JP5351867B2 - Bundle fiber and manufacturing method thereof - Google Patents

Description

  The present invention relates to a bundle fiber in which a plurality of optical fibers having a core and a clad having a refractive index lower than that of the core are bundled, and a method for manufacturing the same.

  Conventionally, as this type of bundle fiber, for example, as in Patent Document 1, a main body portion in which a plurality of optical fibers are bundled, and a tapered portion that is provided at the front end of the main body portion and serves as an incident end of light. The tapered portion is formed by integrating an optical fiber and has a partial conical shape whose outer diameter decreases toward the distal end side, and the distal end portion of the main body portion provided with the tapered portion is a core with respect to the entire cross-sectional area. The cross-sectional area ratio is known to be 0.85 to 1.00.

JP 2010-72485 A

  However, in the bundle fiber of Patent Document 1, the clad is removed, and the cores function as one core integrated with the glass tube covering the cores in the tapered portion, so that each optical fiber is optically independent. There is a problem in that it is impossible to allocate light projection and light reception to individual optical fibers.

  The present invention has been made in view of such a point, and an object of the present invention is to allow light projection and light reception to be allocated to individual optical fibers with a simple configuration in a bundle fiber having a tapered tip. Is to make it.

  In order to achieve the above object, in the present invention, taper processing is performed while the structure of each fiber is maintained in the taper processing portion.

Specifically, in the first invention,
Assume a bundle fiber in which a plurality of optical fibers having a core and a clad having a refractive index lower than that of the core are bundled.

And the bundle fiber is
A bundle part in which a plurality of the optical fibers are bundled;
Continuing on the tip of the bundle part, comprising a taper processed part that gradually decreases in outer diameter toward the tip,
At least the tapered portion is melted while applying tension in a state covered with a glass tube having a refractive index lower than that of the clad, and is processed so that the outer diameter gradually decreases toward the tip. In the section, the optical fibers are integrated, the cores are deformed from a circular cross section, and are separated from each other so as to be optically independent by the integrated cladding.

  According to the above configuration, since the cores of the optical fibers are separated from each other by the integrated clad in the tapered portion, it becomes easy to maintain optical independence in the optical fibers. For this reason, it is possible to allocate light projection and light reception to individual optical fibers. In addition, the core is processed to have an appropriate thickness by applying tension by pulling the core so that the core is deformed from a circular shape in the molten state. Furthermore, even if the tapered portion is not provided with a coating, it is covered with a glass tube having a refractive index lower than that of the cladding, so that light with a numerical aperture increased by tapering can be confined and propagated to the tip surface. .

In the second invention, the bundle fiber based on the above premise is:
A bundle part in which a plurality of the optical fibers are bundled;
Continuing on the tip of the bundle part, comprising a taper processed part that gradually decreases in outer diameter toward the tip,
At least the tapered portion is melted while applying tension in a state covered with a glass tube, and is processed so that the outer diameter gradually decreases toward the tip. In the tapered portion, each optical fiber is integrated. ized, each of the core while being deformed from a circular cross section, separated from each other so as to keep the optically independent by integrated the cladding, is used in a state where the glass tube touches the outer air.

  According to the above configuration, since the cores of the optical fibers are separated from each other by the integrated clad in the tapered portion, it becomes easy to maintain optical independence in the optical fibers. For this reason, it is possible to allocate light projection and light reception to individual optical fibers. In addition, the core is processed to have an appropriate thickness by applying tension by pulling the core so that the core is deformed from a circular shape in the molten state. In addition, even if it is not a glass tube that contains additives, light leaked from each optical fiber by being covered with the outside air such as air having a refractive index lower than that of the glass tube if used in a state where it is exposed to the outside air. However, since light is refracted at the interface between the glass tube and the outside air, light is prevented from leaking out from the glass tube.

In the third invention, in the first or second invention,
A processing light source is connected to each optical fiber, and processing is performed by laser light emitted from the tip of the taper processing portion.

  According to the above configuration, the laser light incident from the laser light source is emitted from the tip at a high density at the tapered portion, so that the surface can be selectively processed.

In a fourth invention, in any one of the first to third inventions,
A signal incident on a part of each optical fiber from the bundle part side is emitted from the tip of the tapered portion through the optical fiber, and the remaining optical fibers from the tip of the tapered portion. Another signal incident on the optical fiber is emitted from the bundle portion through the optical fibers.

  According to the above configuration, since each optical fiber is kept separated from each other by the clad in which the core is melted in the tapered processing portion, for example, light is incident on each optical fiber on the center side of the bundle portion, Through these optical fibers, light having a high power density collected from the tip of the tapered processing part is emitted toward the irradiation object, and the light reflected by this irradiation object is reflected on the outer peripheral side of the tip of the taper processing part. It becomes possible to make it enter from each optical fiber of this, and to take out from a bundle part.

In the fifth invention, in the fourth invention,
A surface analysis probe that receives signal light reflected by incident probe light is used.

  According to the above configuration, since the surface of the irradiation object can be irradiated with the probe light with high power density and the reflected light can be received, it is suitable for surface analysis.

In a sixth invention, in any one of the first to fifth inventions,
Outgoing light having a numerical aperture of 0.5 or more and 0.9 or less can be emitted from the tip of the tapered portion.

  According to said structure, since the front-end | tip is tapering in the taper process part, the emitted light of high numerical aperture which is not in the past is obtained. The numerical aperture (NA) is an index indicating the maximum angle at which light can enter and exit.

In a seventh invention, in the sixth invention,
It is used together with an array type light emitting device, and is configured such that light emitted from the array type light emitting device can be incident from the front end surface of the tapered portion.

  According to said structure, the emitted light of the high numerical aperture array type light-emitting device arranged in high density can be received from the front end surface of a taper process part.

In an eighth invention, in any one of the first to seventh inventions,
The glass tube has a two-layer structure, and the outer glass tube has a lower refractive index than the inner glass tube.

  According to said structure, since light is refracted by an outside glass tube, it is prevented reliably that light leaks outside from a glass tube.

In the ninth invention,
A method for manufacturing a bundle fiber in which a plurality of optical fibers having a core and a clad are bundled is assumed.

And in the above manufacturing method,
A bundle part is formed by bundling a plurality of optical fibers having the core and the cladding,
The bundle part is inserted into a glass tube having a refractive index lower than that of the cladding, and the bundle part and the glass tube are heated and melt processed,
Apply tension to the bundle part where the glass tube is fused and integrated,
The bundle part in the above state is heated so that each optical fiber is melted, and the respective cores are deformed from a circular cross section while being separated from each other so as to be optically independent by the melted clad. , Forming a tapered part that gradually reduces the outer diameter,
End the above heating,
Cut the tip of the taper part,
The tip end surface of the tapered portion is polished.

  According to the above configuration, since the bundle portion is melted in a state where a tension is applied, each outer core is deformed from a circular cross-section, and the outer diameter gradually decreases while being separated from each other by the melted clad. Easy to machine the machined part. In the taper processed portion processed in this way, the cores of the optical fibers are separated from each other by the melted clad, so that it becomes easy to maintain optical independence in each optical fiber. For this reason, it is possible to allocate light projection and light reception to individual optical fibers. Furthermore, even if the tapered portion is not provided with a coating, it is covered with a glass tube having a refractive index lower than that of the cladding, so that light with a numerical aperture increased by tapering can be confined and propagated to the tip surface. .

As described above, according to the present invention, each optical fiber is integrated at the tip of the bundle portion, each core is deformed from a circular cross section, and optically independent by the integrated clad. As described above, by providing the tapered portion where the outer diameter gradually decreases toward the tip while being separated from each other, it is possible to allocate light projection and light reception to each optical fiber with a simple configuration. Further, by narrowing the tip diameter of the bundle fiber in accordance with a small irradiation object, it can be guided to an arbitrary irradiation area without using an optical system, and irradiation with a high power density is possible.

Further, according to the present invention, a tension is applied to the bundle portion in which a glass tube having a refractive index lower than that of the cladding is fused and heated to melt each optical fiber, and each core is deformed from a circular cross section. In order to maintain optical independence by the melted clad, tapered portions that gradually decrease in outer diameter are formed while being separated from each other, so that each optical fiber can be easily cast. A bundle fiber that can allocate light and light reception can be manufactured.

It is a front view which shows the structure of a bundle fiber typically. It is an expanded sectional view of an optical fiber. It is a side view which expands and shows the front end surface of a taper process part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a bundle fiber 1 according to an embodiment of the present invention. The bundle fiber 1 surrounds a core 2 made of quartz glass or the like as shown in FIG. A plurality of optical fibers 4 (19 in the present embodiment) having a clad 3 made of quartz glass or the like having a refractive index lower than 2 are included. One end of the optical fiber 4 is provided with a connector 4a for connecting to a device that inputs and outputs signals. The number of optical fibers 4 is not particularly limited, but is preferably 7, 19, 31, 61, etc. that can realize a hexagonal close-packed structure. However, if it exceeds 31, it does not have to be strictly a hexagonal close-packed structure. The size of the optical fiber 4 is not particularly limited. For example, in this embodiment, the outer diameter of the core 2 is 115 μm and the outer diameter of the optical fiber 4 is 125 μm.

  The bundle fiber 1 includes a bundle portion 5 in which a plurality of these optical fibers 4 are bundled. In addition, a taper-processed portion 6 that is gradually reduced in outer diameter toward the tip is continuous with the tip of the bundle portion 5. The taper processed portion 6 and the bundle portion 5 are melted in a state covered with the glass tube 7. The glass tube 7 is made of quartz glass containing an additive (for example, boron, fluorine, etc.) that lowers the refractive index than the optical fiber 4 (cladding 3). In the molten state of the optical fiber 4 in the bundle portion 5, the cross section of the core 2 remains circular.

  As shown in FIG. 3, in the taper processing portion 6, each optical fiber 4 is melted, and each core 2 is separated from each other by a melted clad 3. The cross-sectional shape of the core 2 is slightly deformed from a circular shape. Adjacent clads 3 are fused together and integrated. The outer diameter of the tip surface 6a of the taper processing portion 6 is, for example, 50 μm. Although it is possible to reduce the thickness to about 30 μm, if the diameter is further increased, the outer diameter of each core 2 becomes smaller than 5 μm, and the ability to propagate light is lowered, and polishing of the tip surface 6 a becomes difficult. Therefore, it is not preferable.

-Manufacturing method of bundle fiber-
Next, the manufacturing method of the bundle fiber 1 concerning this embodiment is demonstrated.

  First, a plurality (for example, 19) of optical fibers 4 having a core 2 and a clad 3 are prepared.

  Next, the optical fibers 4 are aligned and bundled to form a hexagonal close-packed structure to form a bundle portion 5. Note that the coating (silicone coating or the like) of the optical fiber 4 is removed with alcohol or the like after or before alignment.

  Next, a glass tube 7 containing an additive such as boron or fluorine is prepared. The size of the glass tube 7 is, for example, an inner diameter of 650 μm, an outer diameter of 780 μm, and a length of about 100 mm.

  Next, the bundle part 5 is inserted into the glass tube 7.

  Next, the bundle portion 5 and the glass tube 7 are heated and melt processed by a gas torch, a heater, or the like. At this time, since the tension is not applied to the bundle portion 5, the outer diameter of the core 2 is maintained.

  Next, tension is applied by pulling the bundle part 5 in which the glass tube 7 is fused and integrated. At this time, since no heat is applied, the bundle portion 5 does not stretch.

  Next, the bundle part 5 in a state where the tension is applied is heated by the gas torch 20, a heater or the like. At this time, the tapered portion 6 is gradually extended by being pulled by the applied tension. Then, by adjusting the tension and the amount of heat, as shown in FIG. 3, the taper processed portion 6 gradually decreases in outer diameter while the core 2 of each optical fiber 4 is separated from each other by the melted cladding 3. It is formed.

  Next, when the heating is finished, the elongation of the taper processed portion 6 is stopped.

  Next, the front end surface 6a of the taper processing portion 6 is cut at an appropriate position.

  Finally, the front end surface 6a of the tapered portion 6 is polished.

  In this way, since the bundle portion 5 is melted in a state where tension is applied, the outer diameter is gradually increased while being separated from each other by the melted clad 3 so that the outer size of each core 2 is not biased as much as possible. It is easy to process the taper processing portion 6 in which becomes smaller.

  Since the core 2 of each optical fiber 4 is separated from each other by the melted clad 3 in the taper processing portion 6 processed in this way, it becomes easy to maintain optical independence in each optical fiber 4. For this reason, it becomes possible to allocate light projection and light reception to each optical fiber 4.

-How to use bundle fiber-
The bundle fiber 1 manufactured in this way can obtain a very high power density by reducing the cross-sectional area of the plurality of transmission lights incident from the connector 4a side by the taper processing portion 6. Since the refractive index of the glass tube 7 is lower than the refractive index of the cladding 3, even if light leaks from each optical fiber 4, light is prevented from leaking out from the glass tube 7. For example, a power density of 92 kW / cm 2 can be obtained at a wavelength of 405 nm.

  Further, a signal is incident on a part of each optical fiber 4 from the connector 4 a side, and this signal is emitted from the front end surface 6 a of the taper processing portion 6 through each optical fiber 4, while remaining from the front end surface 6 a of the taper processing portion 6. Another signal can be incident on each optical fiber 4 and emitted from the bundle portion 5 through each optical fiber 4. Thus, light projection and light reception can be assigned to each optical fiber 4 and can be used as a small-diameter optical probe.

  For example, light is incident on each optical fiber 4 on the center side of the bundle portion 5, and this light is condensed from the tip surface 6 a of the tapered processing portion 6 through each optical fiber 4 to emit light with high power density. The target is irradiated with light, and the light reflected by the irradiation target is incident on each optical fiber 4 on the outer peripheral side of the distal end surface 6a of the taper processed portion 6 and used as a surface analysis probe that is taken out from the connector 4a on the opposite side. be able to.

  Furthermore, by individually entering the connector 4a, the amount of light emitted from the distal end surface 6a or the irradiation pattern can be changed.

  Moreover, the numerical aperture of the incident light incident from the connector 4a is increased when the incident light is emitted through the taper processing portion 6. In a normal taper structure with a coating, incident light is radiated at the taper processing portion and is not propagated to the tip surface. However, in the bundle fiber 1 of the present embodiment, the taper processing portion 6 is not provided with a coating, and fluorine or boron is used. Since it is covered with the glass tube 7 containing additives such as these, light having a numerical aperture increased by taper can be confined and propagated to the tip surface 6a. For this reason, a high power density is obtained. Furthermore, because of the high numerical aperture (0.5 or more and 0.9 or less), the high power density region is limited to the tip surface 6a, and there is little influence on the axial direction (depth), and power is concentrated on the surface of the irradiation object. it can. For this reason, it is suitable for a processing probe that requires a power density for a workpiece (irradiation site) such as fine processing by laser and laser medical treatment.

  Furthermore, since it is a melting terminal, it can be applied to products that require high heat resistance, weather resistance, etc., and is characterized by being clean and free from outgassing.

  Further, when used with an array type light emitting device, emitted light with a high numerical aperture arranged from the array type light emitting device can be made incident from the tip surface 6a of the taper processed portion 6. As the array type light emitting device, a surface emitting laser LED or the like can be considered.

(Other embodiments)
The present invention may be configured as follows with respect to the above embodiment.

  That is, in the above-described embodiment, the taper processed portion 6 is covered with the quartz glass tube 7 containing an additive such as fluorine or boron. When used in a touched state, even if light leaks from each optical fiber 4 by being covered with outside air such as air having a refractive index lower than that of the glass tube 7, light is emitted at the interface between the glass tube 7 and outside air. Since the light is refracted, the light is prevented from leaking out from the glass tube 7.

  The glass tube 7 may have a two-layer structure, and the outer glass tube 7 may have a lower refractive index than the inner glass tube 7. Even in this case, the light is refracted by the outer glass tube 7, so that the light is surely prevented from leaking out from the glass tube 7.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or a use.

  As described above, the present invention is useful for a bundle fiber in which a plurality of optical fibers having a core and a clad having a refractive index lower than that of the core are bundled, and a manufacturing method thereof.

DESCRIPTION OF SYMBOLS 1 Bundle fiber 2 Core 3 Clad 4 Fiber 4 Optical fiber 4a Connector 5 Bundle part 6 Taper process part 6a Tip surface 7 Glass tube

Claims (9)

In a bundle fiber in which a plurality of optical fibers having a core and a clad having a refractive index lower than that of the core are bundled,
A bundle part in which a plurality of the optical fibers are bundled;
Continuing on the tip of the bundle part, comprising a taper processed part that gradually decreases in outer diameter toward the tip,
At least the tapered portion is melted while applying tension in a state covered with a glass tube having a refractive index lower than that of the clad, and is processed so that the outer diameter gradually decreases toward the tip. The optical fibers are integrated, the cores are deformed from a circular cross section, and are separated from each other by the integrated clad so as to be optically independent. Bundle fiber. In a bundle fiber in which a plurality of optical fibers having a core and a clad having a refractive index lower than that of the core are bundled,
A bundle part in which a plurality of the optical fibers are bundled;
Continuing on the tip of the bundle part, comprising a taper processed part that gradually decreases in outer diameter toward the tip,
At least the tapered portion is melted while applying tension in a state covered with a glass tube, and is processed so that the outer diameter gradually decreases toward the tip. In the tapered portion, each optical fiber is integrated. ized, that with each of said core is deformed from a circular cross section, separated from each other so as to keep the optically independent by integrated the cladding, is used in a state where the glass tube touches the outer air Bundle fiber characterized by The bundle fiber according to claim 1 or 2,
A bundle fiber characterized by being a processing probe in which a laser light source is connected to each of the optical fibers, and processing is performed by laser light emitted from the tip of the taper processing portion. In the bundle fiber according to any one of claims 1 to 3,
A signal incident on a part of each optical fiber from the bundle part side is emitted from the tip of the tapered portion through the optical fiber, and the remaining optical fibers from the tip of the tapered portion. A bundle fiber characterized in that another signal incident on the optical fiber is emitted from the bundle part through each optical fiber. The bundle fiber according to claim 4,
A bundle fiber, which is a surface analysis probe that receives signal light reflected by incident probe light. The bundle fiber according to any one of claims 1 to 5,
A bundle fiber characterized in that it can emit outgoing light having a numerical aperture of 0.5 or more and 0.9 or less from the tip of the tapered portion. The bundle fiber according to claim 6,
A bundle fiber, which is used together with an array type light emitting device, and is configured such that light emitted from the array type light emitting device can be incident from a tip end surface of the tapered portion. The bundle fiber according to any one of claims 1 to 7,
The bundle fiber characterized in that the glass tube has a two-layer structure, and the outer glass tube has a lower refractive index than the inner glass tube. In a method of manufacturing a bundle fiber in which a plurality of optical fibers each having a core and a clad are bundled,
A bundle part is formed by bundling a plurality of optical fibers having the core and the cladding,
The bundle part is inserted into a glass tube having a refractive index lower than that of the cladding, and the bundle part and the glass tube are heated and melt processed,
Apply tension to the bundle part where the glass tube is fused and integrated,
The bundle part in the above state is heated so that each optical fiber is melted, and the respective cores are deformed from a circular cross section while being separated from each other so as to be optically independent by the melted clad. , Forming a tapered part that gradually reduces the outer diameter,
End the above heating,
Cut the tip of the taper part,
A method of manufacturing a bundle fiber, wherein the tip end surface of the tapered portion is polished.

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