JPS5965808A - Production of optical waveguide - Google Patents

Abstract

PURPOSE:To obtain an optical waveguide having a large diameter and a high difference in refractive index by disposing photomasks having the same pattern on the top and bottom surfaces of a film of a photo-polymerizing material, irradiating light thereto from top and bottom thereby forming a high refractive index layer and coating the top and bottom surfaces with a coating agent having a low refractive index. CONSTITUTION:A soln. of a photo-polymerizing material of which the refractive index changes when irradiated with light is cast into a casting vessel 2 whereby a sheet-like semi-solid film 3 is formed. Photomasks 6, 7 having the same pattern are disposed on the top and bottom surfaces of such film 3 in tight contact therewith in such positions where the patterns coincide with each other. Light is irradiated alternately and perpendicularly to the photomasks 6, 7 from above and below the film 3 to form a high refractive index layer 3a on the film 3; thereafter, a coating agent having a low refractive index is coated on the top and bottom surfaces of the film 3, whereby an optical waveguide is formed. The optical waveguide having a large diameter connectable to an optical fiber of a large diameter and a high difference in refractive index is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of the Invention The present invention relates to a method for manufacturing an optical waveguide for transmitting light.

(b) Prior art and its problems Some of the manufacturing methods for polymeric optical waveguides using the two-selective photopolymerization method are as follows: First, as shown in the manufacturing process diagram in Figure 1, a cast solvent is cleaned with a2 solvent. Thereafter, a solution of a photopolymerizable material whose refractive index changes upon irradiation with light is poured into a casting vessel a to form a sheet, and a portion of the solvent is evaporated to form a semi-solid transparent film C.

Subsequently, a photomask (1) is placed on the top surface of the film C, and after that, ultraviolet rays (e) are irradiated from above for exposure.

Selectively photopolymerize only the unmasked areas,
Decrease the refractive index. Thereafter, the film C is vacuum-dried to evaporate the monomer molded into the non-photopolymerized portion, and the non-photopolymerized portion is converted into a high refractive index layer having a higher refractive index than the photopolymerized portion.

Finally, the upper and lower surfaces of the film (>) are coated with a resin gr having a low refractive index, and the high refractive index layer f is placed on the core.

An optical waveguide 11 is formed around the optical waveguide 11 as a cladding.

In the manufacturing method of this optical waveguide 1ffi'+1+, the ultraviolet ray e exposure step is explained in more detail.As shown in FIG. 2, a semi-solid transparent film C is formed in a cast container a. A photomask (l) is distributed in a dense layer on one side of this film 0. Then, a parallel beam of ultraviolet rays C is applied from the ultraviolet irradiation device 1 to the photomask (1) on three sides. or irradiated.

Therefore, for the mask portion J of the photomask d, the ultraviolet m
Since photopolymerization is unlikely to occur in the part of the film (5) below this mask portion (5) through which photomask d is transmitted, the mother phase and monomer are separated and the width of the photomask d is 1. The ultraviolet ray d is transmitted through the parts other than the mask part J, and photopolymerization occurs in a part of the film C, and the refractive index decreases to 1, which is determined by the weight percent of the cut material and the monomer, and becomes a low refractive index j-. , and the film part below the mask part 1 is a high refractive index layer.
becomes.

In this exposure process, ultraviolet rays are conventionally irradiated only from above, and are applied to the photopolymerized portion of the low refractive index layer 1.
As shown in Figure 2 (1), the light intensity distribution of ultraviolet light e due to phase separation between the monomer and the monomer becomes an attenuation curve that gradually increases downward from the top surface of the film C.

Therefore, as shown in FIG. 2(e), the difference in refractive index (NA) between the photopolymerized portion that becomes the low refractive index layer k and the high nl (non-Kyuun taichung I5 that becomes the refractive index layer 1) or the film ( - The apex decreases from the top to the bottom.

This phenomenon does not cause any problem if the film C is thin, but as shown in FIGS. 6 and 4, the thickness of the film O is a +
If you increase it (for example, d2.1[X]II m or (is 2
00 μm), the light intensity distribution is significantly attenuated, and the refractive index difference is also reduced accordingly. This is technically true, when transmitting light +
At the boundary between the core of the high refractive index layer r and the crat of the low refractive index layer 1 at the bottom of the film (2), light scattering and leakage are large, and the light confinement effect is weak, so there is no loss as an optical waveguide. This invention has the disadvantage of being thick, making it difficult to manufacture an optical waveguide 11 with a large diameter and a high refractive index difference. The object of the present invention is to provide a method for manufacturing an optical waveguide having a large diameter as possible and a high P1 index difference.

B) Structure and Effects of the Invention In order to achieve the above object, the present invention injects a photopolymerizable material with the same pattern on the upper and lower surfaces of a sheet-like semi-solid photopolymerizable material film formed in a CAST FB device. The masks are arranged so that their patterns match, and a high refractive index layer is formed by alternately irradiating light from above and below the film toward the sod mask, and then a low refractive index layer is applied to the top and bottom surfaces of the film. It is configured to form an optical waveguide using a coating agent as a coat.

Therefore, according to this invention, since light is irradiated from above and below the film, the attenuation of the light intensity distribution is small even when the film thickness increases, and the refractive index difference between the high refractive index layer and the low refractive index layer is reduced. Since the optical waveguide can be maintained in a large state over the upper and lower surfaces of the optical waveguide, waveguide loss in a large-diameter optical waveguide can be reduced.

Furthermore, since the diameter of the optical waveguide can be increased, alignment of the optical axis becomes easy when connecting to an optical fiber, and connection to a large-diameter plastic eyeglass fiber with a core diameter of 1000 μm is also possible.

(E) Explanation of Examples FIG. 5(a) shows an exposure apparatus 1 in step 2 of the optical waveguide manufacturing process.
It shows.

This exposure apparatus 1 forms a high refractive index layer 3a and a low refractive index layer 6.1) on a polymer film 5 in a cast container 2. This CAST FB device 2 is placed on spirit levels 4 on both sides, and is provided with L-shaped positioning fittings 5 inside.

Further, inside the cast container 2, a photomask 6 is provided at the bottom in close contact with the positioning metal fitting 5, a film 6 is formed above this photomask 6, a photomask 7 is formed above this film 6, and a photomask 7 is formed above this film 6. Damping plates 8 are provided above the positioning fittings 7 in order in close contact with the positioning fittings 5. The upper and lower photomasks 6.7 have mask portions 6a+7a and are formed in the same pattern, and are provided so that the two patterns match, with both mask portions 6a and 7B sandwiching the film 6 and matching. .

In addition, ultraviolet rays 9 and 1 are provided above and below the cast container 2.
0 irradiation device 11.12 is provided, and this irradiation device 11
．． 12 as a light source, parallel beams of ultraviolet rays 9 and 10 enter the photomasks 6 and 7 and are irradiated perpendicularly to the photomasks 6 and 7.

The film 6 is formed from a solution of a photopolymerized compound whose refractive index decreases when irradiated with light, and this solution is made of binuphenol polycarbonate (PCZ, ) 70 as ff1U.
'li', monomer (MA) 42i ml + solvent tl, -(methane tetrachloride (CH2Cd2) 100.O
f, benzoin ethyl ether (B
ZEE) 2.1g, hydroquinone (H
Q) It is composed of a blend of 0,079.

This solution was poured into a casing with a volume of 52 and a film thickness of 200/J.
The monomer and a portion of the solvent are evaporated to form a sheet-like semi-solid transparent film filter.

Next, a method for manufacturing an optical waveguide using this exposure apparatus 1 will be explained.

First, after preliminarily cleaning the cast container 2 and the positioning metal fittings 5 with a solvent such as methylene chloride (CHzC, g2), the cast container 2 is placed on the level 4.

The positioning fitting 5 is installed inside the cast container 2.

Subsequently, the lower photomask 6 is placed in close contact with the positioning metal fitting 5 at the bottom of the cast container 2, and the mask portion 6a is placed facing ``D''.

Subsequently, a solution consisting of the above-mentioned predetermined photopolymerization agent is poured into the casting container 2 so that the film has a thickness of 200 μm, and is leveled using a spirit level 4. This cast container 2
Is it semi-sealed and 100mj of Chitusoganu inside? /
After flowing for 150 minutes, monomer vapor was flowed for 30 minutes,
A portion of the solvent and monomer is evaporated to form a sheet-like semi-solid transparent film 6.

The upper photomask 7 is placed on the upper surface of this film 6 with the mask part 7a facing downward and aligned with the mask part 6a of the lower photomask part 2, and in close contact with the positioning metal fitting 5. After it has reached the extent of slipping, the lower first mask 6 and 7 are precisely aligned using a microscope, and the attenuation plate 8 is placed on the upper photomask 7''.

Next, the upper and lower irradiation devices 11 and 12 are activated.

Using a timer control or the like, ultraviolet rays 9 and 10 are alternately applied to the lower surface of the film 5 at a switching speed of about 20 times per second for 60 minutes perpendicularly to both photomasks 6.7. This variation in the intensity of ultraviolet rays 9 and 100 is corrected by changing the attenuation plate 8 or the ratio of the irradiation time.

Due to the irradiation of the ultraviolet rays 9 and 10, a part of the film 6 between the mask parts 6a and 7a is not irradiated with the ultraviolet rays 9 and 10, so photopolymerization does not occur, and pcz and MA are separated.
Part 12 of Film B other than 6a and 7a undergoes photopolymerization9. Polymerized.

The non-photopolymerized portion becomes the high refractive index layer 3a, and the photopolymerized portion becomes the low refractive index layer 3b.

After this exposure, the film 6 is left for 30 minutes or more, then peeled off from the cast container 2, transferred to a vacuum dryer, and dried at 90°C for 10 hours to remove unpolymerized monomers from the high refractive index layer 3a. Next, a coating agent with a low refractive index is coated on the upper and lower surfaces of FILM B and dried at 90° C. for 5 hours using a hot air dryer to form an optical waveguide. and.

High refractive index layer7. A is the core, and the surrounding area is the cladding.

According to this manufacturing method, as shown in FIG.

The ultraviolet light intensity distribution within the film 5 is a combination of the light intensity distributions of the upper ultraviolet ray 9 and the lower ultraviolet ray 10.

It is almost flat across the top and bottom surfaces (Fig. 5 (1)).
.

(see FIG. 6(b)), high refractive index layer 3a and low refractive index layer 3b
Similarly, the distribution of the refractive index difference between the two surfaces is substantially flat over the upper and lower surfaces (see FIGS. 5(C) and 6(C)).

Therefore, a large diameter optical fiber 13 can be connected.

In FIG. 7, the thickness of the film B is k 4 D D It m, and in this case as well, the light intensity distribution and the refractive index difference distribution are substantially flat over the upper and lower surfaces.

However, as shown in FIG. 8, a film 6 having a thickness of +40,071 m may be bonded with an adhesive to form an optical waveguide with an even larger diameter.

Figure 9 shows an exposure system with one irradiation device 14 serving as a light source.
The parallel beam-shaped ultraviolet rays 15 from this irradiation device @14 are separated into upper and lower parts by a mirror 16 (reflecting means), and guided above and below the cast container 2.

This allows the number of irradiation devices 14 to be reduced.

In addition, although the refractive index of this fruit 7 (photopolymerized reliquary in Example 1) decreases upon irradiation with light, the refractive index of the photopolymerizable material of this invention may increase upon irradiation with light. In addition to organic materials, inorganic materials may also be used.

Further, the light may be visible light or infrared light in addition to ultraviolet light.

[Brief explanation of the drawing]

1 to 4 show conventional examples, FIG. 1 is a manufacturing process diagram of an optical waveguide, FIG. 2 (a) is a cross-sectional side view of an exposure device, and FIG. , Fig. 2 (C1 is a distribution diagram of the same refractive index difference, Fig. 3 (al and Fig. 4 fal are enlarged front views of different films, Fig. 6 (1))
and FIG. 4(b) is an open light intensity distribution diagram, FIG. 6(C) and FIG. 4 (C1 is a distribution diagram of the same refractive index difference, and FIGS. 5 to 9 show examples of the present invention, FIG. 5(a) is a cross-sectional side view of the exposure device, FIG. 5(b) is a light intensity distribution diagram of the film,
Figure 5 (C1 is a distribution diagram of the same refractive index difference, Figures 6 (a) and 7 (al are front views of different films, respectively,
Figure (()) and Figure 7 (b) are the same intensity distribution maps. Figure 6 FC+ and Figure 7 (C1 are the same refractive index difference distribution maps,
FIG. 8 is a front view of another film, and FIG. 9 is a side view of another exposed cross-section. 1: Exposure device, 2: Cast container. 6: Film, 5a: High refractive index layer. 3b = low refractive index layer, 4: level, 5: positioning metal fittings, 6 and 7: photomask. 6a and 7a: mask portion, 8: attenuation plate. 9.10.15: Ultraviolet light, 11.12.14: Irradiation device, 16: Optical fiber. 16: Mirror. Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Shigeru Naka Toshige 1aM1 Figure 5 (Q) $8 Figure 9 Procedural amendment (voluntary) December 8, 1980 To the Commissioner of the Japan Patent Office 1 Indication of the case Showa 1957 Special Revision Request No. 475828 2
Name of Komei Optical waveguide manufacturing method 6 Relationship with the amended case Patent 1”3 Applicant address 10 Hanazono Tsuchido-cho, Ukyo-ku, Kyoto City Name
(294) Tateishi Electric Co., Ltd. 7-1 Representative Tateishi
Takashi Wholesaler 4 Agent 5 Target of oil stop (1) Figure 1 W of the drawing, Figure 1 above

Claims (3)

[Claims] (1) d of a photopolymerized material whose refractive index changes with light irradiation
Pour the liquid into a casting container to form a sheet-like, half-shaped film, and place photomasks with the same pattern on the top and bottom surfaces of this film in a dense layer so that the patterns match. A high refractive index layer is formed on the film by alternately irradiating light from above and below the film perpendicularly to the photomask. 1. A method for manufacturing an optical waveguide, the method comprising forming an optical waveguide by coating with a coating agent of a certain amount. (2) The method for manufacturing an optical waveguide according to claim 1, wherein the light is irradiated onto the upper and lower surfaces of the film from two light sources. (3) The method for manufacturing an optical waveguide according to claim 1, wherein the light is divided into upper and lower parts by a reflecting means from one light source and irradiated onto the upper and lower surfaces of the film.