JPS60208711A - Optical coupler - Google Patents

Abstract

PURPOSE:To improve performance and to reduce cost by constituting an optical waveguide installed with a grating of an accumulated monomolecular film of a photopolymerizable olefin compd. so that sharp-edged microshapes are easily formed. CONSTITUTION:The accumulated monomolecular film 10 (hereunder abbreviated as LB film) is formed on a substrate 2 by Langmuir-Projet method (hereunder abbreviated as LB method) using a photopolymerizable monomer (e.g.; formula I , formula II) having a hydrophilic group, hydrophobic group and at least one unsatd. bond in the molecule. After the LB film 10 is patterned and exposed, the unexposed part is dissolved away by developing the film to build a lower part 12 of a waveguide consisting of the polymerized LB film. The polymerizable LB film 13 is formed by the LB method on the part 12 and the film 13 is exposed to a grating pattern by an energy ray 11, then the unexeposed part is dissolved away by developing the film, by which the intended grating type optical coupler is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical coupler made of a photopolymerizable compound, and more particularly to an optical coupler having a grating structure made of a polymerized monomolecular cumulative film of a photopolymerizable olefin compound.

In recent years, with the development of optical integrated circuits, there has been a demand for highly accurate and efficient optical couplers.

However, in the past, in order to obtain a coupler with the desired precision, advanced microfabrication techniques were required, which resulted in lower yields and higher costs.

The grating type optical coupler here will be explained.

FIG. 1 is a cross-sectional view of a grating type optical coupler. In this figure, 2 is a substrate, for example, a transparent substrate such as glass, plastic or lithium niobate (LiNbOs), or an opaque substrate such as silicon or ceramics. It will be done. An optical waveguide 1 is arranged on the surface of a substrate 2. The optical waveguide l has a higher refractive index than the substrate 2.

For example, in the case of using -optic acid TECHUM as a substrate, the optical waveguide 1 having a film thickness of about 0.5 to 5 .mu.m can be obtained by thermally diffusing titanium (Ti) onto its surface.

Alternatively, if glass with a refractive index of 1.5 is used as a substrate, the surface of the glass has a refractive index of 1.55 (wavelength 6828A).
) glass (for example, Corning C-7059)
) is formed into a film with a thickness of about 0.5 to 5 μm by sputtering to obtain an optical waveguide l.

6 is a grating, usually pitch 0.8~1μ depth 0
．． It is 1 to 0.2μ. When the incident light 8 enters the optical coupler configured in this way, the light 4 propagates through the waveguide by total reflection, is diffracted by the grating 6, and the emitted light 5 is taken out.

In this case, it is generally difficult to manufacture the grating.

In order to more effectively exhibit the function of the grating 6, a completely rectangular grating is preferable, but it is generally difficult to obtain such a completely rectangular grating.

2. Description of the Related Art Optical couplers having a grating structure using a photopolymerizable organic compound in the form of a thin film have been known.

The manufacturing method is to first apply a solution of a photopolymerizable organic compound to glass, plastic, semiconductors, etc. using a spin coating machine.
It is applied onto a substrate such as a dielectric material to form a thin film. Next, it is masked and irradiated with ultraviolet rays to selectively polymerize, and the unexposed portions are removed to create a grating or the like, which is used as an optical coupler.

However, in this conventional method, since the molecular orientation of the thin film is random, when viewed microscopically, the following disadvantages occur. In other words, no matter how good the resolution of a photopolymerizable organic compound is, it is not possible to obtain sharp edges in a microscopic area, and as a result, a high-performance optical coupler, which is essential for the production of optical integrated circuits, cannot be obtained. was there.

The present invention has been made in view of the above, and an object of the present invention is to provide a high-performance optical coupler that is easy to miniaturize. Also,
The object of the present invention is to provide hydrophilic groups within the molecule.

This is achieved by using a compound for optical recording media consisting of a photopolymerizable polymer having a hydrophobic group and at least one unsaturated bond, especially a photopolymerizable olefin compound.

The photopolymerizable layer of the present invention can form a monomolecular film or a monomolecular layer stack on a substrate. A monomolecular layer cumulative film formed on a substrate is irradiated with light to cause a polymerization reaction in the irradiated areas, and unpolymerized portions in non-irradiated areas are removed by development to form an optical coupler.

As the photopolymerizable polymer used in the present invention, a wide variety of photopolymerizable polymers can be used as long as they have a hydrophilic group, a hydrophobic group, and at least one unsaturated bond in the molecule.

Such a photopolymerizable polymer has the general formula (I[a).

(nb).

R, -CH=CH-R1 (IIa) R, -CH=C
H-R, -CH=CH-R1 (nb) above formula (I[a)R
Either both a hydrophilic site and a hydrophobic site are present in the + part or R1 and a part, or Ro is hydrophobic in relation to the bird and R1 is hydrophilic in relation to R. In the above formula (nb), both a hydrophilic site and a hydrophobic site are present in either R1-R1 or R, or any of Rt, Rt, and R1 is present in the relationship with other parts. It is hydrophobic and any of the remaining parts are hydrophilic. In particular, a long-chain alkyl group having 10 to 8 carbon atoms can have R1 parts, or R1-R parts, or R1-R parts.
A photopolymerizable polymer containing at least 1 or 4 parts is desirable.

Specific examples of the photopolymerizable polymer of the present invention include the following compounds.

53- Is the above-mentioned photopolymerizable polymer known per se (References: Kagaku to Kogyo Vol. 82, No. 10, pp. 768-765), except that a long-chain alkyl group is newly introduced? , or
It is a compound with a similar structure. Therefore, it can be synthesized by a known method. For example, the number of carbon atoms is 1
Perchloric acid 1.4- is a photopolymerizable onfin monomer having 8 long-chain alkyl groups (n-octadecanoyl groups).
Di-n-octadecanoyl-2,5-distyrylpyrazine A can be synthesized by the following method.

10.8# 2.5-dimethylpyrazine and 44.5gp
-chlorobenzenesulfonic acid-n-octadecanoyl ester was dissolved in 100 mJ DMF and heated under reflux for 1 hour under nitrogen atmosphere. After cooling, a solution of 10 g of sodium perchlorate in 200 d of water is added.

After washing the precipitated solid with ether, it is recrystallized in methyl alcohol. Thus obtained perchloric acid 1.4-
n-octadecanoy/l/-fj,, 4.7 g of 5-dimethylpyrazine and 1.0411 g of benzaldehyde are heated under reflux in acetic anhydride for 8 hours, and after cooling, recrystallized in methyl alcohol to obtain A (yield: 40 chi.

Other compounds can also be synthesized by a similar method.

As a method for creating the monomolecular film or monomolecular layer cumulative film, for example, 1. The Langmuir-Prodgett method (LB method) developed by Langmuir et al. is used. The Langmuir-Prodgett method uses a molecule with a structure that has a hydrophilic group and a hydrophobic group, and when the balance between the two (balance of amphiphilicity) is maintained appropriately, the molecule lowers the hydrophilic group on the water surface. This is a method of creating a monomolecular film or a cumulative film of monomolecular layers by utilizing the fact that it becomes a monomolecular layer towards the end.

A single molecule 1 on the water surface has the characteristics of a two-dimensional system. When the molecules are sparsely dispersed, the area per molecule A and the surface pressure
The two-dimensional ideal gas equation, A=KT, holds true between the two, resulting in 'gas film 1'. Here, K is Portzmann's constant and T is absolute temperature. If A is made sufficiently small, the intermolecular interaction will be strengthened, resulting in a two-dimensional solid condensation film (or solid film). The condensed film can be transferred layer by layer to the surface of a substrate such as glass. Using this method, a monomolecular film or a monomolecular layer stack is produced, for example, as follows.

First, a photopolymerizable upper layer is dissolved in a solvent, and this is spread in an aqueous phase to precipitate the photopolymerizable upper layer in the form of a film. Next, to prevent this precipitate from freely diffusing on the aqueous phase and spreading too much, a partition plate (or float) is installed to limit the area of development and control the state of aggregation of the film substance, and the Obtain the surface pressure. By moving this partition plate, the developed area can be reduced to control the state of aggregation of the membrane material, and the surface pressure can be gradually increased to set the surface pressure suitable for producing a cumulative membrane.

The monomolecular film is transferred onto the substrate by gently vertically moving the clean substrate up and down while maintaining this surface pressure.

A monomolecular layer film is produced as described above, and a monomolecular layer cumulative film having a desired degree of accumulation is formed by repeating the above-mentioned operations. The monomolecular film and monomolecular layer cumulative film thus formed are referred to as LB films.

When this monomolecular cumulative film (LB film) is irradiated with light capable of supplying the energy necessary for polymerization, such as gamma rays, X-rays, and ultraviolet rays, according to the pattern, polymerization occurs at the irradiated area as shown in equation (2).

In these reactions, the distance between adjacent unsaturated bonds is 4A.
This can occur in the following cases, and in a monomolecular film or a monomolecular stacked film created by the method described above, it can occur between adjacent molecules in the same layer or between adjacent molecules in the cumulative layer. It is. In addition, after polymerization, depolymerization does not occur even in the dark, and the non-irradiated parts remain monomers.
It is dissolved in a developer to obtain a predetermined shape.

Next, a manufacturing example of the present invention will be explained with reference to the drawings.

Figure 2 (I, (C7), (C), ni), (E)
) and (f) are sectional views showing the manufacturing order of the present invention,
In these figures, 1. A polymerizable LB film 10 is attached and formed on the surface of a substrate 2 by the LB method (Figure 2 (a)).
.

2. The polymerizable LB film 10 is patterned and exposed to energy rays 11 such as light (FIG. 2 (b)).

8. Next, it is developed (soaked in alcohol, chloroform, benzene, etc.) and the unexposed areas are dissolved and removed. The polymerized LB film is insoluble in developer. Thus polymerization LB
A lower waveguide 12 made of a film is constructed (second section (c)
).

4. A polymerizable LB film 18 is deposited on the lower part 12 of the waveguide by the LB method (see FIG. 2).

5. Next, polymerizable LB is formed by energy rays 11 such as light.
The film 18 is exposed in a grating pattern (FIG. 2 (e)).

6. The unexposed areas are dissolved and removed by development (Fig. 2(f)).

In this way, a grating type optical coupler is obtained.

Example 1 (see Figure 2) The film forming molecule was quaternary salt A in which an n-octadecanoyl group was introduced onto the pyrazine ring of 2.5-distyrylpyrazine, and the surface was sufficiently coated while keeping the surface pressure constant. A monomolecular film was transferred onto the substrate by gently raising and lowering a clean, hydrophilic glass substrate into water, and then the monomolecular film was transferred onto the substrate at 50, 100, 200, 800.
A monomolecular stacked film (LB film) with 500 layers was manufactured. The produced film is in contact with the pyrazine ring side or the substrate.

In FIG. 4, the first @10-25, 50, 100.

Accumulated to 150, 200 layers, second layer 12~25.50°1
Accumulated on 00, 150, and 2009.

Reference Example 1 X-ray irradiation was carried out according to the LB film pattern prepared in Example 1, polymerization was carried out as shown in formula (2), and a grating was formed by patterning.

The results showed that sharp etching was obtained and high performance was not exhibited. Minimum grating pitch: 200 x grating depth: 0.1μ Example 2 In the same manner as Example 1, using the photopolymerizable monomers shown in Table 1, A coupler was manufactured.

The unique effects of the present invention are as follows.

1. Due to the above-mentioned characteristics of the LB film, a fine shape with sharp edges can be easily formed, so that an optical coupler with good lens performance can be obtained.

2. Since it is easy to manufacture, the manufacturing cost is low.

8. Since high-temperature treatment is not required during the manufacturing process, non-heat resistant components can be used.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a grating type optical coupler. Figure 2 (a), tcr+, (c), ni) 9 bodies),
(f) is a sectional view of a manufacturing example of the present invention. l... Optical waveguide, 2... Substrate. 8... Grating, 4... Waveguide light. 5...Emission light, 6...Mode index lens. 7...Exposed, 8.8'...Non-exposed area (monomer LB
Membrane) 9...LB film (polymerization) lO...Polymerizable LB film. 11... lower part of waveguide, 12... polymerizable LB film. Patent Applicant: Canon Co., Ltd. 4 Agent: Kuwai, Hyoushi

Claims (1)

[Claims] 1. An optical coupler having an optical waveguide provided with a grating, wherein the optical waveguide provided with the grating is made of a monomolecular cumulative film of a photopolymerizable olefin compound.