JPH1152128A - Dielectric multilayer optical filter and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: Provided is a low-cost dielectric multilayer optical filter having improved adhesion between a dielectric vapor-deposited film layer and a resin substrate, and a method of manufacturing the same. (1) A resin layer in which a general-purpose transparent resin material such as polystyrene, amorphous polyolefin, acrylic polymer, and polycarbonate, a transparent adhesive layer, and a dielectric multilayer film having a different refractive index are sequentially laminated. Multi-layer film optical filter, and (2) a step of forming a resin thin film substrate on a temporary substrate having a smooth surface, a dielectric multi-layer film in which a dielectric material having a different refractive index is laminated on the resin thin film substrate by an ion-assisted vapor deposition method Forming a transparent resin layer after providing a transparent adhesive layer on the dielectric multilayer film, and separating the resin thin film substrate and the dielectric multilayer film from each other. Manufacturing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a dielectric multilayer optical filter used in optical communication and a method of manufacturing the same.

[0002]

2. Description of the Related Art In optical communication, a component (optical element) having a dielectric multilayer optical filter provided with a minute gap in an optical path is used. As such an optical element, an unnecessary wavelength component is removed from two or more wavelength components propagating through the optical fiber by being inserted in the middle of a linear optical fiber, and only the necessary wavelength component is passed through the optical fiber. In addition to the propagating optical elements, a directional coupler (fiber coupler) having a function of controlling the guided light (for example, a two-wavelength multiplexed light passing through each of two input optical fibers is divided into other wavelengths by splitting the (A wavelength separator that outputs light from an output optical fiber).

In order to reduce the diffraction loss of the light propagating through the fiber in the groove where the dielectric multilayer optical filter is provided,
The groove portion needs to be made as narrow as possible. This depends on how thin the dielectric multilayer optical filter provided in the groove can be. Practically, for example, in the case of an optical fiber having a core diameter of 10 μm and a relative refractive index of 0.3%, the groove width (thickness of the dielectric multilayer optical filter) is reduced to about several tens μm so that the input optical fiber and the output optical fiber can be formed. Diffraction loss caused by the gap can be suppressed to about 0.5 dB.

Conventionally, such a dielectric multilayer optical filter has a low refractive index dielectric layer and a high refractive index dielectric layer alternately formed on a hard substrate such as an optical glass having a thickness of 0.5 mm or more.
After laminating to about μm, the back surface where the dielectric layer of the substrate is not present is polished to a desired thickness, and then cut to a predetermined size. There is a limit to the cost reduction due to the need for skill and the fact that the substrate is easily broken and the yield is poor. Furthermore, when ion-assisted vapor deposition is used to obtain a dense dielectric multilayer film, compressive stress remains in the multilayer film, causing a problem in that the filter is warped and cannot be thinly polished.

Therefore, a method of using an optically transparent resin film as a substrate and laminating a dielectric multilayer film thereon has been studied and developed. As a method of forming a multilayer interference film on a film, there is a method in which both ends of a polyester film are held straight by a winding mechanism and coating is performed with a roll (JP-A-63-88505, etc.). A multilayer film with a controlled and uniform thickness cannot be obtained, cracks or peeling of the multilayer film at the time of winding up, and a certain degree of strength is required for the film substrate. Cannot be applied to a dielectric multilayer optical filter because of its limitations.

A method of using a thin film of a polyimide film as a resin film is also being studied. This is, after forming a multilayer film composed of SiO ₂ and TiO ₂ by ion-assisted vapor deposition, on a polyimide-based film thin film formed in close contact with a temporary substrate surface by a coating method such as spin coating.
This is to separate the temporary substrate and the polyimide thin film.

[0007] Japanese Patent Application Laid-Open No. 4-111203 discloses that a temporary substrate and a polyimide thin film can be peeled off by using a substrate having a smooth surface as a temporary substrate, and the resulting multilayer film is curled due to curling. However, it is described that the curling problem can be solved by using a fluorinated polyimide having a smaller coefficient of thermal expansion than the multilayer film portion as the polyimide.

Further, Japanese Patent Application Laid-Open No. Hei 9-159850 discloses that a polyimide layer is provided on a Si substrate by a spin coating method, a glass multilayer film is deposited thereon by an ion beam evaporation method, and then a spin coating method is applied thereon. An optical filter obtained by dissolving a Si substrate with an ammonium fluoride solution after providing a polyimide coating is described.

[0009]

In the dielectric multilayer optical filter described in the above publication, since the dielectric multilayer is formed by an ion-assisted vapor deposition method, a general-purpose transparent resin film cannot be used and heat resistance is high. It is necessary to use a fluorinated polyimide-based film substrate, which is a transparent resin, and the surface of the substrate directly deposited thereon is exposed to oxygen plasma and becomes hot, resulting in a dielectric multilayer film layer and a fluorinated polyimide layer And the gas generated from the fluorinated polyimide layer reduces the adhesiveness between the dielectric multilayer film layer and the fluorinated polyimide layer interface, and may be peeled off during chipping or assembly. .

[0010] Accordingly, an object of the present invention is to provide a dielectric multilayer optical filter in which a dielectric multilayer film formed by a vapor deposition method is formed on a substrate of a general-purpose transparent resin film such as an acrylic polymer, and its manufacture. It is to provide a method. Still another object of the present invention is a dielectric multilayer optical filter formed by laminating an optically transparent resin film and a dielectric multilayer film formed by a vapor deposition method. And to provide a method of manufacturing a dielectric multilayer optical filter in which peeling does not occur at the interface of the dielectric multilayer film.

[0011]

Means for Solving the Problems The present inventors have ion-assisted vapor deposition of a dielectric multilayer film on a resin thin film substrate and form a transparent resin layer thereon. According to the method of peeling off at the interface, the adhesion between the dielectric multilayer film by ion-assisted vapor deposition and the transparent resin layer thereon is not affected by oxygen plasma or the like at the time of vapor deposition at all,
It has been confirmed that ordinary optically transparent resin can be used for the substrate, and the above-mentioned problems can be solved. Thus, the present invention has been completed.

That is, the present invention provides: 1) a dielectric multilayer optical filter in which a transparent resin layer, a transparent adhesive layer, and a dielectric multilayer having different refractive indices are sequentially laminated; 2) the transparent resin layer is made of polystyrene and amorphous. 2. The dielectric multilayer optical filter according to the above item 1, wherein the optical filter is selected from porous polyolefin, acrylic polymer, polycarbonate, and fluorinated polyimide. 3) a step of forming a resin thin film substrate on a temporary substrate having a smooth surface, a step of forming a dielectric multilayer film in which dielectrics having different refractive indices are laminated on the resin thin film substrate by an ion-assisted vapor deposition method, A method of manufacturing a dielectric multilayer optical filter, comprising: forming a transparent resin layer after providing a transparent adhesive layer on the multilayer film; and separating the resin thin film substrate and the dielectric multilayer film. 4) After forming the transparent resin layer, the transparent resin layer, the transparent adhesive layer, and the dielectric multilayer film are cut from the transparent resin layer side to the resin thin film substrate, and the dielectric multilayer film and the resin thin film substrate are separated. Description of the method for manufacturing a dielectric multilayer optical filter,

[0013] 5) After forming the transparent resin layer, the dielectric multilayer film and the resin thin film substrate are separated, and the transparent resin layer, the transparent adhesive layer and the dielectric multilayer film are cut into chips to form a chip. 6) The method for producing a dielectric multilayer optical filter according to the above item 3, wherein polyimide or fluorinated polyimide is used as the resin thin film substrate; 7) Polystyrene, amorphous polyolefin as the transparent resin; 4. The method for producing a dielectric multilayer optical filter according to the above item 3, wherein an acrylic polymer, polycarbonate, or fluorinated polyimide is used. 8) As a transparent adhesive, a titanium coupling agent, a silane coupling agent, or a zirconium coupling agent is used. 9. The method for manufacturing a dielectric multilayer optical filter according to the above item 3, and 9) the method according to any one of the above items 3 to 8. Provided is a dielectric multilayer optical filter obtained by the method.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a dielectric multilayer optical filter according to the present invention will be described with reference to the accompanying drawings (FIG. 1).
First, a resin thin film substrate (2) is formed on a temporary substrate (1) having a smooth surface (step (a) in FIG. 1). As the temporary substrate (1), silicon, glass (eg, BK-7), quartz glass, ceramics, or the like can be used. However, since the temporary substrate is not finally included in the filter, it is inexpensive and further formed into chips. A material that is easy to cut is preferred from the viewpoint of easy work.
Preferably, a silicon or glass material having a smooth surface is used.

Since the resin thin-film substrate (2) formed on the temporary substrate (1) is not finally included in the filter, any one capable of being separated from the deposited dielectric layer in the final separation step. There is no particular limitation on the resin material that can be used. It is preferable that the substrate has good consistency with the temporary substrate and is stable even at a temperature rise in the next step of ion-assisted vapor deposition.
Polyimide or fluorinated polyimide is particularly preferred from the viewpoint of adhesion to the deposited dielectric layer.

The case where fluorinated polyimide is used as the resin thin film will be described below. Resin thin film substrate (2)
In order to form a fluorinated polyimide layer as a substrate, a liquid fluorinated polyimide material or an N, N-dimethylacetamide solution of fluorinated polyamic acid which is a precursor of the fluorinated polyimide is coated on the temporary substrate (1) with a required thickness. Apply to. At this time, in order to increase the adhesion between the temporary substrate (1) and the fluorinated polyimide layer (2), a coupling agent such as isopropyl tri (N-aminoethyl-aminoethyl) titanate or zirconium tributoxyacetylacetonate is used in advance. It may be processed.

The liquid fluorinated polyimide material or fluorinated polyamic acid solution is prepared from a polymer comprising the unit represented by the formula (A) or a unit represented by the formula (A) and a unit represented by the formula (B). Is used, and the molar ratio is A: B = 100-65: 0-3.
5 is preferred.

[0018]

Embedded image

Fluorinated polyamic acid, which is a precursor of the polymer comprising the unit represented by the formula (A), or a copolymer comprising the unit represented by the formula (A) and the unit represented by the formula (B) Fluorinated polyamic acid, which is a precursor of, is composed of pyromellitic dianhydride (PMDA) and 2,
From 2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFDB) or from TFDB and P
It can be prepared from MDA and 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). A commercially available liquid varnish can also be used.

The application of the liquid fluorinated polyimide or fluorinated polyamic acid solution is carried out by a spin coating method in order to apply a thin film having a uniform thickness. Next, the liquid fluorinated polyimide or fluorinated polyamic acid solution applied on the temporary substrate (1) is dried and cured (at a temperature of 35 ° C.).
Heat treatment at 0 ° C. for about 2 hours) to form a fluorinated polyimide thin film substrate (2) (step (a) in FIG. 1).

On the surface of the resin (fluorinated polyimide) thin film substrate (2) obtained as described above, a dielectric multilayer interference film (3) made of TiO ₂ / SiO _{2 is formed} by ion-assisted vapor deposition. It is formed to a thickness (FIG. 1 step (b)). In this case, the first layer depends on the filter design,
Any of TiO ₂ and SiO ₂ may be used, and there is no problem in adhesion.

Next, a transparent adhesive layer (4) is formed on the surface of the dielectric multilayer film (3) (step (c) in FIG. 1). As the transparent adhesive, coupling agents such as a titanium-based coupling agent, a silane-based coupling agent, and a zirconium-based coupling agent can be used. Various optical adhesives such as epoxy-based and acrylic-based adhesives can also be used as long as they have adhesiveness to the surface layer of the dielectric multilayer film and the transparent resin layer described later.

As the zirconium-based coupling agent used in the present invention, zirconium esters and zirconium chelate compounds are preferred. Examples of the zirconium ester include tetrapropyl zirconate and tetrabutyl zirconate, and examples of the zirconium chelate compound include tetrakis (acetylacetonate).
Zirconium, zirconium monobutoxytris (acetylacetonate), zirconium dibutoxybis (acetylacetonate), zirconium tributoxyacetylacetonate, zirconium tetra (ethylacetylacetate), zirconium monobutoxytris (ethylacetylacetate), zirconium dibutoxybis (ethylacetylacetate) ) Zirconium, tributoxyethyl acetyl acetate, tetrakis (ethyl lactonate) zirconium, bis (bisacetylacetonate)
Bis (ethyl acetylacetonate) zirconium, monoacetylacetonate tris (ethylacetylacetonate) zirconium, monobutoxymonoacetylacetonate bis (ethylacetylacetonate) zirconium and the like can be mentioned.

The application of the coupling agent solution is carried out by a spin coating method in order to apply a thin coating having a uniform thickness. After the application, the coating is dried (heat treatment at a temperature of 250 ° C. for about 2 hours) to form a coupling agent layer (4). The thinner the coupling agent layer can be formed, the better.

A transparent resin layer (5) is formed on the transparent adhesive layer (4) (step (d) in FIG. 1). The transparent resin layer (5) serves as a substrate of the optical filter of the present invention, but does not need to have heat resistance because it is not exposed to ion-assisted vapor deposition. it can. Specifically, polystyrene, amorphous polyolefin, acrylic polymer, polycarbonate, fluorinated polyimide and the like can be used, but fluorinated polyimide is preferable from the viewpoint of stability and the like. The formation of the fluorinated polyimide layer as the transparent resin layer can be performed by applying a liquid fluorinated polyimide or fluorinated polyamic acid solution in the same manner as the formation of the resin thin film substrate (2). In order to apply a thin film having a uniform thickness, it is preferable to use a spin coating method. After the application, the coating is dried and cured (heat treatment at a temperature of 350 ° C. for about 2 hours) to form a transparent resin layer (5) made of a fluorinated polyimide thin film.

Next, a cut (6) is formed until it reaches the resin thin film substrate (2) (step (e) in FIG. 1), and the interface between the resin thin film substrate (2) and the dielectric multilayer film (3) is formed. 7) to obtain a dielectric multilayer optical filter which is separated into chips and formed into chips (FIG. 1)
Step (f)). The separation between the resin thin film substrate (2) and the dielectric multilayer film (3) can be easily performed by inserting a sharp object such as a knife edge into a cut in water.

As another method, the peeling and cutting work steps may be interchanged. That is, as shown in FIG.
Steps (a) to (d) are the same as steps (a) to (d) in FIG. ), After the dielectric multilayer filter is peeled off (step (e) in FIG. 2), the dielectric multilayer optical filter cut into chips can be obtained (FIG. 2 (f)).

[0028]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 A varnish for fluorinated polyimide (manufactured by Hitachi Chemical Co., Ltd .: OPIN) on BK-7 glass having a diameter of 30 mm and a thickness of 0.5 mm
1805 (50 Ps), component A: component B = 80: 20)
Was applied by spin coating so that the thickness after heat curing became 10 μm, and heat treatment was performed at a maximum temperature of 350 ° C. for 2 hours to form a fluorinated polyimide layer. On top of this, TiO ₂ / Si
A dielectric multilayer film made of O ₂ was formed to a thickness of about 10 μm. Next, a zirconium coupling agent (OPI coupler manufactured by Hitachi Chemical Co., Ltd.) is applied thereon by spin coating so that the thickness after drying becomes 0.01 μm or less.
Heat at 0 ° C. for 30 minutes. On top of this, a varnish for fluorinated polyimide (OPIN1805 (50P, manufactured by Hitachi Chemical Co., Ltd.)
s), component A: component B = 80: 20) was applied by spin coating so that the thickness after heat curing became 10 μm, and heat treatment was performed at a maximum temperature of 350 ° C. for 2 hours.
A fluorinated polyimide layer was formed. Next, while the filter on the BK-7 glass substrate was running with a dicing saw, cuts of 2 mm × 1 mm were made in a grid pattern. Peeled off easily by inserting a knife edge into the cut in water. A peeling test was conducted in which an adhesive tape (Mending Tape 810, manufactured by Sumitomo 3M Limited) was attached to the front and back surfaces of the produced filter and then peeled off, but no peeling of the deposited layer was observed.

Example 2 Instead of a varnish for fluorinated polyimide (Hitachi Kasei Kogyo Co., Ltd .: OPIN1805 (50 Ps), component A: component B = 80: 20) as a transparent resin layer, a norbornene resin (ARTON-made by Nippon Synthetic Rubber) was used. Using the toluene solution of G), similarly, by applying by spin coating so that the thickness after heat curing becomes 10 μm, a heat treatment is performed at a maximum temperature of 120 ° C. for 3 hours to form a transparent resin layer. Was performed in the same manner as in Example 1 to obtain an optical filter chip. The film was subjected to a peeling test in the same manner as in Example 1. As a result, no peeling of the deposited layer was observed, and the adhesion was good.

[0030]

According to the present invention, after a dielectric multilayer film is ion-assisted deposited on a resin thin film substrate, a transparent resin layer is formed thereon, and then the resin thin film substrate and the dielectric multilayer film are interfaced with each other. In order to manufacture a dielectric multilayer optical filter by peeling off with a filter, the adhesion between the dielectric multilayer by ion-assisted vapor deposition and the transparent resin layer thereon is not affected by oxygen plasma or the like at the time of vapor deposition. The layer does not require heat resistance, and general-purpose transparent resin materials such as acrylic resin and polycarbonate resin can be used. The resulting dielectric multilayer optical filter has good adhesion between the dielectric multilayer film and the resin thin film substrate, and is made into a chip. In addition, the assembly work can be performed stably, and the cost of the optical filter can be reduced.

[Brief description of the drawings]

FIG. 1 shows a manufacturing process of a dielectric multilayer filter according to the present invention.

FIG. 2 shows another manufacturing process of the dielectric multilayer filter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temporary board 2 Resin thin film board 3 Dielectric multilayer film 4 Transparent adhesive layer 5 Transparent resin layer 6 Break 7 Peeling interface

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 33/04 C08L 33/04 69/00 69/00 79/08 79/08

Claims (9)

[Claims] 1. A dielectric multilayer optical filter in which a transparent resin layer, a transparent adhesive layer, and dielectric multilayer films having different refractive indexes are sequentially laminated. 2. The dielectric multilayer optical filter according to claim 1, wherein the transparent resin layer is selected from polystyrene, amorphous polyolefin, acrylic polymer, polycarbonate, and fluorinated polyimide. 3. A step of forming a resin thin film substrate on a temporary substrate having a smooth surface, a step of forming a dielectric multilayer film in which dielectrics having different refractive indices are laminated on the resin thin film substrate by an ion assisted vapor deposition method. A step of forming a transparent resin layer after providing a transparent adhesive layer on the dielectric multilayer film, and a step of peeling off the resin thin film substrate and the dielectric multilayer film. Manufacturing method. 4. After the formation of the transparent resin layer, the transparent resin layer, the transparent adhesive layer, and the dielectric multilayer film are cut from the transparent resin layer side to the resin thin film substrate, and the dielectric multilayer film and the resin thin film substrate are separated. Item 4. A method for manufacturing a dielectric multilayer optical filter according to Item 3. 5. The dielectric material according to claim 3, wherein after forming the transparent resin layer, the dielectric multilayer film and the resin thin film substrate are peeled off, and the transparent resin layer, the transparent adhesive layer and the dielectric multilayer film are cut into chips. Of manufacturing a multi-layer film optical filter. 6. The method for manufacturing a dielectric multilayer optical filter according to claim 3, wherein polyimide or fluorinated polyimide is used as the resin thin film substrate. 7. The method according to claim 3, wherein polystyrene, amorphous polyolefin, acrylic polymer, polycarbonate or fluorinated polyimide is used as the transparent resin. 8. The method for producing a dielectric multilayer optical filter according to claim 3, wherein a titanium coupling agent, a silane coupling agent or a zirconium coupling agent is used as the transparent adhesive. 9. A dielectric multilayer optical filter obtained by the method according to claim 3. Description: