JP2001189509A - Laser device, laser working device using it, and optical signal amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small laser device with high freedom in design which provides a high output laser beam, a laser working device using it, and optical signal amplifier. SOLUTION: An excitation light guide member 16 comprises facing surfaces, and the excitation light incident on the excitation light guide member advances in the circumferential direction of the excitation light guide member while repeatedly reflected on the facing surfaces. At least, a part of the excitation light advances while deflected inward of the excitation light guide member by an advancement control means which advances the light inward of the excitation light guide member, to form an excitation light distribution region. An optical fiber 12 is so arranged that at least a part of side surface contacts at least one of facing surfaces in the excitation light distribution region directly or indirectly through an optical medium, and a laser active material is excited with the excitation light incident from the side surface of optical fiber through the contact part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device, a laser processing device and an optical signal amplifying device using the same, and more particularly, to a laser device which emits laser light by supplying excitation light to a laser active substance contained in an optical fiber. The present invention relates to a laser device, a laser processing device using such a laser device, and an optical signal amplifying device.

[0002]

2. Description of the Related Art In the technical fields such as optical communication and laser processing, it has been desired to develop a high-power and small-sized laser device. A clad for guiding excitation light was formed around a core doped with laser-active ions, dyes, or other luminescent centers (hereinafter referred to as laser-active substance) as a possibility that this requirement is likely to be satisfied. A laser device using an optical fiber is known.
In such a laser device, in order to realize high output and high efficiency of laser light, it is necessary to efficiently introduce and absorb excitation light into a core doped with a laser active material. However, it is difficult to efficiently introduce the excitation light from the end of the small diameter optical fiber.

To overcome this problem, Japanese Patent Laid-Open Publication No.
No. 284255 discloses a laser device 8 in which an optical fiber 84 is wound around a circumferential surface of a cylindrical or cylindrical excitation light introducing member 82 for confining excitation light, as shown in FIG.
0 is disclosed. In such a laser device 80, as shown in FIG. 23, the excitation light introduced into the excitation light introduction member 82 from one end surface in the axial direction passes through a spiral optical path while repeating total reflection on the circumferential surface. Draw and proceed in the axial direction and become confined. When the excitation light reaches the circumferential surface around which the optical fiber 84 is wound, it is introduced into the inside from the side surface of the optical fiber 84 wound around the cylindrical surface. According to such a laser device 80, since the excitation light is introduced from a side surface much larger in area than the end face of the optical fiber 82, the efficiency of introduction of the excitation light is increased as compared with the case where the excitation light is introduced from the end face. It becomes possible.

As shown in FIGS. 24 (A) and 24 (B), in order to reduce the size of the laser device using the excitation light introducing member as described above while maintaining the output and efficiency of the laser device.
A laser device 90 in which a thin disk-shaped one having upper and lower surfaces which are flat as the excitation light introducing member 92 and an optical fiber 94 wound on this flat surface is arranged has also been proposed.

[0005]

When the excitation light is to be confined in such a thin disk-shaped excitation light introducing member 92, reflection films are formed on the upper and lower surfaces or side surfaces (circumferential surfaces) of the excitation light introducing member 92. To form. However, when a reflection film is used, there is a problem that a part of the excitation light is absorbed by the reflection film, and a loss of the excitation light due to reflection is inevitable.
In particular, when the reflection films are formed on the upper and lower surfaces of the excitation light introducing member 92, the number of reflections on the upper and lower surfaces increases, so that the loss of the excitation light due to absorption on the reflection surface increases. Also,
If a reflection film is formed only on the side surface of the excitation light introducing member 92,
Although the loss of the excitation light due to the reflection is reduced, it is difficult to form a reflection film only on the side surface of the thin plate-shaped excitation light introduction member 92 in the first place.

Therefore, when the excitation light introducing member 92 is formed in a thin disk shape, it is considered that the excitation light is confined in the excitation light introducing member 92 by total reflection at the boundary surface between the excitation light introducing member 92 and the outside (air). Can be However, when the excitation light is to be confined by total internal reflection, in addition to the condition that the refractive index of the excitation light introduction member 92 is higher than the refractive index of the air in the outside world, the excitation light in the excitation light introduction member 92 extends over the entire optical path. The condition that the angle of incidence with respect to the interface must be kept above a predetermined critical angle must be met. When the thin plate-shaped excitation light introducing member 92 is intended to satisfy such conditions, the range in which the excitation light is distributed in the excitation light introducing member 92 is limited, and the incident position and the incident angle of the excitation light are adjusted. There is a problem that it becomes difficult.

For example, when the excitation light is to be confined to the excitation light introducing member of the laser device shown in FIG. 24 by total reflection, the excitation light needs to be incident from a position near the periphery of the plane and along the side surface. There is. Then, as shown in FIGS. 25A and 25B, the excitation light travels straight while repeating total reflection between the planes of the excitation light introduction member 92, and is totally reflected on the side surface of the excitation light introduction member 92. Need to be repeated. FIG. 26 (A), (B)
FIG. 9 is a diagram showing a result of analyzing the optical path of the excitation light introduced into the disk-shaped excitation light introduction member 92 made of quartz disk having a diameter of 110 mm, a thickness of 3.5 mm, and upper and lower surfaces being flat by a ray tracing method. The excitation light is incident through a triangular prism 96 provided at a position 50 mm from the center of the plane such that the angle between the plane and the excitation light is 45 ° from the direction parallel to the tangential direction of the side surface. Black dots on the optical path indicate reflection positions on the upper and lower surfaces. As shown in FIGS. 26A and 26B, the excitation light introduced into the excitation light introduction member 92 is distributed only near the periphery of the excitation light introduction member 92, and is distributed near the center. Absent. For this reason, the position where the optical fiber is arranged is limited to the peripheral portion, and the degree of freedom in design is reduced.

In addition, since the pumping light is introduced only from the optical fiber 94 disposed in a narrow area near the periphery of the plane, the efficiency of pumping light introduction deteriorates, and a high-power laser beam cannot be obtained. In such a case, it is conceivable to increase the efficiency of the excitation light introduction by setting the diameter of the excitation light introduction member 92 large, but this does not allow the laser device 90 to be downsized. Further, although the excitation light is reflected on the plane and the side surface of the excitation light introduction member 92, a part of the excitation light is not totally reflected on the side surface,
It has jumped out of the excitation light introducing member 92. In this case, in order to satisfy the condition of total reflection on the side surface, it is difficult to adjust the incident position and the incident angle of the excitation light, and the design freedom of the laser device is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to obtain a small and high-output laser beam, and furthermore, a laser device having a high degree of freedom in design and such a laser device. It is an object to provide a laser processing device and an optical signal amplifying device using a laser device.

[0010]

To achieve the above object, a laser device according to the present invention has the following contents. First, an invention according to claim 1 has an optical fiber having a core containing a laser active substance, outputting a laser beam from at least one end when the laser active substance is excited, and an excitation light for exciting the laser active substance. An excitation light source for generating the excitation light; and an excitation light introduction member for introducing the excitation light into the optical fiber. The excitation light introduction member has opposing surfaces facing each other, and the excitation light incident on the excitation light introduction member has an opposing surface. While traveling in the circumferential direction of the excitation light introducing member while repeating reflection at the same time, at least a part of the excitation light is directed inward of the excitation light introducing member by a traveling control means that causes the path of the excitation light to travel inward of the excitation light introducing member. The optical fiber forms an excitation light distribution region while being bent, and at least a part of the side surface of the optical fiber has at least one of opposing surfaces in the excitation light distribution region. And a laser device that is disposed so as to directly or indirectly contact through an optical medium, and the laser active substance is excited by excitation light incident from the side surface of the optical fiber through the contacted portion. .

In the present invention, the excitation light generated by the excitation light source is incident on the excitation light introducing member. The excitation light travels in the circumferential direction of the excitation light introducing member while being repeatedly reflected between the opposing surfaces of the excitation light introducing member. Then, the excitation light travels while being bent inward of the excitation light introduction member by the progress control means to form an excitation light distribution region. Therefore, according to the present invention, it is possible to form the excitation light distribution region as wide as the inside of the excitation light introduction member. When the excitation light reaches the portion of the excitation light distribution region where the optical fiber is disposed on the opposing surface, the excitation light is introduced into the optical fiber from the side surface. The excitation light excites the laser active substance doped in the core, and generates laser light by the stimulated emission effect. This laser light propagates through the optical fiber and is output from the end.

As described above, according to the present invention, since the excitation light distribution region can be formed to be wide toward the inside of the excitation light introducing member, the optical fiber is arranged in an arbitrary range in the wide region of the opposing surface. It is possible to increase the degree of freedom regarding the arrangement of the optical fiber.
Further, since it becomes possible to introduce the excitation light into the optical fibers arranged over this wide area, it becomes possible to provide a high-output laser device even when a thin plate-like excitation light introduction member is used. . In addition, since the excitation light introduced into the excitation light introducing member is bent inside the excitation light distribution region, it is not always necessary to reflect the light on the side surface of the excitation light introducing member in order to confine the excitation light by total reflection. Disappears. In addition, even if it is assumed that the excitation light is reflected on the side surface, the incident angle with respect to the side surface should be larger than the critical angle, which is the condition of total reflection, by bending the optical path of the excitation light inside the excitation light distribution region. Becomes easier. Therefore, it is possible to easily adjust the incident position and the incident angle of the excitation light, and to increase the degree of freedom in designing the laser device. Furthermore, according to the laser device of the present invention, since the optical fiber is disposed on the opposing surface in the excitation light distribution region, it is different from the conventional laser device in which the optical fiber is wound around the side surface of the cylindrical excitation light introducing member. Differently, the distance (thickness) between the facing surfaces can be reduced. Therefore, it is possible to reduce the size of the device while maintaining the output of the laser light. The invention according to claim 2 is the laser device according to claim 1, wherein the progress control means is formed by a change in thickness between the facing surfaces. According to the present invention,
Since the progress control means can be configured by changing the thickness between the opposing surfaces, the manufacture of the excitation light introducing member is facilitated.

[0013] According to a third aspect of the present invention, there is provided an optical fiber having a core containing a laser active substance and outputting a laser beam from at least one end when the laser active substance is excited, and an excitation light for exciting the laser active substance. And an excitation light introduction member for introducing excitation light into the optical fiber, the excitation light introduction member has opposing surfaces facing each other, and the excitation light incident on the excitation light introduction member is The excitation light distribution member is circulated around the excitation light introducing member while being repeatedly reflected on the opposing surface to form an excitation light distribution region. In the excitation light distribution region, the distance between the opposing surfaces is excited because the excitation light is bent inward of the excitation light introduction member. A thickened portion expanding toward the inside of the light introducing member is formed, and at least a part of the side surface of the optical fiber is directly in contact with at least one of the opposing surfaces in the excitation light distribution region. Or it is arranged so as to indirect contact via an optical medium, a laser and wherein the laser active material is excited by excitation light incident from the side surface of the optical fiber through the contact portion. According to the present invention, the excitation light repeatedly circulates around the excitation light introduction member to form an excitation light distribution region while repeatedly reflecting between the opposing surfaces of the excitation light introduction member. The excitation light travels while being bent inward of the excitation light introducing member by the thickened portion in which the distance between the opposing surfaces increases toward the inside of the excitation light introducing member. Therefore, it is possible to obtain the same effect as the laser device of the first aspect.

According to a fourth aspect of the present invention, there is provided the laser device according to the third aspect, wherein the excitation light introducing member has a shape in which the distance between the opposing surfaces continuously increases toward the center of the excitation light introducing member. According to the present invention, the excitation light introducing member can be formed into various shapes such as a plano-convex lens shape, a biconvex lens shape, a meniscus lens shape, and a conical shape. Claim 5
The invention according to claim 4 is the laser device according to claim 4, wherein the excitation light introducing member has a convex lens shape in which the distance between the opposing surfaces continuously increases toward the center of the excitation light introducing member. ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to use what has a plano-convex lens shape or a biconvex lens shape which is easy to manufacture, arrange, and handle as the excitation light introducing member. The invention according to claim 6 is the laser device according to any one of claims 1 to 5, wherein the optical fiber is disposed so as to be wound around at least one of the opposing surfaces in the excitation light distribution region. ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to arrange | position an optical fiber in the excitation light distribution area | region at high density, and it becomes possible to introduce | transduce an excitation light with respect to an optical fiber efficiently. In addition, it is possible to wind the optical fiber in a high-density and stable state around a portion where the distance between the facing surfaces increases.

According to a seventh aspect of the present invention, there is provided a laser device according to any one of the first to sixth aspects, and a laser device for converging a laser beam output from at least one end of an optical fiber of the laser device onto an object to be processed. This is a laser processing apparatus provided with an optical optical system. ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to comprise a laser processing apparatus using a small and high-power laser apparatus. According to an eighth aspect of the present invention, there is provided an optical signal comprising the laser device according to any one of the first to sixth aspects, wherein one end of the optical fiber is an input end of a signal light and the other end is an output end of an amplified light. It is an amplification device. ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to comprise an optical signal amplifying device using a small high-power laser device.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a laser device according to the present invention. The laser device 10 is a light oscillation device or a light amplification device utilizing the stimulated emission effect of a laser active substance, and is used in laser processing, optical communication, laser measurement, and the like. This laser device 10 has a core containing a laser active substance, an optical fiber 12 that emits a laser beam from an end when the laser active substance is excited, and an excitation fiber that generates an excitation light for exciting the laser active substance. A light source 14 and an excitation light introducing member 16 for introducing excitation light into the optical fiber 12 are provided.

As shown in FIGS. 1 and 2, the excitation light introducing member 16 has a flat surface 16b and a flat surface 16b.
The surface facing b is a convex surface 16a, and a disc-shaped plano-convex lens-shaped transparent body having a shape to be rotated around a rotation axis passing through the center is used. As the excitation light introducing member 16,
By using one having a flat surface 16b on one side of the opposing surface, it becomes possible to stably install the excitation light introducing member and to easily provide accessories such as a radiator. Further, by forming the excitation light introducing member 16 into a rotationally symmetrical shape around a rotation axis passing through the center, it becomes easy to design and dispose the optical fiber, and it is possible to reduce the size of the apparatus. In such an excitation light introducing member 16, the convex surface 16a functions as a progress control means for bending the excitation light inside the excitation light introducing member. The excitation light introducing member 16 can be formed of an optical material such as optical glass such as quartz glass, an optical resin, or an optical crystal.
Usually, the cladding of the optical fiber 12 is formed of the same material in consideration of matching of the refractive index and the coefficient of thermal expansion with the optical fiber 12.

The shape of the convex surface 16a of the excitation light introducing member 16 is not particularly limited as long as the excitation light introduced into the excitation light introducing member 16 can be bent toward the center.
A part of a spherical surface, a paraboloid, a hyperboloid, or the like is used. The distance between the convex surface 16a and the flat surface 16b is set as small as possible within a range where the required mechanical strength can be maintained because the optical path in the excitation light introducing member 16 is reduced and the excitation light is confined at high density. . As shown in FIGS. 3A and 3B, such an excitation light introducing member 16 has a central portion that does not form an optical path in order to reduce the amount of optical materials required for manufacturing and improve heat dissipation. The space 16c may be formed.

When the excitation light is introduced from the vicinity of the periphery of the excitation light introduction member 16 as described above, the excitation light
As shown in (A) and (B), the flat surface 16b and the convex surface 1
The light travels in the circumferential direction of the excitation light introducing member 16 while repeating reflection at 6a. When the light is reflected by the convex surface, it is bent toward the center of the excitation light introducing member. As a result, the excitation light is distributed in the excitation light distribution region having a donut shape in a range from the vicinity of the periphery to the vicinity of the center of the introduction member. The optical fiber 12 is wound around the convex surface 16a in the excitation light distribution region in a spiral shape in which the side surfaces are in close contact with no gap. The winding of the optical fiber 12 is
For example, as shown in FIGS. 4 (A) and 4 (B), the cylinder 1 temporarily erected at the center of the convex surface 16 a of the excitation light introducing member 16.
8, the optical fiber 12 is fixed at one end at the beginning of winding, and the optical fiber 12 is sequentially wound around the outer periphery in such a manner that the side surfaces are in close contact with each other, and the other end is drawn out as a laser light output end 12a. After the winding is performed, the cylinder 18 is
More removed. By winding the optical fiber 12 without gaps in this way, the core can be arranged on the excitation light introducing member 16 at high density, and the excitation light can be efficiently introduced into the optical fiber 12. . The optical fiber 12 wound by the above method is made of an optical resin such as an optical resin or a low melting point glass having a refractive index equal to or close to that of the excitation light introducing member 16 so as not to hinder the introduction of the excitation light from the excitation light introducing member 16. It is fixed to the convex surface 16a by a method such as adhesion with a medium, melting using a carbon dioxide laser or the like.

As shown in FIG. 5, the convex surface 16a
The optical medium layer 20 may be formed so as to cover the optical fiber 12 wound around. If such an optical medium layer 20 having a refractive index equal to or close to that of the excitation light introducing member 16 is used, not only is the optical fiber 12 fixed, but also the excitation light is introduced into the optical fiber 12 through this optical medium layer 20. In addition, the optical fiber 12 is hardly affected by the outside world, and the frequency of the longitudinal mode can be stabilized. As such an optical fiber 12, a laser fiber in which a clad for guiding excitation light to a core around a core doped with a laser active substance is formed is used. This laser active substance is a substance that generates laser light by the stimulated emission effect of the excitation light, and includes neodymium (Nd), ytterbium (Y
b), a rare earth element such as erbium (Er) or the like is appropriately selected according to the use of the laser apparatus. For example, 1.
When amplifying signal light in the 55 μm band, erbium capable of amplifying light in this wavelength band is preferably used.

The material of the optical fiber 12 is selected from glass such as quartz glass and phosphate glass and optical material such as plastic according to the use of the laser device.
For example, when performing high-luminance operation, quartz glass having high laser light resistance is used. The cross-sectional shape of the optical fiber 12 is not particularly limited as long as the excitation light incident on the clad can be efficiently introduced into the core.
It is appropriately selected from a polygon, an ellipse, and the like. Excitation light introduction member 1
One end of the optical fiber 12 fixed to the center of the optical fiber 6 may have a fractured surface, but is usually polished or flat-polished to increase the reflectance of laser light in order to reduce loss at the time of light reflection. Reflection means such as a diffraction grating and a reflection film having a light reflectance close to 100% are provided.
The output end 12a drawn out has a vertical broken surface from which laser light can be extracted. When one end of the optical fiber 12 wound around the excitation light introducing member 16 is used as a signal input end and the other end is used as an output end, or when both ends are used as output ends, as shown in FIG. 12
Both a and 12b are vertically broken surfaces, and are drawn out without being fixed to the excitation light introducing member 16.

The core diameter of the optical fiber 12 can be appropriately set according to the application of the laser device and the like. For example, if the core diameter is set small, the laser light density can be increased. Further, as the optical fiber 12, a multi-mode fiber that guides a plurality of mode lights can be used because the diameter is set to be equal to or greater than a certain value. However, a laser processing device that performs fine processing or a signal that amplifies the signal light When used as an amplifying device, a single mode fiber having a diameter set to be equal to or less than a certain value and guiding only a single fundamental mode light is used. Further, as the optical fiber 12, a first clad for introducing pumping light is formed around a core doped with a laser active substance, and further, around this first clad, for confining pumping light in the first clad. It is also possible to use an optical fiber having a double clad structure in which the second clad is formed. In this case, in order to improve the absorption efficiency of the excitation light with respect to the core, it is preferable to use a first clad having a rectangular cross section.

The optical fiber 12 may be wound on the flat surface 16b or both surfaces 16a, 16b of the excitation light introducing member 16, or may be wound on a plurality of layers as shown in FIG. Furthermore, not only one optical fiber but also a plurality of optical fibers may be wound as necessary. Further, the optical fiber 12 is
The method of arranging is not limited to winding the optical fiber 12, but as shown in FIG. 8, it is also possible to arrange the optical fiber 12 in a state where the optical fiber 12 is repeatedly folded. Plane 1 of excitation light introducing member 16
A triangular prism 22 for introducing the excitation light emitted from the excitation light source 14 to the excitation light introduction member 16 is provided near the periphery of 6b. The prism 22 is fixed in a state in which one of the three surfaces except the both side surfaces that are parallel to each other is an incident surface and the other surface is in close contact with the plane 16 b of the excitation light introducing member 16.

The position where the prism 22 is provided is the plane 16
It is not limited to b, but may be provided on the convex surface 16a or the side surface. As means for introducing the excitation light emitted from the excitation light source 14 into the excitation light introduction member 16, in addition to the above-described prism 22, the excitation light introduction member 16
Groove, a diffraction grating, or the like can be used.
In order to reduce the leakage of the excitation light, the optical fiber 14a for guiding the excitation light emitted from the excitation light source 14 can be directly fusion-bonded to the excitation light introducing member 16. The excitation light source 14 is not particularly limited as long as it can emit excitation light having a wavelength that excites a laser active substance doped in the core of the optical fiber 12, and is usually a light emitting diode (LED) or a laser diode ( Semiconductor devices such as LD) and lamps such as flash lamps are used. In particular, it is preferable to use a semiconductor element having excellent light condensing properties and excitation light generation efficiency. The excitation light generated by the excitation light source 14 is guided to the incident surface of the prism 22 provided on the excitation light introducing member 16 through the optical fiber 14a. In order to increase the excitation light density in the excitation light introducing member 16, a plurality of excitation light sources 14 are provided, and the excitation light from each excitation light source 14 is supplied from a plurality of places to the excitation light introducing member 16.
May be introduced.

The operation of the above laser device 10 will be described below. The excitation light generated by the excitation light source 14 is transmitted to the plane 16 of the excitation light introduction member 16 through the optical fiber 14a.
The light is guided to a prism 22 provided in the vicinity of the periphery of b, and is introduced into the excitation light introducing member 16 at a predetermined angle by the prism 22. This excitation light travels while repeating total reflection on the convex surface 16a and the flat surface 16b of the excitation light introducing member 16 as shown in FIG. 9 (B). ), The course is bent toward the center of the facing surface.

FIGS. 10A and 10B show the case where the diameter is 110 m.
m, thickness of peripheral part 3.5 mm, radius of curvature of convex surface 500 m
FIG. 9 is a diagram showing a result of analyzing the optical path of the excitation light introduced into the excitation light introduction member 16 having a shape of m and a quartz glass plano-convex lens by a ray tracing method. The excitation light is 5 from the center of the plane.
Triangular prism 2 with a side of 3 mm provided at a position of 0 mm
2 through a plane 16b in a direction parallel to the tangential direction of the outer periphery.
And the excitation light are incident at an angle of 45 °. The black dots on the optical path indicate the reflection positions on the convex surface 16a and the plane 16b. In this case, the excitation light is as shown in FIG.
As shown in (B), the light is repeatedly bent at the center of the excitation light introducing member 16 and travels while being repeatedly reflected at the plane 16b and the convex surface 16a. As a result, the excitation light distribution region of the excitation light introducing member 16 has a donut shape formed over a wide range from near the periphery to near the center.

When the excitation light reaches the portion of the convex surface 16a where the optical fiber 12 is wound, the excitation light is introduced into the cladding from the side surface of the optical fiber 12. Thus, by introducing the excitation light from the side surface of the optical fiber 12, it is possible to increase the efficiency of the introduction of the excitation light as compared with the case where the excitation light is introduced from the end face. The excitation light introduced into the optical fiber 12 excites the laser active substance doped in the core, and generates laser light by the stimulated emission effect. This laser light propagates through the optical fiber 12 and is emitted from the output end 12a.

As described above, in the present invention, since the excitation light distribution region of the excitation light introducing member 16 exists in a wide range from the vicinity of the peripheral portion to the vicinity of the center portion, the excitation light distribution region can be formed in any range of the wide region. Optical fiber can be wound.
As a result, compared to a conventional laser device in which the range in which the optical fiber can be wound is limited to the periphery of the excitation light introducing member,
The range in which the optical fiber 12 can be wound can be increased. In addition, since the excitation light can be introduced into the optical fiber 12 wound over a wide range, the excitation light can be efficiently introduced into the optical fiber 12, and as a result, the thin plate-like excitation light can be introduced. Even when the introduction member 16 is used, a high-power laser device can be provided. Further, the excitation light introduced into the excitation light introducing member 16 is bent toward the center of the excitation light introducing member 16 as shown in FIGS. Nothing. Even if it is assumed that the excitation light is reflected on the side surface, since the excitation light is bent toward the center of the excitation light introduction member 16, the incident angle of the excitation light on the side surface should be smaller than the critical angle that is a condition of total reflection. It is easy to increase the size. Therefore, it is possible to easily adjust the incident position and the incident angle of the excitation light, and to increase the degree of freedom in designing the laser device.

Next, another embodiment of the present invention will be described. In the following description, the same members as those described above are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 11 is a sectional view showing an excitation light introducing member 30 used in another embodiment of the present invention. The excitation light introducing member 30 has a flat surface 30b,
Has a disk shape in which two convex portions 30a are continuously formed on the surface facing the surface. In such an excitation light introducing member 30, the convex surface 30a functions as a progress control unit. The thickness δ of the excitation light introducing member 30 is represented by the following equation, where the maximum thickness T, the height H of the unevenness, the diameter D, and the distance r from the center are as follows.

(Equation 1) FIGS. 12A and 12B show, by a ray tracing method, the optical path of the excitation light introduced into the excitation light introduction member 30 made of quartz glass having a maximum thickness T of 4.5 mm, a height of irregularities of H 4.0 mm, and a diameter of D 110 mm. It is a figure showing the result of analysis. The excitation light is provided on one side 3 provided at a position 50 mm from the center of the plane 30b.
The light enters through a triangular prism of mm so that the angle between the plane 30b and the excitation light is 45 ° in a direction parallel to the tangential direction of the side surface.

As shown in FIGS. 12A and 12B,
The excitation light introduced into the excitation light introduction member 30 is bent toward the center of the excitation light introduction member 30 and travels while repeating reflection on the plane 30b and the convex surface 30a. As a result, the excitation light distribution region of the excitation light introducing member 30 has a donut shape that exists over a wide range from near the periphery to near the center. Therefore, since the optical fiber can be wound in an arbitrary range in this wide area, it is possible to relax the restriction on the winding position of the optical fiber 12.
Further, since it becomes possible to introduce the excitation light into the optical fiber 12 wound over a wide range, it is possible to efficiently introduce the excitation light into the optical fiber 12.
As a result, a high-power laser device can be provided even when the thin plate-like excitation light introducing member 30 is used.
The excitation light introduced into the excitation light introduction member 30 is shown in FIG.
2 (A) and 2 (B), the excitation light introducing member 3
It is bent toward the center of 0 and is not reflected on the side. Even if it is assumed that the excitation light is reflected on the side,
By bending the optical path of the excitation light toward the center, it becomes easy to make the angle of incidence on the side surface larger than the critical angle that is the condition of total reflection. Therefore, it is possible to increase the degree of freedom in designing the laser device such as the incident position and the incident angle of the excitation light.

FIG. 13 is a sectional view showing an excitation light introducing member 40 used in another embodiment of the present invention. The excitation light introducing member 40 has a flat surface 40b on one side and a flat surface 40b.
b has a substantially conical shape that is a convex surface 40a formed by a substantially conical surface convex toward a plane. In such an excitation light introducing member 40, the convex surface 40a functions as a travel control unit. The thickness δ of such an excitation light introducing member
Is the maximum thickness T, the uneven height H, the diameter D, and the distance r from the center.
Then, it is represented by the following equation.

(Equation 2) FIGS. 14A and 14B show, by a ray tracing method, the optical path of the excitation light introduced into the excitation light introduction member 40 made of quartz glass having a maximum thickness T of 6.0 mm, a height of irregularities of H 5.5 mm, and a diameter D of 200 mm. It is a figure showing the result of analysis. The excitation light is provided on a side 3 provided at a position 50 mm from the center of the plane 40b.
The light is incident through a triangular prism of mm such that the angle between the plane and the excitation light is 45 ° in the direction parallel to the tangential direction of the side surface. As shown in FIGS. 14A and 14B, the excitation light introduced into the above-described excitation light introduction member 40 repeats reflection on the flat surface 40b and the convex surface 40a while moving toward the center of the excitation light introduction member 40. It is bending and progressing. As a result, the excitation light distribution region of the excitation light introducing member 40 has a donut shape formed in a wide range near the center.

Therefore, the optical fiber can be wound in an arbitrary range in this wide area, and the restriction on the winding position of the optical fiber 12 can be eased. Further, since it becomes possible to introduce the excitation light into the optical fiber 12 wound over a wide range, it is possible to efficiently introduce the excitation light into the optical fiber 12, and as a result,
Even when the thin plate-like excitation light introducing member 40 is used, a high-power laser device can be provided. The excitation light introduced into the excitation light introducing member 40 is the same as that shown in FIG.
As shown in FIGS. 4A and 4B, there is no reflection on the side surface. Even if it is assumed that the excitation light is reflected on the side surface, since the excitation light is bent toward the center of the excitation light introduction member 40, the angle of incidence of the excitation light on the side surface is a condition of total reflection. It is easy to make it larger than the critical angle. Therefore, it is possible to easily adjust the incident position and the incident angle of the excitation light, and to increase the degree of freedom in designing the laser device.

As is clear from the above description, the excitation light introducing member has a portion whose thickness increases toward the center of the excitation light introducing member, that is, toward the center, so that the excitation light is excited in the direction in which the excitation light travels straight. There is no particular limitation as long as it can be bent inside the light introducing member. For example, the excitation light introducing member 50 has a meniscus lens shape in which one surface as shown in FIG. 15 is convex and the surface opposite to the convex surface is concave, and one surface as shown in FIG. The convex surface facing to has a conical shape,
As shown in FIG. 17, one surface is a flat surface, and a surface facing the flat surface has a shape in which a conical surface and a curved surface are mixed.
It is possible to use one having a biconvex lens shape in which both facing surfaces as shown in FIG. 8 are convex, or one in which a convex surface is formed in a part of a flat plate as shown in FIG. . As another excitation light introducing member 60, as shown in FIG. 20, one surface is a flat surface 60b, and a groove 6 composed of a vertical surface and a curved surface is formed on the opposing surface 60a.
It is also possible to use one having a Fresnel lens shape where 0c is formed. In this case, the optical fiber 1
Although 2 is wound around the flat surface 60b, the groove 60c may be formed in a spiral shape, and the optical fiber 12 may be wound around this groove. It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately modified. For example, in the above-described embodiment, a case has been described in which the excitation light is confined by total reflection due to a difference in refractive index between the excitation light introduction member and the outside world (air). However, the present invention is not limited to this. A reflection coat having high reflectance may be applied to the excitation light introducing member, and the excitation light may be confined by the reflection coat. Further, in the above-described embodiment, the progress control means for controlling the optical path of the excitation light by changing the distance (thickness) between the opposing surfaces in the excitation light introducing member is configured. Alternatively, it is also possible to configure the progress control means by forming a refractive index distribution on the excitation light introducing member. Such a refractive index distribution can be formed, for example, by adding a doping material to a predetermined region of the excitation light introducing member.

[0034]

EXAMPLES Hereinafter, the present invention will be specifically described using examples.
I do.Example 1  Laser light emission using the laser device 10 shown in FIG.
Shaking and laser processing were performed. As the excitation light introducing member 16
The diameter of 110 mm, the thickness of the peripheral edge 3.5 mm,
Disk-shaped plano-convex lens made of quartz glass with a radius of curvature of 500 mm
The shape used was small. This excitation light introduction member 16
3 mm on each side at 50 mm from the center of the plane 16 b
A square prism 22 was provided. Projection of excitation light introducing member 16
Light within a range of inner radius 32 mm and outer radius 52 mm of surface 16a
A whirlpool in which the fibers 12 adhere closely to each other without gaps
It was wound in a shape. This winding, as shown in FIG.
An outer radius of 32 m temporarily provided at the center of the excitation light introducing member 16
m Teflon cylinder 18 and the optical fiber 12
One end of the winding start is fixed to the cylinder 18 and around this
It was carried out in such a manner that it was sequentially wound in the outer circumferential direction. Light fa
After the river was wound, the cylinder 18 was removed.
The other end on the winding end side of the optical fiber 12 is
It was drawn out as the output end 12a. Like this
The turned optical fiber 12 has a refractive index after curing of 1.4.
The excitation light introducing member 16 is made of an ultraviolet-curable adhesive material 2
Fixed to.

The optical fiber 12 has a clad diameter 12
5 μm, core diameter about 50 μm, core has 0.5 at
Quartz glass fibers doped with neodymium ions (Nd ³⁺ ) at a concentration of% were used. One end fixed to the center side of the optical fiber 12 is polished flat, and then has a reflectance of 9 at a laser oscillation wavelength of 1.06 μm.
The output end 12a, which was coated with a multilayer film of 8% or more and was drawn out, had a fracture surface with a reflectivity of about 4% at a laser oscillation wavelength of 1.06 μm. Excitation light source 14
A fiber-coupled semiconductor laser device that outputs an excitation light having an oscillation wavelength of 0.8 μm and an output of 30 W through an optical fiber 14 a having a diameter of 600 μm was used. The optical fiber 14a is brought close to the prism 22 provided on the excitation light introducing member, and the excitation light introducing member 16 is set so that the angle between the plane 16b and the excitation light is 45 ° in a direction parallel to the tangential direction of the outer periphery. Introduced within. As a result, a good output laser light having a wavelength of 1.06 μm and a laser output of 11 W was obtained from the output end 12 a of the optical fiber 12 wound around the excitation light introducing member 16. Further, as shown in FIG. 21, when the laser processing apparatus 70 is configured by providing the laser apparatus 10 with the meniscus lens 15 having a focal length of 25 mm for condensing laser light, energy of 90% or more is collected within a diameter of 150 μm. I could light. In this case, the focused diameter of the output laser light was always stable irrespective of the laser output and the state of heat.

[0036]Example 2  Optical signal amplification is performed using the laser device shown in FIG.
Was. As the laser device, a core as the optical fiber 12 is used.
A diameter of 8 μm is used.
Both ends 12a and 12b of the turned optical fiber 12 are suspended.
The same one as in Example 1 is used, except that it has a straight section.
I was. One end 12b on the winding start side of this optical fiber
1.06μm wavelength and 500μW output signal light
After that, 310 mW from the other end 12a on the winding end side
, And a gain of 28 dB was obtained.

[0037]

As is clear from the above description, according to the present invention, the excitation light introduced into the excitation light introduction member is bent inwardly of the excitation light introduction member, so that the excitation light distribution region can be widened. Can be formed. Therefore, the optical fiber can be arranged in an arbitrary range in a wide area, and as a result, the degree of freedom regarding the arrangement of the optical fiber can be increased. In addition, since the excitation light can be introduced into the optical fibers arranged over a wide area, a high-output laser device can be provided even when a thin plate-like excitation light introduction member is used. Also, by bending the excitation light introduced into the excitation light introduction member to the inside of the excitation light distribution region, the excitation light is not necessarily reflected on the side surface in order to confine the excitation light to the excitation light introduction member by total reflection. No longer needed. Further, even if the excitation light is reflected by the side surface, it becomes easy to make the incident angle with respect to the side surface larger than the critical angle which is a condition of total reflection. Therefore,
The adjustment of the incident position and the incident angle of the excitation light becomes easy, and the degree of freedom in designing the laser device can be increased. Furthermore, since the optical fiber is disposed on the opposing surface in the excitation light distribution region, the distance between the opposing surfaces is smaller than that of a conventional laser device in which the optical fiber is wound on the side surface of a cylindrical excitation light introducing member. (thickness)
Can be reduced. Therefore, it is possible to reduce the size of the device while maintaining the output of the laser light.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a laser device according to the present invention.

FIG. 2 is a cross-sectional view illustrating an example of an excitation light introducing member.

FIG. 3 is a view showing an example of an excitation light introducing member, and FIG.
Is a plan view, and (B) is a sectional view.

4A and 4B are diagrams showing a state in which an optical fiber is wound, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view.

FIG. 5 is a cross-sectional view illustrating an example of a state where an optical fiber is arranged on an excitation light introducing member.

FIG. 6 is a perspective view showing a laser device according to the present invention.

FIG. 7 is a cross-sectional view showing an example of a state where an optical fiber is arranged on an excitation light introducing member.

FIG. 8 is a plan view showing an example of a state where an optical fiber is arranged on an excitation light introducing member.

9A and 9B are diagrams for explaining the optical path of the excitation light introduced into the excitation light introduction member, where FIG. 9A is a plan view and FIG. 9B is a cross-sectional view.

FIG. 10 is a diagram showing a result of analyzing the optical path of the excitation light introduced into the excitation light introduction member by a ray tracing method, and FIG.
Is a sectional view, and (B) is a plan view.

FIG. 11 is a sectional view showing an example of an excitation light introducing member.

FIG. 12 is a diagram showing a result of analyzing the optical path of the excitation light introduced into the excitation light introduction member by a ray tracing method, and FIG.
Is a sectional view, and (B) is a plan view.

FIG. 13 is a sectional view showing an example of an excitation light introducing member.

14A and 14B are diagrams showing the results of analyzing the optical path of the excitation light introduced into the excitation light introduction member by a ray tracing method, and FIG.
Is a sectional view, and (B) is a plan view.

FIG. 15 is a cross-sectional view illustrating an example of an excitation light introducing member.

FIG. 16 is a sectional view showing an example of an excitation light introducing member.

FIG. 17 is a cross-sectional view illustrating an example of an excitation light introducing member.

FIG. 18 is a cross-sectional view illustrating an example of an excitation light introducing member.

FIG. 19 is a sectional view showing an example of an excitation light introducing member.

FIG. 20 is a sectional view showing an example of an excitation light introducing member.

FIG. 21 is a view schematically showing a laser processing apparatus according to the present invention.

FIG. 22 is a perspective view showing an example of a conventional laser device.

FIG. 23 is a perspective view showing an optical path of excitation light introduced into an excitation light introduction member of a conventional laser device.

FIG. 24 is a diagram showing an example of a conventional laser device;
(A) is a perspective view, (B) is a sectional view.

FIG. 25 is a diagram for explaining an optical path of excitation light introduced into an excitation light introduction member of a conventional laser device, and FIG.
Is a plan view, and (B) is a sectional view.

26A and 26B are diagrams showing results of analyzing the optical path of excitation light introduced into an excitation light introduction member of a conventional laser device by a ray tracing method, where FIG. 26A is a cross-sectional view and FIG. 26B is a plan view. .

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 laser device 12 optical fiber 14 excitation light source 16 excitation light introduction member 16 a convex surface 16 b plane 30 excitation light introduction member 40 excitation light introduction member 50 excitation light introduction member 60 excitation light introduction member 70 laser processing device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E068 CE08 5F072 AB08 AB09 AK06 FF09 JJ01 JJ04 KK02 KK30 PP01 PP07 RR01 YY06 YY11 YY17

Claims (8)

[Claims] 1. An optical fiber having a core containing a laser active substance and outputting a laser beam from at least one end when the laser active substance is excited, and generating excitation light for exciting the laser active substance. In a laser device comprising: an excitation light source; and an excitation light introduction member for introducing the excitation light into the optical fiber, wherein the excitation light introduction member has opposing surfaces facing each other, and is incident on the excitation light introduction member. The excitation light travels in the circumferential direction of the excitation light introduction member while repeating reflection on the facing surface, and at least a portion of the excitation light travels its path inward of the excitation light introduction member. The optical fiber is bent by the progress control means while being bent inward of the excitation light introducing member to form an excitation light distribution region. At least a part of the side surface is disposed so as to be in direct contact with at least one of the opposed surfaces in the excitation light distribution region or indirectly via an optical medium, and is incident from the side surface of the optical fiber through the contacted portion. The laser active substance is excited by the excitation light. 2. The laser device according to claim 1, wherein said progress control means is formed by changing a thickness between said opposed surfaces. 3. An optical fiber having a core containing a laser active substance and outputting a laser beam from at least one end when the laser active substance is excited, and generating excitation light for exciting the laser active substance. In a laser device comprising: an excitation light source; and an excitation light introduction member for introducing the excitation light into the optical fiber, wherein the excitation light introduction member has opposing surfaces facing each other, and is incident on the excitation light introduction member. The pumping light travels around the pumping light introducing member while repeatedly reflecting on the opposing surface to form a pumping light distribution region, and the pumping light is bent inward in the pumping light introducing member in the pumping light distribution region. A thickened portion is formed in which the distance between the opposing surfaces increases toward the inside of the excitation light introducing member, and the optical fiber has a small side surface. And a part thereof is disposed so as to be in direct contact with at least one of the opposed surfaces in the excitation light distribution region or indirectly via an optical medium, and is incident from a side surface of the optical fiber through the contacted part. A laser device wherein the laser active substance is excited by excitation light. 4. The laser device according to claim 3, wherein the excitation light introducing member has a shape in which the distance between the opposing surfaces continuously increases toward the center of the excitation light introducing member. 5. The laser device according to claim 4, wherein the excitation light introducing member has a convex lens shape in which a distance between the opposing surfaces continuously increases toward a center of the excitation light introducing member. 6. The laser device according to claim 1, wherein the optical fiber is arranged so as to be wound around at least one of the opposing surfaces in the excitation light distribution region. 7. A laser device according to claim 1, further comprising: a condensing optical system for condensing a laser beam output from at least one end of an optical fiber of the laser device on a processing target. Laser processing equipment equipped with. 8. An optical signal amplifying device comprising the laser device according to claim 1, wherein one end of the optical fiber is an input end of a signal light and the other end is an output end of an amplified light. .