JPH0262502A - New optical device - Google Patents

Abstract

PURPOSE:To offer an optical waveguide type optical device whose optical axis is easily aligned by processing photosensitive resin on a filmy base by photolithography and forming a guide for optical axis alignment and an optical waveguide at the same time. CONSTITUTION:The filmy base 1 can hold the guide 2 for optical axis alignment and optical waveguide 3 and when the photolithography is applied, any film which has resistance to a liquid developer is usable. The photosensitive resin which is formed on the base 1 forms the optical waveguide by the photolithography, so the resin should substantially be transparent to the wavelength of guided light. The photosensitive resin formed on the base 1 by coating is exposed to light such as ultraviolet rays through a photomask which has a desired shape pattern and then an unexposed part is washed out by utilizing the difference in solubility between an exposed part and the unexposed part to obtain the optical waveguide 3 which has the desired shape pattern and the guide 2 for optical axis alignment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical device in which an optical axis alignment guide and an optical waveguide are formed of a photosensitive resin. Fields of use of the optical device of the present invention include optical transmission devices used in connection with optical fibers, optical sensors combined with light emitting elements, light receiving elements, polarizers, diffraction gratings, and the like. Specific examples of the optical device include an optical branching coupler, an optical star coupler, an optical multiplexer/demultiplexer, a photoelectric switch, an object detector, a smoke detector, a tape end sensor, and the like.

[Conventional technology]

Conventionally, the method for connecting optical components such as optical fibers, light emitting elements, light receiving elements, and optical elements to optical devices using film-type optical waveguides involves polishing the end face of the film-type optical waveguide and aligning the optical components with the optical axis. A method for connecting the two together is disclosed.

[Problem that the invention seeks to solve]

When using the above conventional method to align the optical axes and connect the waveguide and optical components, there are problems in that it is difficult to align the two with high precision, and that extremely high precision equipment is required. .

[Means for solving problems]

The present invention was made as a result of extensive research to overcome the above problems, and its purpose is to provide an optical waveguide type optical device in which an optical axis alignment guide can be formed easily and with high precision. It is in.

That is, the present invention provides an optical device that allows easy optical axis alignment by simultaneously forming an optical axis alignment guide and an optical waveguide by subjecting a photosensitive resin to photolithography.

Various types of photosensitive resins can be used in the present invention. According to the classification by composition, they can be broadly divided into three types: (1) photosensitive compound + polymer type, (2) polymer type with photosensitive group, and (2) photopolymerization composition type. Examples of substances that are susceptible to This method takes advantage of the fact that the composition has different properties. Items belonging to category (2) include, for example, polyvinyl cinnamate or similar compounds thereof, or polymers having a diazo group or an azide group, which utilize crosslinking between polymers by light. As for those belonging to category (1), many systems containing a mixture of a photopolymerization initiator and a polymerizable additive are known.

Although it is possible to achieve the purpose of the photosensitive resin of the present invention with the above-mentioned composition alone, it is preferable to add additives as necessary. Examples of additives include, but are not limited to, photosensitizers, stabilizers, thermal polymerization initiators, plasticizers, colorants, and the like.

The photosensitive resin of the present invention is used as a single layer or in a stack of two or more layers on a support.

Since the photosensitive resin becomes an optical waveguide by photolithography, it must be substantially transparent to the wavelength of the light to be guided. When the light to be guided is visible light or near-infrared light, the photosensitive resin is preferably one that is sensitive to, that is, absorbs, ultraviolet light. Such photosensitive resins include polymethyl methacrylate,
Examples include photosensitive resin compositions containing polymers such as polystyrene, polyfunctional (meth)acrylate monomers, and photopolymerization initiators.

Specific examples of preferred photosensitive resins include Japanese Patent Application No. 63-1
Photosensitive resin comprising polymethyl methacrylate, methyl methacrylate, bifunctional (meth)acrylate, photopolymerization initiator, etc. described in No. 01257, Japanese Patent Application No. 1983-293
A photosensitive resin comprising a polystyrene brominated aromatic (meth)acrylate and a photopolymerization initiator described in No. 946 may be mentioned.

As the film support used in the present invention, any film can be used as long as it can hold the optical axis alignment guide and the optical waveguide and is resistant to a developer when photolithography is applied.

Specific examples of materials for the support include polyvinylidene fluoride, polyethylene terephthalate, polyvinyl chloride, polyethylene, polyacrylonitrile, polymethyl methacrylate, polyoxymethylene, polypropylene, polymethylpentene, silicone resin, polytetrafluoroethylene, etc. Polymer materials include:

Further, for the purpose of improving the adhesion between the surface of the support and the guide for optical axis alignment and the optical waveguide, it is also possible to subject the polymer film to a corona discharge treatment or the like.

The method of coating the photosensitive resin on the support is not particularly limited, but a coating method is preferred. Application methods include a barcode method, a roll coating method, a dipping method, and the like.

The photolithography method in the present invention refers to exposing a photosensitive resin on a support to light such as ultraviolet rays through a photomask having a desired shape pattern, or exposing the photosensitive resin on a support to light such as an electron beam in a desired pattern. After exposing the resin to light, the unexposed areas are washed away using the difference in solubility in a developing solution between the exposed areas and the unexposed areas, thereby obtaining an optical waveguide and an optical axis alignment guide having a pattern of a desired shape. say.

At the time of the above exposure, methods such as carrying out the exposure in an inert atmosphere or attaching a sheet with low oxygen permeability to the photosensitive resin in order to reduce oxygen that inhibits polymerization of the photosensitive resin in the exposed area are adopted. is also possible. The developer is not particularly limited as long as it has a lower solubility in the polymer of the photosensitive resin in the exposed area than in the photosensitive resin in the unexposed area; Naturally, the suitable developer also depends on the composition of the photosensitive resin.

Examples of preferred developing solutions for the specific examples of the photosensitive resins mentioned above include methyl ethyl ketone, methyl isobutyl ketone, Ll, 1-trichloroethane, ethyl acetate,
Examples include butyl acetate, toluene, xylene, and tetrahydrofuran.

The optical axis alignment guide in the present invention refers to an optical fiber, a light emitting element, and a light receiving element connected to the end face of an optical waveguide,
It is provided to precisely align the optical axis of an optical element, etc. used between the optical waveguides, and the optical axis of the optical waveguide, and its shape is suitable for optical fibers, light emitting elements, light receiving elements, or optical elements, etc. Of course it depends on the shape.

A specific example of the optical axis alignment guide of the present invention will be described with reference to the drawings, but the invention is not limited thereto.

FIG. 1 shows an optical axis alignment guide suitable for connecting the end faces of an optical fiber and an optical waveguide.

In the figure, 1 is a support, 2 is an optical axis alignment guide, and 3 is a support body.
is an optical waveguide, and 4 is an optical fiber. Note that the numbers 1 to 4 mean the same thing throughout FIG. 1.2.

FIG. 1 shows that the optical fiber is suitable for cases where the cladding part is thinner than the core part, such as a plastic optical fiber.
The optical waveguide and optical axis alignment guide are made of a single layer of photosensitive resin.

As shown in Figure 1, in the end-face connection of an optical fiber and an optical waveguide, a matching liquid is injected in order to reduce the connection loss due to end-face reflection, and an adhesive is used to bond the optical fiber to an optical axis alignment guide. Naturally, it is also possible to inject. Moreover, an overcladding can be applied to the optical waveguide as necessary.

The optical fiber shown in FIG. 1 can be used in place of a light emitting element such as a semiconductor laser or a light emitting diode, or a light receiving element such as a photodiode or phototransistor.

FIG. 2 shows an optical axis alignment guide 2 used in an optical device in which a gap is provided between the optical waveguides 3 and an interference filter 6 and an attenuation plate 5 are placed. Other optical elements that can be used include prism polarizers, ball lenses, diffraction gratings, and the like.

The thickness of the optical waveguide and optical axis alignment guide in the present invention can vary depending on the application, and may be 10 μm to 10 m.
A range of m is preferred. Furthermore, the pattern of the cough optical waveguide can have various shapes. To give an example of the shape of the pattern,
There are straight lines, L-shapes, S-shapes, U-shapes, T-shapes, Y-shapes, X-shapes, planar shapes, and combinations thereof, but the shapes are not limited to these.

〔Example〕

Examples are shown below.

Example 1 58 parts by weight of polymethyl methacrylate, 42 parts by weight of difunctional methacrylate HX-220M (manufactured by Nippon Kayaku), and 135 parts by weight of methyl ethyl ketone were heated and mixed at 70°C, and then the photopolymerization initiator dimethoxyphenylacetophenone was added. 1 part by weight was mixed to form a uniform solution.

This solution was applied onto a 200 μm thick polyvinylidene fluoride film using a bar coater and dried to form a 250 μm thick photosensitive layer. A photomask having a pattern of a Y-branch optical waveguide and an optical fiber alignment guide was placed on top of this.

Ultraviolet rays are emitted from a high-pressure mercury lamp through a photomask at 50°C.
After irradiating 0 mJ/cJ and heating at 70°C for 10 minutes,
．． 1.1-) Developed with dichloroethane to a thickness of 250μ
Y-branch optical waveguide with a line width of 250 μm, a length of 25 mm, and a branching angle of 2.9°, and a thickness of 250 μm as shown in FIG.
An optical fiber optical axis alignment guide with a diameter of 1 mm, a line width of 1 mm, and a length of 5 n+m was obtained.

Take out the core wire at one end of a plastic optical fiber Luminous LB-250 (manufactured by Asahi Kasei Corporation) with a fiber diameter of 250 μm and a length of 2 m, polish the end face, and attach it to each end face of the above Y-branch optical waveguide via an optical axis alignment guide. The ends were connected. U-curing fluororesin is used as the matching liquid, and the light wavelength is 0.
．． Optical transmission characteristics were evaluated using a 66 μm LED light source (NA5°=0.21).

The results were an excess loss of 4.2 dB and distribution uniformity of 0.4 dB (including connection loss of the optical connector).

Note that trifunctional methacrylate HX-220M is a compound having the following chemical structural formula.

FIG.

1...Support film 2...Optical axis alignment guy 3... Optical waveguide 4...Optical fiber 5... Damping plate 6...Interference filter de A conceptual diagram of the obtained optical branching coupler is shown in FIG.

〔Effect of the invention〕

The present invention provides an optical device in which optical axes of an optical waveguide, an optical fiber, a light emitting element, a light receiving element, an optical element, etc. can be easily aligned.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a connection between an optical fiber and an optical waveguide of an optical device having an optical fiber optical axis alignment guide and an optical waveguide formed from a single-layer photosensitive resin according to the present invention.

Claims (2)

[Claims] (1) An optical device in which an optical axis alignment guide and an optical waveguide are simultaneously formed by applying photolithography to a photosensitive resin on a film-like support. (2) After coating a photosensitive resin on a film-like support, the photosensitive resin is exposed to light through a photomask and developed to simultaneously form an optical axis alignment guide and an optical waveguide. A method for manufacturing a featured optical device.