JP2022079887A - Optical fiber for blue laser light transmission - Google Patents

Abstract

To provide an optical fiber for blue laser light transmission capable of emitting blue laser light with a satisfactory beam quality from which Rayleigh scattered light is removed while suppressing damage caused by Rayleigh scattered light when transmitting blue laser light.SOLUTION: An optical fiber for blue laser light transmission 10 includes a core 111, a first clad 112, and second clad 113. The second clad includes a bare fiber 11 in which multiple vacancies 113a arranged to surround the first clad are formed. At the end of the fiber on the emission side, the bare fiber is exposed, and a clad mode stripper 13 is provided on the outer peripheral surface thereof and multiple holes in the second clad are embedded.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical fiber for blue laser light transmission.

Optical fibers are known in which a plurality of pores are formed in a clad provided so as to cover the core so as to surround the core, thereby enhancing the light confinement effect in the region surrounded by the pores (for example). Patent Document 1).

Japanese Unexamined Patent Publication No. 2010-78701

In general, an optical fiber generates Rayleigh scattered light that causes Rayleigh scattering loss due to the influence of stress or the like acting at the time of drawing. In the processing of so-called yellow metal such as copper and gold, blue laser light in the visible light region having a wavelength of around 400 to 470 nm is used, and in particular, Rayleigh scattered light is remarkably generated in this blue laser light. Therefore, there is a problem that Rayleigh scattered light leaks from the core during transmission of the blue laser light, which damages the jacket or the like.

An object of the present invention is a blue laser beam capable of suppressing damage due to Rayleigh scattered light during transmission of blue laser light and emitting a blue laser beam having good beam quality from which Rayleigh scattered light is removed. It is to provide an optical fiber for transmission.

The present invention has a core, a first clad provided to cover the core, and a second clad provided to cover the first clad, and the second clad has the first clad. An optical fiber for blue laser light transmission including a bare fiber having a plurality of holes formed so as to surround one clad, and the bare fiber is exposed at the fiber end on the emitting side. At the same time, a clad mode stripper is provided on the outer peripheral surface thereof, and the plurality of holes in the second clad are filled.

According to the present invention, in addition to the plurality of holes being arranged in the second clad so as to surround the first clad, the bare fiber is exposed at the fiber end on the exit side and the outer periphery thereof is exposed. Since a clad mode stripper is provided on the surface and a plurality of holes in the second clad are filled, damage due to Rayleigh scattered light can be suppressed during transmission of blue laser light, and Rayleigh scattered light can be suppressed. It is possible to emit a blue laser light with good beam quality from which the light has been removed.

It is a perspective view of the fiber end portion on the exit side of the optical fiber for blue laser light transmission which concerns on embodiment. It is a vertical sectional view of the fiber end portion on the emission side of the optical fiber for blue laser light transmission which concerns on embodiment. It is sectional drawing of the optical fiber for blue laser light transmission which concerns on embodiment.

Hereinafter, embodiments will be described in detail.

1 to 3 show an optical fiber 10 for blue laser light transmission according to an embodiment. The blue laser light transmission optical fiber 10 is a transmission member for blue laser light in the visible light region having a wavelength of 400 to 470 nm, and is, for example, a laser processing machine that cuts or welds so-called yellow metal such as copper or gold. It is incorporated in the optical fiber cable mounted on the.

The blue laser optical transmission optical fiber 10 according to the embodiment includes a bare fiber 11 and a jacket 12 covering the bare fiber 11. The outer diameter of the blue laser light transmission optical fiber 10 is, for example, 1 mm or more and 2 mm or less. The fiber length of the blue laser light transmission optical fiber 10 is, for example, 5 m or more and 50 m or less.

The bare fiber 11 has a core 111 at the center of the fiber, a first clad 112 that covers the core 111, and a second clad 113 that further covers the core 111. The bare fiber 11 may be a multi-core optical fiber having a plurality of cores.

The core 111 is preferably made of, for example, non-doped pure quartz. The first clad 112 has a lower refractive index than the core 111, and is preferably formed of quartz doped with a dopant (F, B, etc.) that lowers the refractive index, for example. The second clad 113 is preferably made of the same material as the first clad 112.

The diameter of the core 111 is, for example, 50 μm or more and 600 μm or less. Therefore, the blue laser optical transmission optical fiber 10 according to the embodiment is a multimode fiber. The diameter of the first clad 112 is, for example, 70 μm or more and 700 μm or less. The diameter of the second clad 113, that is, the outer diameter of the bare fiber 11, is, for example, 500 μm or more and 1500 μm or less.

The second clad 113 is formed with a plurality of holes 113a arranged so as to surround the first clad 112. The shape of each of the plurality of holes 113a in the cross section of the fiber is preferably an oval shape having a long axis in the radial direction. The inner diameter of the major axis is preferably 10 μm or more and 100 μm or less, and more preferably 10 μm or more and 40 μm or less. It is preferable that the plurality of holes 113a have the same shape. The shape of each of the holes 113a in the cross section of the fiber may be another shape such as a circle or an ellipse.

It is preferable that the plurality of holes 113a are arranged so that their hole centers are continuous in the circumferential direction on the circumference of a circle centered on the fiber center in the fiber cross section. The distance between adjacent holes 113a is preferably smaller than the inner diameter of the minor axis of the holes 113a. The number of holes 113a is, for example, 40 or more and 250 or less. The plurality of holes 113a may be provided in a plurality of layers in the radial direction. From the viewpoint of confining the blue laser light in the region surrounded by the pores 113a, it is preferable that the plurality of holes 113a are arranged outside the circle having a radius of 62.5 μm centered on the center of the fiber in the cross section of the fiber.

The jacket 12 may be composed of a single layer made of an ultraviolet curable resin, a thermosetting resin, or the like, or may be composed of, for example, an inner buffer layer of a silicone resin and an outer side of a nylon resin or a fluororesin that covers the inner buffer layer. It may be composed of two layers with a coating layer. The thickness of the jacket 12 is, for example, 50 μm or more and 500 μm or less.

In the blue laser light transmission optical fiber 10 according to the embodiment, the jacket 12 is peeled off at the fiber end on the exit side, and the bare fiber 11 protrudes from the jacket 12 and is exposed. A groove is provided along the length direction on the outer peripheral surface of the bare fiber 11 protruding from the jacket 12 and exposed, and the clad mode stripper 13 is formed by the groove. The length of the portion of the bare fiber 11 in which the clad mode stripper 13 is configured is, for example, 5 mm or more and 50 mm or less.

The groove constituting the clad mode stripper 13 is provided on the outer peripheral surface of the bare fiber 11 so as to extend continuously in a spiral along the length direction. The cross-sectional shape of the groove may be a U-shape, a V-shape, a trapezoidal shape, or the like, in addition to the U-shape. The depth of the groove is, for example, 25 μm or more and 70 μm or less. The opening width of the groove is, for example, 20 μm or more and 300 μm or less. The spiral pitch of the groove is, for example, 0.05 mm or more and 5 mm or less.

In the blue laser light transmission optical fiber 10 according to the embodiment, a plurality of holes 113a of the second clad 113 are filled in the fiber end portion on the emission side corresponding to the portion provided with the clad mode stripper 13. There is. It is preferable that the holes 113a are filled by being crushed by heating to form solids. As a result, it is preferable that the first and second claddings 112 and 113 are formed in a single material layer.

According to the blue laser light transmission optical fiber 10 according to the embodiment of the above configuration, although Rayleigh scattered light is remarkably generated in the blue laser light in the visible light region, the first clad 112 is surrounded by the second clad 113. Since a plurality of holes 113a are arranged in the space, the Rayleigh scattered light is confined in the region surrounded by the plurality of holes 113a during the transmission of the blue laser light, and the outer peripheral surface of the bare fiber 11 of the Rayleigh scattered light is confined. Radiation from to the outside is regulated. Therefore, damage to the jacket 12 and the like due to Rayleigh scattered light can be suppressed. In addition, heat generation due to Rayleigh scattered light can be suppressed.

In addition, the Rayleigh scattered light confined in the region surrounded by the plurality of pores 113a propagates toward the emitting side, but the bare fiber 11 is exposed at the fiber end on the emitting side. At the same time, since the clad mode stripper 13 is provided on the outer peripheral surface thereof and the plurality of holes 113a of the second clad 113 are filled, the confinement of the Rayleigh scattered light by the holes 113a is released and the Rayleigh scattered light is released. Is radiated from the outer peripheral surface of the bare fiber 11 to the outside via the clad mode stripper 13. Therefore, it is possible to emit a blue laser beam having good beam quality from which Rayleigh scattered light is removed from the fiber end face on the emitting side. Further, this enables long-distance transmission of blue laser light, and the fiber length can be as long as 10 m or more, preferably 20 m or more.

Further, in the optical fiber 10 for transmitting blue laser light according to the embodiment, even if the reflected light from the irradiated object irradiated with the emitted blue laser light is incident, the reflected light is emitted at the fiber end portion on the emitting side. It is radiated to the outside from the outer peripheral surface of the bare fiber 11 via the clad mode stripper 13. Therefore, damage to the jacket 12 and the like due to the reflected light can be suppressed.

For the fiber end portion on the exit side of the optical fiber 10 for blue laser light transmission according to the embodiment, a jacket 12 having a predetermined length is peeled off from the fiber end, and the exposed bare fiber 11 is heat-treated or filled to be subjected to a second clad 113. After filling the plurality of holes 113a, the outer peripheral surface of the bare fiber 11 can be obtained by irradiating a laser beam from, for example, a CO ₂ laser to form a groove and providing a clad mode stripper 13.

The blue laser light transmission optical fiber 10 according to the embodiment preferably has a similar structure at the fiber end on the incident side. That is, the jacket 12 is peeled off so that the bare fiber 11 protrudes from the jacket 12 and is exposed, and a clad mode stripper is provided on the outer peripheral surface thereof, and a plurality of holes 113a of the second clad 113 corresponding to the portion thereof. Is a buried structure. In this case, when the blue laser light from the laser light source is incident on the fiber end on the incident side, the blue laser light is mainly incident on the core 111 of the bare fiber 11 and propagates, but a part thereof is misaligned or the like. Therefore, the leaked light that is not incident on the core 111 is incident on the first and second claddings 112 and 113. However, even if such leaked light is incident, the leaked light is radiated to the outside from the outer peripheral surface of the bare fiber 11 via the clad mode stripper at the fiber end on the incident side. Therefore, damage to the jacket 12 and the like due to leaked light can be suppressed.

In the above embodiment, the clad mode stripper 13 is configured by a groove provided on the outer peripheral surface of the bare fiber 11 so as to spirally extend along the length direction, but the clad mode stripper 13 is particularly limited to this. Instead, the clad mode stripper 13 may be configured by a plurality of grooves extending in the circumferential direction provided on the outer peripheral surface of the bare fiber 11 at intervals in the length direction.

The present invention is useful in the technical field of optical fibers for blue laser light transmission.

10 Optical fiber for blue laser light transmission 11 Bare fiber 111 Core 112 First clad 113 Second clad 113a Pore 12 Jacket 13 Clad mode stripper

Claims (5)

It has a core, a first clad provided to cover the core, and a second clad provided to cover the first clad, and the first clad is surrounded by the second clad. An optical fiber for blue laser optical transmission including a bare fiber having a plurality of holes arranged in such a manner.
A blue laser beam in which the bare fiber is exposed at the fiber end on the emission side, a clad mode stripper is provided on the outer peripheral surface thereof, and the plurality of holes in the second clad are filled. Optical fiber for transmission. In the optical fiber for blue laser light transmission according to claim 1,
An optical fiber for blue laser light transmission in which the plurality of pores of the second clad at the fiber end on the emission side are filled by being crushed by heating to form solids. In the optical fiber for blue laser light transmission according to claim 1 or 2.
The second clad is an optical fiber for blue laser light transmission, which is made of the same material as the first clad. In the optical fiber for blue laser light transmission according to any one of claims 1 to 3.
An optical fiber for blue laser light transmission having a core diameter of 50 μm or more. In the optical fiber for blue laser light transmission according to any one of claims 1 to 4.
The plurality of holes are optical fibers for blue laser light transmission arranged outside a circle having a radius of 62.5 μm centered on the center of the fiber in the cross section of the fiber.

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