JP2007134560A - Solid-state laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state laser device capable of preventing a core from locating inside a circulating light path occurring in a laser medium to prevent parasitic oscillation, preventing a light path of incident light from covering the core to increase an output of laser in a desired direction, and improving efficiency of the laser. <P>SOLUTION: The solid-state laser device has the core in a cylindrical laser oscillating medium for transmitting excitation light to the core through four linear windows provided at equal intervals along the circumference of a non-laser oscillating medium formed around the core. The relation R<SP>2</SP>≥r<SP>2</SP>+(w/√2+r)<SP>2</SP>is satisfied where the radius of the core is (r), the width of the linear window is (w), and a distance is R between the center of the core and the edge of the linear window. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-state laser device having a cylindrical laser oscillation medium in a core and a linear window on the outer periphery of a non-laser oscillation medium formed around the core.

Conventionally, as a solid-state laser device having a cylindrical laser oscillation medium in the core and a linear window on the outer periphery of a non-laser oscillation medium formed around the core, as shown in FIG. A core 201 of (Yb: YAG) is provided, a non-laser oscillation medium (undoped YAG) 202 is provided on the outer periphery of the core 201, and excitation light is irradiated from the horizontal direction of the non-laser oscillation medium (undoped YAG) 202. An edge-pumped Yb: YAG microchip laser that oscillates and outputs laser light is disclosed (Non-Patent Document 1).
IEICE Transactions C, Vol. J84-C, No. 10, pp. 918-925, October 2001

  However, in conventional solid-state laser devices, there is generally an optical path that is folded back by a straight window and circulates in a non-laser medium, and gain is generated in the optical path when a part of the core is placed in the optical path. In addition, so-called parasitic oscillation causes self-internal oscillation that does not go through the resonator mirror. When this parasitic oscillation occurs, the energy in the core is consumed inside the medium, making it difficult for the laser to be emitted in a direction perpendicular to the configuration of the laser resonator, which is the direction in which it is intended to be extracted, and reducing the laser output and efficiency. There was a problem.

  In view of the above situation, the present invention is a solid-state laser capable of increasing the output of a laser in a desired direction and increasing the efficiency of the laser so that the circulating optical path in the non-laser medium does not reach the core. An object is to provide an apparatus.

In order to achieve the above object, the present invention provides
[1] A solid-state laser having a cylindrical laser oscillation medium in the core and propagating excitation light to the core through four linear windows provided at equal intervals on the outer peripheral surface of a non-laser oscillation medium formed around the core R ² ≧ r ² + (w / √2 + r) where r is the radius of the core, w is the width of the straight window, and R is the distance between the center point of the core and the end of the straight window. ²
It is characterized by satisfying.

  [2] The solid-state laser device according to [1], wherein a non-window region which is an outer peripheral surface between four linear windows on the outer periphery of the non-laser oscillation medium is roughened.

  [3] The solid-state laser device according to [2], wherein the non-laser oscillation medium has a substantially circular cross-sectional shape.

  [4] The solid-state laser device according to [2], wherein the non-laser oscillation medium has a quadrangular cross-sectional shape.

  [5] In the solid-state laser device according to [1], the cross-sectional shape of the non-laser oscillation medium is an octagon.

[6] A solid-state laser having a cylindrical laser oscillation medium in the core and propagating excitation light to the core through five linear windows provided at equal intervals on the outer peripheral surface of a non-laser oscillation medium formed around the core In the apparatus, R ² ≧ r ² + (a + b) ² where r is the radius of the core, w is the width of the linear window, and R is the distance between the center point of the core and the end of the linear window.
However, a = r × tan (π / 5)
b = w / (2 × cos (π / 5))
It is characterized by satisfying.

  [7] The solid-state laser device according to [6], wherein a non-window region which is an outer peripheral surface between five linear windows on the outer periphery of the non-laser oscillation medium is roughened.

  [8] The solid-state laser device according to [6], wherein the non-laser oscillation medium has a substantially circular cross-sectional shape.

[9] A solid-state laser device having a cylindrical laser oscillation medium in a core and propagating excitation light to the core through n linear windows provided at equal intervals on the outer periphery of a non-laser oscillation medium formed around the core Where R ² ≧ r ² + (a + b) ² where r is the radius of the core, w is the width of the linear window, and R is the distance between the center point of the core and the end of the linear window.
However, a = r × tan (π / n)
b = w / (2 × cos (π / n))
A solid-state laser device characterized by satisfying

  [10] The solid-state laser device according to [9], wherein a non-window region which is an outer peripheral surface between n linear windows on the outer periphery of the non-laser oscillation medium is used as a ground surface. apparatus.

[11] A cylindrical laser oscillation medium is provided in the core, and a non-laser oscillation medium formed around the core has a circular cross section, and excitation light is propagated to the core through a window on the outer circumferential surface of the circle. In a solid-state laser device, R ≧ 2 × r where r is the core radius and R is the outer radius of the non-laser oscillation medium.
It is characterized by satisfying.

  [12] The solid-state laser device according to any one of [1] to [11], wherein the core and the non-laser oscillation medium are thin films of 1 mm or less.

  [13] The solid-state laser device according to [12], wherein at least one surface of the core and the non-laser oscillation medium is fixed to a heat sink.

  According to the present invention, in a solid-state laser device, it is possible to prevent energy loss due to parasitic oscillation by designing and manufacturing so that an optical path that is turned around by a window in a non-laser medium does not reach the core. As a result, it is possible to provide a solid-state laser device that is equipped with a thin film type laser medium and has excellent laser output, efficiency, and stability.

The solid-state laser device of the present invention has a cylindrical laser oscillation medium in a core, and pumps excitation light to the core through four linear windows provided at equal intervals on the outer periphery of a non-laser oscillation medium formed around the core. R ² ≧ r ² + (( ^2), where R is the radius of the core, w is the width of the linear window, and R is the distance between the center point of the core and the end of the linear window. w / √2 + r) ²
Satisfied.

  Hereinafter, embodiments of the present invention will be described in detail.

  FIG. 1 is a plan view of a solid-state laser device showing a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  In this figure, as shown in FIG. 2, the solid-state laser device is such that one surface of the medium including the core is fixed on the heat sink 11, and has a core (for example, Yb: YAG) 1 in the center. Four linear windows (mirror surfaces) 3 to 6 are formed at equal intervals on the outer peripheral surface of a non-laser oscillation medium (for example, undoped YAG) 2 formed in the periphery, and the four linear windows 3 to 6 are formed. The excitation light 7 to 10 is propagated to the core 1 through the core 1. Here, a thin film having a thickness of 1 mm or less is used for the core 1 and the non-laser oscillation medium 2. The side surfaces of the four linear windows 3 to 6 are processed to be flat (mirror surface) so that the excitation light introduced from the outside does not scatter and enter the non-laser medium 2 efficiently. The side surfaces of the four non-window regions 12 to 15 which are the outer peripheral surfaces of the non-laser oscillation medium 2 between the windows 3 to 6 are roughened (sand surface) processed.

In this solid-state laser device, the radius of the core 1 is r, the width of the linear windows 3 to 6 is w, the outer radius of the non-laser oscillation medium 2 is R (the distance between the center point of the core 1 and the end of the linear window). ) R ² ≧ r ² + (w / √2 + r) ²
To be satisfied.

  A film having a high reflectance with respect to the wavelength of the laser light is formed between the laser medium (core 1) and the heat sink 11, and the laser oscillation direction of the laser output light 16 is upward.

  Here, as a comparative example, FIG. 3 is a plan view of a conventional solid-state laser device that does not satisfy the conditions of the claims of the present invention, and FIG. ing.

  As shown in FIG. 3, when the non-laser oscillation medium 22 has linear windows 23 to 26 at four positions at equal intervals, there are a plurality of optical paths that are turned around the linear windows 23 to 26 and circulate. The optical path that is turned around the windows 23 to 26 is totally reflected because the return incident angle is 45 °, which is larger than the total reflection angle 33 °, and there is no energy loss due to reflection (as shown in FIG. Assuming that the refractive index of YAG is n = 1.8 and the refractive index of the atmosphere is n = 1, the reflection angle at the window of the circulating optical path 33 is 45 °, which is larger than the total reflection angle 33 °, so that it is totally reflected. ). In this state, the radius of the core 21 disposed in the center is larger than the condition of the claims of the present invention, and when the core 21 is placed in a part of the circulating optical path (optical paths 27 and 28 in FIG. 3), the gain is increased in the optical path. In addition, parasitic oscillation easily occurs because there is no loss during rotation. In addition, 29-32 is excitation light.

  As described above, when parasitic oscillation occurs, the energy in the core circulates in the medium along the optical path, so that the laser does not emit outside the medium to be originally taken out, and the laser output and efficiency are reduced. appear.

  Therefore, in the solid-state laser device of the present invention, the core 21 is reduced or the non-laser oscillation medium 22 is increased. Alternatively, if the linear windows 23 to 26 are made small, any folded optical path that can exist in the non-laser medium 22 does not pass through the core 21, so that no gain is generated and no parasitic oscillation occurs. By producing the medium with such a design, the efficiency of the laser output can be increased.

  FIG. 5 is a detailed explanatory view of the principle. Circumferential optical path passing regions where parasitic oscillation may occur are 41 to 44. Since the optical path of parasitic oscillation is considered to be a band-like shape that is folded back by the width w of the linear window, it is closest to the core. The core should not be in contact with the optical path.

  FIG. 6 is an explanatory diagram of the geometric configuration of the solid-state laser device of the present invention.

The radius of the core 51 is r, the width of the linear windows 53 to 56 of the non-laser oscillation medium (transparent guide) 52 is w, and the distance between the center point of the core 51 and the end of the linear window (of the non-laser oscillation medium 52). When the outer radius is R,
When R ² = r ² + (w / √2 + r) ² , the core is in contact with the optical path.

  When two parameters in the above relational expression are fixed, and the remaining parameters satisfy the following conditions, the core is not applied to the optical path and parasitic oscillation does not occur.

(1) When R is large (2) When r is small (3) When w is small, that is, in the solid-state laser device of the present invention,
R ² ≧ r ² + (w / √2 + r) ²
To be satisfied.

  FIG. 7 is a plan view of a solid-state laser device showing a second embodiment of the present invention.

  In this figure, 61 is a core disposed at the center, 62 is a non-laser oscillation medium having a square cross section formed around it, and 63 to 66 are four locations formed on the outer peripheral surface of the non-laser oscillation medium 62. It is a straight window.

Also here, the side surfaces of the four non-window regions 67 to 70 which are outer peripheral surfaces between the four linear windows 63 to 66 formed on the outer peripheral surface of the non-laser oscillation medium (transparent guide) 62 are rough surfaces ( Sand surface) is processed. Further, when the radius of the core 61 is r, the width of the linear windows 63 to 66 of the non-laser oscillation medium (transparent guide) 62 is w, and the distance between the center point of the core 61 and the end of the linear window is R. ,
R ² ≧ r ² + (w / √2 + r) ²
If this condition is satisfied, parasitic oscillation does not occur.

  FIG. 8 is a plan view of a solid-state laser device showing a third embodiment of the present invention.

  In this embodiment, 71 is a core disposed at the center, 72 is a non-laser oscillation medium having an octagonal cross section formed around it, and 73 to 76 are four locations formed on the outer peripheral surface of the non-laser oscillation medium 72. The linear windows 77 to 80 are four non-window regions which are outer peripheral surfaces formed between the four linear windows. The side surfaces of the four non-window regions 77 to 80 are subjected to rough surface (sand surface) processing.

Similarly, when the radius of the core 71 is r, the width of the linear windows 73 to 76 of the non-laser oscillation medium (transparent guide) 72 is w, and the distance between the center point of the core 71 and the end of the linear window is R. R ² ≧ r ² + (w / √2 + r) ²
If this condition is satisfied, parasitic oscillation will not occur.

  FIG. 9 is a plan view of a solid-state laser device showing a fourth embodiment of the present invention.

  In this figure, 81 is a core disposed at the center, 82 is a non-laser oscillation medium having a substantially pentagonal cross section formed around it, and 83 to 87 are five locations formed on the outer peripheral surface of the non-laser oscillation medium 82. This is a straight window.

  Also here, the side surfaces of the five non-window regions 88 to 92 which are outer peripheral surfaces between the five linear windows 83 to 87 formed on the outer peripheral surface of the non-laser oscillation medium 82 are roughened (sand surface) processed. Like to do. Reference numerals 93 to 97 denote excitation light.

When the radius of the core 81 is r, the width of the linear windows 83 to 87 of the non-laser oscillation medium 82 is w, and the outer radius of the non-laser oscillation medium 82 is R,
R ² ≧ r ² + (a + b) ²
However, a = r × tan (π / 5)
b = w / (2 × cos (π / 5))
If this condition is satisfied, parasitic oscillation will not occur.

  FIG. 10 shows a detailed explanatory diagram thereof. That is, the circulating optical path passing region of the parasitic oscillation is 98 to 102, and the optical path of the parasitic oscillation is considered to be a belt-like shape that is folded back with the width w of the linear windows 83 to 87, as shown in FIG. The core 81 may not be in contact with the innermost optical path.

  FIG. 11 is an explanatory diagram of the geometric configuration of the solid-state laser apparatus shown in FIG.

When there are five straight windows as in this embodiment, the radius of the core 81 is r, the width of the straight windows 83 to 87 of the non-laser oscillation medium 82 is w, and the outer radius of the non-laser oscillation medium 82 is When R is R, a = r × tan (π / 5), b = w / [2 cos (π / 5)], and R ² = r ² + (a + b) ² , the core is in contact with the optical path. Therefore, in order to prevent parasitic oscillation, each value may be set so that R ² ≧ r ² + (a + b) ² .

Similarly, when there are n linear windows (n-fold symmetry type), a = r × tan (π / n), b = w / [2 cos (π / n)], R ² = r ² + ( a + b) When ^2, the core is in contact with the optical path. Therefore, in order to prevent the core from being applied to the optical path, the lengths of R, r, and w may be set so as to satisfy the above formula. For example, in the case of a three-fold symmetric type, the lengths of R, r, and w may be set so that a = r√3, b = w and R ² ≧ r ² + (r√3 + w) ² is satisfied.

  It should be noted that the outer diameter shape of the non-window region whose side surfaces are roughened in the above embodiments is circular or linear, and any action or effect for preventing parasitic oscillation remains the same. Belongs to.

  FIG. 12 is a plan view of a solid-state laser device showing a fifth embodiment of the present invention.

  In this embodiment, reference numeral 111 denotes a core disposed at the center, and 112 denotes a circular non-laser oscillation medium having an extremely flat plane formed around the core. The non-laser oscillation medium 112 has a window 113 on the entire outer peripheral surface, and can be excited from any direction.

  In manufacturing the solid-state laser device of the present embodiment, consider an optical path in which light is reflected three times. In the case of the three-reflection optical path 114, the incident angle on the side surface is 30 °, and since it is smaller than the total reflection, the total reflection is not achieved (a slight loss occurs at the time of reflection). Since the three-time reflected light path 114 is closest to the core 111, if the core 111 is not in contact with this optical path, the light path that is reflected more times (for example, the four-time reflected light path 115 and the fifth reflected light path 116) is the core. No contact with 111.

  Geometrically, it is sufficient that R is larger than r / R = sin (30 °) or r is small. That is, R ≧ 2 × r may be satisfied. In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The solid-state laser device of the present invention can be used as a solid-state laser device capable of outputting highly efficient laser light not only for physics and chemistry but also in industrial fields such as processing.

FIG. 1 is a plan view of a solid-state laser device showing a first embodiment of the present invention. It is the sectional view on the AA line of FIG. It is a top view of the solid-state laser apparatus as a comparative example. It is explanatory drawing of the reflection angle of the light of the A section of FIG. It is a detailed explanatory view of the solid-state laser device shown in FIG. It is explanatory drawing of the geometric structure of the solid-state laser apparatus which shows 1st Example of this invention. It is a top view of the solid-state laser apparatus which shows 2nd Example of this invention. It is a top view of the solid-state laser apparatus which shows 3rd Example of this invention. It is a top view of the solid-state laser apparatus which shows 4th Example of this invention. It is detailed explanatory drawing of the solid-state laser apparatus shown in FIG. It is explanatory drawing of the geometric structure of the solid-state laser apparatus shown in FIG. It is a top view of the solid-state laser apparatus which shows 5th Example of this invention. It is sectional drawing of the conventional solid-state laser apparatus.

Explanation of symbols

1, 21, 51, 61, 71, 81, 111 Core 2, 22, 52 Non-laser oscillation medium 3-6, 53-56, 63-66, 73-76 Four linear windows (mirror surfaces)
7 to 10, 29 to 32, 93 to 97 Excitation light 11 Heat sink 12 to 15, 67 to 70, 77 to 80 Four non-window regions 16 Laser oscillation direction 27, 28, 33 Optical path 41 to 44, 98 to 102 Parasitic Non-laser oscillation medium having a square cross section 72 Non-laser oscillation medium having an octagonal cross section 82 Non-laser oscillation medium having a substantially pentagonal cross section 83 to 87 Five linear windows 88 to 92 Five non-laser media Window region 112 Circular non-laser oscillation medium 113 Window formed on the entire outer peripheral surface 114 Three-time reflection optical path 115 Four-time reflection optical path 116 Five-time reflection optical path

Claims (13)

In a solid-state laser device that has a cylindrical laser oscillation medium in a core and propagates excitation light to the core through four linear windows provided at equal intervals on the outer peripheral surface of a non-laser oscillation medium formed around the core, R ² ≧ r ² + (w / √2 + r) ² where r is the radius of the core, w is the width of the straight window, and R is the distance between the center point of the core and the edge of the straight window.
A solid-state laser device characterized by satisfying   2. The solid-state laser device according to claim 1, wherein a non-window region which is an outer peripheral surface between four linear windows provided in the non-laser oscillation medium is roughened.   3. The solid-state laser device according to claim 2, wherein a cross-sectional shape of the non-laser oscillation medium is substantially circular.   3. The solid-state laser device according to claim 2, wherein a cross-sectional shape of the non-laser oscillation medium is a quadrangle.   3. The solid-state laser device according to claim 2, wherein a cross-sectional shape of the non-laser oscillation medium is an octagon. In a solid-state laser device having a cylindrical laser oscillation medium in a core and propagating excitation light to the core through five linear windows provided at equal intervals on the outer peripheral surface of a non-laser oscillation medium formed around the core, R ² ≧ r ² + (a + b) ² where r is the radius of the core, w is the width of the straight window, and R is the distance between the center point of the core and the end of the straight window.
However, a = r × tan (π / 5)
b = w / (2 × cos (π / 5))
A solid-state laser device characterized by satisfying   7. The solid-state laser device according to claim 6, wherein a non-window region which is an outer peripheral surface between five linear windows on the outer periphery of the non-laser oscillation medium is roughened.   7. The solid-state laser device according to claim 6, wherein a cross-sectional shape of the non-laser oscillation medium is substantially circular. A solid-state laser device having a cylindrical laser oscillation medium in a core and propagating excitation light to the core through n linear windows provided at equal intervals on the outer periphery of a non-laser oscillation medium formed around the core. R ² ≧ r ² + (a + b) ² where r is the radius of the straight line, w is the width of the straight window, and R is the distance between the center point of the core and the end of the straight window.
However, a = r × tan (π / n)
b = w / (2 × cos (π / n))
A solid-state laser device characterized by satisfying   10. The solid-state laser device according to claim 9, wherein a non-window region which is an outer peripheral surface between n linear windows on the outer periphery of the non-laser oscillation medium is roughened. A solid-state laser device having a cylindrical laser oscillation medium in the core, and a non-laser oscillation medium formed around the core having a circular cross section, and propagating excitation light to the core through a window on the outer circumferential surface of the circle Where R ≧ 2 × r where r is the core radius and R is the outer radius of the non-laser oscillation medium.
A solid-state laser device characterized by satisfying   12. The solid-state laser device according to claim 1, wherein the core and the non-laser oscillation medium are thin films having a thickness of 1 mm or less.   13. The solid state laser device according to claim 12, wherein at least one surface of the core and the non-laser oscillation medium is fixed to a heat sink.

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