JP4218536B2 - Fiber laser fixing method for fiber laser - Google Patents

Description

  The present invention relates to a fiber laser manufacturing method, and more particularly, to a fiber laser fixing method and a laser medium thereof.

In the field of laser processing, fiber lasers have been developed as laser devices with high output and high beam quality. The fiber laser is doped with rare earth ions such as erbium (Er) ions and neodymium (Nd) ions as a laser active medium in the core of the optical fiber, and the excitation light is incident on the cladding covering the core, thereby exciting the core. The optical fiber itself is a laser device that oscillates.
The “optical fiber” described below refers to an optical fiber capable of laser oscillation doped with rare earth ions unless otherwise specified.

As an optical fiber excitation method, there are end surface excitation in which excitation light is incident from the end surface in the longitudinal direction of the optical fiber, and side surface excitation in which excitation light is irradiated from the side surface of the optical fiber.
The end face pumping is easy to pump, but the end face area is small, so that it is not possible to enter the pump light sufficient to increase the output of the fiber laser. In addition, while the excitation light incident from the end face propagates through the optical fiber, a part of the excitation light that does not satisfy the conditions of total reflection at the boundary between the cladding and the outside leaks to the outside of the cladding and becomes a loss. Excitation is not suitable for increasing the output of a fiber laser.

  It is also conceivable to bundle a plurality of end face excitation optical fibers into a bundle fiber, and consolidate the laser light output from each optical fiber to increase the output, but the collected laser light is not coherent, so a high beam It is difficult to obtain quality laser light.

  On the other hand, in the side excitation, for example, a single optical fiber is spirally wound around a tubular member to form an optical fiber layer, and the side surface of the optical fiber layer is irradiated with excitation light. Since it is possible to increase the output of the pumping light, it is an excitation method that realizes a higher output of the fiber laser. Furthermore, since it is a laser beam output from one optical fiber, it has high beam quality.

  Therefore, Patent Document 1 proposes a method of manufacturing a side-excited fiber laser in which an optical fiber layer is formed by spirally winding an optical fiber around a tubular member, and the optical fiber layer is fixed with an acrylic ultraviolet curable resin.

JP 2002-26432 A

  However, since the heat resistance temperature of the resin that fixes the optical fiber layer is low, there is a problem that if the excitation light is increased in power, the resin absorbs heat due to the heat absorption and heat generation of the resin. It has been difficult to output.

  In Patent Document 1, since the optical fiber layer is held in the horizontal direction and the liquid resin is dropped from above while rotating around the axis of the longitudinal direction of the optical fiber layer, the resin drops downward due to the viscosity of the resin. A manufacturing problem that the resin does not uniformly adhere to the optical fiber layer due to dripping or the like is also estimated.

  In view of the above-described problems of the prior art, the present invention does not cause the material that fixes the optical fiber layer to be burned by the excitation light even when the output of the excitation light is increased, and the optical fiber layer is easily fixed. An object of the present invention is to provide a fiber laser fixing method of a fiber laser and a laser medium of a fiber laser by the optical fiber fixing method.

The first aspect of the present invention, an optical fiber fixation method of the fiber laser as described in claim 1.
Optical fiber fixing method of a fiber laser as claimed in claim 1, an optical fiber having a core and a cladding including a laser active material was deposited folded repeatedly over a glass member, or spirally wound on a glass member in the optical fiber fixing method of the formed by fixing an optical fiber layer with stickies fiber laser for the laser medium, a low melting point softening point is lower than high and the optical fiber than the resin, and a refractive index greater than air as the glass member While using the glass member, the low melting point glass member is melted by heating to cover the entire optical fiber layer, and then the low melting point glass member is cured to bond the optical fiber layer and the low melting point glass member together. by reduction, the low-melting glass member and the stickies Characterized in that it also be used.

The low melting point glass generally refers to a glass having a softening point of 600 ° C. or lower, but in the present application, the softening point is 600 ° C. or lower and a general softening point of resin (about 200 ° C.). ), Preferably in the range of 300 ° C. or higher.
Since the softening point of the low melting point glass member is higher than that of the resin, the low melting point glass member does not soften even if the excitation light is increased in output.
Further, since the softening point of the optical fiber is higher than the softening point of the low melting point glass member, the optical fiber layer can be fixed and integrated with the low melting point glass member without softening the optical fiber.

A second invention of the present invention is a fiber laser fixing method for a fiber laser as described in claim 2.
The fiber laser fixing method for a fiber laser according to claim 2 is the fiber laser fixing method for a fiber laser according to claim 1, wherein the refractive index of the low melting point glass member is smaller than or equal to the refractive index of the cladding of the optical fiber. It is characterized by being.

  By making the refractive index of the low-melting glass member smaller than, or preferably smaller than, the refractive index of the cladding of the optical fiber, the excitation light is totally reflected at the boundary between the cladding and the low-melting glass member. It becomes easy, and it becomes possible to confine the excitation light in the clad and further excite the core.

According to the optical fiber fixing method of a fiber laser according to claim 1, the softening point is lower than high and the optical fiber than the resin, and the refractive index is deposited folded repeatedly fiber to greater than the air low-melting glass member Te, or wound to form a fiber layer spirally, covering the entire fiber layer to melt by heating the equivalent low-melting glass member, by then curing the low-melting glass member, the optical fiber By fixing and integrating the layer and the low-melting-point glass member , the low-melting-point glass member can be used as the fixing substance , and the laser medium can be easily manufactured.
Further, even if the excitation light is increased in output, the substance (low melting point glass member) that fixes the optical fiber layer by the excitation light is not burned out. Furthermore, since laser light is output from a single optical fiber, it is possible to obtain high beam quality laser light.
In addition, by making the refractive index of the low-melting glass member larger than the refractive index of air, the condition of total reflection is established at the boundary between the low-melting glass member and air, and the excitation light is confined in the laser medium. This makes it possible to increase the output power of the excitation light, and it is possible to excite the optical fiber from the side by the increased output of the excitation light.

  According to the optical fiber fixing method of the fiber laser according to claim 2, since the refractive index of the low melting point glass member is smaller than or equal to the refractive index of the cladding of the optical fiber, the boundary between the cladding and the low melting point glass member In this case, the pumping light is easily totally reflected, and the pumping light is confined by the cladding. As a result, the pumping light can be increased in output and the fiber laser can be increased in output.

FIG. 1 is an explanatory view showing an optical fiber fixing method of a fiber laser . FIG. 2A is an explanatory view showing the AA cross section shown in FIG. 1E and the softening point and refractive index of each member.

  Based on FIGS. 1 and 2, an optical fiber 11 is spirally wound around a high melting point glass member 10 to form an optical fiber layer, and the optical fiber layer is fixed with a powdery low melting point glass member 13. The method will be described.

First, as shown in FIG. 1A, an optical fiber 11 is formed by spirally winding an optical fiber 11 on the outer peripheral surface of a cylindrical refractory glass member 10.
At this time, when the low melting point glass member 13 is fixed later, the optical fiber 11 is wound with a small gap so that the low melting point glass member 13 can easily enter the gap. Thereby, the optical fiber layer and the low melting point glass member 13 can be firmly fixed.

  Although the refractory glass member 10 has a columnar shape, the inside may be hollow like a cylinder or a tube.

  As the optical fiber 11 and the high melting point glass member 10, those having a softening point higher than that of the low melting point glass member 13 are used so as not to be softened when the low melting point glass member 13 is heated as shown in FIG. In the present embodiment, a quartz optical fiber having a softening point of 1500 ° C. is used. The refractive index of the optical fiber 11 is 1.5 for the core 11a and 1.49 for the clad 11b.

  As the refractory glass member 10, one having a softening point equal to or higher than that of the core 11a and the clad 11b is used. The refractive index of the refractory glass member 10 is selected to be smaller than that of the clad 11b so that total reflection is established at the boundary between the clad 11b and the refractory glass member 10.

  The core 11a has a diameter of 12 μm, and the cladding 11b has a diameter of 123 μm, which is a single mode optical fiber. The core 11a is doped with neodymium (Nd) ions as a laser active material.

Next, as shown in FIG. 1B, the optical fiber layer is covered with a tubular glass member 12 so that the powdery low melting point glass member 13 is not scattered. At this time, the center of the tubular glass member 12 is made to coincide with the center of the refractory glass member 10.
The softening point of the tubular glass member 12 is the same as that of the core 11a and the clad 11b so as not to soften when the low melting point glass member 13 is heated. The refractive index of the tubular glass member 12 is smaller than that of the clad 11b.

Next, a flat glass member (not shown) is brought into contact with the bottom of the tubular glass member 12 so that the powdery low melting point glass member 13 does not spill.
As the flat glass member, a high melting point glass member is used so as not to be softened when the low melting point glass member 13 is heated.

  Next, as shown in FIGS. 1C and 1D, a powdery low-melting glass member 13 is deposited in the gap between the high-melting glass member 10 and the tubular glass member 12 to cover the entire optical fiber layer.

As shown in FIG. 2B, the low-melting glass member 13 is defined by paragraph number 0012. In this case, the softening point is 450 ° C. lower than that of the resin and lower than that of the optical fiber, and the refractive index is low. 1.48 smaller than the clad 11b is selected.
The refractive index of each member is decreased from the center of the optical fiber 11 toward the outside so that the excitation light is totally reflected. That is, the refractive index of the core 11a of the optical fiber 11 is the largest, followed by the cladding 11b, then the low melting glass member 13, and then the high melting glass member 10 or the tubular glass member 12.

Next, as shown in FIG. 1 (e), the low-melting glass member 13 deposited between the high-melting glass member 10 and the tubular glass member 12 is heated 14 evenly from the side surface over the entire circumference, thereby producing a low-melting glass. The member 13 is melted. Thereafter, the low melting point glass member 13 is gradually cooled and cured, and the optical fiber layer between the high melting point glass member 10 and the tubular glass member 12 is fixed by the low melting point glass member 13.
As described above, as shown in FIG. 1F, the laser medium 100 of the fiber laser is manufactured.

  As shown in FIG. 2A, the excitation light incident from one end surface of the refractory glass member 10 is confined inside the laser medium 100 by total reflection, and excites the optical fiber 11 from the side surface.

  Since a single optical fiber 11 is spirally wound around a cylindrical high melting point glass member 10 to form an optical fiber layer, and the optical fiber layer is fixed by a powdery low melting point glass member 13, a laser medium is manufactured. The medium can be easily manufactured, and even if the excitation light is increased in power, the fixing substance (low melting point glass member) is not burned, the fiber laser can be increased in power, and high beam quality laser light can be obtained.

In the fiber laser fixing method of the fiber laser , the powdery low melting point glass member 13 is deposited. However, the low melting point glass member is heated and melted in advance, and the high melting point glass member 10 and the tubular glass member 12 are joined from above. It may be poured into the gap.
Further, by processing the advance spiral groove refractory glass member 10, by winding the optical fiber 11 along the groove, it may be firmly more fixation.

FIG. 3 is a schematic view showing a laser medium of another fiber laser . FIG. 4 is an explanatory view showing a method of manufacturing the laser medium of the fiber laser with respect to the BB cross section. FIG. 3 shows a laser medium of a fiber laser in which an optical fiber layer formed on the surface of a flat refractory glass member 30 is fixed by a low melting point glass member 32. FIG. 4 is an explanatory diagram of an optical fiber fixing method for the laser medium shown in FIG.

Based on FIG. 4, an optical fiber fixing method of the laser medium of the fiber laser shown in FIG. 3 will be described. As shown in FIG. 4A, a plurality of optical fiber layers are formed by folding a single optical fiber 31 with a gap on the upper surface of a flat refractory glass member 30.
The softening point of the high melting point glass member 30 is higher than that of the low melting point glass member 32 and is equal to the optical fiber 31. Further, the refractive index of the high melting point glass member 30 is smaller than that of the clad 31 b and further smaller than that of the low melting point glass member 32.

Next, as shown in FIGS. 4B and 4C, a powdery low-melting glass member 32 is deposited on the upper surface of the optical fiber layer. Since the low melting point glass member 32 is in the form of powder, it enters the gap between the optical fibers 31 and is deposited.
The softening point and refractive index of the low-melting glass member 32 are the same as those of the fiber laser fixing method of the fiber laser shown in FIGS.

  Next, as shown in FIG. 4 (d), the low melting point glass member 32 deposited on the optical fiber layer is melted by heating evenly from above, and then gradually cooled and hardened to cure the low melting point optical fiber layer. The glass member 32 is fixed.

By making excitation light enter the optical fiber layer fixed by the low melting point glass member 32, the excitation light can be confined in the low melting point glass member 32 and the optical fiber 31 can be excited from the side.
That is, the bottom surface of the low melting point glass member 32 is in contact with the high melting point glass member 30 having a refractive index smaller than that of the low melting point glass member 32, and the remaining surface is similarly covered with air having a small refractive index. The total reflection is established at each boundary, and the excitation light can be confined in the low melting point glass member 32.

According to the laser medium of the fiber laser shown in FIG. 3, an optical fiber layer is formed on the upper surface of the high melting point glass member 30 by bending a single optical fiber at intervals, and the optical fiber layer is formed into a powdery low melting point. Since it is fixed by the glass member 32, the laser medium 300 can be easily manufactured, and the excitation light is confined in the low melting point glass member 32 and excited from the side surface of the optical fiber 31. It becomes possible to increase the output of the fiber laser. Furthermore, since the laser light is output from one optical fiber, it has high beam quality.

In the laser medium of the fiber laser shown in FIG. 3, powdery low-melting glass is used as the fixing substance. However, plate-like low-melting glass may be placed on the optical fiber layer and melted and cured. Further, the optical fiber layer and the high melting point glass member 30 may be surrounded by a wall of the high melting point glass member, and a liquid low melting point glass member may be poured into the inside thereof from above.

First Embodiment (FIG. 5)
FIG. 5 is an explanatory view showing the first embodiment of the present invention. FIG. 5 is an explanatory diagram of a laser fixing method of a fiber laser in which the optical fiber 51 and the low melting point glass member 50 are fixedly integrated.

Hereinafter, a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 5A, an optical fiber layer is formed by spirally winding an optical fiber 51 around a cylindrical low-melting glass member 50.
The softening point of the low melting point glass member is higher than that of the resin and lower than that of the optical fiber 51. Further, the refractive index of the low melting point glass member is smaller than that of the clad of the optical fiber 51.

  Next, as shown in FIG. 5 (b), the low melting point glass member 50 is melted by heating from the side, and then gradually cooled and hardened. As shown in FIG. The member 50 and the optical fiber 51 are fixedly integrated. The surface of the laser medium formed in FIG. 5C has an uneven shape due to heating, melting and curing.

Next, as shown in FIG. 5D, the surface of the laser medium is cylindrically polished and finished to a smooth surface to manufacture the laser medium 500.
Since the surface of the laser medium 500 is polished to a smooth surface, there is no irregular reflection of the excitation light, and the loss of the excitation light can be reduced.

  Since the laser medium 500 is covered with air having a refractive index smaller than that of the low-melting glass member 50, the condition of total reflection is established at the boundary between the low-melting glass member 50 and air, and the excitation light is emitted from the laser medium 500. The pumping light can be confined inside, thereby increasing the output of the pumping light, and the optical fiber 51 can be pumped from the side by the pumping light having the higher output.

According to the first embodiment of the present invention, a single optical fiber 51 is spirally wound around the low-melting glass member 50 to form an optical fiber layer, and the low-melting glass member 50 and the optical fiber layer are fixedly integrated to form a laser medium. Since the surface of the laser medium is polished, the laser medium can be easily manufactured, and even if the excitation light is increased in power, it is not burned, and the fiber laser can be increased in power. Further, since it is a laser beam output from one optical fiber, it has high beam quality.

FIG. 6 is a schematic view of the laser medium with the end face cut obliquely in FIG. 5D of the first embodiment.
The angle θ of the inclined surface 55 is set to be perpendicular to the angle φ when the excitation light emitted from the excitation source 56 is incident at an angle φ that causes total reflection in the laser medium 500. Thereby, since the excitation light is incident so as to be totally reflected, loss in the laser medium 500 can be reduced.

In the first embodiment of the present invention, the surface of the laser medium 500 is polished to prevent irregular reflection of the excitation light. However, AR coating (total reflection coating) is applied to a surface other than the surface on which the excitation light is incident. Thus, more excitation light may be confined in the laser medium 500.

Second Embodiment
Illustrating a second embodiment of the present invention.
Second embodiment of the present invention, in the laser medium of the fiber laser shown in FIG. 3, instead of the high-melting-point glass member 30, using a low-melting glass member, and the laser medium of the fiber laser of FIG. 3 on its upper surface forming a similar fiber layer is intended to produce a fixed integrated laser medium and a low-melting glass member and the optical fiber layer as in the first embodiment.

According to the second embodiment of the present invention, the low melting point glass member and the optical fiber layer are fixed and integrated to manufacture the laser medium. Therefore, the laser medium can be easily manufactured, and the excitation light has a high output. It is possible to increase the output of the Faber laser without burning even if it is made higher. Also, Ru mower since a high beam quality laser light is output from a single optical Farber.

The “fiber laser fixing method and laser medium thereof” of the present invention can be changed, added, or deleted without changing the gist of the present invention.
Further, the shape of the optical fiber layer is not limited to the description of the embodiment.
The numerical values used in the present embodiment are examples, and are not limited to these numerical values.

  The laser medium manufactured by the “fiber laser fixing method and laser medium thereof” of the present invention can be applied to various apparatuses using laser light such as a laser processing apparatus.

It is explanatory drawing explaining the optical fiber fixing method of a fiber laser . Is an explanatory view showing the softening point and the refractive index with A-A cross section of FIG. It is the schematic which showed the laser medium of the fiber laser . It is explanatory drawing which showed the manufacturing method of the laser medium of a fiber laser about the BB cross section. It is explanatory drawing explaining the 1st Embodiment of this invention. It is the schematic which provided the slope in the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Laser medium 10 Cylindrical glass member 11 Optical fiber 11a Core 11b Clad 12 Tubular glass member 13 Low melting point powder glass 300 Laser medium 30 Flat glass member 31 Optical fiber 31a Core 31b Clad 32 Low melting point powder glass 500 Laser medium 50 Low melting point glass member 51 Optical fiber 55 Slope 56 Excitation light source 57 Excitation light

Claims (2)

An optical fiber having a core and a cladding including a laser active material was deposited folded repeatedly over a glass member, or a laser medium by fixing the optical fiber layers formed by winding helically stickies to the glass member In the fiber laser fixing method of fiber laser,
With a softening point lower than high and the optical fiber than the resin, and the refractive index using large low-melting glass member from the air as the glass member, the optical fiber layer to melt by heating the low-melting glass member The low melting point glass member is also used as the fixing substance by covering the whole and then curing the low melting point glass member and fixing and integrating the optical fiber layer and the low melting point glass member. Fiber laser fixing method for fiber laser. In the fiber laser fixing method of the fiber laser according to claim 1,
An optical fiber fixing method for a fiber laser, wherein a refractive index of the low melting point glass member is smaller than or equal to a refractive index of a clad of the optical fiber.

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