JP2001350027A - Method for removing coating of optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in optical fiber strength by removing its coating layer, without coming into contact with optical fiber in the manufacture of optical fiber gratings, etc. SOLUTION: The coating layer composed of a UV-curing resin is partly mechanically chipped off from the optical fiber 1 by a UV-removing device 2. Next, an organic solvent is penetrated into the segment from which the coating layer 3 is party chipped off, by which the coating layer 3 is dissolved and is removed from the optical fiber 1. Furthermore, the segment, from which the coating layer 3 is removed, is irradiated with UV rays 4 adjusted to 2 to 3.5 mJ/mm2 for energy density, to heat, sublimate and remove the resin particulates 6 remaining on the surface of the optical fiber 7. A phase mask 5 is fixed, in proximity to the optical fiber 1, and the optical fiber is subjected to exposure work by irradiation with the UV rays 4, by which the optical fiber gratings are manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a coating layer of an optical fiber, and more particularly, to a method of manufacturing an optical fiber grating by removing the coating layer without coming into contact with an optical fiber so as not to reduce the strength of the optical fiber. Is to do so.

[0002]

2. Description of the Related Art In manufacturing an optical fiber grating, it is necessary to remove a coating layer of an optical fiber.
FIG. 3 shows a method of manufacturing a conventional optical fiber grating. First, as shown in FIG. 3A, a part of a coating layer made of an ultraviolet-curable resin of the optical fiber 1 is mechanically scraped off by the coating removing device 2.

[0003] Next, as shown in FIG. 3 (2), an organic solvent penetrates into a part of the coating layer which has been cut off to dissolve and remove the coating layer 3 from the optical fiber 1. After removing the coating layer 3, the portion from which the coating layer 3 has been removed is immersed in an organic solvent and subjected to ultrasonic cleaning.

[0006] Next, as shown in FIG. 3 (3), the phase mask 5 is set in a grating manufacturing apparatus, and ultraviolet rays 4 are irradiated from an excimer laser. By this step, lattice stripes are formed on the optical fiber 7, and an optical fiber grating can be formed.

[0005] At this time, when the resin particles 6 forming the coating layer 3 remain on the surface of the optical fiber 7 during the production of the optical fiber grating, the ultraviolet rays 4 having a sufficient energy density to cause an ultraviolet-induced refractive index change in the fiber core. Does not reach the core, it is necessary to completely remove the resin particles 6.

However, when the coating layer 3 was removed by the above-described method, it became clear that the resin particles 6 remained on the surface of the optical fiber 7. When the grating is manufactured without removing the resin particles 6 remaining on the surface of the optical fiber and the ultraviolet rays 4 are irradiated from the excimer laser, the resin particles 6 remaining on the surface of the optical fiber 7 are heated and sublimated. As a result, it may adhere to the phase mask 5 fixed close to the optical fiber 7. The resin once adhered to the phase mask 5 was not removed by the subsequent irradiation with ultraviolet rays, and it was difficult to easily remove the resin even by washing with an organic solvent. Due to such adhesion of the resin, the life of the phase mask 5 is usually 500 to 10
The exposure was for 00 hours.

To avoid shortening the life of the phase mask 5 due to the adhesion of the resin as described above, after removing the coating layer 3, the portion of the optical fiber 1 from which the coating layer 3 has been removed is replaced with an organic solvent. It is necessary to soak and perform ultrasonic cleaning. However, at the time of this re-cleaning, the surface of the portion of the optical fiber 1 from which the coating layer 3 has been removed may be re-contaminated.

When the cause of re-contamination of the surface of the optical fiber 7 was investigated and investigated, a lens cleaner or the like physically contacted the surface of the optical fiber 7 during cleaning.
It has been found that since trace impurities in the organic solvent remain, dust on the surface of the optical fiber 7 cannot be completely removed.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to remove the coating layer without contacting the optical fiber in the manufacture of an optical fiber grating or the like so as not to lower the optical fiber strength. .

[0010]

According to a first aspect of the present invention, there is provided a method for removing an optical fiber coating, comprising irradiating a coating layer of the optical fiber with high energy density ultraviolet rays. The coating layer is removed by heating and sublimation. According to a second aspect of the present invention, there is provided a method for removing an optical fiber wire coating, wherein the energy density of ultraviolet rays in the first aspect is ² to 3.5 mJ / mm ² .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
An example in which the present invention is applied to the manufacture of an optical fiber grating will be described as an example of the method for removing an optical fiber wire coating according to the present invention with reference to FIG. As shown in FIG. 1A, a part of a coating layer made of an ultraviolet-curable resin is mechanically scraped from the optical fiber 1 by a coating removing device 2.

Next, as shown in FIG. 1 (2), an organic solvent is made to permeate a part of the coating layer which has been cut off to dissolve the coating layer 3 and remove it from the optical fiber 1. Further, as shown in FIG. 1 (3), a high energy density ultraviolet ray 4 was applied from an excimer laser to the portion where the coating layer 3 was removed.
And irradiates the optical fiber 7 as shown in FIG.
The resin particles 6 remaining on the surface of the substrate are heated and sublimated to be removed.

Then, as shown in FIG. 1 (5), the phase mask 5 is fixed close to the optical fiber 1 and exposed to ultraviolet light 4 from an excimer laser to perform an exposure operation, and the optical fiber grating is mounted. To manufacture.

In the method of removing the coating of the optical fiber of this embodiment, the ultraviolet rays 4 used in the steps of FIGS.
Are also used as the same light source. The light source is an excimer laser, and the ultraviolet light 4 has an energy density of ^{2 to} 3.5 mJ / mm ² , 100 as shown in FIG.
Irradiate at 0.5 Hz for 0.5 to 10 seconds and at an irradiation interval of 1 to 30 seconds for 1 to 5 times. By the irradiation, the resin particles 6 remaining on the surface of the optical fiber 7 in a non-contact manner can be almost completely removed. At this time, the surface of the optical fiber 7 is not damaged.

When the different steps of removing the coating by heating and sublimation and exposing by a phase mask are performed by irradiating the ultraviolet rays 4 with the same light source, the energy density of the ultraviolet rays is such that the resin particles 6 are removed by heating and sublimation. It is necessary to set the range so that it can be performed effectively and the optical fiber strength is not reduced.

At this time, the energy density of the ultraviolet light 4 irradiated from the excimer laser shown in FIGS.
It is preferred to be ² to 3.5 mJ / mm ² . If the energy density of the ultraviolet light 4 irradiated from the excimer laser is less than ² mJ / mm ² , the resin particles 6 on the surface of the optical fiber 7 cannot be effectively removed by heating and sublimation. Further, when the energy density exceeds 3.5 mJ / mm ² , the strength of the optical fiber 7 decreases.

Therefore, the energy density of the ultraviolet light is 2
In the range from 3.5 to 3.5, the resin forming the coating layer of the optical fiber can be effectively removed, and at this time, the strength of the optical fiber is not reduced.

The following is a specific example. An optical fiber 1 having a coating layer 3 made of an ultraviolet curable resin is prepared.
As shown in FIGS. 1A and 1B, after the coating layer 3 is removed using a mechanical device and an organic solvent, the optical fiber 1 is installed in a grating manufacturing device. Next, in a state where the phase mask 5 is not attached to the grating manufacturing apparatus, the energy density is ^{2 to} 3.5 mJ / mm ² and 100H.
z ultraviolet light 4 intermittently for 0.5 to 10 seconds, irradiation interval 1
Irradiate from excimer laser 10 times or more in 30 seconds.
Thereafter, as shown in FIG. 1 (5), the phase mask 5 is set in a grating manufacturing apparatus, and an optical fiber grating is manufactured.

After heating and removal of the resin particles 6 by sublimation and completion of grating production, the surface of the optical fiber 7 and the surface of the phase mask 5 were observed using an optical microscope. Observation results were taken using a Polaroid (registered trademark) camera. The results are shown in FIG.

From the results shown in FIG. 2, it can be seen that the energy density of the ultraviolet light 4 is 2
If it is ~ 3.5 mJ / mm ² , the coating layer 3 and the resin particles 6 are completely removed without contacting the optical fiber 7, and the phase mask 5 is not damaged without lowering the optical fiber strength. It has been found.

The method for removing the coating of the optical fiber of the present invention can be effectively used for removing the coating layer of the optical fiber in addition to the production of the optical fiber grating. Further, as the resin material forming the coating layer, a silicone resin or the like other than the ultraviolet curable resin may be used.
It is not limited to the method of removing the resin particles of the remaining coating layer by irradiating ultraviolet rays after mechanically removing the coating layer as in the above example, and heating and sublimating all the coating layers by irradiating ultraviolet rays from the beginning. You can also.

[0022]

As described above, in the method for removing the coating of the optical fiber according to the present invention, the coating layer of the optical fiber is irradiated with ultraviolet rays having a high energy density, and the coating is removed by heating and sublimation. Therefore, the coating layer can be removed without damaging the optical fiber.

In the method for removing an optical fiber coating according to the present invention, the energy density of the ultraviolet light is set to ² to 3.5 mJ / mm ^2.
Then, the strength of the optical fiber is not reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an optical fiber wire coating removal method of the present invention.

FIG. 2 is an example of an optical microscope photograph of the surface of an optical fiber after removing resin particles by using the optical fiber strand coating removal method of the present invention.

FIG. 3 is a diagram showing an example of a conventional optical fiber wire coating removal method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber strand, 2 ... Coating removal device, 3 ... Coating layer, 4 ... Ultraviolet, 5 ... Phase mask, 6 ... Resin particles,
7 ... Optical fiber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02G 1/12 303 C03C 25/06 (72) Inventor Kazuya Okamoto 1440 Mutsuzaki, Sakura-shi, Chiba Fuji Corporation Inside the Kura Sakura Office (72) Inventor Masakazu Ohashi 1440 Mutsuzaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office Co., Ltd. Inventor Daiichiro Tanaka 1440 Mutsuzaki, Sakura-shi, Chiba F-term in Fujikura Sakura Works (reference) 2H038 CA01 CA02 CA05 2H050 AC82 AC84 4E068 AH00 CA01 DA00 4G060 AA03 AC14 AD43 AD51 5G353 BA03 BA06 CA04 DA08 EA12

Claims (2)

[Claims] 1. A method for removing an optical fiber coating, comprising irradiating a coating layer of the optical fiber with ultraviolet rays having a high energy density and heating and sublimating the coating layer. 2. The energy density of ultraviolet rays is 2 to 3.5 m.
^{2. The} method according to claim 1, wherein the coating is J / mm ² .