WO2011027731A1

WO2011027731A1 - Planar waveguide laser device

Info

Publication number: WO2011027731A1
Application number: PCT/JP2010/064703
Authority: WO
Inventors: 武司崎村; 平野　嘉仁; 俊行安藤; 山本　修平; 拓哉高崎; 柳澤　隆行; 陽介秋野
Original assignee: 三菱電機株式会社
Priority date: 2009-09-07
Filing date: 2010-08-30
Publication date: 2011-03-10

Abstract

Disclosed is a planar waveguide laser device comprised of a solid-state laser module (100) and an excitation light source (1). The solid-state laser module (100) is comprised of a pair of main surfaces (31, 32) which are opposed in a predetermined direction, a pair of side surfaces (33, 34) provided on both sides of each main surface, a pair of end surfaces (35, 36) which are opposed at both ends in the predetermined direction, a laser medium (3) in which one side surface (33) is inclined at a predetermined taper angle with respect the other side surface (34) extending in the predetermined direction, an antireflection film (7) which is provided on the largely-spaced side of the side surfaces and which allows laser light to pass therethrough, and a total reflection film (6) provided on the portions of the side surfaces, which are not provided with the antireflection film. In the solid-state laser module (100), the laser light introduced into the laser medium through the portion of the side surfaces, which is provided with the antireflection film is transmitted within the laser medium while being reflected repeatedly by the side surfaces, and is returned by the narrowly-spaced side within the laser medium and, then, is transmitted to the antireflection film on the largely-spaced side, and is output through the antireflection film. The excitation light source (1) irradiates the laser medium with excitation light to excite the laser medium.

Description

Planar waveguide laser device

The present invention relates to a measurement device using a laser, a processing laser device, a high-power laser device suitable for a light source such as a printer or a projection television, and more particularly to a planar waveguide laser device.

For example, the shape of a solid-state laser medium used in a solid-state laser as shown in Non-Patent Document 1 below generally includes a rod type, a slab type, a disk type, a planar waveguide type, a two-dimensional waveguide type, and a fiber type. Among these, rod type, slab type, disk type, planar waveguide type, etc. introduce pumping light from the side surface or laser end face, generate gain, configure laser oscillator or laser amplifier, and obtain laser output .

Here, when high-power excitation is performed to obtain a high-power laser output, since the amplification gain in the laser medium increases, parasitic oscillation and parasitic amplification occur, and energy is consumed. Laser power and efficiency may be reduced. The cause of parasitic amplification and parasitic oscillation is that the optical path length of laser light passing through the laser medium is shorter than the optical path length of parasitic oscillation and parasitic amplified light in a laser oscillator or laser amplifier. For this reason, in general, the total reflection part in the laser medium is used as a roughened surface so that parasitic oscillation and parasitic amplification do not occur, and the propagation path length of parasitic oscillation and parasitic amplified light is shortened. May be suppressed.

However, with this configuration, it becomes impossible to reflect the laser beam to be amplified by using the roughening surface as a total reflection surface. As a result, the laser optical path in the laser medium is limited, and a long optical path length is obtained. Since it cannot be obtained, a high amplification factor cannot be obtained, and the laser output and efficiency may be lowered. Furthermore, since the amplification factor of the laser is low, parasitic oscillation and parasitic amplification generation threshold are low, and parasitic oscillation and parasitic amplification are likely to occur.

On the other hand, in the two-dimensional waveguide type or fiber type, light confinement is performed by the refractive index distribution in the two-dimensional direction of the cross section of the laser beam, and the light propagation direction is the one-dimensional direction. For this reason, since the optical path of parasitic oscillation or parasitic amplification is equal to the optical path of laser oscillation or laser amplification, there is a feature that parasitic oscillation or parasitic amplification is difficult to occur. However, since the cross-sectional area of the laser medium is small, it is difficult to introduce excitation light, and a complicated configuration is required. Therefore, there are features such as high cost and low reliability.

Generally, there is a disk type as a form using a flat plate laser medium. In the disk type, laser light is introduced from a flat plate surface, and the laser light is amplified when passing through a thin laser medium or reflecting and reciprocating. In such a case, the laser amplification gain is small because the passing distance of the laser medium is short. For this reason, the optimum output mirror reflectivity is increased in the laser oscillator. In such a case, there is a feature that the output is reduced by a slight loss in the resonator. Further, when used as an amplifier, the amplification factor is small, so that the efficiency is low, or multipath may be used for the purpose of improving the efficiency, but the configuration is complicated. Further, since the propagation length in the disk-shaped flat plate surface is longer than the thickness direction, parasitic oscillation and parasitic amplification in the flat plate surface are likely to occur. For this reason, there is a feature that it is difficult to increase the output. As described above, since the disk type is likely to cause parasitic oscillation and parasitic amplification, it is difficult to increase the output, and a complicated parasitic oscillation suppressing structure is required.

Generally, in a slab type laser medium, excitation light is introduced from the side or end face, and laser light is introduced from the end face. Further, the laser beam is output from the end surface facing the end surface to which the laser beam is introduced. In some cases, laser light propagates in a zigzag manner in the slab type laser medium to increase the optical path length. Further, by propagating in this zigzag manner, the thermal lens effect generated in the laser medium may be averaged and reduced.

However, in such a case, a region where there is no overlap between the laser beam and the laser medium is generated due to propagation in a zigzag manner. For this reason, the extraction efficiency is low. Furthermore, since the gain in a portion where energy is not extracted is high, parasitic oscillation and parasitic amplification are likely to occur. Further, there is a feature that parasitic oscillation is likely to occur in a reciprocating optical path between two opposing surfaces of the zigzag reflecting surface. As described above, the zigzag slab type is prone to parasitic oscillation and parasitic amplification, so that it is difficult to increase the output, and a complicated parasitic oscillation suppressing structure is required.

In this type of conventional high-power laser device, when the laser medium has a rod type, slab type, disk type, planar waveguide type, etc., the optical path of parasitic oscillation or parasitic amplification is higher than the optical path of laser oscillation or laser amplification. Since it is long, parasitic oscillation and parasitic amplification occur at the time of high output excitation, and there are problems such as a decrease in laser output and efficiency.
Furthermore, when the laser medium has a two-dimensional waveguide type or fiber type, since the cross-sectional area of the laser medium is small, it is difficult to introduce pumping light and a complicated configuration is required. There was a problem such as low.

The present invention has been made to solve the above-described problems, by suppressing parasitic oscillation and parasitic amplification, obtaining the longest laser amplification optical path, and performing high output excitation with a simple excitation configuration. Another object of the present invention is to provide a planar waveguide laser device that obtains high-efficiency and high-power laser output.

The present invention has a pair of main surfaces opposed along a predetermined direction, a pair of side surfaces on both sides of the main surface, and a pair of end surfaces opposed to each other in the predetermined direction, and one side surface of the pair of side surfaces is A flat plate-shaped laser medium that is inclined at a predetermined taper angle with respect to the predetermined direction so that a distance from the other side surface extending along the predetermined direction gradually increases, and a side surface distance on the pair of side surfaces An antireflection film that transmits at least the laser light provided at at least one location on the wide side, and a total reflection film that reflects the laser light provided on the pair of side surfaces other than the antireflection film. The laser light introduced into the laser medium from the part of the antireflection film on the pair of side surfaces is propagated in the laser medium while reflecting between the side surfaces, and further, on the side where the side surface spacing in the laser medium is narrow. Occasionally A flat surface comprising: a solid-state laser module that is returned and propagated to the antireflection film on the side having a larger side surface spacing and output; and an excitation light source that is excited by irradiating the laser medium with excitation light It is in a waveguide type laser device.

In the present invention, a planar waveguide laser that suppresses parasitic oscillation and parasitic amplification, obtains the longest laser amplification optical path, and obtains high-efficiency and high-power laser output by performing high-output pumping with a simple pumping configuration. An apparatus can be provided.

1 is a top view of a planar waveguide laser device according to Embodiment 1 of the present invention. FIG. FIG. 2 is a side view of the planar waveguide laser device of FIG. It is a side view of the planar waveguide type laser apparatus by Embodiment 2 of this invention. It is a side view of the planar waveguide type laser apparatus by Embodiment 3 of this invention. It is a side view of the planar waveguide type laser apparatus by Embodiment 4 of this invention. It is a side view of the planar waveguide type laser apparatus by Embodiment 5 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 6 of this invention. It is an enlarged view of the area | region C shown with the broken line of FIG. It is a top view of the planar waveguide type laser apparatus by Embodiment 7 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 8 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 9 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 10 of this invention. It is a figure for demonstrating the beam of an actual laser beam. It is a top view for demonstrating the structure of the input / output part of the laser beam of the solid-state laser module by this invention. It is a fragmentary figure which shows another example of a structure of the input / output part of the laser beam of the solid-state laser module by this invention. It is a fragmentary figure which shows another example of the structure of the input / output part of the laser beam of the solid-state laser module by this invention. It is a fragmentary figure which shows another example of the structure of the input / output part of the laser beam of the solid-state laser module by this invention. It is a partial side view which shows an example of a structure of the introduction part of the excitation light of the solid-state laser module by this invention. It is a partial side view which shows another example of a structure of the introduction part of the excitation light of the solid-state laser module by this invention. It is a partial side view which shows another example of the structure of the introduction part of the excitation light of the solid-state laser module by this invention. It is a partial side view which shows another example of the structure of the introduction part of the excitation light of the solid-state laser module by this invention. It is a partial side view which shows another example of the structure of the introduction part of the excitation light of the solid-state laser module by this invention. It is a partial side view which shows another example of the structure of the introduction part of the excitation light of the solid-state laser module by this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 11 of this invention. FIG. 25 is a side view of the planar waveguide laser device of FIG. 24 from the lower side of the drawing. It is a top view of the planar waveguide type laser apparatus by Embodiment 12 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 13 of this invention. It is a side view of the planar waveguide type laser apparatus by Embodiment 14 of this invention. It is a side view of the planar waveguide type laser apparatus by Embodiment 15 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 16 of this invention. It is a side view of the planar waveguide type laser apparatus by Embodiment 17 of this invention. It is a side view of the modification of the planar waveguide type laser apparatus by Embodiment 17 of this invention. It is a side view of the further modification of the planar waveguide type laser apparatus by this invention. It is the side view of the planar waveguide type laser device for demonstrating the subject in Embodiment 18 of this invention, and the figure which showed the heat-generation distribution of the y direction, temperature distribution, and refractive index distribution of a laser medium. FIG. 35 is a top view of the planar waveguide laser device of FIG. 34. It is a top view of the planar waveguide type laser apparatus by Embodiment 18 of this invention. It is the side view of the planar waveguide type laser apparatus by Embodiment 18 of this invention, and the figure which showed the heat-generation distribution of the y direction, temperature distribution, and refractive index distribution of a laser medium. It is a top view of the planar waveguide type laser apparatus by Embodiment 19 of this invention. It is a top view of the planar waveguide type laser apparatus by Embodiment 20 of this invention. It is the side view shown with the partial cross section of the planar waveguide type laser apparatus by Embodiment 20 of this invention. It is the figure which showed the expanded sectional view of the planar waveguide type laser apparatus by Embodiment 20 of this invention, the temperature difference of the y direction of a laser medium, and a refractive index difference. It is a top view of the planar waveguide type laser apparatus by Embodiment 21 of this invention. It is the side view shown by the partial cross section of the planar waveguide type laser apparatus by Embodiment 21 of this invention. It is the expanded sectional view of the planar waveguide type laser apparatus by Embodiment 21 of this invention, the figure which showed the temperature difference of the y direction of a laser medium, and a refractive index difference. It is a figure which shows the example of the wavelength dependence characteristic of the reflectance of the total reflection film of the planar waveguide type laser apparatus containing the solid state laser module by Embodiment 22 of this invention. It is a figure which shows another example of the wavelength dependence characteristic of the reflectance of the total reflection film of the planar waveguide type laser apparatus containing the solid state laser module by Embodiment 22 of this invention. It is a figure which shows the example of the wavelength dependence characteristic of the reflectance of the total reflection film of the planar waveguide type laser apparatus containing the solid state laser module by Embodiment 23 of this invention.

Hereinafter, a planar waveguide laser device according to the present invention will be described with reference to the drawings based on preferred embodiments. Note that the same or corresponding parts in the respective embodiments are denoted by the same reference numerals and redundant description is omitted.

Embodiment 1 FIG.
1 is a top view of a planar waveguide laser device including a solid state laser module according to Embodiment 1 of the present invention, and FIG. 2 is a side view of the planar waveguide laser device of FIG. However, the solid-state laser module 100 between the semiconductor lasers 1 serving as excitation light sources on both sides in both figures is a cross-sectional view taken along the line AA in FIG. 2, and in FIG. 2 is taken along the line BB in FIG. It is shown in a sectional view along.

1 and 2, a solid-state laser module 100 includes a laser medium 3, clads 4 a and 4 b respectively bonded to a pair of

main surfaces

31 and 32 facing the parallel of the laser medium 3, and a pair of side surfaces facing each other. A total reflection film 6 that reflects the laser light bonded to each of the

layers

33 and 34 and an antireflection film 7 that transmits the laser light provided in place of the total reflection film 6 on a part of the side surface 34 are provided. A pair of end faces 35 and 36 of the laser medium 3 facing each other in parallel introduce the excitation light 2 from the semiconductor laser 1.

As the laser medium 3, a general solid laser material can be used. For example, Nd: YAG, Nd: YLF, Nd: Glass, Nd: YVO4, Nd: GdVO4, Yb: YAG, Yb: YLF, Yb: KGW, Yb: KYW, Er: Glass, Er: YAG, Tm: YAG, Tm: YLF, Ho: YAG, Ho: YLF, Tm, Ho: YAG, Tm, Ho: YLF, Ti: Sapphire, Cr: LiSAF, etc. are used. These solid laser materials may be ceramics in addition to crystals. Moreover, glass may be sufficient. Further, a solid laser material in which an active medium not described above is added to a base material not described above may be used.

The laser medium 3 is a planar waveguide type and has a shape of a flat plate having a thin thickness in one axial direction. Here, for the sake of explanation, the thickness direction of the laser medium 3 is taken as the z axis, and the two axes in the plane of the laser medium 3 are called the x axis and the y axis as shown in FIG. 1, and the three axes are orthogonal to each other. Use a coordinate system.

The laser medium 3 has a quadrangular shape in the xy plane parallel to the

main surfaces

31 and 32. Here, the pair of opposing side surfaces 33 and 34 are not parallel, and the side surface 33 is inclined with respect to the side surface 34 along a predetermined direction at a taper angle θ1 in the xy plane. That is, the one side surface 33 is inclined at a predetermined taper angle with respect to the predetermined direction so that the interval between the one side surface 33 and the other side surface 34 extending along the predetermined direction gradually increases. A total reflection film 6 that reflects laser light is provided on the side surface 34 of the laser medium 3, and an antireflection film 7 that transmits laser light is further provided in part. On the side surface 33, a total reflection film 6 for reflecting laser light is applied to the entire surface. With this structure, as will be described later, the laser light propagates in one round-trip while being reflected between the side surfaces 33 and 34 in the laser medium 3.

The

clads

4a and 4b shown in FIG. 2 have a refractive index smaller than that of the laser medium 3, and are respectively joined to

main surfaces

31 and 32 parallel to the xy plane of the laser medium 3. The

clads

4a and 4b are configured by, for example, depositing a film made of an optical material as a raw material, or optically bonding the optical material to the laser medium 3 by optical contact or diffusion bonding. The

clads

4a and 4b may be bonded to a substrate (not shown). Further, the substrate may be bonded to a heat sink (not shown). The substrate and the heat sink may be on one side of the xy plane of the laser medium 3 or may be bonded to both sides of the two opposing surfaces. The laser medium 3, the substrate, the heat sink, and the like are bonded with a bonding material (preferably a bonding material with good thermal conductivity) (the same applies hereinafter).

The semiconductor lasers 1 on both sides are arranged close to the end faces 35 and 36 of the laser medium 3, and although not shown, a cooling heat sink is joined as necessary. The size of the semiconductor laser 1 in the x-axis direction is substantially equal to the size of the laser medium 3 in the x-axis direction, and pumping light is output substantially uniformly in the x-axis direction. The semiconductor laser 1 outputs excitation light 2. Here, the semiconductor laser 1 that outputs the excitation light 2 may be a multi-emitter semiconductor laser in which a plurality of active layers are arranged in the x-axis direction. In this case, since a plurality of LD (laser diode) lights are output from the plurality of active layers, a plurality of laser output lights (excitation light) arranged in the x-axis direction can be obtained. Further, the active layer of the semiconductor laser 1 may be a broad area LD that is wide in the x direction.

Next, the operation will be described. The excitation light 2 output from the semiconductor laser 1 enters the laser medium 3 from the end faces 35 and 36 of the laser medium 3 and is absorbed by the laser medium 3 while propagating in the y direction (corresponding to a predetermined direction). When the pumping light 2 is absorbed by the laser medium 3, a gain for the laser light is generated inside the laser medium 3. Due to the gain generated inside the laser medium 3, the passing laser beam is amplified and the laser output is increased. A laser seed light is prepared, introduced into the laser medium 3 and amplified so that it becomes a laser amplifier, and an output mirror (not shown) that reflects a part of the laser light is arranged on the laser optical axis so as to be perpendicular to the axis. By doing so, it becomes a laser oscillator. For this reason, the following description applies to both the laser oscillator and the laser amplifier unless otherwise specified.

Here, the laser incident light 8 is introduced into the laser medium 3 from the antireflection film 7 that transmits the laser light on the side surface 34. The laser incident light 8 is inclined by θin0 in the xy plane with respect to the vertical line of the antireflection film 7. Here, when the refractive index of the laser medium 3 is n, the inclination angle of the laser incident light 8 introduced into the laser medium 3 in the xy plane with respect to the vertical line of the antireflection film 7 is θin1 = Sin ⁻¹ (1 / N · Sinθin0). The laser incident light 8 is introduced with an inclination with respect to the vertical line of the side surfaces 33 and 34 in the xy plane. The laser incident light 8 that has entered the laser medium 3 is reflected by the total reflection film 6 that propagates in the laser medium and reflects the laser light applied to the side surface 34 and the side surface 33 facing the side surface 34. Since the laser incident light 8 is introduced with an inclination with respect to the vertical line of the side surfaces 33 and 34 in the xy plane, the laser light reflected by the side surface 33 does not return to the antireflection film 7 but the antireflection film on the side surface 34. 7 hits the total reflection film 6 at a position adjacent to 7 and reflects again. As described above, the laser beam propagating through the laser medium 3 is reflected by the total reflection film 6 on the side surfaces 33 and 34 while being repeatedly reflected between the side surfaces 33 and 34 as indicated by the laser reflected light 10 in FIG. Is done.

The side surface 33 is within the xy plane with respect to the side surface 34 so that the distance between the side surfaces 33 and 34 is wider at one end side where the antireflection film 7 of the side surface 34 is applied than at the other end side of the side surface 34. Inclination angle (taper angle) θ1 is inclined. For this reason, every time the laser beam incident from the antireflection film 7 is reflected by the side surface 33, the sum of the incident angle and the reflection angle at the side surface 34 of the laser reflected light 10 is reduced by 2θ1. Therefore, the laser reflected light 10 is repeatedly reflected while the interval between the reflection positions of the laser reflected light 10 on the side surfaces 33 and 34 is narrowed, and the reflection angle at the side surface 34 approaches 0, that is, perpendicular to the side surface 34. .

When the reflection angle at the side surface 34 becomes vertical, the laser reflected light 10 is folded back within the laser medium 3 by the taper angle θ1 of the side surface 33. The reflected laser reflected light 10 is repeatedly reflected between the side surfaces 33 and 34 by the total reflection film 6 again. In the return path, the sum of the incident angle and the reflection angle at the side surface 34 increases 2θ1 each time the side surface 33 reflects. Then, the laser reflected light 10 is propagated while increasing the interval between the reflection positions of the laser reflected light 10 on the side surfaces 33 and 34. In this way, the return path is finally output as the laser output light 9 from the antireflection film 7 on the side surface 34 while passing through the optical path substantially the same as the forward path.

Here, the angle in the xy plane of the laser incident light 8 introduced from the antireflection film 7 with respect to the vertical line of the antireflection film 7 is θin1, and the refractive index of the laser medium 3 is n. At this time, the maximum value of the internal incident angle θin1 of the laser incident light 8 is equal to the internal total reflection angle and θin1max = Sin ⁻¹ (1 / n). For example, when the laser medium 3 is Nd: YAG, the maximum internal incident angle θin1max = 33.3 degrees. Here, if the number of reflections per side surface (33, 34) on one side in the laser medium 3 is m, the inclination angle θ1 of the side surface 33 with respect to the side surface 34 is θ1≈θin1 / (2 (m−1)). An angle satisfying (≈: substantially equal) is set. For example, if the laser medium is Nd: YAG, the internal incident angle of the laser beam is the maximum angle θin1max, and the number of reflections is 10, then θ1≈1.85 degrees. In order to improve the beam overlap efficiency in the laser medium 3, the incident angle of the laser incident light 8 should be small. In addition, it is better that the number of reflections m is larger. For this reason, for example, when the internal incident angle θin1 of the laser incident light 8 is 5 degrees and the number of reflections is 20, the inclination is θ1≈0.13 degrees.

As described above, the inclination angle θ1 between the side surfaces 33 and 34 depends on the length in the y direction in the xy plane of the laser medium 3, the width in the x direction, the beam width w of the laser light, the width of the antireflection film 7, and the like. The wrap efficiency is set to be high and the number of reflections is increased. As described above, such an angle is mainly set to an inclination angle θ1 <2 degrees between the side surfaces 33 and 34.

As described above, since the inclination angle between the side surfaces 33 and 34 is set to θ1, the interval at which the laser beam is reflected by the side surface 33 or the side surface 34 in the forward path becomes shorter as the reflection is repeated. For this reason, the beam overlap efficiency between the laser medium 3 and the laser light is increased. Further, near the turning point of the laser beam, the laser beam passes many times through the adjacent points, so that the beam overlap efficiency is higher, and as a result, the extraction efficiency of the laser is increased, resulting in high efficiency and high output. Laser light is obtained.

1 and FIGS. 7 to 12, the main axis of the laser beam is displayed. In practice, however, the laser beam is introduced from the antireflection film 7 with a wide beam as shown in FIG.

According to this configuration, the optical path length of the laser light (laser reflected light 10) in the laser medium 3 can be maximized, so that there is a feature that parasitic oscillation and parasitic amplification are difficult to occur. Since the side surfaces 33 and 34 are inclined at an angle θ1, there is no optical path that circulates between the two opposing surfaces. For this reason, the optical path in the laser medium 3 having the longest parasitic oscillation or parasitic amplified light is the same optical path as the laser reflected light 10 from the vicinity of the antireflection film 7 on the side surface 34. In general, since the optical path length of parasitic oscillation and parasitic amplification light is longer than the optical path of laser light, when a large gain is generated with an increase in excitation output, extraction of energy due to parasitic oscillation and parasitic amplification becomes large, and laser output power is increased. Incurs efficiency loss. On the other hand, in this configuration, the longest optical path of parasitic oscillation and parasitic amplification is substantially the same as the laser reflected light optical path, so that even when the gain increases as the pumping output increases, the amplification of the laser light increases as well. Therefore, the amplification factor of the laser beam is not exceeded. For this reason, high-efficiency and high-power laser light can be obtained even during high-power excitation.

Since the forward path and the return path of the laser beam are substantially the same, separation using the polarization of the laser beam can be performed using the separation means 50 as shown in FIG. The separating means 50 may transmit the laser incident light 8 and reflect and separate the laser output light 9. Alternatively, the separating means 50 may reflect the laser incident light 8 and transmit the laser output light 9 to be separated. You may do. The separating means 50 can be composed of a polarizer 51 and a quarter wavelength plate 52 as shown in FIG. 15, for example. The linearly polarized laser incident light 8 is circularly polarized by the quarter wavelength plate 52 and introduced into the laser medium 3. When the laser incident light 8 is output, it passes through the quarter-wave plate 52 again, so that the laser output light 9 becomes a polarization direction of linearly polarized light whose polarization direction is orthogonal to the laser incident light 8. For this reason, it becomes separable by the polarizer 51.

Further, as shown in FIG. 16, the separating means 50 may be constituted by an isolator 54. For example, after passing through an isolator 54 including a polarizer 51 and a 45 degree Faraday rotator 53, laser light is introduced into the laser medium 3. The laser light amplified by reciprocating in the laser medium 3 exits the laser medium 3 and passes through the 45 degree Faraday rotator 53 again. Since the polarization of the laser light that has passed through the Faraday rotator is rotated by 90 degrees with respect to the incident light, it is separated from the incident light by the polarizer. When incident light passes through the polarizer, the output light is reflected by the polarizer, and when incident light is reflected by the polarizer, the output light passes through the polarizer. Further, the laser light introduced into the laser medium 3 becomes linearly polarized light inclined by 45 degrees by the 45 degree Faraday rotator 53.

Further, as shown in FIG. 17, a half-wave plate 55 may be further disposed between the 45-degree Faraday rotator 53 and the laser medium 3 in the configuration of FIG. With the half-wave plate 55, the linearly polarized light inclined at 45 degrees can be converted into linearly polarized light that is parallel or orthogonal to the flat plate surface (main surface) of the laser medium 3. Since the half-wave plate is reversible, the incident light before passing through the half-wave plate and the output light passing through the half-wave plate 55 have the same polarization direction and a polarization direction inclined by 45 degrees. . For this reason, polarization separation can be performed by the isolator 54 as in the case where the half-wave plate 55 is not disposed. As described above, since the linearly polarized light is parallel or orthogonal to the main surface of the laser medium 3, for example, even when the laser medium 3 has different gains or different amplification wavelengths with respect to different polarization directions, Can be amplified.

Thus, by using the separating means 50, it is possible to separate the laser incident light and the laser output light which are substantially the same optical path. Such separation can be used in both laser oscillator and laser amplification configurations, but is particularly effective when used as a laser amplifier.

When the total reflection film 6 is used as a laser oscillator, a high reflectance is set with respect to the wavelength for laser oscillation. For example, when the active medium of the laser medium 3 is Nd, there are gains in the 0.9 μm band, 1.06 μm band, and 1.3 μm band, and the 1.06 μm band, 1.3 μm band, The 0.9 μm band. Here, when it is desired to obtain laser oscillation in the 0.9 μm band, these wavelengths have transmission characteristics so that lasers with high gain in the 1.0 μm band and 1.3 μm band do not oscillate. The desired laser oscillation light in the 0.9 μm band can be obtained by giving total reflection characteristics to the wavelength to be performed, in this case, the 0.9 μm band.

As described above, the total reflection film 6 may have total reflection characteristics with respect to a wavelength band in which laser oscillation is desired, and may have transmission characteristics with respect to other gain wavelengths. With this configuration, there is a feature that laser oscillation light having a desired wavelength can be obtained. Similarly, even when used as a laser amplifier, it may be totally reflected at the wavelength of the laser beam to be amplified and may have transmission characteristics for other wavelengths. By configuring in this way, it is possible to amplify a desired wavelength at which the laser medium 3 has gain. For this reason, there is no extraction of energy by parasitic amplification at other wavelengths, and a high-efficiency, high-power laser amplifier can be obtained.

FIG. 2 is a side view of the planar waveguide laser device including the solid state laser module of FIG. The pumping light 2 output from the semiconductor laser 1 is incident on the laser medium 3 from one end face 35 of both end faces 35 and 36 in the propagation direction of the laser light traveling while reflecting between the side faces of the laser medium 3, and is in the y direction. And is absorbed by the laser medium 3 while propagating to. The excitation light 2 propagates while spreading, but is reflected by the

clads

4a and 4b having a refractive index lower than that of the laser medium 3, so that it is confined by the

clads

4a and 4b facing each other in the z direction and propagates in the y direction. Similarly, since the laser light incident from the antireflection film 7 is reflected by the

clads

4a and 4b in the z direction, it is confined by the

clads

4a and 4b in the z direction and propagated in the xy plane. Strictly speaking, the propagation direction of the laser light is shifted from the y-axis defined as a predetermined direction because one of the side surfaces is inclined, but here the propagation direction is the same as the y-axis.

Here, a substrate (not shown) may be bonded to the outside of the

clads

4a and 4b. Thus, rigidity can be improved by joining a board | substrate. Further, a heat sink (not shown) may be disposed outside the

clads

4a and 4b or outside the substrate. By arranging the heat sink in this way, the temperature rise of the laser medium can be suppressed, so that high output excitation is possible and high output laser light can be obtained. In addition, when the laser medium 3 has a quasi-3 level, a quasi-4 level, and a 3 level, the gain decreases due to the temperature rise, and therefore it is important to reduce the temperature rise for high efficiency. In this way, by joining the heat sink directly to the

clads

4a and 4b to reduce the thermal resistance and to suppress the temperature rise of the laser medium 3, it is possible to obtain a laser beam with high efficiency and high output.

Embodiment 2. FIG.
3 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 2 of the present invention, viewed from the same direction as FIG. The configuration viewed from above is basically the same as that of FIG. The first cladding 20 is disposed on the xy plane of the laser medium 3, that is, the

main surfaces

31 and 32, respectively, and the

second claddings

4 a and 4 b are disposed outside the first cladding 20. . Here, each refractive index of the first cladding 20 is lower than the refractive index of the laser medium 3, and the refractive indexes of the

second claddings

4 a and 4 b are lower than the refractive index of the first cladding 20. . The pumping light 2 is confined in the z direction between the opposing

second claddings

4a and 4b, and propagates through the combined portion of the laser medium 3 and the first cladding 20 on both sides thereof. On the other hand, since the laser beam is configured to be reflected by the first clad 20, it propagates through the laser medium 3.

Due to the above-described configuration, the end surfaces 35a and 36a on both sides of the laser beam propagation direction of the solid-state laser module 100 are combined with the laser medium 3 and the first cladding 20 above and below the laser medium 3. It becomes the end face. For this reason, since the end surface which introduces the excitation light 2 has a large area, the introduction of the excitation light 2 is facilitated. FIG. 3 shows a configuration example using the single-layer semiconductor laser 1, but a stack LD 60 in which semiconductor lasers are stacked in the z direction can be used as shown in FIG. Thus, since the introduction surface of the excitation light 2 can be widened, excitation from the side surface can be easily performed, and a high-output excitation light source such as a stack LD can also be used. Here, the excitation light 2 propagating through the first clad 20 and the laser medium 3 is absorbed when passing through the laser medium 3, and propagates without being absorbed by the first clad 20. With this configuration, high-power excitation can be easily performed, so that high-power laser light can be easily obtained.

The high-power pumping light source (semiconductor laser 1) includes a broad area LD, an array LD, a stack LD, a single mode fiber, a multimode fiber, a large core fiber, a bundle fiber, and a fiber in which these fibers are arranged in the x direction. An array or the like can be used. In addition to the configuration in which these excitation light sources are directly excited close to the side surfaces 33 and 34 of the laser medium 3, the excitation light 2 is condensed by the lens 61 as shown in FIG. It may be introduced from 36a). By configuring in this way, the beam diameter and divergence angle of the excitation light 2 can be arbitrarily adjusted, so that the angle can be adjusted to reflect by the clad. For this reason, since the excitation light can be absorbed by the laser medium 3 with high efficiency, high-efficiency and high-power laser light can be obtained.

Further, as shown in FIG. 20, the beam diameter and divergence angle of the excitation light 2 may be adjusted by a lens group 62 including a plurality of lenses 61. Such a plurality of lenses 61 can minimize the spread of the excitation light due to the aberration, so that the excitation light can be introduced from the end face with higher efficiency. For this reason, high-efficiency and high-power laser light can be obtained.

Further, as shown in FIG. 21, the excitation light 2 output from the stack LD 60 may be collimated by the microlens array 63 and then collectively collected by the lens 61. With such a configuration, the pumping light 2 with higher output can be introduced into the laser medium 3, so that laser light with higher output can be obtained.

Also, as shown in FIG. 22, the pump light 2 that has been collimated is introduced from the wide surface of the tapered slab waveguide 64 and output from the narrow surface, thereby reducing the cross-sectional area. 2 may be used. With such a configuration, the pumping light 2 with higher output can be introduced into the laser medium 3, so that laser light with higher output can be obtained.

Further, as shown in FIG. 23, excitation light 2 having a large divergence angle is introduced from a narrow surface of a tapered slab waveguide 64 and output from a wide surface, thereby reducing the divergence angle. Light 2 may be used. With this configuration, the excitation light 2 can be adjusted to an angle that can be reflected by the clad 20. For this reason, since the excitation light can be absorbed by the laser medium 3 with high efficiency, high-efficiency and high-power laser light can be obtained.

Embodiment 3 FIG.
4 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 3 of the present invention, viewed from the same direction as FIG. The configuration viewed from above is basically the same as that of FIG. The first clad 20 is disposed on one side of the xy plane of the laser medium 3, that is, the main surface 31, and the second clad 4 a is disposed outside the first clad 20. In addition, the second clad 4 b is disposed on the main surface 32 of the laser medium 3 opposite to the first clad 20. With this configuration, the excitation light 2 propagates between the laser medium 3 and the first cladding 20, and the laser light propagates through the laser medium 3.

Further, since the pumping light 2 can be introduced from the end face where the first clad 20 and the laser medium 3 are combined, the end face is enlarged, so that high-power pumping can be easily performed, and high-power laser light can be easily obtained. . Furthermore, the temperature rise of the laser medium 3 can be reduced by bonding a heat sink (not shown) to the lower surface of the second cladding 4b. As described above, since the second cladding 4b is directly bonded to the heat sink without sandwiching materials such as the first cladding 20 and the substrate, the thermal resistance can be remarkably lowered, and the temperature rise of the laser medium 3 can be reduced. Can be suppressed. For this reason, a laser beam with higher efficiency and higher output can be obtained.

Embodiment 4 FIG.
5 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 4 of the present invention, viewed from the same direction as FIG. The configuration viewed from above is basically the same as that of FIG. Here, as an example, the first clad 20 is disposed on one surface of the xy plane of the laser medium 3, that is, the main surface 31, as shown in FIG. 4, and the second clad 4 a is disposed outside the first clad 20. In this example, the second clad 4b is disposed on the main surface 32 opposite to the first clad 20 of the laser medium 3. In addition, as shown in FIG. 2, you may apply to the structure which joins the 2nd clads 4a and 4b on the

main surfaces

31 and 32 of the laser medium 3, respectively. Furthermore, you may arrange | position the board | substrate and heat sink which are not shown in figure. Further, as shown in FIG. 3, the present invention may be applied to a configuration in which the first clad 20 is disposed on the

main surfaces

31 and 32 of the laser medium 3. Furthermore, you may arrange | position the board | substrate and heat sink which are not shown in figure.

In this embodiment, among the end faces 35a and 36a at both ends in the predetermined direction (y-axis direction) of the solid-state laser module 100, at least the end face of the laser medium 3 for introducing the excitation light 2 and the first clad 20 are yz. It is configured to be inclined in a plane (a plane perpendicular to the

main surfaces

31 and 32 of the laser medium 3 and along the predetermined direction). The excitation light 2 is introduced from the end faces 35a and 36a and is absorbed when passing through the laser medium 3 while propagating between the

second claddings

4a and 4b. Here, since the end surfaces 35a and 36a are inclined in the yz plane, the two

end surfaces

35a and 36a facing each other and the laser medium 3, or between the end surfaces 35a and 36a and the first cladding 20, or the end surface 35a. , 36a and the second clad 4a, 4b can be eliminated by a parasitic oscillation path confined by total reflection. As described above, since the end faces 35a and 36a are inclined, there is no parasitic oscillation in the yz plane and the parasitic amplification path length can be shortened. Therefore, energy extraction by parasitic oscillation and parasitic amplification can be performed during high output excitation. Since it is small and gain reduction is small, a high-power laser beam can be obtained.

Embodiment 5 FIG.
6 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 5 of the present invention, viewed from the same direction as FIG. The configuration viewed from above is basically the same as that of FIG. FIG. 6 shows a case where the present invention is applied to the configuration shown in FIG. 4 as an example, as in FIG. The configuration of the solid-state laser module 100 is the same as that of FIG. 5, but the position of the semiconductor laser 1 for introducing the pumping light 2 is different. Note that, similarly to the fourth embodiment, the present invention can be applied to the configurations shown in FIGS. Further, a substrate or a heat sink may be arranged.

As in the fourth embodiment, of the end faces 35a and 36a of the solid-state laser module 100, at least the laser medium 3 that reflects the pumping light 2 and the end face of the first clad 20 are inclined in the yz plane. Yes. The semiconductor laser 1 is arranged so as to introduce the excitation light 2 from the xy plane of the second cladding 4a (the outermost surface of the solid-state laser module 100). The excitation light 2 introduced from the xy plane of the first cladding 4a is reflected by the inclined end surface. The reflected excitation light 2 propagates through the laser medium 3 and the second cladding 4a and is absorbed when passing through the laser medium 3 while propagating. Since the excitation light 2 is thus introduced from the xy plane and reflected by the inclined end face, the inclination angle of the end face can be greatly inclined. For example, the angle can be 45 degrees. Since the inclination angle is increased to about 45 degrees in this way, when the spontaneous emission light generated in the laser medium 3 is totally reflected by the end face, it is not totally reflected by the

second claddings

4a and 4b but is transmitted. For this reason, parasitic oscillation does not occur, and the parasitic amplification path cannot reciprocate the laser medium 3 once. Therefore, even when a higher pumping power is introduced, extraction of energy due to parasitic oscillation or parasitic amplification is small, and gain reduction is small, so that high-power laser light can be obtained.

Embodiment 6 FIG.
FIG. 7 is a top view of a planar waveguide laser device including a solid-state laser module according to Embodiment 6 of the present invention. FIG. 8 is an enlarged view of a region C indicated by a broken line in FIG. 7, and the scale in the y-axis direction is enlarged. In the solid-state laser module 100 of FIG. 7, the positions of the side surface 33 provided with the inclination angle θ1 and the side surface 34 extending along a predetermined direction (y-axis direction) are interchanged as compared with the module 100 of FIG. An antireflection film 7 is provided on a part of the side having a wide side interval. The laser reflected light 10 incident on the laser medium 3 from the antireflection film 7 is repeatedly reflected between the side surfaces 33 and 34 facing each other, so that the reflection angle approaches perpendicular to the side surface. The incident angle of the laser incident light 8 on the antireflection film 7 is adjusted so that the incident angle of the laser reflected light 10 immediately before turning back to the side surface 33 or the side surface 34 is not 0, that is, the incident light is not perpendicular to the side surface. By doing so, it is possible to prevent the optical paths from overlapping on the forward path and the return path.

Here, as shown in FIG. 8, when the sum of the incident angle and the reflection angle at the side surface 34 and the side surface 33 of the laser reflected light 10 at the time of turning is θ1, the optical path is inverted between the forward path and the return path. With this configuration, the laser medium 3 that does not pass in the forward path can pass through the return path, so that the beam overlap efficiency is improved, the efficiency of the laser oscillator and the laser amplifier is improved, and the high output laser Light is obtained. In addition, since energy can be extracted efficiently with laser light, the gain remaining in the laser medium 3 is reduced, so that parasitic oscillation and parasitic amplification are less likely to occur. For this reason, it is possible to perform excitation with higher output, and it is possible to obtain laser light with higher output.

According to this configuration, since the forward path and the return path of the laser reflected light 10 in the laser medium 3 are not the same, the optical paths of the laser incident light 8 and the laser output light 9 are not the same. For this reason, since the laser incident light 8 and the laser output light 9 are spatially easily separated, it is not necessary to use a polarization separation means. For this reason, it is possible to reduce the number of components, particularly in a laser amplifier, and the reliability is also improved.

Embodiment 7 FIG.
FIG. 9 is a top view of a planar waveguide laser device including a solid-state laser module according to Embodiment 7 of the present invention. In the solid-state laser module 100 of FIG. 9, the antireflection film 7 that transmits the laser light is provided on a part of the side 33 on the side where the side surface interval is wide, and the other part reflects the laser light and emits the excitation light 2. A narrow-band reflective film 30 is provided for transmission. A narrow band reflecting film 30 is provided on the entire side surface 34. Two pairs of semiconductor lasers 1 are also provided on the side surface side. As a result, the excitation light 2 is introduced not only from the end faces 35 and 36 of the laser medium 3 but also from the side faces 33 and 34.

For example, when the laser medium is Nd: YAG, the narrow-band reflecting film 30 is designed to reflect the 1064 nm laser beam and transmit the 808 nm or 880 nm excitation light 2. A film having such characteristics can be manufactured by laminating dielectric films. Thus, since it was set as the structure which pumps from four directions of the xy plane of the laser medium 3, higher output pumping is possible and a higher output laser beam can be obtained.

Embodiment 8 FIG.
10 is a top view of a planar waveguide laser device including a solid-state laser module according to Embodiment 8 of the present invention. In the solid-state laser module 100 of FIG. 10, the antireflection film 7 a is disposed on a part of the side surface 34 facing the antireflection film 7 on the side surface 33. The antireflection film 7a is a film that transmits laser light. Laser light introduced from the antireflection film 7 into the laser medium 3 propagates while being reflected between the side surfaces 33 and 34. Here, the angle of the laser incident light 8 is adjusted so that the same optical path is not used in the forward path and the return path. For this reason, the laser beam propagating along the return path is not output from the antireflection film 7 but is output from the antireflection film 7 a on the opposite side surface 34.

As described above, since the positions of the laser incident light 8 and the laser output light 9 are separated, in the case of a laser amplifier, it is easy to separate the laser incident light and the laser output light. In the case of a laser oscillator, the laser output light 9 that has been amplified through the laser medium 3 can be input to another laser medium 3 or the solid-state laser module 100 for further amplification. As a result, a plurality of laser media or solid-state laser modules can be easily arranged in the resonator of one laser oscillator, and higher output laser light can be obtained.

Embodiment 9 FIG.
FIG. 11 is a top view of a solid-state laser module of a planar waveguide laser device according to Embodiment 9 of the present invention. The pumping light 2 used in the solid-state laser module 100 in FIG. 11 is, for example, light obtained by collimating fiber output light with a collimating lens (both not shown). The pumping light 2 is generally manufactured by coupling a semiconductor laser beam to a fiber. Alternatively, the output of fiber laser light (not shown) may be used. The excitation light 2 and the laser incident light 8 are introduced from the antireflection film 7 of the laser medium 3 through substantially the same optical path.

The excitation light 2 incident on the laser medium 3 through the antireflection film 7 propagates between the side surfaces 33 and 34 facing each other in the same manner as the laser light and is folded back in the laser medium 3. By configuring in this way, the propagation optical path of the pumping light 2 in the laser medium 3 can be made long, so that the pumping light 2 can be absorbed by the laser medium 3 with high efficiency and with high efficiency and high output. Laser beam can be obtained. Here, when the laser active medium is a quasi-3 level, a quasi-4 level, or a 3 level, it absorbs the laser beam when it is not excited because of the lower level absorption. For this reason, high-density excitation is required to generate a gain for the laser light in the laser medium 3. In other words, when the laser medium 3 contains a large amount of active medium, the high-power excitation light 2 is necessary to generate a gain for the laser light. When the number of active media in the laser medium 3 is small, the excitation output for generating a gain for the laser light may be small.

On the other hand, when the laser medium is small, that is, when the active medium is a low-concentration laser medium 3, the absorption coefficient of the excitation light 2 also decreases. Therefore, in order to keep the absorption rate constant, it is necessary to increase the absorption length. There is. According to the said structure, since the excitation light 2 reciprocates between the side surfaces which have the inclined side surface, absorption length is long. For this reason, even when a low-concentration laser medium 3 is used, a high absorption rate of the excitation light 2 can be obtained. As described above, since the low-concentration laser medium 3 is used, the loss of the pumping light 2 due to lower level absorption is small, and high-efficiency and high-power laser light is obtained. In addition, since the low-concentration laser medium 3 has a small number of active media that generate gain, the gain for the laser light is small. However, in the above configuration, the laser light is reciprocally propagated between the side surfaces having the inclined side surfaces. Long propagation length. For this reason, even when the gain of the laser medium 3 per unit length is small, high-efficiency and high-power laser light can be obtained.

Embodiment 10 FIG.
12 is a top view of a planar waveguide laser device including a solid-state laser module according to Embodiment 10 of the present invention. In the solid-state laser module 100 of FIG. 12, the laser medium 3 is not rectangular, and the side surface 33 is angled in the xy plane with respect to the portion where the antireflection film 7 is provided and the portion where the total reflection film 6 is provided. (Sloped). Here, the portion provided with the antireflection film 7 on the side surface 33 has an angle so that the laser incident light and the laser output light of the laser reflected light 10 having the same optical path in the reciprocating optical path are perpendicular to the antireflection film 7. It is attached.

Further, the wavelength conversion element 40 is disposed outside the laser medium 3 and close to the antireflection film 7. The wavelength conversion element 40 is a nonlinear optical material, and may be a nonlinear optical material such as periodic polarization inversion LuNb ₃ (PPLN) or LBO, for example. An incident film 42 is provided on the input side, and an output film 41 is provided on the output side on the end faces of both ends of the wavelength conversion element 40 in the propagation direction of laser light or the like. The output film 41 exhibits reflection characteristics with respect to laser light having a wavelength amplified by the laser medium 3, and exhibits transmission characteristics with respect to wavelength converted light. Further, the incident film 42 on the antireflection film 7 side also shows transmission characteristics with respect to the wavelength of the laser light and the wavelength converted light. With this configuration, the laser light is confined by the reciprocating optical path in the output film 41 and the laser medium 3. When the laser light passes through the wavelength conversion element 40, the wavelength is converted, and the laser light amplified by the laser medium 3 and the wavelength conversion laser light 43 of other wavelengths are obtained. The wavelength conversion laser beam 43 is reflected by the incident film 42 and transmitted through the output film 41 to be output.

In this way, for example, in the laser resonator, the wavelength conversion element 40 is arranged in combination with the laser medium 3 having the above-described configuration to obtain an internal wavelength conversion method. Since the laser medium 3 has a long reciprocal optical path length and no parasitic oscillation or parasitic amplification occurs, high-power excitation is possible, and high-efficiency and high-power laser light can be obtained. Further, laser light that has been wavelength-converted by the internal wavelength conversion method is output, and the laser light that has not been converted is again propagated back and forth through the laser medium 3 and amplified. For this reason, highly efficient and high output wavelength conversion output can be obtained. Here, the wavelength conversion may be the generation of the second harmonic that makes the wavelength of the laser light ½, or the generation of the third harmonic that makes the wavelength １／. Further, it may be converted into a wavelength longer than the wavelength of the laser beam by optical parametric.

In each of the above embodiments, propagation and input of laser light and excitation light in a planar waveguide laser device have been described. In the following, a heat sink installed in a solid-state laser module, and further in a planar waveguide laser device An embodiment relating to the excitation light distribution in the plane will be described.

Embodiment 11 FIG.
FIG. 24 is a top view of a planar waveguide laser device including a solid state laser module according to Embodiment 11 of the present invention, and FIG. 25 is a side view of the planar waveguide laser device of FIG. However, the solid-state laser module 100 is shown in cross section. Since the propagation of the laser light of the planar waveguide laser device is the same as that of the above embodiment, the description thereof is omitted here.

24 and 25, the heat sink 102 is bonded to the lower main surface of the solid-state laser module 100, and the position of the heat sink 102 is indicated by a broken line in FIG. The length of each side of the heat sink 102 is shorter than the solid laser module 100 by a predetermined value. The solid-state laser module 100 does not have a heat sink 102 in contact with the periphery, and has non-installation regions 103a to 103d of the heat sink 102. That is, the heat sink 102 is sized so as to be offset inward by a predetermined value from the side surface and end surface of the solid-state laser module 100 (the outer surface including the total reflection film and the like of the side surface and end surface of the laser medium 3). Has a shape. These non-installed areas 103a to 103d are made as uniform and small as possible. However, the non-installed area of the part where the side surface on the inclined side surface 106 side of the solid-state laser module 100 spreads may be not less than the predetermined value.

By reducing the non-installation areas 103a to 103d, the heat sink 102 efficiently exhausts heat from the laser medium 3 of the solid-state laser module 100, and the temperature rise of the solid-state laser module 100 can be reduced. Further, by making the non-installation regions 103a to 103d uniform, the solid surface is formed on the main surface of the solid-state laser module 100 (the outer surface including the cladding of the main surface of the laser medium 3 described above) or the main surface of the laser medium 3. The temperature difference of the temperature distribution can be reduced, and the influence of stress generation due to the in-plane temperature gradient can be mitigated. Further, reducing the non-installation areas 103a to 103d leads to a reduction in the temperature difference between the installation area of the heat sink 102 and the non-installation area, and is effective in mitigating stress generation.

The predetermined width of the non-installed regions 103a to 103d is not limited to the case where the adhesive does not wrap around the side surface and end surface of the solid state laser module 100 when the solid state laser module 100 and the heat sink 102 are adhered. Use a level that can be removed by wiping. Thereby, reflection and scattering when laser light and excitation light are input and output can be prevented. In a normal manufacturing technique, the offset width of the non-installed areas 103a to 103d is about 100 μm.

Further, by providing the non-installation regions 103a to 103d in the solid-state laser module 100 and bonding the heat sink 102, when the laser light and the excitation light are input / output, the laser light and the excitation light do not hit the heat sink 102, and the input / output laser The problem of beam vignetting is eliminated. The excitation light 2 is input so as not to pass over the

non-installation regions

103a and 103c in the vicinity of the incident end of the excitation light 2. That is, the edge of the solid laser module 100 or the peripheral edge of the side surface is avoided and input is performed from the center side. Similarly, the other side (103b side) should not be allowed to pass through the non-installed area near the incident end. Thereby, the temperature rise of the solid state laser module 100 at the corner portion of the heat sink 102 can be prevented, and generation of a large stress due to a difference in thermal expansion coefficient between the solid state laser module 100 and the heat sink 102 can be prevented. Further, in the solid-state laser module 100, the heat dissipation efficiency is reduced on the surface in contact with the air, but since the exhaust heat is efficiently performed at the portion where the heat sink 102 is installed, only the portion where the heat sink 102 is installed. By inputting the excitation light 2, the temperature rise of the solid-state laser module 100 can be reduced and the influence of stress generation and the like can be mitigated.

The excitation light 2 input to the solid-state laser module 100 is absorbed by the laser medium 3 and has a reduced intensity in the propagation process. Therefore, even if it reaches the non-installation area after propagation for a certain length, the generated heat is small, so the influence is ignored. It will be as small as possible. In order to bring the excitation state of the laser medium 3 closer to a uniform distribution, the corners of the heat sink 102 are removed by using excitation light having a width smaller than that of the heat sink 102 and spreading in the laser medium 3 near the incident end. The entire region can be excited.

As described above, the length of each side of the heat sink 102 is made smaller than the solid laser module 100 by a predetermined value, the heat sink non-installation areas 103a to 103d are provided in the solid laser module 100, and these non-installation areas 103a to 103a are provided. By making d equal and small, the temperature rise of the laser medium 3 of the solid-state laser module 100 can be reduced, and the occurrence of stress due to the difference in thermal expansion coefficient and in-plane temperature distribution can be avoided. Further, avoiding the corner portion of the heat sink 102 where local stress is likely to occur, the central portion side of the heat sink 102 where the exhaust heat is efficiently performed (the central side of the end face of the solid-state laser module 100 when viewed from the incident direction of the excitation light 2). By inputting the excitation light from, exhaust heat can be effectively removed, and the temperature rise of the laser medium 3 and the accompanying stress generation can be mitigated. Further, since the temperature difference of the temperature distribution on the main surface of the solid-state laser module 100 and the main surface of the laser medium 3 can be reduced by the above configuration, it is easy to grasp the temperature change of the laser medium 3 due to amplification and oscillation of the laser light. Thus, improvement in accuracy when controlling the temperature of the laser medium 3 can be expected.

Embodiment 12 FIG.
FIG. 26 is a top view of a planar waveguide laser device including a solid state laser module according to Embodiment 12 of the present invention. In FIG. 26, the solid-state laser module 100 and the semiconductor laser 1 are the same as those in the eleventh embodiment shown in FIG. The heat sink 102 in FIG. 24 is a rectangular parallelepiped, whereas the heat sink 102a in FIG. 26 is different in that the shape is the same as that of the solid-state laser module 100. Similarly to FIG. 24, the heat sink 102a is bonded to the lower main surface of the solid-state laser module 100. In FIG. 26, the position of the heat sink 102a is indicated by a broken line.

The heat sink 102a has a length of each side shorter than the solid laser module 100 by a predetermined value, and the solid laser module 100 has heat

sink non-installation regions

103a, 103b, 103d, and 103e. These

non-installed areas

103a, 103b, 103d, and 103e are made as uniform and small as possible. By making the solid-state laser module 100 and the heat sink 102a the same shape, the

non-installed areas

103a, 103b, 103d, and 103e on each side can be made uniform, and all four corners of the laser medium 3 can be uniformly cooled. Thus, the temperature difference of the temperature distribution on the main surface of the solid-state laser module 100 can be reduced.

Embodiment 13 FIG.
FIG. 27 is a top view of a planar waveguide laser device including a solid-state laser module according to Embodiment 13 of the present invention. In FIG. 27, the solid-state laser module 100 and the heat sink 102 are the same as those of the eleventh embodiment shown in FIG. 24, but a lens 108 is provided between the semiconductor laser 1 serving as an excitation light source and the solid-state laser module 100 (laser medium 3). Different points. The excitation light 2 output from the semiconductor laser 1 by the lens 108 is condensed in a plane parallel to the main surface of the solid-state laser module 100 (the lateral direction perpendicular to the propagation direction of the excitation light 2: the x-axis direction). By performing the input from the center side of the end face of the laser medium 3 while performing the excitation light can be input to the center portion side of the heat sink 102 while avoiding the corner portion of the heat sink 102.

With this configuration, the semiconductor laser 1 that outputs the excitation light 2 that is wider than the laser medium 3 of the heat sink 102 and the solid state laser module 100 is used, or the semiconductor that generates the excitation light 2 having a large spread angle in the x-axis direction. Even when the laser 1 is used, excitation light can be input to the center of the heat sink 102 while avoiding the corner of the heat sink 102.

A spherical lens, an aspherical lens, a microlens array, or the like can be used as the lens 108, but the width of the excitation light 2 incident on the laser medium 3 of the solid-state laser module 100 in the x-axis direction is smaller than the width of the heat sink 102. As such, it is selected and installed in consideration of the light collecting function and the focal length.

In addition, the excitation light 2 is accurately obtained in the direction of the surface parallel to the side surface of the solid-state laser module 100 (laser medium 3) of the excitation light 2 (the vertical direction of the surface orthogonal to the propagation direction of the excitation light 2: the z-axis direction). It is necessary to enable input to the end face of the laser medium 3, and it may be necessary to provide the lens with a condensing function in the z-axis direction. In this case, as shown by a broken line 108a in FIG. 27, a lens having a condensing function in each of the x-axis direction and the z-axis direction can be used in combination. When the beam width and divergence angle in the x-axis direction of the excitation light 2 output from the semiconductor laser 1 are small, a lens 108 having a collimating function in the x-axis direction can be used.

Further, by installing the lens 108 so that the focal position in the x-axis direction is closer to the incident end (end face) of the solid-state laser module 100 to the laser medium 3, x of the excitation light 2 inside the laser medium 3 can be obtained. The spread in the axial direction can be increased, and the excited region of the laser medium 3 can be increased.

Embodiment 14 FIG.
FIG. 28 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 14 of the present invention (however, solid-state laser module 100 is shown in cross section). In FIG. 28, the heat sink 102 is the same as that of the eleventh embodiment shown in FIG. 25, for example. The difference is that the solid-state laser module 100 has a double-clad structure in which the upper and lower main surfaces of the laser medium 3 are provided with the grad 20 and the cladding 4a, and the grad 20 and the grad 4b, respectively. In addition, the semiconductor laser 1 is installed with an inclination of an angle θp with respect to the y-axis direction in the yz plane with respect to the solid-state laser module 100 extending in the xy plane.

The excitation light 2 output from the semiconductor laser 1 installed with an inclination of the angle θp is incident on the solid-state laser module 100 at a predetermined spread angle. At this time, the incident angle of the excitation light 2 to the solid-state laser module 100 can be changed by the angle θp. As a result, as shown in FIG. 28, the excitation light 2 can be prevented from being input to the laser medium 3 in the heat sink non-installation region 103 a at the excitation light incident end of the solid-state laser module 100. Thereby, the heat_generation | fever in the non-installation area | region 103a can be prevented. In the portion where the heat sink 102 is installed, the excitation light 2 can be absorbed by the laser medium 3 and the laser medium 3 can be in an excited state. In the excited state, exhaust heat from the heat sink 102 is efficiently performed, so that the influence of temperature rise can be reduced.

The tilt angle θp of the semiconductor laser 1 is set so as to satisfy the total reflection condition in the propagation optical path 109 of the excitation light 2 that allows the excitation light 2 to propagate in the double clad solid-state laser module 100. In FIG. 28, the semiconductor laser 1 is installed with an upward angle, but the semiconductor laser 1 can also be installed downward. The inclination angle in this case is also set to an angle at which the excitation light 2 is not input to the laser medium 3 in the non-installation region 103a and the excitation light 2 can propagate in the double-clad solid laser module 100.

Embodiment 15 FIG.
FIG. 29 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 15 of the present invention (however, solid-state laser module 100 is shown in cross section). 29 differs from FIG. 28 in that the semiconductor laser 1 is installed in parallel to the y-axis direction, like the solid-state laser module 100, and the excitation light 2 is condensed using the lens 110. FIG.

The excitation light 2 output from the semiconductor laser 1 enters the solid-state laser module 100 while being condensed by the lens 110. With this configuration, as shown in FIG. 29, the excitation light 2 can be input to the laser medium 3 without being absorbed in the heat sink non-installation region 103 a at the excitation light incident end of the solid-state laser module 100. Thereby, the heat_generation | fever in the non-installation area | region 103a can be prevented.

The lens 110 sets the condensing condition so that the excitation light 2 can propagate in the double clad solid-state laser module 100 so as to satisfy the total reflection condition of the propagation light path 109 of the excitation light 2. In FIG. 29, the excitation light 2 is incident from the upper side of the laser medium 3 in the solid-state laser module 100. However, the excitation light 2 may be incident from the lower side of the laser medium 3.

Embodiment 16 FIG.
FIG. 30 is a top view of a planar waveguide laser device including a solid-state laser module according to Embodiment 16 of the present invention. In FIG. 30, a heat sink 111 having a width (length in the x-axis direction) wider than that of the solid-state laser module 100 protrudes beyond the inclined side surface 106 provided with the total reflection film in FIG. In this way, they are bonded. The side surface 106, which is a laser light high reflectivity surface, is provided with a total reflection film as indicated by reference numeral 6 in FIG. 1, and reflects the laser light on the side surface of the laser medium 3 provided with the total reflection film, thereby There is no input / output. For this reason, there is no problem even if an adhesive or the like adheres to the outside of the side surface 106. In addition, vignetting of the input / output laser beam does not occur. For this reason, there is no problem in use even if the heat sink 111 is bonded so as to protrude to the side surface 106 side.

With this configuration, the heat sink 111 can be contacted (installed) to the end of the solid-state laser module 100, that is, the laser medium 3 on the side surface 106 side, the efficiency of exhaust heat can be increased, and the temperature rise can be suppressed. The temperature difference of the temperature distribution on the main surface of the module 100 can be reduced.

On the surface for inputting the excitation light 2 and the surface for inputting / outputting the laser light as the signal light, the heat sink 111 is bonded to the solid-state laser module 100 and the heat sink 111 is bonded to the laser medium 3. Reflection and scattering by the adhesive attached to the surface of the laser beam can be prevented, and vignetting of the input / output laser beam can also be prevented. The

non-installation areas

103a, 103b, and 103d are made as uniform and small as possible.

In addition, it is possible to bond the heat sink so that it protrudes beyond the solid laser module on the surface where excitation light, laser light, etc. are not input / output. The efficiency is increased and the temperature rise is suppressed, and there is an effect that the temperature difference of the temperature distribution on the main surface of the solid-state laser module 100 can be reduced.

Embodiment 17. FIG.
FIG. 31 is a side view of a planar waveguide laser device including a solid-state laser module according to Embodiment 17 of the present invention. In FIG. 31, the solid laser module 100 including the respective end surfaces of the laser medium 3 and the

claddings

20, 4a, and 4b has an end surface on which the excitation light is incident, and is in the y axis within the yz plane with respect to the main surface extending in the xy plane direction. The semiconductor laser 1 is installed in the y-axis direction and receives the excitation light 2.

With the above configuration, the excitation light 2 output from the semiconductor laser 1 is incident on the solid-state laser module 100 at a predetermined spread angle. At this time, the excitation light 2 is refracted by the inclination angle θtp of the excitation light incident surface. The excitation light 2 is refracted in the upward direction, and the excitation light 2 can be prevented from being input to the heat sink non-installation region 103a at the excitation light incident end of the solid-state laser module 100. Thereby, the heat_generation | fever in the non-installation area | region 103a can be prevented. In the portion where the heat sink 102 is installed, the excitation light 2 can be absorbed by the laser medium 3, and the laser medium 3 can be in the excitation state. In this part, since the exhaust heat from the heat sink 102 is efficiently performed, the influence of the temperature rise can be reduced.

Here, the inclination angle θtp of the surface on which the excitation light of the solid-state laser module 100 is incident also has a role of suppressing parasitic amplification light due to the circular path in the planar waveguide laser device. In some cases, it is not possible to avoid the incidence of the excitation light 2 on the laser medium 3 in the non-installed region 103a only by refraction of the excitation light 2 with the inclination angle θtp of the excitation light incident surface. In that case, further, the semiconductor laser 1 is inclined and installed as in the fourteenth embodiment shown in FIG. 32, the excitation light is condensed using the lens 110 as in the fifteenth embodiment, or these Both can be applied. In FIG. 31, the excitation light 2 is incident from the upper part of the laser medium 3, but the excitation light 2 may be incident from the lower part of the laser medium 3. The input of the pumping light 2 is set so that the pumping light 2 can propagate in the double clad solid-state laser module 100.

In the above embodiment, an optimal adhesive for bonding the heat sink and the solid laser module is used in consideration of the thermal expansion coefficient, thermal resistance, curing conditions, usage conditions, and the like. In addition, an optimum material for the heat sink is used in consideration of the thermal expansion coefficient, thermal conductivity, processing conditions, and the like. In the above embodiment, the case where the heat sink is bonded to the lower surface side of the solid-state laser module has been described. However, the heat sink can be bonded to the upper surface side of the laser medium, and as shown in FIG. You may adhere to both sides.

Embodiment 18 FIG.
FIG. 34 is a side view of the planar waveguide laser device provided with the heat sink shown in FIG. 25 and the distribution characteristics of the laser medium. 34A is a side view of the planar waveguide laser device, and FIGS. 34B to 34E are heat generation distributions and temperatures along the y-axis direction of the laser medium of the planar waveguide laser device of FIG. A distribution, a positive refractive index distribution, and a negative refractive index distribution are shown. FIG. 35 is a top view of the planar waveguide laser device of FIG. However, in FIG. 34A and FIG. 35, the solid-state laser module 100 is shown in a cross-sectional view.

The pumping light 2 output from the semiconductor laser 1 that is a pumping light source is incident from the end face of the laser medium 3, and the clad 4 b disposed on the lower main surface side of the laser medium 3 and the upper main surface side of the laser medium 3. It is totally reflected by the arranged clad 4 a and propagates in the laser medium 3. The excitation light 2 is absorbed while propagating through the laser medium 3. In this case, the semiconductor laser 1 is provided on each end face side of the laser medium 3 and excited oppositely. The absorption amount of the excitation light 2 in the laser medium 3 is large in the portion near the excitation light incident end face, and the absorption amount is the smallest in the central portion in the y-axis direction. Since the heat generated in the laser medium 3 is proportional to the amount of absorption of the excitation light 2, the amount of heat generation is high near the excitation light incident end face as shown in FIG. Less.

The lower main surface of the laser medium 3 is bonded to the heat sink 102 with a clad 4b and a bonding material (not shown) interposed therebetween to dissipate heat. Here, since there are non-installed regions 103a to 103d (see also FIGS. 24 and 25) where the heat sink 102 is not installed at the periphery of the laser medium 3, the temperature of the periphery of the laser medium 3 is higher than that at the center. Further, since the exhaust heat resistance is large at the end portion of the heat sink 102, the peripheral portion of the surface of the heat sink 102 that contacts the laser medium 3 through the clad 4b has a higher temperature than the central portion. For this reason, the temperature of the laser medium 3 becomes high in the vicinity of the excitation light incident end face as shown in FIG. 34C, and becomes constant at the central portion of the heat sink 102 where exhaust heat is sufficiently performed.

The refractive index of the laser medium 3 changes depending on the temperature. In general, a coefficient of temperature dependence of refractive index variation (refractive index temperature dependence) is represented by dn / dT. dn / dT varies depending on the type of the laser medium 3. In a laser medium with positive dn / dT, the refractive index increases as the temperature increases, and in a laser medium with negative dn / dT, the refractive index decreases as the temperature increases. For this reason, since the temperature rises at the peripheral portion of the laser medium 3, the laser medium 3 has a temperature change region 121 of the laser medium near the excitation light incident end face, and a constant temperature region 120 of the laser medium near the center. In the temperature constant region 120 of the laser medium, there is no change in the refractive index, and in the temperature change region 121 of the laser medium, when dn / dT is positive, as shown in FIG. 34 (d), refraction occurs near the end face of the laser medium. The rate is high. When dn / dT is negative, as shown in FIG. 34 (e), the refractive index is low near the end face of the laser medium.

As shown in FIG. 35, the laser incident light 8 that enters the laser medium 3 from the antireflection film 7 propagates through the laser medium 3 while being repeatedly reflected between the opposing total reflection films 6 that reflect the laser light. Here, since the two side surfaces of the laser medium 3 to which the total reflection film 6 is applied are inclined with respect to the other at an angle θ1, the incident angle to the total reflection film 6 is gradually increased while repeating the reflection. When the light approaches the vertical direction and further propagates, the light is perpendicularly incident on the total reflection film 6 to be propagated. In the vicinity of the turning point, the angle is close to perpendicular to the total reflection film 6, so that the laser light propagates more densely than in the vicinity of the antireflection film 7, and the light is reflected many times in a small region. The returned laser light from the return path returns along the optical path substantially the same as the forward path, and the laser output light 9 is output from the antireflection film 7.

Here, the excitation light 2 is absorbed by the laser medium 3 to generate a gain for the laser light. The laser beam 3 is amplified by the propagation of the laser beam through the gain laser medium 3, and the energy is extracted to become a large output laser output beam 9. For this reason, it is important for improving the beam overlap efficiency by making the excitation region of the laser medium 3 coincide with the propagation region of the laser light in order to improve the output and efficiency. For this reason, the turning point in the laser medium is set in the vicinity of the excitation light incident end face. The setting of the turning point is adjusted by the incident angle of the laser beam to the laser medium 3 (incident angle of the laser incident light 8), the outer shape of the laser medium 3, and the angle θ1 formed by the both side surfaces of the laser medium 3. As described above, since the configuration is such that it is folded back in the vicinity of the excitation light incident end face, the beam overlap efficiency is increased, and a high-power and high-efficiency laser can be obtained.

On the other hand, the vicinity of the excitation light incident end face of the laser medium 3 becomes a temperature change region 121 of the laser medium as shown in FIG. In the temperature change region of the laser medium, a refractive index change depending on dn / dT of the laser material occurs. When there is a refractive index change in the cross-sectional direction perpendicular to the traveling direction of the laser light, the laser light has a characteristic that the traveling direction is bent in a direction in which the refractive index is high. When the refractive index temperature dependence coefficient dn / dT is positive, the temperature increases near the excitation light incident end face in the vicinity of the turning point in the laser medium. Bend toward the excitation light incident end face. When the bent laser light returns and propagates in the return optical path, the propagation angle is shifted by the angle bent in the temperature change region of the laser medium, which does not coincide with the forward optical axis. Since the propagation angle is deviated, the difference in the propagation position becomes larger as the propagation length becomes longer, and may be greatly different in the vicinity of the antireflection film 7. Further, the output angle of the laser beam is obtained by receiving the change in the refractive index of the temperature change region 121 of the laser medium with respect to the laser output beam 9 that is not affected by the temperature change. The laser output light 9a whose position is changed is obtained. Since the change in the angle and position of the laser output light 9a depends on temperature, it depends on the output of the excitation light 2. Therefore, the angle and position of the laser output light 9a may change depending on the excitation output, which is not preferable for use of the laser.

FIG. 36 is a top view of the planar waveguide laser device including the solid-state laser module according to the eighteenth embodiment of the present invention, taking the above into consideration. FIG. 37 is a side view of the planar waveguide laser device of FIG. 36 and the distribution characteristics of the laser medium. FIG. 37 (a) is a side view, and FIGS. 37 (b) to (e) are respectively a heat generation distribution, a temperature distribution, and a positive refractive index distribution along the y-axis direction of the laser medium of the planar waveguide laser device of FIG. And a negative refractive index profile. However, in FIG. 36 and FIG. 37A, the solid-state laser module 100 is shown in a sectional view.

A narrow band which is a laser light high reflection / excitation light antireflection film that transmits the excitation light and reflects the laser light is provided on the side surface 33 of the pair of opposite side surfaces 33 and 34 of the planar waveguide type laser medium 3. The reflection film 30 is applied, and the side surface 34 is provided with a laser light high reflection / excitation light high reflection film 126 that reflects both excitation light and laser light. A part of the side surface 34 is provided with an antireflection film 7 that transmits laser light instead of the laser light high reflection / excitation light high reflection film 126. In the side surface 33, only the portion that transmits the excitation light may be the narrow-band reflection film 30, and the remaining portion may be the laser light high reflection / excitation light high reflection film 126.

The semiconductor laser 1 is disposed on the side surface 33 side, outputs the excitation light 2, passes through the narrow-band reflecting film 30, propagates in the laser medium 3 along the optical axis substantially parallel to the x direction in the laser medium 3 and absorbs it. Let Further, as shown in FIG. 37A (not shown in FIG. 36), the heat sink 102 has a clad 4b on the lower main surface side of the laser medium 3, and a bonding material for the clad 4b and the heat sink 102 (not shown). It is arranged to be bonded with a sandwich.

Here, the excitation light 2 is introduced into the laser medium 3 from a part of the approximate center of the side surface 33. For this reason, the central portion in the y direction of the laser medium is an excitation region 127 to be excited, and both ends of the excitation region 127 in the y direction are two

unexcited regions

128a and 128b that are not excited. The heat sink 102 is bonded to both the excitation region 127 and the

non-excitation regions

128a and 128b of the laser medium 3 through the cladding 4b and a bonding material (not shown), and exhausts heat generated in the laser medium 3. Alternatively, heat is exhausted using a heat radiating means (not shown).

Since the excitation light 2 propagates in the laser medium 3 in the substantially x direction, an absorption distribution accompanying absorption occurs in the x direction, but a uniform excitation distribution depending on the uniformity of the excitation source, that is, the semiconductor laser 1, occurs in the y direction. Is obtained. Therefore, a substantially uniform excitation distribution is obtained in the y direction of the excitation region 127, and a substantially uniform heat generation distribution is obtained in the y direction of the excitation region 127 of the laser medium 3 as shown in FIG. Here, the lower main surface of the excitation region 127 of the laser medium 3 is joined to the central portion of the heat sink 102 in the y direction with the clad 4b and the joining material interposed therebetween. Thus, since the y direction of the excitation region 127 of the laser medium 3 is not joined to the peripheral portion of the heat sink 102 having high heat exhaustion resistance, the excitation region 127 of the laser medium 3 is uniform as shown in FIG. Temperature. For this reason, the excitation region 127 of the laser medium 3 having an amplification gain of the laser beam by the excitation has a uniform refraction regardless of whether dn / dT is positive or negative, as shown in (d) and (e) of FIG. Become a rate. However, the

unexcited regions

128a and 128b have a temperature increase smaller than that of the excitation region due to heat conduction from the excitation region 127, and the temperature increase becomes smaller as the distance from the excitation region increases. For this reason, the refractive index of the

unexcited regions

128a and 128b is lower than the refractive index of the excitation region 127 when dn / dT is positive, and is higher than the refractive index of the excitation region 127 when dn / dT is negative. . However, since the

unexcited regions

128a and 128b are regions in which laser amplification is not performed, the laser light is not propagated to the unexcited region, and the position and angle of the laser output light change depending on the excitation output. Absent.

The laser light introduced from the antireflection film 7 into the first unexcited region 128a of the laser medium 3 is reflected between the opposing narrow band reflective film 30 and the laser light high reflection / excitation light high reflection film 126, The light enters the excitation region 127. Similarly, in the excitation region 127, the light is reflected between the narrow-band reflection film 30 and the high reflection / excitation light reflection film 126 of the laser beam to propagate while narrowing the distance between reflection points in the y direction, and is further turned back to be substantially the same as the forward path. The light travels in the same optical path and is output from the antireflection film 7. Here, since the laser light is amplified by propagating through the laser medium 3 excited by the excitation light 2, the beam overlap is achieved by matching the excitation region 127 of the laser medium 3 with the propagation region of the laser light as much as possible. It is desirable to improve efficiency. For this reason, the turning point of the laser medium 3 is set at the boundary between the excitation region 127 and the second non-excitation region 128b. The setting of the turning point is adjusted by the incident angle of the laser beam to the laser medium 3, the outer shape of the laser medium 3, and the relative angle θ1 between the side surfaces 33 and 34. As described above, since the configuration is such that the excitation region 127 of the laser medium 3 is folded near the boundary with the second non-excitation region 128b, the beam overlap efficiency is increased, and a high-power and high-efficiency laser can be obtained. There is. In addition, since the refractive index distribution of the excitation region having the amplification gain is made uniform in the y direction, there is no change in the propagation angle due to the change in the refractive index of the laser light, and there is no output angle and position shift of the laser output light 9. For this reason, there is a feature that a stable laser output angle and a laser output position can be obtained.

Further, the excitation light 2 introduced into the laser medium 3 through the narrow-band reflection film 30 that reflects the laser light and transmits the excitation light 2 propagates in the substantially x direction while being absorbed. Here, a laser beam high reflection / excitation light high reflection film 126 is provided on the side surface 34 facing the side surface 33 and reflects the excitation light, so that the propagation length of the excitation light in the laser medium 101 is doubled. Thus, a higher absorption rate can be obtained. Therefore, there is a feature that the laser output light 122 with high efficiency and high output can be obtained.

Embodiment 19. FIG.
38 is a top view of a planar waveguide laser device including a solid state laser module according to Embodiment 19 of the present invention. However, in FIG. 38, the solid-state laser module 100 is shown in a sectional view. Further, the basic configuration of the side view is the same as that shown in FIG. A pair of side surfaces 33 and 34 facing each other of the planar waveguide type laser medium 3 is provided with a narrow band reflecting film 30 that transmits the excitation light and reflects the laser light. Further, an antireflection film 7 is provided on a part of the side surface 34 in place of the narrow-band reflection film 30 in order to make the laser light incident. On both sides of the pair of side surfaces 33, 34, the semiconductor laser 1 that is an excitation light generation source is disposed so as to face each other, and each passes through the narrow-band reflection film 30 and is approximately in the x direction in the laser medium 3. The pumping light 2 that propagates and is absorbed in the laser medium 3 along the parallel optical axis is output. A heat sink 102 is installed and fixed on the lower main surface side of the laser medium 3 with a clad and a bonding material interposed therebetween, as in FIG.

The excitation light 2 is introduced by the semiconductor laser 1 from the outside of the pair of side surfaces 33 and 34 facing each other of the laser medium 3. Thus, since it was set as the structure which pumps from 2 side surfaces, excitation higher than the case where excitation is performed from 1 side surface is possible, and a higher output laser beam can be obtained. In addition, since the y direction width of the heat sink 102 is larger in the y direction than the excitation region 127, the temperature distribution in the y direction of the excitation region 127 is uniform and the dn / dT of the laser medium 3 is also uniform. There is no change in the propagation angle due to the change in the refractive index, and there is no deviation in the output angle and position of the laser output light 9. For this reason, there is a feature that a stable laser output angle and a laser output position can be obtained.

Embodiment 20. FIG.
FIG. 39 is a top view of a planar waveguide laser device including a solid state laser module according to Embodiment 20 of the present invention, and FIG. 40 is a side view of the planar waveguide laser device of FIG. However, in FIG. 39, for the sake of explanation, the solid-state laser module 100 shows the structure of the thermal lens effect generating means 150 through the laser medium 3 and the

clads

4a and 4b. FIG. 40 shows the solid-state laser module 100 and the thermal lens effect generating means 150 in a sectional view taken along the line CC of FIG. Further, FIG. 41 shows an enlarged cross section of the portion D of FIG. 40 and the characteristics of the laser medium 3. 41 (a) shows an enlarged cross section of the portion D, and FIGS. 41 (b) and (c) show the temperature difference and refractive index difference of the portion D of the laser medium 3 in FIG. In FIG. 39, the clad 4 b disposed on the lower principal surface side of the planar waveguide type laser medium 3 is bonded to the contact portion 152 of the thermal lens effect generating means 150 by the bonding material 160. In this configuration, dn / dT of the laser medium 3 is positive.

The thermal lens effect generating means 150 includes a contact portion 152 joined to the clad 4d disposed on the lower principal surface side of the laser medium 3 by the joining material 160, and a clad 4b recessed from the contact portion 152 in the z direction. The heat sink is configured by the non-contact portion 153 that is not in contact, and the cross-sectional shape along the xy plane of the contact portion 152 is a reverse pattern of the laser light propagation path 89 on the laser medium 3. That is, the laser light incident on the laser medium 3 from the antireflection film 7 propagates while reflecting between the two

side surfaces

33 and 34 facing each other, but as shown in FIG. The lower side of the laser light propagation path region 89 a is a non-contact portion 153 of the thermal lens effect generating means 150. Further, the lower side of the region where the laser light does not propagate is a contact portion 152 of the thermal lens effect generating means 150, and the contact portion 152 of the thermal lens effect generating means 150 is located on the lower clad 4b where the laser light does not propagate. Bonded and fixed by a bonding material 160. The heat generated in the laser medium 3 is transmitted to, for example, the heat radiating means 102b indicated by the broken line in FIG. 40 disposed on the lower main surface of the thermal lens effect generating means 150, and is exhausted.

For this reason, the laser medium 3 generates heat, but the temperature of the laser medium 3 above the contact portion 152 is lowered as shown in FIG. 41B, and the laser medium 3 above the non-contact portion 153 is in contact with the contact portion 152. The temperature rises because the transmission distance becomes longer. For this reason, the temperature of the laser light propagation path region 89a is higher than the surroundings. Here, since this configuration uses a material with a positive dn / dT for the laser medium 3, as shown in FIG. 41C, the laser light propagation path region 89a has a refractive index higher than that of the surrounding laser medium. Becomes higher. When the refractive index increases, a convex lens effect occurs, and the laser light is bent and propagates to the higher refractive index side. Therefore, the laser light can be confined in the upper portion of the non-contact portion 153 having a high temperature of the laser medium 3 and can propagate through the laser medium along the optical path along the non-contact portion 153. In particular, as the temperature of the laser medium increases with high output excitation, the convex lens effect of the laser medium by the contact portion 152 and the non-contact portion 153 increases. The laser beam confinement effect at the upper part is enhanced, and a more stable laser output angle and laser output position can be obtained. 39 and 40, the excitation light 2 is introduced into the laser medium 3 from the two end face sides of the laser medium 3 substantially orthogonal to the side surfaces 33 and 34 in the xy plane. The number of semiconductor lasers 1 and the pumping configuration are not limited to this. For this reason, the above-described effects can be obtained by the laser medium 3 that generates heat by excitation and the thermal lens effect generating means 150 regardless of the illustrated excitation configuration.

Embodiment 21. FIG.
This embodiment is an example where dn / dT of the laser medium of the twentieth embodiment is negative. 42 is a top view of a planar waveguide laser device including a solid state laser module according to Embodiment 21 of the present invention. FIG. 43 is a side view of the planar waveguide laser device of FIG. However, in FIG. 42, for the sake of explanation, the solid-state laser module 100 shows the structure of the thermal lens effect generating means 150a through the laser medium 3a and the

clads

4a and 4b. FIG. 43 shows the solid-state laser module 100 and the thermal lens effect generating means 150a in a sectional view taken along the line EE of FIG. Further, FIG. 44 shows an enlarged cross section of the portion F of FIG. 43 and the characteristics of the laser medium 3a. 44 (a) shows an enlarged cross section of the portion F, and FIGS. 44 (b) and (c) show the temperature difference and refractive index difference of the portion F of the laser medium 3a of FIG. In FIG. 42, the clad 4b disposed on the lower principal surface side of the planar waveguide type laser medium 3a is bonded to the contact portion 152 of the thermal lens effect generating means 150a by the bonding material 160. In this configuration, dn / dT of the laser medium 3a is negative.

The thermal lens effect generating means 150a includes a contact part 152 joined to the clad 4d disposed on the lower principal surface side of the laser medium 3 by the joining material 160, and a clad 4b recessed from the contact part 152 in the z direction. The heat sink is configured by a non-contact portion 153 that is not in contact, and the cross-sectional shape along the xy plane of the contact portion 152 has the same pattern as the laser light propagation path 89 on the laser medium 3a. That is, the laser light incident on the laser medium 3a from the antireflection film 7 propagates while being reflected between the two opposing side surfaces 33 and 34, but as shown in FIG. The lower side of the laser light propagation path region 89a is a contact portion 152 of the thermal lens effect generation means 150a, and the contact portion 152 of the thermal lens effect generation means 150a is joined to the clad 4b below the laser light propagation path region 89a. The material 160 is joined and fixed. Further, the lower side of the region where the laser beam does not propagate is a non-contact portion 153 of the thermal lens effect generating means 150a. The heat generated in the laser medium 3a is transmitted to, for example, the heat dissipating means 102b indicated by a broken line in FIG. 43 disposed on the lower main surface of the thermal lens effect generating means 150a to be exhausted.

For this reason, the laser medium 3a generates heat, but the temperature of the laser medium 3 above the contact portion 152 is lowered as shown in FIG. 44B, and the laser medium 3a above the non-contact portion 153 is in contact with the contact portion 152. The temperature rises because the transmission distance becomes longer. For this reason, the temperature of the laser beam propagation path region 89a is lower than the surroundings. Here, since this configuration uses a material having a negative dn / dT of the laser medium 3a, the laser light propagation path region 89a has a refractive index higher than that of the surrounding laser medium, as shown in FIG. Becomes higher. When the refractive index increases, a convex lens effect occurs, and the laser light is bent and propagates to the higher refractive index side. For this reason, the laser beam is confined in the upper part of the contact portion 152 having a low temperature of the laser medium 3 a and can propagate through the laser medium along the optical path along the contact portion 152. In particular, since the convex lens effect of the laser medium by the contact part 152 and the non-contact part 153 increases as the temperature rise of the laser medium increases with high output excitation, the confinement effect of the laser light at the upper part of the contact part becomes higher. Features include stable laser output angle and laser output position. 42 and 43, the excitation light 2 is introduced into the laser medium 3a from the two end face sides of the laser medium 3 substantially orthogonal to the side surfaces 33 and 34 in the xy plane. The number of semiconductor lasers 1 and the pumping configuration are not limited to this. For this reason, the above-described effects can be obtained by the laser medium 3a that generates heat by excitation and the thermal lens effect generating means 150a regardless of the illustrated excitation configuration.

Embodiment 22. FIG.
By the way, a more detailed specific example of the reflection characteristics of the total reflection film 6 bonded on the side surface of the laser medium 3 described in the paragraphs 0036 and 0037 in the first embodiment will be described as the twenty-second embodiment. Here, the case where the active medium of the laser medium 3 is Er (Erbium) and the solid laser material is glass will be described. The solid-state laser material may be a solid-state laser material using a crystal such as YAG, glass, or other base material, but the wavelength range or gain intensity in which the active medium has gain may differ depending on the solid-state laser material. In Er, when the solid laser material is glass, it has a large gain in the 1535 nm band. Further, the solid-state laser material may be one in which other atoms having a sensitizing action such as Yb are added in addition to the active medium.

When the active medium of the laser medium 3 is Er, Yb having an absorption in a wavelength band of 900 to 1000 nm is co-doped, so that Yb atoms are excited using a semiconductor laser or the like in the above wavelength band, and the Er from the Yb atoms. Er atoms can be excited by energy transfer to the atoms. Thereby, a high-power semiconductor laser having a wavelength of 940 nm or a wavelength of 975 nm, which is generally available as an excitation light source, can be used. As the kind of atoms to be co-doped to obtain a sensitizing action, an optimum kind is selected according to the energy level of the active medium of the laser medium 3. The addition concentration is set so that the sensitizing action can be obtained most efficiently.

FIG. 45 shows the wavelength dependence characteristics of the reflectance of the total reflection film 6 of the planar waveguide laser device including the solid-state laser module according to Embodiment 22 of the present invention. In FIG. 45, the horizontal axis of the graph represents the wavelength (unit: nm), the left vertical axis represents the gain intensity of the laser medium 3, and the right vertical axis represents the reflectance of the total reflection film 6. The curve 200 in the figure is the gain distribution of the laser medium 3 (left vertical axis), the curve 201 is the reflectance characteristic of the total reflection film 6 with respect to an incident angle of 0 ° (right vertical axis), and the curve 202 is the incident angle (θin1-θ1). The reflectance characteristics (right vertical axis) of the total reflection film 6 with respect to ° are shown. The shape of the solid-state laser module is, for example, the same as that shown in FIG. 1. Here, a case is considered where the wavelength of the laser incident light 8 is 1550 nm using this solid-state laser module.

Er is a three-level system active medium, and there are stimulated emission from the upper level and absorption from the lower level. Here, for simplicity of explanation, the absorption from the lower level is ignored. . The density of excited Er ions per unit volume is N [1 / m ³ ]. The stimulated emission cross section at the wavelength λ [nm] is represented as σ (λ) [m ² ]. When the absorption is ignored, the small signal gain coefficient with respect to the wavelength λ [nm] is expressed as g0 (λ) = σ (λ) × N [1 / m].

The distance between the side surfaces 33 and 34 (the optical path length until the laser incident light 8 incident from the antireflection film 7 is reflected from the opposite side surface 33 starting from the side surface 34) is L [m]. Strictly speaking, the distance between the side surfaces 33 and 34 becomes shorter as it is closer to the end surface 35 side due to the inclination angle θ1 between the side surfaces 33 and 34. However, assuming that the inclination angle θ1 is sufficiently small, L is considered to be constant. Further, the incident laser light propagates at an angle shifted from the angle at which the side surfaces 33 and 34 are perpendicularly incident, but the optical path lengths are considered to be substantially the same. At this time, the small signal gain for the optical path until one reflection occurs is G0 (λ) = exp (g0 (λ) × L).

When the reflectance at the wavelength λ [nm] of the total reflection film 6 applied to the side surface 33 and the side surface 34 is R (λ), the laser incident light 8 having the power P0 [W] incident from the antireflection film 7 is the side surface. It is amplified by G0 (λ) times before reaching 33, and becomes P0 × G0 (λ) × R (λ) after reflection at the side surface 33, and is further amplified by G0 (λ) times before returning to the side surface 34. The Thereafter, the laser beam is amplified in the laser medium 3 by repeating reflection and amplification. For this reason, when the reflectance of the total reflection film 6 is total reflection (reflectance 100%), that is, R (λ) = 1, the power of the laser beam continuously increases with respect to the propagation distance. On the other hand, when the reflectance of the total reflection film 6 is not total reflection, that is, R (λ) ≠ 1, the laser light is lost every time it is reflected by the side surface 33 or the side surface 34, and therefore, the propagation distance is The power is amplified while decreasing the power for each distance L.

When the pumping light power is sufficiently input, the gain distribution of the laser medium 3 has a wavelength characteristic as shown by a curve 200 in FIG. 45 and is maximum in the wavelength 1535 nm band. That is, the small signal gain G0 (λ) with respect to the optical path until one reflection occurs is maximum in the wavelength 1535 nm band, and the laser light in the wavelength 1535 nm band is most easily amplified.

As described above, in the configuration of the present invention, since the longest path of parasitic oscillation and parasitic amplification is substantially the same as the laser reflected light path, the wavelength band where the gain of the laser medium 3 is maximized is equal to the laser wavelength band. If this is the case, even when the gain increases as the pumping output increases, the amplification of the laser beam also increases, so that the parasitic oscillation and the parasitic amplification light do not exceed the amplification factor of the laser beam.

However, when the wavelength band (wavelength 1535 nm band) at which the gain of the laser medium 3 is maximized is different from the laser wavelength band (1550 nm) as in this embodiment, and the gain difference due to these wavelengths is large, Spontaneous emission light generated in the laser medium 3 is easily amplified in a wavelength band in which gain is increased, and energy accumulated in the laser medium is consumed by this amplification, and amplification efficiency of the laser incident light 8 is lowered. . Further, when spontaneous emission light is amplified, parasitic oscillation light and parasitic amplification light are easily generated.

When the reflectance of the total reflection film 6 has no wavelength characteristic, that is, when R (1535) = R (1550) ≈1, amplification of 1535 nm light generated from spontaneous emission light cannot be prevented, and laser incident light 8 As a result, the amplification efficiency decreases.

Here, by giving the reflectance of the total reflection film 6 the wavelength characteristic as shown by the curve 201 in FIG. 45, the laser incident light 8 of 1550 nm can be efficiently amplified. As shown in FIG. 45, the reflectivity is increased as much as possible to reduce the loss with respect to 1550 nm (R (1550) ≈1), and the reflectivity is decreased with respect to 1535 nm to reduce the loss (R ( 1535) ≈0). As a result, the spontaneous emission light in the 1535 nm band amplified in the optical path until one reflection occurs is transmitted through the total reflection film 6 and emitted to the outside, so that the reflection between the side surfaces 33 and 34 is repeated. It is possible to eliminate the occurrence of continuous amplification. On the other hand, the laser incident light 8 of 1550 nm is reflected on the side surface 33 and the side surface 34 without loss and the extraction of energy by the amplified light in the 1535 nm band is reduced, so that a reduction in amplification efficiency can be prevented.

In FIG. 45, as indicated by a curve 201, the reflectance R (1535) ≈0 is set to make the reflectance of the total reflection film 6 with respect to 1535 nm as small as possible, but amplification in the optical path until one reflection occurs. Since the gain is G0 (1535), R (1535) ≦ 1 / G0 (1535) may be set in order to prevent an increase in power due to amplification. As a result, the laser light in the 1535 nm band having the power P0 [W] incident from the side surface 33 or the side surface 34 becomes P0 × G0 (1535) by the time it reaches the opposing side surface. Since × G0 (1535) × R (1535) ≦ P0, it does not become larger than P0 × G0 (1535) even if reflection is repeated.

In this way, the reflectance of the total reflection film 6 is lowered for a wavelength band having a large gain different from the wavelength band of the laser incident light 8, and reflection is performed between the side surfaces 33 and 34 in the wavelength band other than the laser incident light 8. By preventing the continuous amplification performed while being repeated, a decrease in the amplification gain of the laser incident light 8 can be prevented.

The best reflectivity characteristic of the total reflection film 6 is that only the wavelength band of the laser incident light 8 is total reflection (R = 1) and non-reflection (R = 0) in other wavelength bands. Suppressing amplification of spontaneously emitted light at wavelengths other than the wavelength band of the laser incident light 8 only by lowering the reflectivity in accordance with the amplification gain in the optical path until reflection occurs even when non-reflection (R = 0) cannot be achieved. Can do.

Further, the total reflection film 6 is within the range where the incident angle (θin1-θ1) ° with respect to the side surface 33 of the laser incident light 8 (internal incident angle θin1) incident from the antireflection film 7 is perpendicularly incident (angle 0 °). That is, with respect to an angle of 0 ° to (θin1−θ1) °, in the wavelength band of the laser incident light 8, it is necessary to increase the reflectivity in order to reduce the loss and perform the amplification efficiently.

The total reflection film 6 having such wavelength characteristics and incident angle characteristics can be manufactured by laminating dielectric films as described above, and the conditions such as the thickness of the dielectric films to be laminated are controlled. By doing so, it is possible to control the reflection characteristics with respect to the wavelength and the incident angle.

However, in the total reflection film 6 produced by laminating the dielectric films in this way, the reflectance characteristics with respect to the wavelength change when the incident angle of the laser beam changes as shown by the

curves

202 and 201 in FIG. In addition, when the reflectance is decreased at a short wavelength interval with respect to the wavelength having a high reflectance (R = 1), the reflectance in the laser light wavelength band is set to be high with respect to a wide range of incident angles. In some cases, for example, the total reflection film 6 is difficult to adjust the thickness of the dielectric film to be laminated, and the number of laminations increases, so that the configuration becomes complicated and it may be difficult to manufacture.

In such a case, the reflectance of the total reflection film 6 may have a wavelength characteristic as shown in FIG. In FIG. 46, curve 203 is the reflectance characteristic of total reflection film 6 with respect to an incident angle of 0 ° (right vertical axis), and curve 204 is the reflectance characteristic of total reflection film 6 with respect to incident angle (θin1-θ1) ° (right vertical axis). ). 45 differs from FIG. 45 in that the reflectance in the 1535 nm band is larger than 1 / G0 (1535) at both incident angles. However, also in this case, the reflectance in the wavelength band (1550 nm) of the laser incident light 8 is high (R = 1) at both incident angles, and the laser incident light 8 is amplified by the reflection loss. The rate will not drop.

In the case of FIG. 46, the reflectance in the 1535 nm band is larger than 1 / G0 (1535) at any incident angle, but the reflectance is smaller than 1 and is not totally reflected. As a result, even if spontaneous emission light is generated and amplified in the laser medium 3, it is lost every time it is reflected by the total reflection film 6 on the side surface 33 and the side surface 34 in the wavelength 1535 nm band. The amplification factor for the emitted light can be reduced. In the configuration of the present invention, the laser beam is reflected and amplified a number of times in the laser medium 3, so that the amplification factor of spontaneous emission light can be reduced even if the rate of decrease in the reflectance with respect to the wavelength 1535 nm band is small. Will grow.

Thus, even when the reflectance for the wavelength band where the amplification gain is maximum becomes larger than the reciprocal of the amplification gain in the optical path until one reflection occurs, the total reflectance is reduced so that the reflectance is somewhat reduced. By providing the reflectance of the reflective film 6 with wavelength characteristics, the amplification factor of spontaneous emission light can be reduced, and a decrease in amplification gain with respect to the laser incident light 8 can be prevented.

As described above, when the wavelength at which the gain is maximum within the gain band of the laser medium 3 and the laser wavelength are different, the reflectance of the total reflection film 6 is totally reflected at the wavelength of the laser light, and the wavelength band in which the gain is maximized. By reducing the reflectance, the amplification of spontaneous emission light can be suppressed, and the laser light can be efficiently amplified. When the wavelength at which the gain is maximized and the laser wavelength are substantially the same, as described above, in the configuration of the present invention, the optical path with the longest parasitic oscillation or parasitic amplification is substantially the same as the laser reflected light optical path. Since amplification of spontaneous emission light is suppressed by the amplification of light, the amplification factor of laser light does not decrease.

Here, the case where the wavelength of the laser incident light 8 is 1550 nm is considered. However, the wavelength of the laser incident light may be within a range in which Er which is an active medium of the laser medium 3 has a gain, and this wavelength is required. It is selected according to the oscillation wavelength. Further, when this solid-state laser is used as an amplifier, it is determined by the wavelength of a laser light source used as a reference light source.

Embodiment 23. FIG.
FIG. 47 shows the wavelength dependence characteristics of the reflectivity of the total reflection film 6 of the planar waveguide laser device including the solid-state laser module according to Embodiment 23 of the present invention. Here, consider a case where the active medium of the laser medium 3 is Yb and the wavelength of the laser incident light 8 is 1064 nm. The shape of the solid-state laser module is the same as that shown in FIG. In FIG. 47, the horizontal axis of the graph represents the wavelength (unit: nm), the left vertical axis represents the gain intensity of the laser medium 3, and the right vertical axis represents the reflectance of the total reflection film 6. A curve 205 in the figure indicates the gain distribution (left vertical axis) of the laser medium 3, and a curve 206 indicates the reflectance characteristic (right vertical axis) of the total reflection film 6.

The solid-state laser material of the laser medium 3 may be a solid-state laser material using crystals such as YAG, glass, or other base materials, but the wavelength range and gain intensity in which the active medium has a gain differ depending on the solid-state laser material. There is a case. Here, it is assumed that the solid-state laser material is YAG. Since Yb has absorption in the wavelength band of 900 to 1000 nm, a high-power semiconductor laser having a wavelength of 940 nm or 975 nm that is generally available as an excitation light source can be used. Further, since the wavelength band of these excitation light sources is close to the wavelength band having a gain (1000 to 1100 nm), the quantum defect is small, and efficient laser oscillation and laser light amplification can be performed.

The gain distribution of the laser medium 3 has a wavelength characteristic as shown by a curve 205 in FIG. 47, and is maximum in the wavelength 1030 nm band. That is, the small signal gain G0 (λ) is also maximized in the wavelength 1030 nm band, and laser light in the wavelength 1030 nm band is most easily amplified.

On the other hand, since the wavelength of the laser incident light is 1064 nm, which is different from the wavelength band in which the maximum gain is obtained, the spontaneous emission light is amplified in the wavelength 1030 nm band where the gain becomes large as in the case of the twenty-second embodiment. As a result, the energy stored in the laser medium is consumed by this amplification, and the amplification efficiency of the laser incident light 8 is lowered. Further, when spontaneous emission light is amplified, parasitic oscillation light and parasitic amplification light are easily generated.

Here, by giving the reflectance of the total reflection film 6 a wavelength characteristic as shown by a curve 206 in FIG. 47, the 1064 nm laser incident light 8 can be efficiently amplified. The reflectance of the total reflection film 6 is set in the same manner as in the case of the twenty-second embodiment, and thus the description thereof is omitted here. The same applies to the angle characteristics. Further, even when the reflectance for the wavelength band where the amplification gain is maximum becomes larger than the reciprocal of the amplification gain in the optical path until one reflection occurs, it is the same as in the case of the twenty-second embodiment.

As described above, when the wavelength at which the gain is maximum within the gain band of the laser medium 3 and the laser wavelength are different, the reflectance of the total reflection film 6 is totally reflected at the wavelength of the laser light, and the wavelength band in which the gain is maximized. By reducing the reflectance, the amplification of spontaneous emission light can be suppressed, and the laser light can be efficiently amplified.

Here, the case where the wavelength of the laser incident light 8 is 1064 nm is considered. However, the wavelength of the laser incident light may be within a range in which Yb as the active medium of the laser medium 3 has a gain. A wavelength band of 1048 nm may be used. This wavelength is selected according to the required oscillation wavelength. Further, when this solid-state laser is used as an amplifier, it is determined by the wavelength of a laser light source used as a reference light source.

Also, the above-described Embodiments 22, 23. In the above description, the case where the reflectance of the total reflection film 6 has a wavelength characteristic within the wavelength band in which the laser medium 3 has gain has been described. However, as described above, the active medium of the laser medium 3 is Nd. When gain is obtained over different wavelength bands, desired laser oscillation light can be obtained by providing total reflection characteristics only for the required wavelength band. Furthermore, if the wavelength at which the gain is maximized and the laser wavelength are different within the wavelength band where the total reflection characteristics are given at this time, the reflectance of the total reflection film is set to total reflection at the wavelength of the laser light even within this wavelength band. By reducing the reflectance in other wavelength bands, the spontaneous emission light can be prevented from being amplified, and the laser light can be efficiently amplified.

In addition, when excitation light is input from the side surfaces 33 and 34, the wavelength characteristics of the total reflection film 6 may have transmission characteristics with respect to the excitation light wavelength in addition to the wavelength characteristics described above.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that all possible combinations thereof are included.

Industrial applicability

The planar waveguide laser device according to the present invention can be applied to laser oscillators and laser amplifiers used in many fields.

1 semiconductor laser (excitation light source), 2 excitation light, 3, 3a laser medium, 4a, 4b, 20 clad, 6 total reflection film, 7, 7a antireflection film, 8 laser incident light, 9, 9a laser output light, 10 Laser reflected light, 30 narrow-band reflective film, 31, 32 main surface, 33, 34 side surface, 35, 36 end surface, 40 wavelength conversion element, 41 output film, 42 incident film, 43 wavelength conversion laser light, 50 separation means, 51 Polarizer, 52 1/4 wavelength plate, 53 45 degree Faraday rotator, 54 isolator, 55 1/2 wavelength plate, 60 stack LD, 61 lens, 62 lens group, 63 microlens array, 64 slab waveguide, 89 laser light Propagation path, 89a Laser light propagation path area, 100 Solid laser module, 102, 102a, 111 Heat sink, 103a to 103e not installed area, 106 side surface, 108, 108a, 110 lens, 109 propagation optical path, 120 temperature constant area, 121 temperature change area, 126 laser light high reflection / excitation light high reflection film, 127 excitation area 128 not yet Excitation region, 150, 150a Thermal lens effect generating means, 152 contact portion, 153 non-contact portion, 160 bonding material.

Claims

A pair of main surfaces facing along a predetermined direction, a pair of side surfaces on both sides of the main surface, and a pair of end surfaces facing each other in the predetermined direction, and one side surface of the pair of side surfaces in the predetermined direction A flat plate-shaped laser medium that is inclined at a predetermined taper angle with respect to the predetermined direction so that an interval with the other side surface extending along the side gradually increases;
An antireflection film that transmits at least the laser beam provided in at least one place on the wide side of the pair of side surfaces;
A total reflection film that reflects laser light provided on the pair of side surfaces other than the antireflection film, and
And the laser light introduced into the laser medium from the part of the antireflection film on the pair of side surfaces is propagated through the laser medium while reflecting between the side surfaces, and further, the distance between the side surfaces in the laser medium is narrow. A solid-state laser module that is folded back and propagates again to the antireflection film on the side where the side surface spacing is wide;
An excitation light source for irradiating the laser medium with excitation light to excite the laser medium;
A planar waveguide laser device comprising:
In order to form a waveguide in a direction perpendicular to the main surface of the laser medium, the laser medium includes a pair of clads disposed on the pair of main surfaces, and in the direction perpendicular to the main surface, the laser light and the excitation light are The planar waveguide laser device according to claim 1, wherein the planar waveguide laser device propagates through a laser medium between the pair of clads.
The solid-state laser module is
A pair of first clads respectively disposed on the pair of main surfaces of the laser medium;
A pair of second claddings disposed respectively outside the pair of first claddings;
With
The laser light propagates through the laser medium between the pair of first clads, and the excitation light propagates through the pair of first clads and the laser medium between the pair of second clads. The planar waveguide laser device according to claim 1.
The solid-state laser module is
A first clad disposed on one main surface of the pair of main surfaces of the laser medium;
A pair of second clads respectively disposed on the other main surface of the first clad and the pair of main surfaces;
With
The laser light propagates through the laser medium between one of the first clad and the pair of second clads, and the excitation light passes through the first clad between the pair of second clads and the second clad. 2. The planar waveguide laser device according to claim 1, wherein the planar waveguide laser device propagates through a laser medium.
Of the pair of end faces at both ends in the predetermined direction of the solid-state laser module, a portion for introducing the excitation light is inclined with respect to a plane perpendicular to the main surface of the laser medium, and excitation light is emitted from the inclined end faces. 5. The planar waveguide laser device according to claim 1, wherein the planar waveguide laser device is introduced.
Of the pair of end faces at both ends in the predetermined direction of the solid-state laser module, a portion for introducing the excitation light is inclined with respect to a plane perpendicular to the main surface of the laser medium, and the excitation light is disposed at the outermost side. 5. The planar waveguide laser device according to claim 2, wherein the planar waveguide laser device is introduced by being reflected from the inclined end face incident from the clad.
A total reflection film provided on a pair of side surfaces of the laser medium is a narrow-band reflection film that reflects laser light and transmits excitation light, and the excitation light is introduced into the laser medium from the side surfaces. The planar waveguide laser device according to any one of claims 2 to 4.
The solid-state laser module has a first antireflection film for introducing the laser beam into a laser medium at a different location on the side where the side-surface distance between the pair of side surfaces is wide, and a second for outputting the laser beam from the laser medium. The planar waveguide laser device according to any one of claims 1 to 4, further comprising an antireflection film.
The planar waveguide laser device according to any one of claims 1 to 4, wherein the excitation light is introduced from the antireflection film through an optical path substantially the same as the laser light to perform excitation.
A wavelength conversion element disposed in the vicinity of the antireflection film, wherein the laser beam generated in the laser medium is converted to another wavelength when passing through the wavelength conversion element and outputs a wavelength conversion laser beam; The planar waveguide laser device according to any one of claims 1 to 4, wherein the planar waveguide laser device is characterized in that:
5. The laser beam is incident on the antireflection film at an incident angle such that an incident angle of the laser beam on the side surface immediately before the laser beam is not folded is perpendicular to the side surface. The planar waveguide laser device according to any one of the above.
The heat sink further provided on at least one main surface of the solid-state laser module, the heat sink on the main surface of the solid-state laser module, on the side surface or the end surface on at least one side of a side surface and an end surface of the solid-state laser module. The planar waveguide laser device according to any one of claims 1 to 11, wherein the planar waveguide laser device is installed offset from the inside by a predetermined length to the inside.
13. The planar waveguide laser device according to claim 12, wherein the heat sink is installed with an offset inward at all end faces and side surfaces of the solid laser module and has the same shape as the solid laser module.
13. The heat sink according to claim 12, wherein the heat sink is disposed offset to the inside on a surface side for inputting excitation light and a surface side for inputting / outputting laser light among side surfaces and end surfaces of the solid-state laser module. Planar waveguide laser device.
The heat sink extends to the side surface or the end surface of the solid laser module or extends beyond the side surface or the end surface on the surface side where the pumping light is input or the laser light is not input / output among the side surface and the end surface of the solid laser module. The planar waveguide laser device according to claim 12, wherein:
The planar waveguide according to any one of claims 12 to 15, wherein the excitation light is input while avoiding a non-installed area where the heat sink is not installed on the main surface of the solid-state laser module. Type laser equipment.
The planar waveguide laser device according to any one of claims 12 to 15, wherein the excitation light is input avoiding a corner of the laser medium and the heat sink of the solid-state laser module.
The solid state laser module is disposed on at least one of the pair of main surfaces of the laser medium, and a pair of second layers disposed on the outer sides of the first clad or the main surface of the laser medium. The pumping light is input while avoiding the laser medium in a non-installation area where the heat sink is not installed on the main surface of the solid-state laser module. The planar waveguide laser device according to any one of the above.
A heat sink installed on at least one main surface of the solid-state laser module;
The excitation light source is provided so as to introduce excitation light from one side surface of the laser medium in order to form an excitation region and an unexcitation region in the predetermined direction in the laser medium. The at least part of the total reflection film into which the excitation light is introduced is a narrow-band reflection film that reflects the laser light and transmits the excitation light, and folds the laser light within the excitation region. 7. The planar waveguide laser device according to any one of 1 to 6.
The laser light high reflection / excitation light high reflection film for reflecting the excitation light and the laser light is used as the total reflection film on the other side opposite to the one side where the excitation light of the laser medium is introduced. Item 20. The planar waveguide laser device according to Item 19.
An additional excitation light source for introducing the excitation light from the other side facing the one side where the excitation light of the laser medium is introduced, and at least the portion of the other side where the excitation light is introduced 20. The planar waveguide laser device according to claim 19, wherein the reflection film is a narrow-band reflection film that reflects laser light and transmits excitation light.
The temperature dependence of the refractive index of the laser medium is positive,
A thermal lens effect generating means installed on one main surface of the solid-state laser module and provided with a non-contact portion that does not come into contact with a contact portion to be joined to the solid-state laser module to partially exhaust heat; The planar waveguide according to any one of claims 1 to 6, wherein the non-contact portion of the generating means is formed along a laser light propagation path region in a laser medium of the solid-state laser module. Type laser equipment.
The temperature dependence of the refractive index of the laser medium is negative,
A thermal lens effect generating means installed on one main surface of the solid-state laser module and provided with a non-contact portion that does not come into contact with a contact portion to be joined to the solid-state laser module to partially exhaust heat; The planar waveguide type according to any one of claims 1 to 6, wherein a contact portion of the generating means is formed along a laser light propagation path region in a laser medium of the solid-state laser module. Laser device.
The planar waveguide laser according to any one of claims 1 to 23, wherein the reflectance of the total reflection film has wavelength dependency within a wavelength band in which the laser medium has gain. apparatus.
25. The reflectance of the total reflection film is total reflection with respect to a laser beam wavelength input to the laser medium, and is not total reflection with respect to other wavelengths. Planar waveguide laser device.
26. The planar waveguide laser according to claim 24, wherein the wavelength at which the reflectance of the total reflection film is not total reflection is a wavelength at which the gain of the laser medium is maximized. apparatus.
27. The planar waveguide laser device according to claim 26, wherein the active substance of the laser medium is Er or Yb.