical axis 6, and part of it is absorbed and part of it is transmitted and reflected by the reflection tube 3, and then returns to the solid-state laser medium 1. and forms an excitation region capable of laser amplification. On the other hand, the laser beam J5 is composed of a high reflection mirror 4 and an output coupling mirror 5, and a laser resonator mode 7 is formed. The excitation region is formed over almost the entire solid-state laser medium 1 without much relation to the mode distribution of the laser resonator modemer. The laser oscillation mode is TEM, which is the fundamental mode among the laser resonator modes 7. mode is preferred. Here, in order to explain the relationship between the excitation region where laser amplification is possible and laser resonator mode 7, the first
A sectional view perpendicular to the optical axis 6 including the solid-state laser medium 1 in FIG. 4 is shown in FIG. In the figure, 1 to 7 are the first
It is the same as that shown in Fig. 4, and 8 is the excitation region.

In this way, most of the excitation energy accompanying the light emitted from the semiconductor laser array 2 is given to the region of the solid-state laser medium l other than the region occupied by the laser G2H mode 17, so that there is a portion that does not contribute to amplification of the laser oscillation mode. Therefore, there was a problem that the excitation efficiency became low.

In order to improve the drawback that there is a large difference in size or volume between the excitation region 8 and the laser oscillation mode, the light emitted from the semiconductor laser that is the excitation light source is made to be approximately parallel to the optical axis 6 of the laser resonator. A so-called edge-pumped solid-state laser is disclosed in U.S. Pat. No. 4,653,056 issued on March 24, 1987, in which the solid-state laser is arranged and excited from an end surface substantially perpendicular to the optical axis 6 of the solid-state laser medium 1. Fig. 16 shows the configuration diagram of this unit. In the figure, 1 to 7 are equivalent to those shown in FIG. 14, 9 is a semiconductor laser, 10 is a lens, and 11 is an excitation light. The diverging emitted light from the semiconductor laser 9 is collected by the lens 10 and then converted into convergent light, which passes through the high-reflection mirror 4 and enters the solid-state laser medium 111 from one end surface substantially perpendicular to the optical axis 6 of the solid-state laser medium 1. will be introduced in In order to increase the excitation efficiency, the excitation region 8 is set to T E which is the fundamental mode 1 of the laser resonator modes 7.
It is designed to match the mode volume of the M oo mode. In this way, in the edge-pumped solid-state laser using the semiconductor laser 9, the excitation region 8 is 1"F, M,...
Since it is possible to match the mode volume of mode I, high excitation efficiency can be obtained.

However, the output of conventional semiconductor lasers is often limited to IW at most, and even if a higher output semiconductor laser is used as a pumping light source, there is a limit to the energy that can be used with so-called edge-pumped solid-state lasers. Therefore, the output of the solid-state laser is limited. On the other hand, as mentioned above, in the so-called side-pumped solid-state laser, more energy from the excitation light source can be transferred into the solid-state laser medium, but the excitation region and T E Mo. There is a problem with matching the mode volumes of the modes.

Next, in order to improve the drawbacks of the above two examples, the semiconductor laser array that is the excitation light source is arranged in a side-light pumping arrangement, and the configuration of the laser resonator is changed so that the light from the semiconductor laser array that is the excitation light source is A solid-state laser configured to substantially coincide with the optical axis is disclosed in U.S. Pat. No. 4,710,940, issued December 10, 1987. This configuration diagram is shown in FIG. 17. In the figure, 4 to 7,
9 is the same as shown in FIGS. 14 and 16 above, 12 is a solid laser medium having a trapezoidal cross section, 13 is the first side surface of the solid laser medium 12, and 14 is a solid laser medium. 12 is the second side surface, 15 is the solid laser medium 1
2 and 16 are the second end surfaces of the solid-state laser medium 12. Note that a plurality of semiconductor lasers 9 are arranged facing each other on the first side surface 13 and the second side surface 14.

The first side surface 13 and the second side surface 14 are provided with l', 4, which is a pumping light source and is highly reflective to the oscillation wavelength of the solid-state laser.
A dielectric multilayer film is formed that has low reflection for the oscillation wavelength of the W-body Rayleigh '9. In addition, a dielectric multilayer film is formed on the first end face 15 and the second end face 16 to provide low reflection to the oscillation wavelength of the solid-state laser. In such a configuration, the laser resonator mode 7 within the laser resonator is located between the first side surface 13 and the second side surface 14 as shown in FIG.
The laser beam travels in a zigzag pattern through the solid laser medium 12 while repeating reflections alternately. On the other hand, the emitted light from the semiconductor laser 9, which is the excitation light source, is directed toward the first side surface 13 or the second side surface 14 so that the laser resonator mode 7 traveling in a zigzag manner and its leading axis are almost lost. incident from an angle. Therefore, similarly to the edge-pumped solid-state laser shown in FIG. 15, the excitation region can be matched to the mode volume of the fundamental mode TEM among the laser resonator modes 7. However, the first aspect [
The reflectance of the highly reflective dielectric multilayer film formed on the third side surface 3 and the second side surface 14 cannot be 100% due to manufacturing precision, and is approximately 99.5% at most. Therefore, if the number of reflections is increased in an attempt to obtain high output, the loss also increases accordingly.

Furthermore, a high-efficiency mode harmonic solid-state laser resonator 1--Mass is equipped with a semiconductor laser array composed of a plurality of semiconductor lasers having the same configuration as shown in FIG. - Disclosed in Japanese Patent Application Laid-Open No. 1122180 by Maigel Heyer. This configuration diagram is shown in FIG. In the figure, 1, 4, 5.
1314 is the same as shown in FIGS. 14 and 17 above, 7 is a semiconductor laser, 18 is a semiconductor laser array composed of a plurality of semiconductor lasers 17 arranged at appropriate intervals, and 19 is a fiber lens, 20
21 is a first entrance end surface formed on the second side surface 14, and 21 is a second entrance end surface formed on the second side surface 14.

Next, the operation will be explained. The output light from the semiconductor laser 17 constituting the semiconductor laser array 18 generally has a wider spread angle in the direction perpendicular to the paper than in the direction parallel to the paper. Therefore, the fiber lens 19 converts only the direction perpendicular to the plane of the paper into a parallel light beam, and the beam diameter matches the size of the transverse mode of the solid-state laser, and the beam is made incident on the solid-state laser medium rt1. Here, the semiconductor laser array 18
The wavelength of the output light from the solid-state laser medium 1 is set to the absorption band of the solid-state laser medium 1.
If this is done, the output light from the semiconductor laser array 18 will be absorbed exponentially as it propagates in the solid-state laser medium 1, forming a population inversion having a gain at the oscillation wavelength of the solid-state laser. The population inversion at this time is the fiber lens 19
Reflecting the spatial distribution of the output light from the semiconductor laser array 18 that has passed through the semiconductor laser array 18, the semiconductor laser 17
Small in position between each. In the solid-state laser medium l in which such a population inversion is formed, the position of the first side surface 13 almost coincides with the light emission position of each semiconductor laser 17, and the first
A second mirror 5 is placed opposite to the side surface 13 of. In this case, the side surface 13 in FIG. 18, on which the output light from the semiconductor laser array 18 is incident, is non-reflective for the wavelength of the output light from the semi-quadram laser array 18, and is high for the oscillation wavelength of the solid-state laser. It has a reflective coating. The second side surface 14 is coated with a high reflection coating for the oscillation wavelength of the solid-state laser.
．． The first entrance end face 20 and the second entrance end face 21, which are the portions from which the laser beam is output to the output coupling vL5, are coated with a coating that makes them substantially non-reflective at the oscillation wavelength of the solid-state laser. By configuring the laser resonator in this way, the energy of the light emitted from the semiconductor L/-the array 18 can be coupled to the laser oscillation mode with high efficiency. Therefore, by increasing the number of semiconductor lasers constituting the semiconductor laser array 18 and increasing the number of zig-zig reflections, the oscillation output of the solid-state laser can be increased.

[Problem to be solved by the invention]

As explained above, in the conventional side optical pumping device shown in FIG. Therefore, there is a problem in that there are many parts that do not contribute to amplification of the laser oscillation mode, and the excitation efficiency is low.

In addition, in the conventional device for end-face optical pumping shown in FIG. 16, the solid-state laser for end-face optical pumping using a semiconductor laser has an excitation region of TIEM. High excitation efficiency can be obtained because it can be matched to the mode volume, but the output is often limited to about 1W at most, and it is difficult to use a higher output semiconductor laser as the excitation light source. In the so-called edge-pumped solid-state laser, there is a limit to the energy that can be used, so the output of the solid-state laser is limited, and there is a problem in that high output cannot be obtained.

Furthermore, the conventional apparatus shown in FIG. 17 or 18 has the following problems. First, in order to achieve highly efficient excitation, it is necessary to match the installation positions of the multiple semiconductor lasers that make up the semiconductor laser array and the reflection positions of the zigzag optical paths that make up the laser resonator. ．． It was difficult to adjust the mutual arrangement of the output coupling mirror 5 and the semiconductor laser array 18. Second, although the high reflection film applied to the solid-state laser medium 1 is made of a dielectric multilayer film, it is difficult to achieve a reflectance of 100% due to absorption and scattering in the multilayer film, manufacturing accuracy, etc. 99 at most
．． It is about 5%. Therefore, for each single reflection, 0
．． There is a loss of about 5%, and when the number of reflections in the zigzag optical path is increased to increase the laser oscillation output, the laser resonance reaches 3g.
There was a problem that the number of internal fires increased. Thirdly, the first entrance end surface 20 and the second entrance end surface 21, which are opposite to the end surface on which the output light from the diode par 18 enters, have
In order to output laser light to the high-reflection mirror 4 and the output coupling mirror 5, it is necessary to apply a non-reflection coating to the oscillation wavelength of the solid-state laser, and the high-reflection coating area on the second side surface 14 and the above-mentioned non-reflection coating area must be coated. There was a problem in that it had to be manufactured separately, which increased the number of manufacturing steps.

This invention was made to solve the above-mentioned problems, and although it uses a side light excitation method, it is possible to excite a solid laser medium with large energy, and the mode volume of the laser oscillation mode and the excitation The object of the present invention is to obtain a high-output and highly efficient semiconductor laser-excited solid-state laser device that has good matching with the region.

[Means to solve the problem]

The semiconductor laser pumped solid-state laser device according to the first invention includes:
A diffraction grating (transmission type diffraction grating 24 or reflection type diffraction grating 38) that diffracts the emitted light from the semiconductor laser 9 and makes it enter the solid laser medium 22 so as to match the direction in which the laser resonator mode 7 is formed. It is something that

The semiconductor laser pumped solid-state laser device according to the second invention includes:
Portions 24a, 24b, 24 having substantially parallel opposing side surfaces and anti-reflective coatings on both sides of the side surfaces.
c, 24d and a portion having at least one reflective diffraction grating 23a, 23b, 23c, 23d installed close to or in contact with the side surface are arranged alternately, and a portion is coated with the anti-reflection coating. 24a, 24b
, 24c, 24d, the reflection type diffraction grating 23a
, 23b, 23c, and 23d are arranged on the block 22[3 of the solid-state laser medium 22, and -F reflection type diffraction grating 23
At least one or more semiconductor laser arrays 2a, 2b, 2c, 2d each consisting of a plurality of semiconductor lasers 9 arranged opposite to each other, and the anti-reflection coating described above is applied. At least one rod lens 27 installed between the side surface and the semiconductor array I (2a, 2b, 2c, 2d). J27b,
27c and 27d.

(Function) In the semiconductor laser-excited solid-state laser device according to the first invention, the diffraction grating diffracts the incident light from the semiconductor laser 9 that excites the solid-state laser 1 and the medium 22, thereby changing the direction of the excitation light. Therefore, the direction of the excitation light in the solid-state laser medium 2 and the direction in which the laser resonator mode 7 is formed are as follows:
They are set in approximately the same direction, and the mode volume of laser oscillation mode 7 and the excitation region are well matched.

In the semiconductor laser pumped solid-state laser device according to the second invention, the reflective diffraction gratings 23a, 23b, 23c, and 23d diffract the incident light from the semiconductor laser 9 that pumps the solid-state laser medium 22, and change the propagation direction of the pumping light. change. Therefore, the direction of the excitation light in the solid-state laser medium 22 and the direction in which the laser resonator mode 17 is formed are set to be approximately the same direction, and the mode volume of the laser oscillation mode 7 and the excitation region are well matched.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In the explanatory diagram of the configuration of the embodiment according to the first invention shown below, the shape of the solid-state laser medium is a square prism, and the main axis direction of the square prism is the optical axis direction of the laser resonator, for the sake of simplicity. In this example, the laser resonator is configured so that explain.

FIG. 1 is a block diagram of the first embodiment of the semiconductor laser pumped solid-state laser device of the first invention, and 24 to 7 and 9 are the same as shown in FIGS. 14 and 16 above. , 22 is a solid laser medium, and 23 is a solid laser medium? f2
2, a transmission type diffraction grating formed on the first side surface 23; 25, a first surface of the solid-state laser medium 22;
2G is the second surface of the solid-state laser medium 22; 27 is the second side surface of the solid-state laser medium 22 opposite to the first side surface 23;
Reference numeral 8 denotes an opening and a drain lens arranged between the semiconductor laser array 2 and the diffraction path 7-24 so that the emitted light from the semiconductor ray 9 of the semiconductor laser array 2 enters the solid-state laser medium 22 efficiently. The grating 24 represents the O-order diffracted light of the light emitted from the semiconductor laser 9, 30 represents the 1st-order diffracted light, and 31 represents the 11th-order diffracted light.

Note that the first surface 25 and the second surface 26 are provided with a semiconductor ray
A dielectric multilayer coating is formed that is highly reflective to the excitation light from the array 2 but non-reflective to the oscillation wavelength of the solid-state laser.

Furthermore, a dielectric multilayer coating that is highly reflective to excitation light from the semiconductor laser array 2 is formed on the second side surface 27 . Here, in the semiconductor laser array 2, the bonding surface of each semiconductor laser 9 is connected to the optical axis 6 of the laser resonator.
It consists of a plurality of separate semiconductor lasers 9 arranged substantially parallel to and spaced apart from each other.

Next, the operation will be explained.

The beam 1 emitted from the semiconductor laser 9 has a larger spread angle in the direction perpendicular to the plane of the paper than the angle of spread in the direction parallel to the plane of the paper. It passes through and becomes a parallel beam of light. The substantially parallel light flux that has passed through the rot lens 28 enters the diffraction grating 24 and becomes O-order diffracted light 29, 1st-order diffracted light 30, -1st-order diffracted light 31, ±2
Generates second-order diffraction light or higher-order diffraction light. Note that whether 0th-order diffracted light, ±2nd-order diffracted light, or higher-order diffracted light is generated depends on the grating pinch of the diffraction grating 24, the wavelength λ of the emitted light from the semiconductor laser array 2 which is the excitation light source, and the refractive index of the solid-state laser medium 22. It is determined by n, the grating cross-sectional shape of the diffraction grating 24, etc. Here, diffraction grating 2
Although an example in which the lattice cross-sectional shape of No. 4 is rectangular is shown, it goes without saying that this is not necessarily limited to dirt. Furthermore, even if the cross-sectional shape of the diffraction grating 24 is rectangular, the O-th order diffracted light can be suppressed by appropriately selecting the grating pinch and the grating depth.

The 0th-order diffracted light 29 is absorbed by the solid-state laser medium 2 while undergoing absorption whose intensity is exponentially attenuated in a direction substantially perpendicular to the optical axis 6.
2, is reflected by the second side surface 27, and is absorbed again by the solid laser medium 2, whose intensity is exponentially attenuated.
Propagate and excite 2? Forms n region. Next, the first-order diffracted light 30
moves in the direction of the normal to the diffraction grating 24 and a non-zero angle θ expressed by the following equation (11).Here, the grating pitch d of the diffraction grating 24 is set so that the angle θ is close to 90°. .

θ-3I N-'λ/ nd fi
When the grating pitch d is set as described above, the first-order diffracted light 30 propagates through the solid-state laser medium 22 while undergoing absorption whose intensity is exponentially attenuated in a direction substantially parallel to the optical axis 6. The light is reflected by the surface 25 of 1 and propagates through the solid-state laser medium 22 while receiving absorption whose intensity is exponentially attenuated again to form an excitation region. Next, the 1st-order diffracted light 31 travels in a direction that is approximately symmetrical to the 1st-order diffracted light with respect to the normal to the diffraction grating 24, and undergoes absorption whose intensity attenuates exponentially in a direction approximately parallel to the optical axis 6. The laser beam propagates through the solid-state laser medium 22 while being absorbed, is reflected by the first surface 26, and is again propagated through the solid-state laser medium 22 while receiving absorption whose intensity is attenuated exponentially, forming an excitation region. Similarly, semiconductor laser array 2
The excitation light emitted from each of the plurality of semiconductor lasers 9 forming the solid-state laser medium also generates 0th-order diffraction light, 1st-order diffraction light, −1st-order diffraction light, ±2nd-order diffraction light, or higher-order diffraction light by the diffraction grating 24. By propagating through 22, an excitation region is formed. Therefore, the excitation region is formed as an overlapping region of these diffracted lights.

Note that here, the diffraction grating 24 is set to conditions that suppress the 0th order diffracted light (.

As described above, the first-order diffracted light 30 or the -first-order diffracted light 3
1 propagates in a direction substantially parallel to the optical axis 6, so the absorption length can be long, and the solid laser medium 2 of laser resonator mode 7
Since the mode volume can be made to match the mode volume in No. 2, there is an effect that the excitation efficiency can be increased.

FIG. 2 shows O-order diffracted light 29.1 in the diffraction grating 24.
Next diffraction light 30. - This is a partially enlarged view of FIG. 1 for explaining the relationship between the first-order diffracted light 31 and the relationship between the excitation region 8 and the laser resonator modulus 17 in the solid-state laser medium 22, and FIG. 2 fal is a solid-state A portion of the laser medium 22,
Fig. 2 (bl is a cross-sectional view at -A to the position ta+ in Fig. 2.
As can be seen from the overlap with i-mode 7, the diffraction grating 24
The means for forming the excitation region 8 using . Here, the mode volume of both Lely' and g2H is the high-reflection mirror 4
This is determined by the installation position and shape of the output coupling mirror 5.

Among laser resonator modes 7, 1'E Mo. Since the mode is single 1111 and there is no site lobe, it is extremely useful and desirable. In this excitation region forming means using the diffraction grating 24, a large number of semiconductor lasers can be arranged along the side surface of the solid laser medium 22 on which the diffraction grating 24 is formed, so that The laser gain portion can be significantly increased, and the excitation region 8
High pumping efficiency can be obtained by matching the desired mode volume of the laser resonator. Therefore, a semiconductor laser pumped solid-state laser device with high efficiency and gain can be obtained.

FIG. 3 is a block diagram of a second embodiment of the semiconductor laser pumped solid-state laser device of the first invention, and is a partially enlarged view of the semiconductor laser pumped solid-state laser device similar to FIG. In this embodiment, the diffraction grating 24 is not formed on the surface of the solid-state laser medium 22, and the transmission type diffraction grating 32 is formed on the surface of the solid-state laser medium 22.
It is disposed close to or in contact with the first side surface 23 of. Here, transmission type diffraction grating 3
2 and the solid laser medium 22 are matched in refractive index.

FIG. 4 is a block diagram of a third embodiment of the semiconductor laser pumped solid-state laser device of the first invention, and is a partially enlarged view of the semiconductor laser pumped solid-state laser device similar to FIG. In this embodiment, instead of the diffraction grating 24 directly formed on the surface of the solid-state laser medium 22 and the rot lens 28 having a circular cross section, a rod having a half-moon cross section and a transmission diffraction grating formed on its flat surface is used. The lens 33 is disposed close to or in contact with the first side surface 23 of the solid-state laser medium 22. Like the rod lens 28 having a circular cross section, the rod lens 33 having a semicircular cross section has refractive power only in the direction perpendicular to the plane of the paper, and converts the light emitted from the semiconductor laser 9 into a parallel light beam. Note that the refractive index is matched between the rod lens 33 on which the transmission type diffraction grating is formed and the solid laser medium 22.

Here, also in the second and third embodiments described above, the diffraction grating operates in the same manner as in the first embodiment, and the same effects as described above can be obtained.

FIG. 5 is a block diagram of a fourth embodiment of the semiconductor laser IJ-' pumping solid-state laser device of the first invention. This embodiment differs from the first embodiment shown in FIG. 1 in that a diffraction grating 34 is also formed on the second side surface 27 of the solid-state laser medium 22,
Similar to the first side surface 23 side, a circular 11'/l lens 35 and a semiconductor laser array 36 are provided, and in order to inject more excitation light from the surroundings into the solid state laser medium 22, one configuration example is shown. It shows. Note that the other configurations are the same as the first embodiment, and 37 is the diffraction grating 2.
4 or the ±1st-order diffracted light of the diffraction path 7-34.

In addition, although FIG. 5 above shows the case where the diffraction gratings 24° 34 are formed on the first side surface 23 and the second side surface 27 of the solid-state laser medium 22, it is also possible to form the diffraction gratings on the remaining two side surfaces for excitation. It may also be configured to inject light.

It goes without saying that the configurations of the second and third embodiments can be applied to the formation of the diffraction grating in the fourth embodiment shown in FIG. 5 above.

In the above embodiments, the configuration of a semiconductor laser-excited solid-state laser device using a transmission type diffraction grating was shown. Next, the configuration of an example of a semiconductor laser-excited solid-state laser device using a reflection type diffraction grating will be described.

FIG. 6 is a block diagram of a first embodiment using a reflective diffraction grating, and corresponds to the first embodiment shown in FIG. 1 above. In the figure, 38 is a reflection type diffraction grating formed on the first side surface 23 of the solid-state laser medium 22, and is coated with a dielectric multilayer film or a metal film that is highly reflective to the excitation light from the semiconductor laser array 2. It has been subjected.

The Ii nodolen lens 28 and the semiconductor laser array 2 are provided on the second side surface 27 side, and the light emitted from the semiconductor laser 9 is converted into a parallel light beam in the direction perpendicular to the plane of the paper by the rot lens 28, and then enters the solid laser medium 22. The light is then diffracted by the reflective diffraction grating 38 to form the excitation region 8. Note that the grating depth and grating pitch of the reflection type diffraction grating 38 are set to conditions that suppress the 0th order diffraction light as in the case of the transmission type diffraction grating.

FIG. 7 shows O-order diffracted light 2 in the reflection type diffraction grating 38.
9.1st-order diffracted light30. - FIG. 7(a) is a partially enlarged view of FIG. 6 for explaining the relationship between the first-order diffracted light 31 and the relationship between the excitation region 8 in the solid-state laser medium 22 and the laser resonator mode IS'7; is a 1υi plane view of a portion of the solid-state laser medium 22 at position A-8 in FIG. 7 (bl is (+) in FIG. 7). As can be seen from the overlap between the excitation region 8 and the laser resonator mode 7 in FIG. This has the effect of providing a semiconductor laser pumped solid-state laser device with high efficiency and gain as in the case of the above transmission type diffraction grating. Since the same diffraction effect can be obtained at the same depth as the amount of material, it is possible to easily manufacture diffraction gratings.

FIG. 8 is a block diagram of a second embodiment using a reflective diffraction grating, and corresponds to the second embodiment shown in FIG. 3 above. 8 is a partially enlarged view of a semiconductor laser-excited solid-state laser device similar to FIG. 7. FIG.

In this embodiment, the reflective diffraction grating 38 is not formed on the surface of the solid-state laser medium 22, but is disposed close to or in contact with the first side surface 23 of the solid-state laser medium 22. . Here, the refractive index is matched between the reflection type diffraction grating 38 and the solid laser medium 22. 2nd above
In this embodiment as well, the reflective diffraction grating 38 functions in the same manner as in the first embodiment, and the same effects as described above can be obtained.

In addition to the above effects, there is a means for diffracting the emitted light from the semiconductor laser using a diffraction grating so as to match the direction in which the laser resonator mode is formed in the solid-state Rayleigh' medium and making it enter the solid-state laser medium. According to this, there is an effect that the setting precision of each part can be relaxed.

In the above explanation, the shape of the solid-state laser medium is a square prism, the laser resonator is configured such that the main axis direction of the square prism is the optical axis direction of the laser resonator, and the excitation light source is located on the side surface of the square prism. An example has been shown in which the excitation light of the semiconductor laser is emitted from the periphery in a direction substantially perpendicular to the main axis, but the present invention is not limited to this, and as is clear from the above description. By using a diffraction grating, the emitted light from the semiconductor laser is diffracted so as to match the direction in which the laser resonator mode is formed in the solid-state laser medium, and is made to enter the solid-state laser medium. Needless to say, any configuration that forms part of the mode volume of the laser resonator is sufficient.

Further, the solid-state laser of the present invention can be used in a wide range of solid-state laser materials such as N(1: YAC, Nd: Glass).
Alternatively, Nd:YLF can be used.

Furthermore, the solid-state laser of the present invention can match the excitation region to the mode volume of the T E M oo mode, which is the lowest mode of the laser resonator, and can be made compact, making it suitable for frequency multiplication operations. There is. This embodiment is shown in FIG. In the figure, numeral 39 is a frequency multiplier inserted into the laser resonator, which can generate a laser beam with a wavelength 1/2 times the fundamental number.

Further, in the solid-state laser of the present invention, pulsed light can be generated by inserting a Q-switch 40 into the laser resonator as shown in FIG. 1O.

Next, an embodiment according to the second invention will be described.

In the explanatory diagram of the configuration of the example shown below, the shape of the solid-state laser medium is a square prism to simplify the explanation, and the laser resonance is set such that the main axis direction of the square prism is the optical axis direction of the laser resonator. The excitation light source is installed so that the excitation light of the semiconductor laser is emitted from around the sides of the square prism in a direction approximately perpendicular to the principal axis, and includes a reflective diffraction grating, a non-reflective coating, and An example will be explained in which there are four semiconductor laser arrays. It goes without saying that these numbers are not limited to four.

FIG. 11 is a block diagram of a first embodiment of a semiconductor laser pumped solid-state laser device according to the second invention. In FIG. 11, 2. lli, 2b, 2C2d are semiconductor laser arrays made up of a plurality of semiconductor lasers 9 disposed facing reflection diffraction gratings 23a, 23b, 23c23d.

22B has substantially parallel opposing side surfaces, and portions 24a, 24b that are anti-reflective coated on both sides of the side surfaces;
24c, 24d, and a reflective diffraction grating 23a installed close to or in contact with the side surfaces.

23b, 23c, and 23d are arranged alternately, and opposing reflective diffraction gratings 23a, 23b, 23c, and 23d are arranged on the antireflection-coated parts 24a, 24b, 24c, and 24d. This is a block of solid-state laser medium 22. 27a, 27
Reference numerals b, 27c and 27d designate lenses installed between the above-mentioned side surfaces coated with antireflection coating and the semiconductor laser arrays 2a, 2b, 2c, and 2d. 28L is the 0th-order diffracted light, 29L is the 1st-order diffracted light, 230L is the 11th-order diffracted light, 3
1 is an intra-cavity optical element. The above reflection type diffraction grating 23
a, 23b, 23c, and 23d are disposed close to or in contact with the surface of the block 22B of the solid-state laser medium 22, and are coated with the anti-reflection coating 24a;
24b.

It is arranged opposite to 24c and 24d. Also, the first
The semiconductor laser array 2 is formed on the surface 25 and the second surface 26.
A dielectric multilayer coating is formed that is highly reflective to excitation light from the laser beam, but substantially non-reflective to the oscillation wavelength of the solid-state laser.

The portion 24a is coated with the anti-reflection coating.

The semiconductor laser arrays 2a, 2b, 2c, and 2d arranged opposite to the semiconductor laser arrays 24b, 24c, and 24d constitute excitation light sources. These semiconductor laser arrays 2a, 2b, 2c, 2
d in the length direction? It is composed of a plurality of separate semiconductor lasers 9 whose bonding surfaces are substantially parallel and are spaced apart from each other. Below, a portion forming a pair with the semiconductor laser array 2a will be explained. The same applies to other parts. The light emitted from one of the semiconductor lasers 9 constituting the semiconductor laser array 2a has a larger spread angle in the direction perpendicular to the page than the spread angle in the direction parallel to the page. The light beam passes through the rod lens 27a, which has refractive power, and becomes a parallel beam of light. The substantially parallel light beam passing through the rod lens 27a enters the reflective diffraction grating 23a, and the 0th order diffracted light 28L,
First-order diffracted light 29L, −1st-order diffracted light 30L, ±2nd-order diffracted light, or higher-order diffracted light are generated. 0th order diffraction light,
Whether ±second-order diffraction light or higher diffraction light is generated depends on the grating pinch of the reflective diffraction grating 23a and the wavelength λ of the output light of the semiconductor laser array 2a, which is the excitation light source.
is determined by the refractive index n of the block 22B of the solid-state laser medium 22 and the grating cross-sectional shape of the reflective concave grating 23a. Here, an example is described in which the grating cross-sectional shape of the reflective diffraction grating 23a is rectangular, but it goes without saying that the cross-sectional shape is not necessarily limited to this.

Even if the cross-sectional shape of the reflective diffraction grating 23a is rectangular, the zero-order diffracted light can be suppressed by appropriately selecting the grating pinch and the grating depth. The above O-order diffracted light 28L is on the optical axis 6
Block 22['(
propagates to form an excitation region. Next, the first-order diffracted light 29L
travels in the direction of a non-zero angle θ expressed by the first equation with respect to the perpendicular to the reflective diffraction grating 23a. The grating pitch d of the reflective diffraction grating 23a is set to 9 as much as possible so that the angle θ is
The angle is set to be close to 0°.

The first-order diffracted light 29L propagates through the block 22B of the solid-state laser medium M22 while undergoing absorption whose intensity is exponentially attenuated in a direction substantially parallel to the optical axis 6, is reflected by the second surface 26, and its intensity is increased again. The light propagates through the block 22B of the solid-state laser medium i'2 while receiving exponentially attenuated absorption and forms an excitation region. Next, the first-order diffracted light 3OL travels in a direction that is approximately symmetrical with respect to the perpendicular to the reflective diffraction grating 23a, and its intensity is attenuated exponentially in a direction substantially parallel to the optical axis 6. The block 2 of the solid laser medium 22 propagates through the block 22I3 of the solid laser medium 22 while undergoing absorption, is diffracted by the reflection type diffraction grating 23b, and is again subjected to absorption whose intensity is exponentially attenuated.
2B to form an excitation region.

Similarly, the excitation light emitted from another one of the plurality of separate semiconductor lasers 9 constituting the semiconductor laser array 2a is also filtered by the reflection type diffraction grating 23a into 0th-order diffraction light, 1st-order diffraction light, −1st-order diffraction light, ±2 The block 22B of the solid-state laser medium 22 generates the next-order diffraction light or higher-order diffraction light.
An excitation region is formed by propagating the The excitation region is formed as an overlapping region of these diffracted lights. Since the first-order diffracted light 29L or the first-order diffracted light 30I7 travels in a direction substantially parallel to the optical axis 6, the absorption length can be long, and the modulus i' volume in the block 22B of the solid-state laser medium 22 in laser resonator mode 7 is This has the effect of increasing excitation efficiency.

FIG. 12 shows the 0th-order diffracted light 28I1.1st-order diffracted light 29I-1-1st-order diffracted light 30L in the reflective diffraction grating 23.
This figure shows the relationship between the excitation region 8 and the laser resonator mode 7 in the block 22B of the solid-state laser medium 22. The major advantage of this means of forming an excitation region using the reflection type diffraction grating 23 is that
The advantage is that the pump volume of the excitation light and the mode volume of the laser resonator can be controlled well. The mode volume of the laser resonator is determined by the installation positions and shapes of the high reflection mirror 4 and the output coupling mirror 5. TEMo among laser resonator modes. The mode is extremely useful and desirable since it is unimodal and has no site LJ-p. In this means for forming an excitation region using the reflection type diffraction grating 23, a large number of semiconductor lasers 1y can be arranged along the side surface of the block 2213 of the solid-state laser medium 22 on which the reflection type diffraction grating 23 is formed. , the laser gain portion of the block 22B of the solid-state laser medium 22 to be excited can be greatly increased, and high pumping efficiency can be obtained by matching the pumping region to the desired mode volume of the laser resonator. . Therefore, a structure with high efficiency and gain is obtained.

FIG. 13 shows the structure of a second embodiment of the second invention, which includes a block 22B of the solid laser medium 22 and a rod lens 27a.

Wavelength Fi32a between 27b, 27c, and 27d.

32b, 32c, and 32d are arranged.

For example, the block 22B of the solid-state laser medium f22 is N
d: The semiconductor laser array 2a when composed of a uniaxial crystal such as YLF.

Since the absorption coefficient differs depending on the polarization direction of the emitted light from 2b, 2c, and 2d, the semiconductor laser arrays 2a, 2b are arranged in the direction in which the absorption coefficient becomes larger.

Wave plates 32a, 32b, 32c are used to match the polarization directions of the emitted lights from 2c and 2d.

32d is installed.

The solid-state laser of the present invention can match the excitation region to the mode volume of the rEMoo mode, which is the lowest mode of the laser resonator, and can be made compact, so it is suitable for frequency multiplication operation.

A frequency multiplier is inserted into the laser resonator to generate 1/2 of the fundamental wave.
Can generate laser light with twice the wavelength. This multiplier is represented by an intra-resonator optical element 41 in FIG.

Furthermore, in order to generate pulsed light, a Q-switch may be used as the intra-cavity optical element 41 in FIG. 11.

〔Effect of the invention〕

As described above, according to the first invention, the light emitted from the semiconductor laser is aligned in the direction in which the laser resonator mode is formed.
Since the configuration is provided with a diffraction grating that diffracts the laser beam in a U direction and enters the solid-state laser medium, an excitation region is formed by using the diffraction grating, and a large number of semiconductor lasers are arranged around the solid-state laser medium. It becomes possible to significantly increase the laser gain part of the solid-state laser medium to be pumped, and also the direction of the pumping light in the solid-state laser medium and the direction in which the laser cavity modulus 1 is formed. can be set in approximately the same direction, and by matching the excitation region to the required mode volume of the laser resonator, high excitation efficiency can be obtained. Therefore, it is possible to provide a half-W body laser-pumped solid-state laser device with high efficiency and gain.Furthermore, according to the second invention, the side surfaces are substantially parallel to each other, and the non-reflective structure is provided on both sides of the side surfaces. At least one coated portion and a portion having a reflective diffraction grating installed close to or in contact with the side surface are alternately rewritten, and the anti-reflective coating is opposed to the portion having a reflective diffraction grating. a block of solid laser medium in which the reflective diffraction grating is disposed; at least one semiconductor laser array comprising a plurality of semiconductor lasers disposed opposite to the reflective diffraction grating; Since the structure includes at least one loft lens installed between the side surface on which the reflective coating is applied and the semiconductor laser array, An excitation region is formed by using the reflective diffraction grating provided, which makes it possible to arrange a large number of semiconductor lasers along the side surface of the block of solid-state laser medium on which the diffraction grating is formed, The laser gain fraction of the block of solid-state laser medium to be pumped can be significantly increased, and high pumping efficiencies can be obtained by matching the pump region to the desired mode volume of the laser cavity. Therefore, a structure with higher efficiency and gain can be obtained, the device can be made inexpensive, and a semiconductor laser-excited solid-state laser device can be provided in which the laser light output can be set over a wide range (with high precision).

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of a semiconductor laser pumped solid-state laser device of the first invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a semiconductor laser of the first invention. FIG. 4 is an explanatory diagram of the configuration of the second embodiment of the pumped solid-state laser device, and FIG.
FIG. 5 is an explanatory diagram of the configuration of the fourth embodiment of the semiconductor laser pumped solid-state laser device of the first invention, and FIG. FIG. 7 is a partially enlarged view of FIG. 6, FIG. 8 is an explanatory diagram of the configuration of the second embodiment using a reflective diffraction grating, and FIG. 9 shows the frequency multiplication operation. Fig. 10 is a block diagram of the operation of generating pulsed light; Fig. 11 is a block diagram of the first embodiment of the semiconductor laser pumped solid-state laser device of the second invention; Fig. 12 is a block diagram for explaining the action of the diffraction grating in this first embodiment, FIG. 13 is a block diagram of a semiconductor laser pumped solid-state laser device of this second invention, and FIG. 14 is a block diagram of a conventional semiconductor laser pumped solid-state laser device. A configuration diagram of a laser device, FIG. 15 is a cross-sectional view perpendicular to the optical axis including a solid-state laser medium, FIG. 16 is a configuration diagram of a conventional semiconductor laser pumped solid-state laser device, and FIG. 17 is a conventional semiconductor laser FIG. 18 is an explanatory diagram of the configuration of a conventional semiconductor Rayleigh pumped solid-state laser device. 2.2a-2d... Semiconductor laser array 7.
... Laser resonator mode, 9 ... Semiconductor laser, 22 ... Solid laser medium, 22I3.
... Solid laser medium block, 23a-23
d, Iko 3 B =...Reflection type diffraction grating, 2
4.32... Transmission type diffraction grating, 24a to 24d
・・・・・・Part with anti-reflection coating, 27
a~27d, 28... Rondo lens, 32a~
32d... Wave plate.

Claims (4)

[Claims] (1) A semiconductor laser that emits laser light, a solid-state laser medium that receives and amplifies the light emitted from this semiconductor laser, and a laser resonator that includes this solid-state laser medium and is installed to form a laser resonator mode. a semiconductor laser excitation solid-state laser device, comprising: a semiconductor laser excitation solid-state laser device that excites the solid-state laser medium from the surroundings with light emitted from the semiconductor laser and sends out amplified laser light; 1. A semiconductor laser pumped solid-state laser device, characterized in that a diffraction grating is provided to diffract light into the solid-state laser medium so as to match the direction in which a resonator mode is formed. (2) The semiconductor laser pumped solid-state laser device according to claim 1, wherein the diffraction grating is a reflection type diffraction grating. (3) A semiconductor laser that emits laser light, a solid-state laser medium that receives and amplifies the light emitted from this semiconductor laser, and a laser resonator that includes this solid-state laser medium and is installed to form a laser resonator mode. a semiconductor laser excitation fixed laser device that excites the solid-state laser medium from the surroundings with light emitted from the semiconductor laser and sends out amplified laser light, the fixed laser device having substantially parallel opposing side surfaces, and At least one or more portions having a non-reflective coating on both sides of the side surface and a portion having a reflective diffraction grating installed close to or in contact with the side surface are arranged alternately, and the non-reflective coating is applied to the side surface. a block of solid laser medium in which the reflective diffraction grating is disposed opposite to the reflective diffraction grating; A semiconductor laser-excited solid-state laser device comprising: a semiconductor laser array; and at least one rod lens installed between the side surface on which the anti-reflection coating is applied and the semiconductor laser array. (4) Between the side surface of the block of the solid-state laser medium and the rod lens, at least one lens is provided for aligning the polarization direction of the light emitted from the semiconductor laser array in the direction in which the absorption coefficient becomes larger. 4. A semiconductor laser-excited solid-state laser device according to claim 3, further comprising a wavelength plate.