JPH0793469B2 - Semiconductor laser pumped solid state laser device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser device that pumps a solid-state laser medium with a semiconductor laser, and more particularly to a means for guiding pumping light from the semiconductor laser to the solid-state laser medium.

[Conventional technology]

FIG. 14 is a block diagram of a semiconductor laser pumped solid-state laser device disclosed in, for example, US Pat. No. 3,624,545 issued on Nov. 30, 1971, in which 1 is a solid-state laser medium and 2 is a semiconductor. A semiconductor laser array in which a large number of lasers are arranged in an array, 3 is a reflecting cylinder, 4 is a high-reflecting mirror, 5 is an output coupling mirror, 6 is an optical axis of a laser resonator formed from the high-reflecting mirror 4 and the output coupling mirror 5. , 7 are laser resonator modes. This is a so-called side-light pumped solid-state laser device in which light emitted from a semiconductor laser array 2 in which a large number of semiconductor lasers each having an emission spectrum that substantially matches the absorption spectrum of the solid-state laser medium 1 are arrayed is used to pump the solid-state laser medium 1. Is.

Light emitted from the semiconductor laser array 2 is incident on the side surface of the solid-state laser medium 1 substantially orthogonal to the optical axis 6, part of which is absorbed, part of which is transmitted and reflected by the reflecting cylinder 3, and then again enters the solid-state laser medium 1. It forms an excitation region which is incident and can be laser-amplified. On the other hand, the laser resonator is composed of the high-reflecting mirror 4 and the output coupling mirror 5, and the 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 mode 7. The laser oscillation mode is preferably the TEM ₀₀ mode which is the basic mode among the laser resonator modes 7. Here, in order to explain the relationship between the excitation region capable of laser amplification and the laser resonator mode 7, FIG. 15 shows a sectional view perpendicular to the optical axis 6 including the solid-state laser medium 1 in FIG. In the figure, 1 to 7 are the same as those shown in FIG. 14, and 8 is an excitation region. As described above, most of the excitation energy associated with the emitted light from the semiconductor laser array 2 is given to the region of the solid-state laser medium 1 other than the region occupied by the laser resonator mode 7,
There are many parts that do not contribute to the amplification of the laser oscillation mode,
Therefore, there is a problem that the excitation efficiency becomes low.

In order to improve the above-mentioned disadvantage that there is a large difference in the size or volume of the laser oscillation mode from the excitation region 8, the light emitted from the semiconductor laser, which is the excitation light source, is made substantially parallel to the optical axis 6 of the laser resonator. A so-called end-face-pumped solid-state laser, which is arranged and pumped from an end face substantially perpendicular to the optical axis 6 of the solid-state laser medium 1, is disclosed in U.S. Pat. No. 4653056 issued March 24, 1987. This block diagram is
Shown in the figure. 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 excitation light. The divergent emitted light from the semiconductor laser 9 is collected by a lens 10 and then converted into convergent light, which passes through the high-reflecting mirror 4 and the inside of the solid-state laser medium 1 from one end face substantially perpendicular to the optical axis 6 of the solid-state laser medium 1. Will be introduced to. In order to increase the pumping efficiency, the pumping region 8 is made to match the mode volume of the TEM ₀₀ mode which is the fundamental mode in the laser resonator mode 7. As described above, in the solid-state laser of end-face light excitation using the semiconductor laser 9, the excitation region 8 is
Since it is possible to match the mode volume of the TEM ₀₀ mode, high excitation efficiency can be obtained. However,
The output of conventional semiconductor lasers is often limited to about 1 W at most, and even if a higher-power semiconductor laser is used as the excitation light source, there is a limit to the energy that can be used in so-called edge-pumped solid-state lasers. The output of the solid-state laser is limited. On the other hand, as mentioned earlier,
In a so-called side-pumped solid-state laser, more energy from the pumping light source can be transferred into the solid-state laser medium, but there is a problem in matching the pumping region and the mode volume of the TEM ₀₀ mode.

Next, in order to improve the drawbacks of the above two examples, the semiconductor laser array which is the pumping light source has a lateral optical pumping arrangement structure, and the light from the semiconductor laser array which is the pumping light source is changed by changing the configuration of the laser resonator. A solid-state laser of substantially axial alignment is disclosed in U.S. Pat. No. 4,710,940 issued Dec. 1, 1987. This block diagram is shown in FIG. In the figure, 4 to 7 and 9 are the same as those shown in FIGS. 14 and 16, 12 is a solid-state laser medium having a trapezoidal cross section, and 13 is a first solid-state laser medium 12. The side surface, 14 is the second side surface of the solid-state laser medium 12, 15 is the first end surface of the solid-state laser medium 12, and 16 is the solid-state laser medium 12.
Is the second end face of the. A plurality of semiconductor lasers 9 are arranged facing the first side surface 13 and the second side surface 14, respectively. Formed on the first side surface 13 and the second side surface 14 is a dielectric multilayer film having high reflection with respect to the oscillation wavelength of the solid-state laser but low reflection with respect to the oscillation wavelength of the semiconductor laser 9 as the excitation light source. Has been done. Further, on the first end face 15 and the second end face 16, a dielectric multilayer film having a low reflection with respect to the oscillation wavelength of the solid-state laser is formed. In such a configuration, the laser resonator mode 7 in the laser resonator zigzags in the solid laser medium 12 while being repeatedly reflected alternately on the first side surface 13 and the second side surface 14 as shown in FIG. Proceed to. On the other hand, the light emitted from the semiconductor laser 9, which is the excitation light source, is arranged on the first side surface 13 or the second side surface 13 so that the optical axis of the light emitted from the semiconductor laser 9 and the laser resonator mode 7 traveling in zigzag are substantially aligned.
Is obliquely incident on the side surface 14 of the. Therefore, the fifteenth
Similar to the edge-pumped solid-state laser shown in the figure, the pumping region can be matched to the mode volume of the TEM ₀₀ mode which is the fundamental mode in the laser resonator mode 7. However, the reflectance of the highly reflective dielectric multilayer film formed on the first side surface 13 and the second side surface 14 cannot be 100% due to manufacturing precision and the like, and is about 99.5% at most. Since each reflection receives a loss of 0.5%, there is a disadvantage in that the loss increases correspondingly when the number of reflections is increased in order to obtain a high output.

Further, a high-efficiency mode harmonic solid-state laser device equipped with a semiconductor laser array composed of a plurality of semiconductor lasers, which are semiconductor lasers as pumping light sources arranged at appropriate intervals in a configuration similar to that shown in FIG. It is disclosed in Japanese Patent Application Laid-Open No. 1-122180 by Bayer. This block diagram is shown in FIG. In the figure, 1,4,5,13,14 are the above 14th
17 is a semiconductor laser, 18 is a semiconductor laser array composed of a plurality of semiconductor lasers 17 arranged at appropriate intervals, 19 is a fiber lens, and 20 is a second lens. Reference numeral 21 denotes a first incident end surface formed on the side surface 14, and reference numeral 21 denotes a second incident end surface formed on the second side surface 14.

Next, the operation will be described. The output light from the semiconductor laser 17 that constitutes the semiconductor laser array 18 generally has a wider divergence angle in the direction perpendicular to the paper surface than the divergence angle in the direction parallel to the paper surface. Therefore, the solid-state laser medium 1 is formed by the fiber lens 19 so that only the direction perpendicular to the plane of the drawing is made into a parallel light beam, and its beam diameter is matched with the size of the transverse mode of the solid-state laser.
Incident on. If the wavelength of the output light from the semiconductor laser array 18 is made to coincide with the absorption band of the solid-state laser medium 1, the output light from the semiconductor laser array 18 is absorbed exponentially as it propagates in the solid-state laser medium 1. An inversion distribution having a gain at the oscillation wavelength of the laser is formed. The population inversion at this time is large at the light emitting position of each semiconductor laser 17 constituting the semiconductor laser array 18 reflecting the spatial distribution of the output light from the semiconductor laser array 18 that has passed through the fiber lens 19, and the position between the semiconductor lasers 17 is large. And small. Solid-state laser medium 1 in which such population inversion is formed
Within the first, the light emitting positions of the respective semiconductor lasers 17 almost coincide with the first
Position of the side surface 13 of the second side surface facing the first side surface 13
A high-reflecting mirror 4 and an output coupling mirror 5 are arranged to form a laser resonator having a zigzag optical path which is alternately reflected at 14.
Here, the side surface 13 of FIG. 18 on which the output light from the semiconductor laser array 18 is incident is non-reflective with respect to the wavelength of the output light from the semiconductor laser array 18, and is highly reflective with respect to the oscillation wavelength of the solid-state laser. It has a dichroic coating. The second side face 14 is provided with a high-reflection coating for the oscillation wavelength of the solid-state laser, and a part of the high-reflectance mirror 4 and the output coupling mirror 5 is the first incident end face 20 which is a part where the laser light is output. The second incident end face 21 is provided with a coating that is almost non-reflective with respect to the oscillation wavelength of the solid-state laser. By thus configuring the laser resonator, the energy of the light emitted from the semiconductor laser array 18 can be coupled to the laser oscillation mode with high efficiency. Therefore, the number of semiconductor lasers forming the semiconductor laser array 18 is increased,
The oscillation output of the solid-state laser can be increased by increasing the number of zigzag reflections.

[Problems to be Solved by the Invention]

As described above, in the conventional device for lateral light pumping shown in FIG. 14, most of the excitation energy accompanying the emitted light from the semiconductor laser array 2 is in the region of the solid laser medium 1 other than the region occupied by the laser resonator mode 7. Since it is given, there are many parts that do not contribute to the amplification of the laser oscillation mode, and there is a problem that the pumping efficiency is low.

Further, in the conventional device for end-face photoexcitation shown in FIG. 16, a solid-state laser for end-face photoexcitation using a semiconductor laser has an excitation region.
High pumping efficiency can be obtained because it can be matched with TEM ₀₀ mode volume.However, its output is often limited to about 1 W at most, and a semiconductor laser with higher output is used as a pumping light source. Even if it is used, there is a problem that the output of the solid-state laser is limited because the usable energy of the so-called end-face pumped solid-state laser is limited, and high output cannot be obtained.

Further, the conventional device shown in FIG. 17 or FIG. 18 has the following problems. First, in order to realize highly efficient pumping, it is necessary to match the installation positions of a plurality of semiconductor lasers forming the semiconductor laser array 18 with the reflection positions of the zigzag optical path forming the laser resonator.
It was difficult to adjust the mutual positional relationship between the output coupling mirror 5 and the semiconductor laser array 18. Secondly, the high reflection film applied to the solid-state laser medium 1 is made of a dielectric multilayer film.
The reflectance is 100 due to the absorption and scattering in the multilayer film and the production accuracy.
It is difficult to adjust the percentage to 99.5% at best. Therefore, each reflection has a loss of about 0.5%, and if the number of reflections in the zigzag optical path is increased to increase the laser oscillation output, the loss inside the laser resonator increases. Third, the first incident end face 20 facing the end face on which the output light from the diode bar 18 is incident.
The second incident end face 21 must be coated with a non-reflective coating with respect to the oscillation wavelength of the solid-state laser in order to output the laser light to the high-reflecting mirror 4 and the output coupling mirror 5.
The high reflection coating region and the non-reflection coating region of 1 have to be separately produced, and there is a problem that the number of production steps increases.

The present invention has been made to solve the above problems, and can pump a solid-state laser medium with a large amount of energy even though the lateral optical pumping method is used, and the mode volume and pumping region of the laser oscillation mode can be excited. It is an object of the present invention to obtain a high-power and high-efficiency semiconductor laser pumped solid-state laser device that is well matched with.

[Means for Solving the Problems]

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

A semiconductor laser pumped solid-state laser device according to the second invention is
Portions 24a, 24b, 24c, 24d having substantially parallel opposing side surfaces and having antireflection coating on both sides of the side surface and reflection type diffraction gratings 23a, 23b installed close to or in contact with the side surface. At least one or more portions having 23c, 23d are alternately arranged, and the reflection type diffraction gratings 23a, 23b, 23c, 23d are opposed to the portions 24a, 24b, 24c, 24d provided with the antireflection coating. At least one semiconductor laser array composed of a block 22B of the solid-state laser medium 22 in which is arranged and a plurality of semiconductor lasers 9 arranged to face the reflection type diffraction gratings 23a, 23b, 23c and 23d. 2a, 2b, 2c, 2
d, and at least one rod lens 27a, 27b, 27c, 27d installed between the side surface provided with the antireflection coating and the semiconductor laser array 2a, 2b, 2c, 2d. Is.

[Action]

In the semiconductor laser pumped solid-state laser device according to the first invention, the diffraction grating diffracts the incident light from the semiconductor laser 9 that pumps the solid-state laser medium 22 and changes the direction of the pumped light. Therefore, the direction of the pumping light in the solid-state laser medium 2 and the direction in which the laser resonator mode 7 is formed are set substantially in the same direction, and the matching between the mode volume of the laser oscillation mode 7 and the pumping region is improved.

In the semiconductor laser pumped solid-state laser device according to the second invention, the reflection type diffraction gratings 23a, 2b, 23c and 23d are the solid-state laser medium 22.
The incident light from the semiconductor laser 9 that excites the laser light is diffracted to change the propagation direction of the excitation light. Therefore, the direction of the pumping light in the solid-state laser medium 22 and the direction in which the laser resonator mode 7 is formed are set substantially in the same direction, and the matching between the mode volume of the laser oscillation mode 7 and the pumping region is improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In addition,
In the following explanatory view of the configuration of the embodiment according to the first invention, the shape of the solid-state laser medium is a quadrangular prism, and the principal axis direction of the quadratic prism is the optical axis direction of the laser resonator for the sake of simplicity. The laser resonator is configured as described above, and the excitation light source will be described as an example in which the excitation light of the semiconductor laser is emitted from the periphery of the side surface of the rectangular prism in a direction substantially perpendicular to the main axis. .

FIG. 1 is a block diagram of the first embodiment of the semiconductor laser pumped solid-state laser device of the first invention, in which 2,4 to 7,9 are the above-mentioned
14 is the same as that shown in FIGS. 14 and 16, 22 is a solid-state laser medium, 23 is a first side surface of the solid-state laser medium 22,
24 is a transmissive diffraction grating formed on the first side surface 23, 25 is the first surface of the solid-state laser medium 22, 26 is the second surface of the solid-state laser medium 22, and 27 is opposed to the first side surface 23. Solid-state laser medium 22
Is a rod lens disposed between the semiconductor laser array 2 and the diffraction grating 24 so that the emitted light of the semiconductor 9 of the semiconductor laser array 2 is efficiently incident into the solid-state laser medium 22, and 29 is a diffraction grating. The 0th order diffracted light of the light emitted from the semiconductor laser 9 by 24, 30 is the 1st order diffracted light, and 31 is the -1st order diffracted light. The first surface 25 and the second surface 26 are coated with a dielectric multilayer film which is highly reflective to the pumping light from the semiconductor laser array 2 but non-reflective to the oscillation wavelength of the solid-state laser. Has been formed. Also, the second side surface 27
Is coated with a dielectric multi-layer film that is highly reflective to the excitation light from the semiconductor laser array 2.
Here, the semiconductor laser array 2 includes each reaction body laser 9
The junction surface of is substantially parallel to the optical axis 6 of the laser resonator, and is composed of a plurality of separate semiconductor lasers 9 spaced apart from each other.

Next, the operation will be described.

The emitted light from the semiconductor laser 9 spreads in the direction perpendicular to the paper surface and is larger than the spread angle in the direction parallel to the paper surface. Therefore, the light emitted from the semiconductor laser 9 passes through the rod lens 28 having a refractive power only in the direction perpendicular to the paper surface to be parallel. Make it a luminous flux. The substantially parallel light flux that has passed through the rod lens 28 enters the diffraction grating 24, and the 0th-order diffracted light 29,
First-order diffracted light 30, negative first-order diffracted light 31, ± second-order diffracted light or higher-order diffracted light is generated. In addition, 0th order diffracted light, ±
Whether the second-order diffracted light or higher-order diffracted light is generated is determined by the grating pitch of the diffraction grating 24, the wavelength λ of the emitted light of the semiconductor laser array 2 which is the excitation light source, the refractive index n of the solid-state laser medium 22, and the grating of the diffraction grating 24. It is determined by the cross-sectional shape and the like. Here, an example in which the grating cross-section of the diffraction grating 24 is rectangular is shown, but it goes without saying that it is not necessarily limited to this. Furthermore, even if the diffraction grating 24 and the grating cross-sectional shape are rectangular, the 0th-order diffracted light can be suppressed by appropriately selecting the grating pitch and the grating depth.

The 0th-order diffracted light 29 propagates through the solid-state laser medium 22 while being absorbed in the direction substantially perpendicular to the optical axis 6 while its intensity exponentially attenuates, is reflected by the second side face 27, and its intensity is exponential again. The laser beam propagates through the solid-state laser medium 22 while receiving absorption that attenuates to form an excitation region. Next, the first-order diffracted light 30 is transmitted to the diffraction grating 24.
And a non-zero angle θ represented by the following equation (1). Here, the grating pitch d of the diffraction grating 24 is set so that the angle θ is close to 90 °.

θ = SIN ⁻¹ λ / nd (1) When the grating pitch d is set as described above, the first-order diffracted light 30 absorbs light whose intensity decreases exponentially in a direction substantially parallel to the optical axis 6. The light propagates through the solid-state laser medium 22 and is reflected by the first surface 25 while being received, and again propagates through the solid-state laser medium 22 to form an excitation region while being absorbed so that its intensity exponentially attenuates again. Next, the -1st-order diffracted light 31 travels in a direction that is substantially symmetrical to the 1st-order diffracted light with respect to the normal line of the diffraction grating 24, and absorbs its intensity exponentially decaying in a direction substantially parallel to the optical axis 6. While being received, it propagates through the solid-state laser medium 22, is reflected by the first surface 26, and again propagates through the solid-state laser medium 22 while receiving absorption whose intensity exponentially attenuates to form an excitation region.
Similarly, the pumping light emitted from each of the plurality of semiconductor lasers 9 forming the semiconductor laser array 2 is also diffracted by the diffraction grating 24 to be the 0th-order diffracted light, the 1st-order diffracted light, the -1st-order diffracted light, the ± 2nd-order diffracted light or higher-order diffracted light. Producing solid laser medium
Propagation of 22 forms an excitation region. Therefore, the excitation region is formed as an overlapping region of these diffracted lights. In addition, here, the diffraction grating 24 is set to a condition for suppressing the 0th-order diffracted light.

As described above, since the first-order diffracted light 30 or the -1st-order diffracted light 31 travels in a direction substantially parallel to the optical axis 6, the absorption length can be long, and the mode volume in the solid laser medium 22 in the laser resonator mode 7 can be Since they can be matched, there is an effect that the excitation efficiency can be increased.

FIG. 2 illustrates the relationship between the 0th-order diffracted light 29, the 1st-order diffracted light 30, and the -1st-order diffracted light 31 in the diffraction grating 24, and the relationship between the pumping region 8 and the laser resonator mode 7 in the solid-state laser medium laser medium 22. FIG. 2 is a partially enlarged view of FIG. 1 for doing so, FIG. 2 (a) is a part of the solid-state laser medium 22, and FIG. 2 (b) is a sectional view taken along the line AA in FIG. 2 (a). . Excitation region 8 and laser resonator mode 7 in FIG. 2 (b)
As can be seen from the overlap with, the means for forming the pumping region 8 using the diffraction grating 24 has the effect of making the pumping volume of the pumping light well match the mode volume of the laser resonator. Here, 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. The laser cavity mode 7, TEM ₀₀ mode, is extremely useful and desirable because it is unimodal and has no side lobes. In the excitation region forming means using this diffraction grating 24, since a large number of semiconductor lasers can be arranged along the side surface of the solid-state laser medium 22 on which the diffraction grating 24 is formed, the excitation of the solid-state laser medium 22 The laser gain part can be greatly increased, and also
A high pumping efficiency can be obtained by matching the pumping region 8 to the required mode volume of the laser cavity. Therefore, a semiconductor laser pumped solid-state laser device having 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, but the transmission-type diffraction grating 32 is arranged close to or in contact with the first side surface 23 of the solid-state laser medium 22. It was done. Here, the transmission type diffraction grating 32 and the solid-state laser medium 22 are matched in refractive index.

FIG. 4 is a constitutional view 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 formed directly on the surface of the solid-state laser medium 22 and the rod lens 28 having a circular cross section,
A rod lens 33 having a half-moon-shaped cross section and a transmission type diffraction grating formed on the flat surface is formed on the first side surface of the solid-state laser medium 22.
It is arranged close to 23 or in contact with the first side surface 23. Like the rod lens 28 having a circular cross section, the rod lens 33 having a semi-lunar cross section has a refracting power only in a direction perpendicular to the paper surface, and makes the light emitted from the semiconductor laser 9 a parallel light flux. The refractive index of the rod lens 33 on which the transmission diffraction grating is formed and the solid-state laser medium 22 are matched.

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

FIG. 5 is a block diagram of a fourth embodiment of the semiconductor laser pumped solid-state laser device of the first invention. This embodiment is similar to the first embodiment shown in FIG.
The diffraction grating 34 is also formed on the second side face 27 of the
A circular rod lens 35 and a semiconductor laser array 36 are provided similarly to the side, and one configuration example is shown for injecting more excitation light into the solid-state laser medium 22 from the surroundings. The rest of the configuration is the same as that of the first embodiment, and 37 indicates the ± first-order diffracted light of the diffraction grating 24 or the diffraction grating 34.

Further, in FIG. 5 above, the first side surface 23 of the solid-state laser medium 22 is
Although the case where the diffraction gratings 24 and 34 are formed on the second side surface 27 is shown, the diffraction grating may be formed on the remaining two side surfaces to inject the excitation light.

Needless to say, the structures of the second and third embodiments can be applied to the formation of the diffraction grating in the fourth embodiment shown in FIG.

In the above embodiments, the structure of the semiconductor laser pumped solid-state laser device using the transmission type diffraction grating was shown. Next, the structure of the embodiment of the semiconductor laser pumped solid-state laser device using the reflection type diffraction grating is shown.

FIG. 6 is a block diagram of the first embodiment using a reflection type diffraction grating, and corresponds to the first embodiment shown in FIG. In the figure, reference numeral 38 denotes a reflection type diffraction grating formed on the first side surface 23 of the solid-state laser medium 22, and a coating of a dielectric multilayer film or a metal film, which is highly reflective to the excitation light from the semiconductor laser array 2, is formed. It has been subjected. The rod lens 28 and the semiconductor laser array 2 are provided on the side of the second side surface 27, and the light emitted from the semiconductor laser 9 is converted into a parallel light beam in the direction perpendicular to the paper surface by the rod lens 28 and is incident on the solid-state laser medium 22. Then, the excitation region 8 diffracted by the reflection type diffraction grating 38 is formed. The grating depth and grating pitch of the reflection type diffraction grating 38 are 0 as in the case of the transmission type diffraction grating.
The condition is set to suppress the second-order diffracted light.

FIG. 7 shows the 0th order diffracted light 29,1 in the reflection type diffraction grating 38.
FIG. 7 is a partially enlarged view of FIG. 6 for explaining the relationship between the 30th-order diffracted light 30 and the −1st-order diffracted light 31 and the relationship between the pumping region 8 and the laser resonator mode 7 in the solid-state laser medium 22, and FIG. a) is a part of the solid-state laser medium 22, FIG. 7 (b)
FIG. 7 is a sectional view taken along the line AA in FIG. As can be seen from the overlap between the pumping region 8 and the laser resonator mode 7 in FIG. 7 (b), the means for forming the pumping region 8 using the reflection type diffraction grating 38 is the pump volume of the pumping light of the laser resonator. There is an effect that a semiconductor laser pumped solid-state laser device that can match the mode volume well and has high efficiency and high gain can be obtained as in the case of the transmission type diffraction grating. Further, since the reflection type diffraction grating 38 can obtain the same diffraction action with the depth of the grating groove which is half that of the transmission type diffraction grating, there is an effect that the diffraction grating can be easily manufactured.

FIG. 8 is a configuration diagram of a second embodiment using a reflection type diffraction grating, and corresponds to the second embodiment shown in FIG. FIG. 8 is a partially enlarged view of a semiconductor laser pumped solid-state laser device similar to FIG. 7. In this embodiment, the reflection type diffraction grating 38 is not formed on the surface of the solid-state laser medium 22, but is arranged close to or in contact with the first side surface 23 of the solid-state laser medium 22. . Where the reflective grating
The refractive index of the solid-state laser medium 22 and that of the solid-state laser medium 22 are matched. Also in the second embodiment, the reflection type diffraction grating 38 operates in the same manner as in the first embodiment, and the same effect as described above can be obtained.

In addition to the above effects, the diffraction grating diffracts the light emitted from the semiconductor laser so as to match the direction in which the laser resonator mode in the solid laser medium is formed, and makes the solid laser medium enter the solid laser medium. This has the effect of loosening the setting accuracy of each part.

In the above description, the shape of the solid-state laser medium is a quadrangular prism, the laser resonator is configured such that the principal axis direction of the quadrangular prism is the optical axis direction of the laser resonator, and the pumping light source is the side surface of the quadrangular prism. Although an example is shown in which the semiconductor laser is installed so as to be emitted from the periphery of the semiconductor laser in a direction substantially perpendicular to the main axis, the present invention is not limited to this, and as will be apparent from the above description. By using a diffraction grating for, the light emitted from the semiconductor laser is diffracted so as to be aligned with the direction in which the laser resonator mode is formed in the solid-state laser medium, and is incident on the solid-state laser medium. It goes without saying that any structure may be adopted as long as it matches the mode volume of the laser resonator.

Further, the solid-state laser of the present invention can use a wide range of solid-state laser materials such as Nd: YAG.Nd: GIass or Nd: YLF.

Further, the solid-state laser of the present invention can match the pumping region with the mode volume of the TEM ₀₀ mode, which is the lowest mode of the laser resonator, and can be downsized, which is suitable for frequency-doubling operation. This embodiment is shown in FIG. In the figure, reference numeral 39 denotes a frequency multiplier inserted in the laser resonator, which can generate a laser beam having a wavelength half the fundamental number.

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

Next, an embodiment according to the second invention will be described. In addition,
In the explanatory view of the configuration of the embodiment shown below, the shape of the solid-state laser medium is a quadrangular prism in order to simplify the description, and the laser resonator is arranged so that the principal axis direction of the quadrangular prism is the optical axis direction of the laser resonator. The pumping light source is installed so that the pumping light of the semiconductor laser is emitted from the periphery of the side surface of the rectangular prism in a direction substantially perpendicular to the main axis, and the reflection type diffraction grating, the antireflection coating part and the semiconductor laser array are arranged. 4 each
An example of the case where there are two will be described. It goes without saying that these numbers are not limited to four.

FIG. 11 is a configuration diagram of a first embodiment of a semiconductor laser pumped solid-state laser device according to the second invention. In FIG. 11, reference numerals 2a, 2b, 2c and 2d denote semiconductor laser arrays composed of a plurality of semiconductor lasers 9 arranged to face the reflection type diffraction gratings 23a, 23b, 23c and 23d. 22B has substantially parallel opposing side surfaces, and the reflection type diffraction gratings 23a, 23b, which are installed in proximity to or in contact with the side surfaces and the portions 24a, 24b, 24c, 24d which are antireflection coated on both sides of the side surface. At least one or more portions having 23c, 23d are alternately arranged, and the portions 24a, 24b, 24 to which the above antireflection coating is applied
This is a block of the solid-state laser medium 22 in which opposed reflection type diffraction gratings 23a, 23b, 23c and 23d are arranged at c and 24d. 27a, 27b, 27c,
Reference numeral 27d denotes a rod lens installed between the above-mentioned side surface provided with the 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, 30L
Is the −1st order diffracted light, and 31 is an intracavity optical element. The reflection type diffraction gratings 23a, 23b, 23c, 23d are arranged close to or in contact with the surface of the block 22B of the solid-state laser medium 22 and the portions 24a, 24b, 24 provided with the antireflection coating.
It is arranged opposite to c and 24d. The first surface 25 and the second surface 26 are made of a dielectric multilayer film which is highly reflective to the pumping light from the semiconductor laser array 2 but is substantially non-reflective to the oscillation wavelength of the solid-state laser. The coating is formed. Part 24a, 24 with anti-reflection coating
The semiconductor laser arrays 2a, 2b, 2c, 2d arranged so as to face b, 24c, 24d constitute an excitation light source. This semiconductor laser array 2a, 2b, 2c, 2d is composed of a plurality of separate semiconductor lasers 9 whose bonding surfaces are substantially parallel to each other along the length direction thereof and which are arranged at intervals. Hereinafter, a portion forming a pair with the semiconductor laser array 2a will be described.
The same applies to the other parts. Light emitted from one of the semiconductor lasers 9 constituting the semiconductor laser array 2a has a divergence angle in a direction perpendicular to the paper surface larger than a divergence angle in a direction parallel to the paper surface. Only the rod lens 27a having a refracting power is passed to form a parallel light beam. The substantially parallel light flux passing through the rod lens 27a is incident on the reflection type diffraction grating 23a and the 0th order diffracted light 28
L, 1st-order diffracted light 29L, -1st-order diffracted light 30L, ± 2nd-order diffracted light or higher-order diffracted light higher than that is generated. 0th order diffracted light, ±
Whether the second-order diffracted light or higher diffracted light is generated depends on the grating pitch of the reflection type diffraction grating 23a, the wavelength λ of the emitted light of the semiconductor laser array 2a which is the excitation light source, and the refractive index of the block 22B of the solid laser medium 22. n and the grating cross-sectional shape of the reflection type diffraction grating 23a. Here, an example in which the grating cross-sectional shape of the reflection type diffraction grating 23a is rectangular is described, but it goes without saying that it is not necessarily limited to this. Even if the reflection grating 23a has a rectangular cross section, the 0th order diffracted light can be suppressed by appropriately selecting the grating pitch and the grating depth. 0 above
The secondary diffracted light 28L propagates through the block 22B of the solid-state laser medium 22 and forms an excitation region while being absorbed in the direction substantially perpendicular to the optical axis 6 with its intensity being exponentially attenuated. Next, the first-order diffracted light 29L travels in the direction of the non-zero angle θ expressed by the first equation with the perpendicular of the reflection type diffraction grating 23a. The grating pitch d of the reflection type diffraction grating 23a is set so that the angle θ is as close to 90 ° as possible.

The first-order diffracted light 29L propagates through the block 22B of the solid-state laser medium 22 while being absorbed in the direction substantially parallel to the optical axis 6 such that its intensity exponentially attenuates, is reflected by the second surface 26, and is reflected again. Propagates through the block 22B of the solid-state laser medium 2 while receiving absorption that exponentially attenuates to form an excitation region. Next, the -1st-order diffracted light 30L travels in a direction in which the 1st-order diffracted light is almost symmetrical with respect to the perpendicular of the reflection type diffraction grating 23a,
The light propagates through the block 22B of the solid-state laser medium 22 and is diffracted by the reflection type diffraction grating 23b while being absorbed in the direction substantially parallel to the optical axis 6 so that the intensity exponentially attenuates again. Absorbing solid laser medium
Propagate through the block 22B of 22 to form an excitation region.

Similarly, the pumping light emitted from another one of the plurality of separate semiconductor lasers 9 constituting the semiconductor laser array 2a is also 0-order diffracted light, 1st-order diffracted light, -1st-order diffracted light, ± 2 by the reflection type diffraction grating 23a. An excitation region is formed by generating second-order diffracted light or higher-order diffracted light and propagating through the block 22B of the solid-state laser medium 22. The excitation region is formed as an overlapping region of these diffracted lights. First-order diffracted light
The 29L or -1st-order diffracted light 30L travels in a direction substantially parallel to the optical axis 6, so that the absorption length can be long, and the mode volume in the block 22B of the solid-state laser medium 22 in the laser resonator mode 7 can be made to substantially match. Therefore, there is an effect that the excitation efficiency can be increased.

FIG. 12 shows the 0th order diffracted light 28 in the reflection type diffraction grating 23.
A diagram for clarifying the relationship between L, first-order diffracted light 29L, and -1st-order diffracted light 30L, and a block of the solid-state laser medium 22.
22 shows the relationship between the pumping region 8 and the laser resonator mode 7 at 22B. A great advantage of the pumping region forming means using the reflection type diffraction grating 23 is that the pumping volume of the pumping light and the mode volume of the laser resonator can be well matched. 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. Among the laser cavity modes, the TEM ₀₀ mode is extremely useful and desirable because it has a single peak and no side rope. This reflective diffraction grating 23
In the means for forming the pumping region using, a large number of semiconductor lasers can be arranged along the side surface of the block 22B of the solid-state laser medium 22 on which the reflection type diffraction grating 23 is formed. The laser gain portion of block 22B of 22 can be significantly increased and high pumping efficiency can be obtained by matching the pumping region to the desired mode volume of the laser cavity. Therefore, a structure having high efficiency and high gain can be obtained.

FIG. 13 shows the configuration of the second embodiment relating to the second invention, and is a block 22 of the solid-state laser medium 22.
Wave plates 32a, 32b, between B and rod lenses 27a, 27b, 27c, 27d
32c and 32d are arranged. For example, when the block 22B of the solid-state laser medium 22 is composed of a uniaxial crystal like Nd: YLF, the semiconductor laser array 2a, 2b,
Since the absorption relationship differs depending on the polarization direction of the emitted light from 2c, 2d, the wavelength plate for adjusting the polarization direction of the emitted light from the semiconductor laser array 2a, 2b, 2c, 2d in the direction in which the absorption coefficient becomes larger. 32a, 32b, 32c, 32d are arranged.

The solid-state laser of the present invention can match the pumping region with the mode volume of the TEM ₀₀ mode, which is the lowest mode of the laser resonator, and can be made compact, so that it is suitable for frequency multiplication operation. A frequency multiplier can be inserted in the laser resonator to generate laser light having a wavelength half the fundamental wave. This multiplier is represented by the intracavity optical element 41 shown in FIG.

Further, in order to generate pulsed light, a Q-switch may be used as the intracavity optical element 41 of FIG.

〔The invention's effect〕

As described above, according to the first aspect of the invention, the diffraction grating which diffracts the emitted light from the semiconductor laser so as to match the direction in which the laser resonator mode is formed and makes it enter the solid-state laser medium is provided. , A pumping region is formed by using a diffraction grating, which makes it possible to arrange a large number of semiconductor lasers around the solid-state laser medium and to significantly increase the laser gain portion of the pumped solid-state laser medium. In addition, the direction of the pumping light in the solid-state laser medium and the direction in which the laser resonator mode is formed can be set to be approximately the same direction, and high pumping can be achieved by matching the pumping region with the required mode volume of the laser resonator. You can get efficiency. Therefore, it is possible to obtain the effect that a semiconductor laser pumped solid-state laser device having high efficiency and high gain can be provided.

According to the second aspect of the present invention, there is provided a reflection type diffraction grating, which has substantially parallel opposing side surfaces and which is provided on both sides of the side surface with anti-reflection coating and close to or in contact with the side surface. A solid laser medium block in which at least one portion having the reflection grating is disposed alternately, and the reflection type diffraction grating is arranged so as to face the portion provided with the antireflection coating; At least one or more semiconductor laser array composed of a plurality of semiconductor lasers arranged to face each other, and at least one or more installed between the side surface provided with the antireflection coating and the semiconductor laser array. Since it is configured by using the rod lens of the solid laser medium, it is possible to use a reflection type diffraction grating installed close to a pair of substantially parallel side surfaces of the block of the solid-state laser medium. A pumping region is formed, which allows a large number of semiconductor lasers to be arranged along the side surface of the block of the solid-state laser medium on which the diffraction grating is formed. It can be significantly increased and high pumping efficiency can be obtained by matching the pumping region to the desired mode volume of the laser cavity. Therefore, it is possible to obtain a structure in which the efficiency and the gain are higher, the device can be made inexpensive, and the semiconductor laser pumped solid-state laser device that can set the laser light output widely and accurately can be provided.

[Brief description 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 view of the configuration of a second embodiment of the pumping solid-state laser device, and FIG. 4 is a third view of the semiconductor laser pumping solid-state laser device of the first invention.
5 is a configuration diagram of a semiconductor laser pumped solid-state laser device according to a fourth embodiment of the present invention, and FIG. 6 is a schematic view of the first embodiment using a reflection type diffraction grating. FIG. 7 is a partially enlarged view of FIG. 6, and FIG. 8 is an explanatory view of the configuration of the second embodiment using a reflection type diffraction grating.
FIG. 9 is a block diagram of the case of performing frequency multiplication operation, FIG. 10 is a block diagram of the operation of generating pulsed light, and FIG. 11 is a first diagram of the semiconductor laser pumped solid-state laser device of the second invention. FIG. 12 is a constitutional view of an embodiment, FIG. 12 is a constitutional view for explaining the action of the diffraction grating in the first embodiment, and FIG.
Of the semiconductor laser pumped solid-state laser device of the invention of FIG.
FIG. 14 is a block diagram of a conventional semiconductor laser pumped solid-state laser device, FIG. 15 is a sectional view perpendicular to the optical axis containing a solid-state laser medium, FIG. 16 is a block diagram of a conventional semiconductor laser-pumped solid-state laser device, and FIG. FIG. 18 is an explanatory diagram of the configuration of a conventional semiconductor laser pumped solid state laser device, and FIG. 18 is an explanatory diagram of the configuration of a conventional semiconductor laser pumped solid state laser device. 2,2a to 2d ... Semiconductor laser array, 7 ... Laser resonator mode, 9 ... Semiconductor laser, 22 ... Solid laser medium,
22B ... Block of solid-state laser medium, 23a-23d, 38 ... Reflective diffraction grating, 24, 32 ... Transmission diffraction grating, 24a-24d ...
… No reflection coating, 27a ～ 27d, 28…
… Rod lens, 32a ～ 32d …… Wave plate.

Claims (4)

[Claims] 1. A semiconductor laser that emits laser light, a solid-state laser medium for receiving and amplifying the emitted light of the semiconductor laser, and a laser that includes the solid-state laser medium and is arranged to form a laser resonator mode. In the semiconductor laser pumped solid-state laser device, which comprises a resonator forming means and sends out amplified laser light by exciting the solid-state laser medium from the surroundings with the light emitted from the semiconductor laser, the emitted light from the semiconductor laser is A semiconductor laser pumped solid-state laser device comprising a diffraction grating which is diffracted so as to match the direction in which the laser resonator mode is formed and is incident on the solid-state laser medium. 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 a laser beam, a solid-state laser medium for receiving and amplifying the emitted light of the semiconductor laser, and a laser that includes the solid-state laser medium and is arranged to form a laser resonator mode. In a semiconductor laser pumped solid-state laser device that includes a resonator forming means and pumps the amplified laser light by exciting the solid-state laser medium from the surroundings with the emitted light from the semiconductor laser, And at least one or more portions each provided with an antireflection coating on both sides of the side surface and portions each having a reflection type diffraction grating installed close to or in contact with the side surface, and the antireflection coating. A block of the solid-state laser medium in which the reflection type diffraction grating is arranged so as to face the portion provided with At least one semiconductor laser array composed of a plurality of semiconductor lasers provided, and at least one rod lens provided between the side surface provided with the antireflection coating and the semiconductor laser array. A semiconductor laser pumped solid-state laser device comprising: 4. At least one unit for aligning the polarization direction of the light emitted from the semiconductor laser array between the side surface of the block of the solid-state laser medium and the rod lens so that the absorption coefficient becomes larger. A semiconductor laser pumped solid-state laser device according to claim 3, wherein the above-mentioned wave plate is provided.