JPH04165311A - Manufacture of photo waveguide passage - Google Patents

Abstract

PURPOSE:To provide a refractive index distribution type photo waveguide passage through the low number of processes with a high yield by immersing the emission end of an optical fiber in a photo curable material, waveguiding light through an optical fiber to form a cured part at an emission end, and polishing the cured part to an end part. CONSTITUTION:When, after an emission end 12a of an optical fiber 12 is im mersed in light transmissive photo curable resin 11, the incident end of the optical fiber 12 is irradiated with ultraviolet rays from a light source 13, the photo curable resin 11 in the vicinity of the emission end 12a is started to cure and finally forms a cured part 14. The cured part 14 is taken out from the uncured photo curable resin 11 together with the optical fiber 12. After the uncured photo curable resin 11 is washed, the surface thereof is coated with light transmissive resin 15 having a refractive index lower than that of the photo curable resin 11. Cutting and grinding are applied on a cured part 14A, formed by cutting the cured part 14 from the optical fiber 12, by a cutting and a grinding means to form an end surface 14b. This method simplifies provi sion of a refractive index distribution type photo waveguide passage 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an optical waveguide used as an optical transmission line in an optical writing device, an optical reading device, an optical circuit, or the like.

[Conventional technology]

Conventionally, as a method for manufacturing this kind of graded index optical waveguide or graded index rod lens, there has been the method described below.

That is, by immersing a glass rod in molten salt for a long time,
Monovalent ions doped into the glass in advance and having a high electronic polarizability and easily moving through the glass at high temperatures are exchanged with alkali ions in the molten salt. The parabolic approximation of the resulting ion diffusion distribution is utilized to form the refractive index distribution required for the waveguide or lenticular medium. Next, by cutting and polishing, end faces are formed at necessary positions to form a substantially cylindrical shape, thereby obtaining a gradient index leading waveguide or a gradient index rod lens.

[Problem to be solved by the invention]

However, in order to obtain an optical waveguide as an optical transmission line using the above-mentioned manufacturing method, there are problems in that the number of steps is large and the yield is not good.

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing an optical waveguide that can obtain a gradient index optical waveguide with a high yield with a small number of steps. shall be.

[Means to solve the problem]

In order to achieve this object, the method for manufacturing an optical waveguide of the present invention includes a first step of immersing the output end of an optical fiber in a photocurable material, and guiding light into the optical fiber and emitting it from the output end. a second step of forming a hardened portion of the photocurable material at the output end of the optical fiber by polishing the hardened portion, and a third step of creating an optical waveguide by polishing the hardened portion to form an end portion. Prepared.

[Effect]

According to the invention, in a first step, an optical fiber is dipped into a photocurable material. Light is emitted from the emitting end of the immersed optical fiber in the second step, and the photocurable material is cured with a molecular weight distribution according to the optical power density distribution of the emitted light.

That is, this molecular weight' distribution becomes a refractive index distribution and becomes a light waveguide structure.

In a third step, the hardened portion is polished to create an optical waveguide.

〔Example〕

Embodiments embodying the present invention will be described below with reference to the drawings.

Hereinafter, the steps in the method for manufacturing an optical waveguide will be explained in order. FIGS. 1('a) to 1(d) show a method for manufacturing an optical waveguide according to the present invention.

First, as shown in FIG. 1(a), the output end 12a of the optical fiber 12 is immersed in a transparent photocurable resin 11. As the photocurable resin 11, an ultraviolet curable resin is used, such as a fluorine-based monomer or an acrylic monomer mixed with an initiator (photoreaction initiator). Specifically, the fluorine-based monomer Defe
nsa 479-18 (trade name, manufactured by Dainippon Ink & Chemicals Co., Ltd., refractive index before curing 1.512, refractive index after curing 1
．． 535) was used. A plastic optical fiber is used for the optical fiber 12, specifically Esca CK-10 (trade name, manufactured by Mitsubishi Rayon Co., Ltd., diameter 250 μm, aperture angle 30°).
) was used.

Next, as shown in FIG. 1(b), ultraviolet light is applied from the light source 13 to the input end 12b of the optical fiber 12. The ultraviolet rays are guided through the optical fiber 12 and emitted from the emission end 12a at an aperture angle of 30°.

As a result, the photocurable resin 11 near the output end 12a starts to harden, and finally becomes a hardened portion 14 having a mosque-shaped shape as shown in the figure. Assuming that the power of the ultraviolet rays emitted from the emission end 12a is 300 μW at a wavelength of 360I,
This photocurable resin became a cured portion 14 having the shape shown in the figure in about 5 seconds. The cured portion 14 had a width of 1.2+o+ and a length of 8.5 m. Moreover, since the hardened portion 14 has a refractive index distribution radially from the central axis as described later, the hardened portion 14 alone has an optical waveguide structure.

Next, as shown in FIG. 1(c), the cured portion 14 and the optical fiber 12 are taken out from the uncured photocuring resin 11, and after washing off the uncured photocuring resin 11 remaining on the surface, The surface is coated with a translucent resin 15 having a lower refractive index than the photocuring resin 11. The translucent resin 15 has the effect of protecting the surface of the cured part 14 from dust and scratches and increasing its strength, and also prevents the light beam incident on the cured part 14 from leaking out from the side surface 14a due to scattering or other causes. It has the effect of preventing it from being put away as much as possible. A specific example of the translucent resin 15 is PMMA.
(refractive index 1.49), etc.

Next, as shown in FIG. 1(d), the hardened portion 14 is separated from the optical fiber 12 to form a hardened portion 14A, and the hardened portion 14A is cut, ground, etc. to a surface roughness of 0.01.
By forming the end face 14b of about μm or less, the end face 14b is processed into a cylindrical shape, and the final graded index optical waveguide 20 is obtained.

Next, using FIGS. 2(a) to (c), the above-mentioned hardened part 14 is
We will explain the formation status over time.

As shown in 21M (a), ultraviolet light 21 is emitted from the optical fiber 12 into the photocurable resin 11 at an angle (aperture angle) of 30'. At this time, the optical power density distribution 22 of the ultraviolet rays 21 shows a two-dimensional Gaussian distribution with the maximum value on the optical axis extension line 23 of the optical fiber 12, and the photocurable resin 1
1 starts curing gradually from the region where the power is stronger according to the power density distribution 22. In the figure, the path of the ultraviolet rays 21 is shown with an arrow.

Next, as shown in FIG. 2(b), since the area on the optical axis extension line 23 is the area where the puff density of the ultraviolet rays 21 is highest, the photocurable resin 11 is first applied from the area where the puff density of the ultraviolet rays 21 is highest. Polymerized and hardened.

This phenomenon is equivalent to an increase in the molecular weight and a high refractive index.

Due to the above action, a refractive index distribution is formed radially along the optical axis extension line 23, so that the output end 12a of the optical fiber 12
The ultraviolet rays 21 emitted are spread out at an angle of 30',
It was observed that the optical path was bent inward due to the difference in refractive index.

Next, as shown in FIG. 2(C), since the polymerized photocurable resin 11 has a refractive index distribution radially along the optical axis extension line 23, the ultraviolet rays 21 are emitted from the optical axis extension line 23. It continues to meander along the path as shown by the arrow in the figure, and continues to form a refractive index distribution in the same way. Therefore, a mosque-shaped hardened portion 14 that is long in the optical axis direction is formed. However, the ultraviolet rays 21 traveling through the photocurable resin 11 gradually attenuate due to transmission loss, and beyond a certain length, the ultraviolet rays 21 propagating through the photocurable resin 11
1 cannot be cured. Therefore, under the conditions shown in FIG. 1, the length did not exceed 8.5 mm. Note that the width and length of the cured portion 14 are determined by the type of photocurable resin and the optical power of the ultraviolet rays 21, and therefore, various changes can be made depending on the purpose.

Next, the operation of the optical waveguide 20 will be explained using FIG.

Light beam 30 incident on the input end 20a of the optical waveguide 20
travels through the optical waveguide 20 in a meandering manner as shown by the arrow in the figure according to the radial refractive index distribution with respect to the central axis of the optical waveguide 20, and from the output end 20b has an aperture angle of 15.2
It is emitted at °. Therefore, it is possible to obtain a high-quality optical waveguide with low loss.

Note that the present invention is not limited to the above-described embodiments, and can be modified as appropriate.

For example, a similar optical waveguide can be obtained by omitting the step of coating the transparent resin shown in FIG. 1(C).

In addition, by configuring the refractive index distribution of the optical waveguide as shown by where r is the radial distance from the central axis, no: refractive index on the central axis A: refractive index distribution constant, a refractive index distribution type rod lens can be obtained. It is also possible to obtain

〔Effect of the invention〕

As is clear from the detailed description above, according to the present invention, it is possible to obtain a gradient index optical waveguide with a high yield with a small number of steps.

[Brief explanation of drawings]

Figures 1 (a) to (d) are diagrams showing the manufacturing process of the present invention, Figures 2 (a) to (c) are diagrams showing the curing status of the photocurable material, and Figure 3 is a diagram showing the present invention. FIG. 3 is an explanatory diagram of the operation of the invention. 11...Photocurable material 12...Optical fiber 14...Curing part 15...Transparent material Yasushi Ishikawa (a/)
(b) A certain prisoner (C) Art 2

Claims (1)

[Scope of Claims] A first step of immersing the output end of the optical fiber in a photocurable material; and guiding light into the optical fiber and emitting the light from the output end. Manufacturing an optical waveguide, comprising: a second step of forming a hardened portion using a photocurable material; and a third step of creating an optical waveguide by polishing the hardened portion to form an end portion. Method.