JP6210732B2 - Laser amplifier and laser oscillator - Google Patents

Description

  The present invention relates to a laser amplifier and a laser oscillator using a solid as an excitation medium.

  A laser amplifier and an oscillator using a solid as an excitation medium excite the laser medium with excitation light such as a semiconductor laser and amplify the excitation light in the laser medium. Here, excitation refers to the transition of electrons in the ground state to an outer orbit by absorption of external energy (here, excitation light) by atoms constituting the laser medium. The excited atom returns to the ground state after a certain time. At this time, the atom emits energy (laser light).

  At this time, in order to excite the laser medium, a laser amplifier and an oscillator using a solid as an excitation medium must efficiently make the excitation light incident on the laser medium by a laser light source (excitation light source) or the like. Also, in planar waveguide laser amplifiers and oscillators that use a thin plate-like laser medium, the excitation light is condensed below the plate thickness of the thin planar waveguide to increase the incident efficiency of the excitation light. It is necessary to make it incident. (For example, Patent Document 1)

In general, a planar waveguide type laser amplifier and oscillator need to irradiate excitation light at an angle that does not totally reflect the planar waveguide. On the other hand, the planar waveguide type laser amplifier and oscillator need to totally reflect the excitation light in the planar waveguide. Therefore, it is assumed that the excitation light is irradiated at an angle satisfying these conditions. For example, when excitation light enters a planar waveguide having a refractive index N ₁ from a medium having a refractive index N ₀ , the relationship between the incident angle θ ₀ to the planar waveguide and the refractive angle θ ₁ in the planar waveguide is N _0. sin θ ₀ = N ₁ sin θ ₁ (Expression 1) At this time, excitation light having an incident angle larger than the critical angle θ _C = sin ⁻¹ (N ₀ / N ₁ ) (Equation 2) is reflected by the incident surface of the planar waveguide and is not incident on the planar waveguide. On the other hand, since the total reflection is a condition in the planar waveguide, the reflection condition is expressed by (π / 2−θ ₁ )> sin ⁻¹ (N ₀ / N ₁ ) (Formula 3). Therefore, the condition of the incident angle θ ₀ that satisfies the propagation in the planar waveguide is sin θ ₀ <(N ₁ / N ₀ ) sin [π / 2−sin ⁻¹ (N ₀ / N ₁ )] (Formula 4). . Therefore, the planar waveguide type laser amplifier and oscillator need to make the excitation light incident on the planar waveguide at an angle (θ ₀ ) or less represented by (Equation 4).

  When the excitation light output from the excitation light source has a diameter larger than the waveguide thickness, the excitation light is condensed using a lens or the like in order to increase the coupling efficiency between the excitation light and the planar waveguide. At this time, the condensing diameter of the excitation light and the numerical aperture (expressed by NA: Numerical Aperture, which is synonymous with “incident angle” here), which is the divergence angle of the excitation light, have an approximately inversely proportional relationship.

Table WO2009 / 028078

  The planar waveguide can increase the excitation density by being formed thin. However, the thinner the planar waveguide, the smaller the incident excitation light must be collected. However, when the excitation light is condensed to a small size, there is a problem that NA increases and excitation light components exceeding the critical angle increase, and the coupling efficiency between the excitation light and the planar waveguide decreases.

  Therefore, an object of the present invention is to obtain a laser amplifier and a laser oscillator that allow excitation light to be incident on a planar waveguide with high coupling efficiency without increasing the NA of the excitation light.

The laser amplifier according to the present invention includes a first excitation light source that generates and outputs a first excitation light, and is excited when the first excitation light is incident thereon, and amplifies the input signal light from the outside. A planar waveguide that outputs and a reflection part that directly reflects all of the excitation light that is not irradiated to the planar waveguide among the first excitation light to the incident surface of the planar waveguide , a groove through which the refrigerant flows therein, and said to Rukoto and characterized by cooling said planar waveguide.

The laser oscillator according to the present invention includes a first excitation light source that generates and outputs first excitation light, and amplifies the laser light that is excited and incident inside the first excitation light. And outputting a planar waveguide, a reflection mirror for resonating the laser beam generated in the planar waveguide and returning it to the planar waveguide, and outputting a part of the laser beam amplified by the planar waveguide to the outside a resonance output mirror, characterized in that it comprises a reflecting portion which reflects directly all of the first not irradiated to the planar waveguide of the excitation light excitation light to the incident surface of the planar waveguide.

  According to the laser amplifier and the oscillator of the present invention, it is not necessary to collect the excitation light below the plate thickness of the planar waveguide, and the excitation light and the planar waveguide can be excited with high coupling efficiency with a small NA.

FIG. 3 shows a laser amplifier according to the first embodiment. FIG. 3 is a diagram for explaining amplification of input signal light by the planar waveguide according to the first embodiment. FIG. 4 shows a laser amplifier according to a second embodiment. FIG. 6 shows a laser amplifier according to a third embodiment. FIG. 6 shows a laser amplifier according to a fourth embodiment. FIG. 6 shows a laser amplifier according to a fifth embodiment. FIG. 10 shows a laser oscillator according to a sixth embodiment.

Embodiment 1 FIG.
The laser amplifier according to the first embodiment will be described below with reference to FIGS. FIG. 1 is a diagram showing a laser amplifier according to the first embodiment. FIG. 2 is a diagram for explaining amplification of input signal light by the planar waveguide according to the first embodiment.

  The laser amplifier according to the first embodiment includes an excitation light source 1 (first excitation light source), a lens 2, a planar waveguide 3, and a reflection mirror 4 (reflection part).

  The excitation light source 1 generates excitation light R (first excitation light) for exciting the planar waveguide 3. In addition, the excitation light source 1 irradiates the excitation light R obliquely from above so that the excitation light R has a predetermined incident angle with respect to a surface 3a on which the excitation light R of the planar waveguide 3 described later enters. Further, the excitation light source 1 may be any light source that can output a wavelength for exciting the planar waveguide 3, and a semiconductor laser or the like is used. In addition, the arrow written with the dotted line has shown the advancing direction of the excitation light R. FIG.

  The lens 2 condenses the excitation light R output from the excitation light source 1. The lens 2 is arranged on the optical path of the excitation light R output from the excitation light source 1 and applied to the planar waveguide 3 described later. Furthermore, the lens 2 only needs to have a function of condensing the excitation light R, and a curvature mirror or the like can be used instead of the lens 2.

  The planar waveguide 3 absorbs and excites the excitation light R collected by the lens 2, amplifies the input signal light, and outputs it as laser light R2. At this time, the input signal light is light that is the source of the laser light R2.

  The laser medium of the planar waveguide 3 is, for example, Nd: YAG, Yb: YAG, Er: YAG, Tm: YAG, Ho: YAG, Nd: YLF, Yb: YLF, Er: YLF, Tm: YLF, Ho: YLF. Nd: Glass, Cr: LiSAF, Ti: Sapphire, etc. are used. The planar waveguide 3 is formed in a hexahedron as shown in FIG. The planar waveguide 3 confines the light in the planar waveguide and propagates the excitation light R using the difference in refractive index between the laser medium and the air around the laser medium. A non-reflective coating (AR coating) that does not reflect the light in the wavelength band of the excitation light is applied to the surface 3a on which the excitation light R of the planar waveguide 3 is incident. The AR coating is also applied to the surface of the planar waveguide 3 that faces the surface 3a. In the planar waveguide 3, the excitation light R is incident from the portion of the surface 3a on which the AR coating is applied, and the laser medium is excited by the excitation light R. Further, the surface 3e and the surface 3f of the planar waveguide 3 are provided with an AR coating for the input signal light and a reflection coating (HR coating: high reflection coating) for totally reflecting the input signal light. The input signal light input from the AR coated portion of the surface 3e is amplified by multiple reflection between the HR coatings of the surface 3e and the surface 3f, and the laser light R2 is transmitted from the AR coated portion of the surface 3f. Is output as

  The reflection mirror 4 reflects a part of the excitation light R collected by the lens 2 so as to enter the planar waveguide 3. The reflection mirror 4 is provided below the planar waveguide 3 so that a part thereof protrudes toward the excitation light source 1, and a surface 4 a (reflection surface) that reflects the excitation light R is a surface of the planar waveguide 3. It is provided to be perpendicular to 3a. Further, the reflecting surface 4a of the reflecting mirror 4 is provided with an HR coating that reflects light in the wavelength band of the excitation light R.

  Next, the operation of the laser amplifier according to the first embodiment will be described with reference to FIGS. In the following description, an example in which a part of the excitation light R collected by the lens 2 is irradiated below the surface 3a without being incident on the surface 3a will be described.

The excitation light R generated by the excitation light source 1 is collected by the lens 2. A part of the condensed excitation light R is directly incident on the planar waveguide 3 from the surface 3a on which the AR coating is applied. At this time, the irradiation direction of the excitation light source 1 and the formation angle of the surface 3a are adjusted so that the excitation light R incident on the planar waveguide 3 enters the planar waveguide 3 at a critical angle or less. A part of the excitation light R incident on the planar waveguide 3 from the surface 3a is within the planar waveguide 3 on the surface 3b and the surface 3c of the planar waveguide 3, and the planar waveguide 3 has a refractive index N ₀ and a planar waveguide. The reflection using the refractive index difference with the refractive index N ₁ around the waveguide 3 is confined and propagated in the planar waveguide 3 to excite the planar waveguide 3.

On the other hand, a part of the excitation light R collected by the lens 2 and not directly irradiated onto the surface 3 a of the planar waveguide 3 changes its traveling direction by reflection by the reflection mirror 4, moves toward the planar waveguide 3, and the planar waveguide 3. The light enters the planar waveguide 3 from the surface 3a. At this time, the excitation light R reflected by the reflection mirror 4 is adjusted to be less than the critical angle of the planar waveguide 3 from the irradiation direction of the excitation light source 1. The excitation light R incident from the surface 3 a of the planar waveguide 3 is reflected by the refractive index N ₀ of the planar waveguide 3 and the planar waveguide 3 on the surfaces 3 b and 3 c of the planar waveguide 3 in the planar waveguide 3. By reflection using a refractive index difference with the refractive index N _{1 of} air or the like in contact therewith, it is confined and propagated in the planar waveguide 3 to excite the laser medium in the planar waveguide 3.

  When the planar waveguide 3 is excited by the excitation light R and the excitation light Ra to be in an inversion distribution state (a state in which the number of excited state atoms is larger than the number of ground state atoms in the laser medium), Then, the input signal light is irradiated onto the surface 3e of the planar waveguide 3 to amplify the light of the input signal light and output it from the surface 3f as the laser light R2. This completes the operation of the laser amplifier according to the first embodiment.

  The planar waveguide 3 according to the first embodiment is formed as a hexahedron. However, the planar waveguide 3 is not limited to this, and may be any shape that can confine the excitation light R and excite the laser medium. A part of the planar waveguide 3 may be chamfered. Similarly, the surface 3a on which the excitation light R of the planar waveguide 3 is incident and the surfaces 3b and 3c in contact with the surface 3a do not necessarily have to be perpendicular to the surface 3a. Furthermore, the surface 3b and the surface 3c that are in contact with the surface 3a on which the excitation light R of the planar waveguide 3 is incident are not necessarily parallel to each other.

  Further, in the laser amplifier according to the first embodiment, the AR coating is applied to the surface 3 a of the planar waveguide 3 in order to make the excitation light R efficiently enter the planar waveguide 3. However, since the planar waveguide 3 generates heat by being excited by the excitation light R, the AR coating may be damaged. Therefore, in the laser amplifier according to the first embodiment, instead of the AR coating, a part of the surface 3a of the planar waveguide 3 may be formed at a Brewster angle that does not totally reflect light. By forming the surface 3a of the planar waveguide 3 at the Brewster angle, the AR coating is not necessary, and the problem due to the damage of the AR coating can be improved.

  As described above, in the laser amplifier according to the first embodiment, the reflection mirror 4 is arranged at a position below the planar waveguide 3 and protruded from the surface 3 a toward the excitation light source 1, and is excited by the lens 2. Of the light R, the excitation light R that is not directly incident on the planar waveguide 3 is reflected by the reflecting mirror 4 and is incident on the planar waveguide 3. There is no need to collect light below, and the NA of the excitation light R can be kept large, and the coupling efficiency between the excitation light R and the planar waveguide 3 can be increased.

Embodiment 2. FIG.
Hereinafter, the configuration of the laser amplifier according to the second embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the configuration of the laser amplifier according to the second embodiment. In the following description, parts corresponding to those of the laser amplifier according to the first embodiment are denoted by the same reference numerals as those in FIG. 1 and description thereof is omitted. In the following description, the input signal light and the laser light R2 are not shown because they are the same as those in FIG.

  In the laser amplifier according to the second embodiment, the excitation light source 1 is disposed at a position where the irradiated excitation light R is perpendicularly incident on the surface 3 a of the planar waveguide 3. Further, the reflection mirror 4 is characterized in that the reflection surface 4a is installed so as to face the excitation light source 1 side from the perpendicular to the surface 3a of the planar waveguide 3. Note that the laser amplifier according to the second embodiment does not include the lens 2.

  Next, the operation of the laser amplifier according to the second embodiment will be described with reference to FIG.

  First, the excitation light R generated by the excitation light source 1 is applied to the planar waveguide 3 so as to enter perpendicularly to the surface 3 a of the planar waveguide 3. Therefore, the position where the excitation light source 1 is disposed is a position where the surface on which the excitation light source 1 irradiates the excitation light R and the surface 3 a of the planar waveguide 3 face each other. A part of the excitation light R enters the planar waveguide 3 directly from the surface 3a on which the AR coating is applied. The excitation light R incident on the planar waveguide 3 from the surface 3 a is confined and propagated in the planar waveguide 3 to excite the laser medium in the planar waveguide 3.

  On the other hand, a part of the excitation light R that is not directly irradiated onto the surface 3 a of the planar waveguide 3 changes its traveling direction due to reflection by the reflection mirror 4, travels toward the planar waveguide 3, and from the surface 3 a of the planar waveguide 3 to the planar waveguide. 3 is incident. At this time, the excitation light R reflected by the reflection mirror 4 is irradiated onto the surface 3 a so as to be equal to or less than the critical angle of the planar waveguide 3 by adjusting the arrangement angle of the reflection mirror 4. A part of the excitation light R incident from the surface 3 a of the planar waveguide 3 is confined and propagated in the planar waveguide 3 to excite the laser medium of the planar waveguide 3.

  In the laser amplifier according to the second embodiment, the planar waveguide 3 is not limited to a hexahedron, and may be any shape that can confine the excitation light R and excite the laser medium. For example, a part of the planar waveguide 3 may be chamfered, or the surface 3a on which the excitation light R of the planar waveguide 3 is incident, and the surfaces 3b and 3c in contact with the surface 3a are not necessarily relative to the surface 3a. It does not have to be vertical. Furthermore, the surface 3b and the surface 3c that are in contact with the surface 3a on which the excitation light R of the planar waveguide 3 is incident are not necessarily parallel to each other.

  Further, in the laser amplifier according to the second embodiment, the excitation light source 1 is arranged so that the excitation light R is incident in the direction perpendicular to the surface 3a of the planar waveguide 3, and the reflection mirror 4 is excited by the reflection surface 4a. Since it is arranged so as to face the light source 1, the lens 2 for condensing the excitation light R becomes unnecessary, and the number of components can be reduced.

Embodiment 3 FIG.
Hereinafter, the configuration of the laser amplifier according to the third embodiment will be described with reference to FIG. FIG. 4 is a diagram showing the configuration of the laser amplifier according to the third embodiment. In the following description, parts corresponding to those of the laser amplifier according to the first embodiment are denoted by the same reference numerals as those in FIG. In the following description, the input signal light and the laser light R2 are not shown because they are the same as those in FIG.

As shown in FIG. 4A, the laser amplifier according to Embodiment 3 includes a diffraction grating 5 that diffracts the excitation light R instead of the reflection mirror 4. The diffraction grating 5 is disposed below the planar waveguide 3 so that the surface 5 a (diffraction surface) for diffracting the excitation light R is perpendicular to the surface 3 a of the planar waveguide 3. When light is incident at an incident angle θ _i , the diffraction grating 5 reflects the light in the θ _d direction by a diffraction effect.

  Next, the operation of the laser amplifier according to the third embodiment will be described with reference to FIG.

First, the excitation light R generated by the excitation light source 1 is incident on the diffraction grating 5 without being condensed. The excitation light R is incident on the diffraction grating 5 at an incident angle θ _i . The excitation light R is diffracted by the diffraction grating 5 and reflected by the diffraction angle θ _d with respect to the diffraction grating 5. When θ _i and θ _d are different in size, the diameter of the excitation light R after diffraction is sin (θ _i ) / sin (θ _d ) with respect to the diameter of the excitation light R before diffraction. Therefore, the surface 5a of the diffraction grating 5 is designed so that θ _i <θ _d , so that the diameter of the excitation light R after diffraction can be made smaller than the diameter of the excitation light R before diffraction. .

The excitation light R generated by the excitation light source 1 and diffracted by the diffraction grating 5 and having a reduced beam diameter is incident on the planar waveguide 3 from the surface 3 a of the planar waveguide 3. At this time, the excitation light R diffracted by the diffraction grating 5 is incident below the critical angle of the planar waveguide 3 by adjusting the diffraction surface of the diffraction grating 5. The excitation light R that has entered the planar waveguide 3 from the surface 3 a passes through the planar waveguide 3 on the surfaces 3 b and 3 c of the planar waveguide 3, and the refractive index N ₀ of the planar waveguide 3 and the periphery of the planar waveguide 3. Due to the reflection using the difference in refractive index from the refractive index N ₁ , the light is confined and propagated in the planar waveguide 3 to excite the planar waveguide 3.

  In the laser amplifier according to the third embodiment, the reflection type diffraction grating 5 has been described with reference to FIG. 4A. However, the diffraction grating 5 only needs to be capable of diffracting the excitation light R, and as shown in FIG. Alternatively, the diffraction grating 5 may be used.

  Also in the laser amplifier according to the third embodiment, the planar waveguide 3 is not limited to a hexahedron, and may be any shape that can confine the excitation light R and excite the laser medium. For example, a part of the planar waveguide 3 may be chamfered, or the surface 3a on which the excitation light R of the planar waveguide 3 is incident, and the surfaces 3b and 3c in contact with the surface 3a are not necessarily relative to the surface 3a. It does not have to be vertical. Furthermore, the surface 3b and the surface 3c that are in contact with the surface 3a on which the excitation light R of the planar waveguide 3 is incident are not necessarily parallel to each other.

  As described above, the laser amplifier according to the third embodiment includes the diffraction grating 5 instead of the reflection mirror 4, and diffracts the excitation light R so as to enter the planar waveguide 3, so that the excitation light R is condensed. Therefore, the diameter of the excitation light R can be reduced without using the lens 2 for the purpose. Therefore, the number of parts can be reduced.

Embodiment 4 FIG.
Hereinafter, the configuration of the laser amplifier according to the fourth embodiment will be described with reference to FIG. FIG. 5 is a diagram showing a configuration of a laser amplifier according to the fourth embodiment. In the following description, parts corresponding to those of the laser amplifier according to the first embodiment are denoted by the same reference numerals as those in FIG. 1 and description thereof is omitted.

  The laser amplifier according to Embodiment 4 includes a plurality of excitation light sources and a plurality of lenses. Specifically, the laser amplifier according to the fourth embodiment includes an excitation light source 1a (second excitation light source) in addition to the excitation light source 1 that generates the excitation light R for exciting the planar waveguide 3, and the excitation light. In addition to the plurality of lenses 2 for condensing R, a lens 2a (second reflecting portion) is provided. Further, in the laser amplifier according to the fourth embodiment, a reflecting mirror 4 wider than the area of the planar waveguide 3 is arranged below the planar waveguide 3 so as to protrude toward the excitation light source 1 side and the excitation light source 1a side. , A part of the excitation light R is reflected. Since the installation angle of the reflection mirror 4 can be adjusted by the angle between the surface 3c of the planar waveguide 3 and the reflection surface of the reflection mirror 4, it is possible to arrange the angles with high accuracy.

  Next, the operation of the laser amplifier according to the fourth embodiment will be described with reference to FIG.

  First, the operation for exciting the planar waveguide 3 by the excitation light R generated by the excitation light source 1 is the same as that of the laser amplifier shown in FIG.

  The excitation light Ra generated by the excitation light source 1a is collected by the lens 2a. A part of the excitation light Ra enters the planar waveguide 3 from the surface 3d on which the AR coating is applied. At this time, the irradiation direction of the excitation light source 1a and the formation angle of the surface 3d are adjusted so that the excitation light Ra incident on the planar waveguide 3 enters the planar waveguide 3 at a critical angle or less. The excitation light Ra incident on the planar waveguide 3 from the surface 3d is confined and propagated in the planar waveguide 3 to excite the laser medium in the planar waveguide 3.

  Of the excitation light Ra collected by the lens 2a, a part of the excitation light Ra that has not been directly irradiated onto the surface 3d of the planar waveguide 3 is reflected by the reflection mirror 4, and the plane direction is changed by changing the angle of the traveling direction. It goes to the waveguide 3 and enters the planar waveguide 3 from the surface 3 d of the planar waveguide 3. At this time, the excitation light Ra reflected by the reflection mirror 4 is irradiated so that the surface 3a of the planar waveguide 3 has a critical angle or less depending on the irradiation direction of the excitation light source 1a. The excitation light R reflected by the reflecting mirror 4 and incident from the surface 3d of the planar waveguide 3 is confined and propagated in the planar waveguide 3 to excite the laser medium in the planar waveguide 3.

  When the planar waveguide 3 is excited by the excitation light R and the excitation light Ra to be in an inversion distribution state, the input signal light is irradiated from the outside onto the surface 3e of the planar waveguide 3 to thereby generate light of the input signal light. Is output from the surface 3f as laser light R2.

  In the laser amplifier according to the fourth embodiment, the excitation light R is incident on the surface 3a of the planar waveguide 3 and the excitation light Ra is incident on the surface 3d. However, the present invention is not limited to this, and the planar waveguide 3 is a hexahedron. The excitation light R and the excitation light Ra can be incident from any of the four surfaces other than the surface 3b and the surface 3c.

  Further, in the laser amplifier according to the fourth embodiment, if the surface of the planar waveguide 3 that is a hexahedron is a surface other than the surfaces 3b and 3c, an excitation light source is further arranged in addition to the excitation light source 1 and the excitation light source 1a. A configuration in which excitation light is incident may be employed.

  Furthermore, in the laser amplifier according to the fourth embodiment, the input signal light is incident from the surface 3e of the planar waveguide 3 and is output as the laser light R2 from the surface 3d. However, the present invention is not limited to this, and the planar waveguide is a hexahedron. Input signal light can be incident from any of the six surfaces of the waveguide 3 and output as laser light R2.

  In the laser amplifier according to the fourth embodiment, a diffraction grating 5 may be used instead of the reflection mirror 4. In this case, the diameter of the excitation light R can be reduced without using the lens 2 for condensing the excitation light R, as in the laser amplifier shown in FIG. Therefore, the number of parts can be reduced.

  Furthermore, in the laser amplifier according to the fourth embodiment, the reflection mirror 4 may be tilted like the reflection mirror 4 shown in FIG. In this configuration, the reflection surface 4a on the excitation light source 1 side is tilted in the direction in which the excitation light R of the excitation light source 1 is irradiated, and the reflection surface 4a on the excitation light source 1a side is the excitation light source 1a. Is tilted in the direction in which the excitation light R is irradiated. Also in this case, like the laser amplifier shown in FIG. 3, the lens 2 for condensing the excitation light R is not necessary, and the number of components can be reduced.

  As described above, the laser amplifier according to the fourth embodiment reflects the excitation light R and Ra emitted from the plurality of excitation light sources 1 and 1a by the reflection mirror 4 to change the traveling direction, and the planar waveguide 3 Since it can be made incident, the coupling efficiency between the excitation light R and the planar waveguide 3 can be further increased.

  In addition, the laser amplifier according to the fourth embodiment reflects a plurality of excitation lights R and Ra with a single reflection mirror 4 wider than the area of the planar waveguide 3, so that a plurality of reflection mirrors 4 are provided. Thus, the number of reflection mirrors 4 can be reduced.

Embodiment 5. FIG.
Hereinafter, the configuration of the laser amplifier according to the fifth embodiment will be described with reference to FIG. FIG. 6 is a diagram showing a configuration of a laser amplifier according to the fifth embodiment. In the following description, parts corresponding to those of the laser amplifier according to the first embodiment are denoted by the same reference numerals as those in FIG. 1 and description thereof is omitted. In the following description, the input signal light and the laser light R2 are not shown because they are the same as those in FIG.

  In the laser amplifier according to the fifth embodiment, a groove for flowing cooling water is formed inside the reflection mirror 4, and the refrigerant pipe 6 is provided in this groove.

  Next, the operation of the laser amplifier according to the fifth embodiment will be described with reference to FIG.

  Excitation light R generated by the excitation light source 1, condensed by the lens 2, and directly irradiated onto the surface 3a of the planar waveguide 3, and not directly irradiated onto the surface 3a, but reflected off the reflection mirror 4 and irradiated onto the surface 3a. The excited excitation light R enters the planar waveguide 3 from the surface 3a.

  The planar waveguide 3 absorbs the excitation light R and generates heat.

  The coolant pipe 6 provided in the groove in the reflection mirror 4 in contact with the planar waveguide 3 cools the reflection mirror 4 by flowing cooling water therein. Thus, the refrigerant tube 6 can lower the temperature of the planar waveguide 3 that has generated heat due to absorption of the excitation light R by indirect cooling.

  In the laser amplifier according to the fifth embodiment, the reflection mirror 4 is made of a metal having high thermal conductivity, so that the cooling effect is further enhanced. Furthermore, the planar waveguide 3 and the reflection mirror 4 are fixed with an adhesive or solder having high thermal conductivity, so that the cooling effect is further enhanced.

  In the laser amplifier according to the fifth embodiment, the configuration in which the planar waveguide 3 is cooled by flowing cooling water through the refrigerant pipe 6 provided in the groove in the reflection mirror 4 has been described. Indirect cooling may be performed by attaching protrusions to the mirror 4 to increase the surface area and to enhance the heat dissipation effect.

  Further, the reflection mirror 4 of the laser amplifier according to the fifth embodiment can be applied to the laser amplifier described in FIGS. 1 and 3 to 5.

  In addition, the reflection mirror 4 of the laser amplifier according to the fifth embodiment has obtained the cooling effect using the cooling water, but is not limited thereto, and any refrigerant having a cooling effect may be used.

Embodiment 6 FIG.
Hereinafter, the configuration of the laser oscillator according to the sixth embodiment will be described with reference to FIG. FIG. 7 is a diagram for explaining a laser oscillator according to the sixth embodiment. In the following description, parts corresponding to those of the laser amplifier according to the first embodiment are denoted by the same reference numerals as those in FIG.

  A laser oscillator according to Embodiment 6 is obtained by applying the laser amplifier described in FIG. 1 to a laser oscillator. A laser oscillator is an apparatus that outputs amplified laser light R2 as a laser beam from a reflection mirror on one side by sandwiching a laser medium between two reflection mirrors and reciprocating light between them. The laser oscillator according to the sixth embodiment includes a resonance reflection mirror 8 and a resonance output mirror 9 as two reflection mirrors.

  The resonance reflecting mirror 8 transmits the excitation light R and reflects the laser light R2. The resonance reflecting mirror 8 is provided at a position facing a resonance output mirror 9 (to be described later) across the planar waveguide 3.

  The resonance output mirror 9 transmits the excitation light R and outputs a part of the amplified laser light R2 to the outside. The resonance output mirror 9 is provided at a position facing the planar waveguide 3.

  Hereinafter, the operation of the laser oscillator according to the sixth embodiment will be described with reference to FIG.

  First, the excitation light R generated by the excitation light source 1, condensed by the lens 2, and directly irradiated onto the surface 3a of the planar waveguide 3, and the surface 3a not directly irradiated onto the surface 3a but reflected by the reflection mirror 4 are reflected. Excitation light R applied to the light enters the planar waveguide 3 from the surface 3a.

  The excitation light R incident on the planar waveguide 3 excites the planar waveguide 3.

  The laser light R2 is amplified while reciprocating between the resonance reflecting mirror 8 and the resonance output mirror 9 via the planar waveguide 3, and becomes laser light with good directivity. A part of the laser beam R2 is emitted from the resonance output mirror 9 to the outside of the laser oscillator.

  In the laser oscillator according to the sixth embodiment, the resonance reflecting mirror 8 is provided on the surface 3a side and the resonance output mirror 9 is provided on the surface 3d side. However, the present invention is not limited to this, and the resonance reflecting mirror 8 is provided. The resonance output mirror 9 may be provided on the surface 3a side on the surface 3d side.

  In the laser oscillator according to the sixth embodiment, the resonance reflecting mirror 8 is provided on the surface 3a side and the resonance output mirror 9 is provided on the surface 3d side. What is necessary is just to be provided in a position.

  Further, the laser oscillator according to the sixth embodiment can apply the configuration of the laser amplifier shown in FIGS. 1 and 3 to 6. Note that when the laser amplifier configuration shown in FIGS. 1 and 3 to 6 is applied to the laser oscillator according to the sixth embodiment, input signal light is unnecessary.

  As described above, the laser oscillator according to the sixth embodiment is provided with the reflection mirror 8 for resonance and the output mirror 9 for resonance so as to face each other with the planar waveguide 3 therebetween, so that it can be used as a laser oscillator. it can.

DESCRIPTION OF SYMBOLS 1 Laser light source, 2 Lens, 3 Planar waveguide, 4 Reflection mirror, 5 Diffraction grating, 6 Refrigerant tube, 8 Resonance reflection mirror, 9 Resonance output mirror

Claims (11)

A first excitation light source that generates and outputs first excitation light;
A planar waveguide that is excited by the incidence of the first excitation light and amplifies and outputs the input signal light from the outside;
A reflection part that directly reflects all of the excitation light that is not irradiated to the planar waveguide among the first excitation light to the incident surface of the planar waveguide ; and
The laser amplifier according to claim 1, wherein the reflection part has a groove through which a coolant flows, and cools the planar waveguide . A second excitation light source that generates second excitation light and outputs the second excitation light to a surface other than the surface on which the first excitation light is incident on the planar waveguide;
The reflective portion is
All of the excitation light that is not irradiated to the planar waveguide among the second excitation light is directly reflected to the incident surface of the second excitation light of the planar waveguide,
The planar waveguide is
The laser amplifier according to claim 1, wherein the second excitation light is incident and excited. The first excitation light source is
Making the first excitation light incident perpendicular to the surface on which the first excitation light is incident;
The reflective portion is
The reflection surface for reflecting the first excitation light is disposed to be inclined toward the first excitation light source from a position perpendicular to the surface of the planar waveguide on which the first excitation light is incident. The laser amplifier according to claim 1 or 2. The reflective portion is a laser amplifier according to any one of claims 1 to 3, characterized in that a reflecting mirror. The reflective portion is a laser amplifier according to any one of claims 1 to 3, characterized in that a diffraction grating. A first excitation light source that generates and outputs first excitation light;
A planar waveguide that is excited by incidence of the first excitation light and amplifies and outputs the laser light generated inside;
A reflection mirror for resonance that reflects laser light generated in the planar waveguide and returns it to the planar waveguide;
An output mirror for resonance that outputs part of the laser light amplified by the planar waveguide to the outside;
A laser oscillator comprising: a reflection portion that directly reflects all of the excitation light that is not irradiated to the planar waveguide among the first excitation light to the incident surface of the planar waveguide. A second excitation light source that generates second excitation light and outputs the second excitation light to a surface other than the surface on which the first excitation light is incident on the planar waveguide;
The reflective portion is
All of the excitation light that is not irradiated on the planar waveguide among the second excitation light is directly reflected to the incident surface of the second excitation light of the planar waveguide,
The planar waveguide is
The laser oscillator according to claim 6 , wherein the second excitation light is incident and excited. The first excitation light source is
Making the first excitation light incident perpendicular to the surface on which the first excitation light is incident;
The reflective portion is
The reflective surface that reflects the first excitation light is disposed so as to be inclined toward the excitation light source from a position perpendicular to a surface of the planar waveguide on which the first excitation light is incident. Item 8. The laser oscillator according to Item 6 or 7 . The reflective portion has a groove through which the refrigerant flows inside, a laser oscillator according to any one of claims 8 claims 6, characterized in that cooling the planar waveguide. The reflecting portion, a laser oscillator according to claims 6 to claim 9, characterized in that a reflecting mirror. The reflecting portion, a laser oscillator according to claims 6 to claim 9, characterized in that a diffraction grating.

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