JPH08286064A - Production of high-polymer optical waveguide - Google Patents

Abstract

PURPOSE: To make it possible to inexpensively and easily produce a high- performance waveguide type optical element so as to meet diverse needs regardless of mass production or small-quantity production by directly forming the core part of the waveguide by mechanical cutting with a dicing saw, etc. CONSTITUTION: A clad layer 2 consisting of a high-polymer material having a flexural property is laminated by spin coating, etc., on a substrate 1 laminated with copper and aluminum by vapor deposition, etc. A clad layer 3 consisting of a high-polymer material having the refractive index higher than the refractive index of the material described above is laminated on the clad layer 2. Both sides of the core part 4 are removed by the dicing saw 5 or a mechanical machining method having the function equiv. to the function thereof in such a manner that the core part 4 having the desired shape is made to remain. The clad material 6 consisting of the high-polymer material having the refractive index lower than the refractive index of the core part 4 is applied in such a manner that the parts upper than the formed groove part and the core part 4 are covered. The copper and aluminum are thereafter melted and only the high-polymer waveguide part is peeled from the substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a waveguide type optical element which constitutes an optical device used in the fields of optical communication and optical information processing, and particularly uses a polymer material having high flexibility. The present invention relates to a method for producing a polymer optical waveguide.

[0002]

2. Description of the Related Art A waveguide type optical element constituting an optical device used in the fields of optical communication and optical information processing is made of a material such as quartz glass and dielectric crystal LNbO ₃ . In addition, this method of producing a waveguide type optical element has a step of performing fine processing by a combination of photolithography and dry etching processes which are generally used in an LSI process. Therefore, it is possible to manufacture a high-performance waveguide type optical element (for example, reference: Masao Kawauchi Optical and Quantum E).
electronics Vol. 22, page 391 (1990)
Year)). Further, in order to reduce the production cost, attempts have been made to use a polymer material, which is a cheaper material, when manufacturing an element by the same process (reference Imamura et al. Electronics Letter).
s 27: 1342 (1991)). In addition, recently, an optical waveguide using a polymer material using a mold has been manufactured.

By the way, in recent years, the LSI manufacturing process has made remarkable progress, and for example, a dicing saw has been developed as a means for cutting off a large number of circuit chips manufactured on a silicon substrate. This dicing saw is known as a high-performance silicon cutting machine (for example, manufactured by DISCO). In addition, recently, it has become possible to control the thickness of the blade used in this dicing saw to a desired thickness (about 5 μm) with high accuracy. Also, the cutting position accuracy
It has become possible to control up to about 0.1 μm.

[0004]

However, the above-mentioned conventional manufacturing method is not suitable for mass production because the manufacturing process is complicated and the manufacturing apparatus is expensive, and it is not possible to significantly reduce the production cost. Have difficulty.

By the way, recently, fabrication of an optical waveguide using a polymer material using a mold has been carried out. However, although the method using a mold is suitable for mass production, the mold is expensive to manufacture and time-consuming. Therefore, it is not suitable as a method for various purposes such as a small quantity and a large number of products.

Further, since a polymeric material is more flexible than an optical waveguide using an inorganic material, it has been considered that a flexible optical waveguide can be manufactured by using a polymeric material. Has no method of making a flexible waveguide by an inexpensive and simple method.

Therefore, the present invention solves the above-mentioned problems and provides a method of manufacturing a high-performance waveguide type optical element that meets various needs and can be manufactured inexpensively and easily regardless of mass production or small quantity production. The purpose is to do.

[0008]

In order to solve the above problems, a method of producing a polymer optical waveguide according to the first invention comprises a step of forming a first layer made of a polymer to be a clad on a substrate. A step of forming a second layer made of a polymer having a refractive index higher than that of the first layer, and a step of mechanically cutting and removing a part of the second layer to form a core portion,
And a step of forming a third layer covering the core portion with a polymer material having a refractive index lower than that of the core portion.

Preferably, a step of removing the substrate is provided after the step of forming the third layer covering the core portion with a polymer material having a refractive index lower than that of the core portion.

Preferably, in the step of forming the core portion by mechanically cutting and removing a part of the second layer, cutting is performed using a dicing saw.

In order to solve the above-mentioned problems, a method for producing a polymer optical waveguide according to the second invention comprises a step of forming a first layer made of a polymer serving as a clad on a substrate and the first step. A step of mechanically cutting and removing a part of the layer to form a groove in the first layer; a step of pouring a polymer material for core having a refractive index higher than that of the first layer into the groove; And a step of removing an unnecessary portion of the polymer material for producing a core part, and a step of forming a second layer covering the core part with a polymer material having a refractive index lower than that of the core part. .

[0012] Preferably, a step of removing the substrate is provided after the step of forming the second layer covering the core portion with a polymer material having a refractive index lower than that of the core portion.

Further, preferably, in the step of mechanically cutting and removing a part of the first layer to form a groove portion in the first layer, cutting is performed using a dicing saw.

[0014]

EXAMPLES A method for producing a polymer optical waveguide according to the present invention is as follows: (1) a polymer material that is low in material cost and easy to process is used; and (2) a process for producing a waveguide that constitutes an element. In (3), no large-scale device is required, and (3) the core portion of the waveguide for guiding light is directly manufactured by mechanical cutting with a dicing saw or the like. In the present invention, preferably, attention is paid to the positional accuracy of the dicing saw and the controllability of the thickness of the blade, and the dicing saw is used for producing an optical material using a polymer material.

FIG. 1 is a schematic sectional view for explaining a method for producing a polymer optical waveguide according to the present invention. FIG.
In the figure, (a) is a diagram for explaining a step of laminating a polymer layer on a substrate, (b) is a diagram for explaining a step of forming a core having a desired shape, and (c) is a clad again. It is a figure for demonstrating the process of providing a layer.

In the method of producing a polymer optical waveguide according to the present invention, first, a clad layer 2 made of a polymer material having high flexibility is laminated on a substrate 1 by means of spin coating, dipping or the like. Subsequently, a clad layer 3 made of a polymer material having a higher refractive index is laminated on the clad layer 2 (FIG. 1A). Next, the core portion 4 having a desired shape
So that both sides of the core portion are removed by a dicing saw 5 or a mechanical cutting method having a function equivalent to that (FIG. 1B). After that, the clad material 6 is applied again so that the produced stagnant portion and the upper portion of the core are covered (FIG. 1C).

The size of the core portion 4 has a great influence on the waveguide characteristics of the optical waveguide. Optical communication wavelength band 1.3
For use in μm and 1.55 μm, it is required to fabricate a waveguide having a rectangular core of several tens of μm square in a multimode waveguide and several μm square in a single mode waveguide. By the way, in the above manufacturing method, the size of the core portion 4 depends on the positional accuracy of the blade to be cut, rather than the accuracy of the thickness of the blade of the dicing saw. The positional accuracy of the dicing saw is about 0.1 μm, which is sufficient as the accuracy required for core production. The core shape depends on the shape of the cut cross section of the dicing saw. In fact, the cross section obtained by cutting a polymer with a dicing saw has good verticality, is smooth, and can be used as the core of a rectangular waveguide.

FIG. 2 is a diagram for explaining a second example of the method for producing a polymer optical waveguide according to the present invention. In the figure,
(A) is a figure for explaining a step of laminating a polymer clad layer on a substrate and then forming a core having a desired shape, and (b) is a core having a refractive index higher than that of the polymer of the clad layer. The figure for demonstrating the process of apply | coating a polymer, (c)
FIG. 4 is a diagram for explaining a step of applying a clad material after forming the core.

In this manufacturing method, the polymer 8 used as a clad is first coated on the substrate 7 by means such as spin coating or dipping, and the core portion having a desired shape has a dicing saw 9 or a function equivalent thereto. It is removed by a mechanical cutting method (FIG. 1 (a)). Next, the core polymer 10 having a refractive index higher than that of the clad polymer is applied so that the core portion is filled (FIG. 1B). Then, the excess polymer for core is removed to form the core 11. After that, the clad material 12 is applied again (see FIG. 1).
(C)). In this manufacturing method, the core size depends on the blade thickness accuracy of the dicing saw. The thickness of the blade of the dicing saw can be an arbitrary thickness with an accuracy of about 5 μm to about 1 μm, which is sufficient as the accuracy of core production. The core shape depends on the shape of the cut cross section of the dicing saw. In fact, the cross section obtained by cutting a polymer with a dicing saw has good verticality, and the surface is smooth, and it can be used as a core of a rectangular waveguide. Further, the width of the cut polymer groove is about 3 to 5 μm wider than that of the blade of the dicing saw. This depends on the combination of the blade used and the polymer to be cut, but if the relationship between the blade and the groove width actually created is first obtained, reproducibility is good and accurate processing is possible. . The method of manufacturing an inflexible optical waveguide on a substrate has been described above with reference to FIGS.

Next, a method of manufacturing an optical waveguide having flexibility will be described.

As the substrate, a substrate in which copper or aluminum is laminated by vapor deposition or the like is used. Then, an optical waveguide is produced according to FIG. 1 or FIG. 2, and finally, only the polymer waveguide portion may be peeled off from the substrate by melting copper or aluminum. Copper is an aqueous ferric chloride solution or hydrochloric acid solution, and aluminum is easily dissolved by immersing it in a phosphoric acid solution, so that the polymer waveguide portion can be separated from the substrate. Since these solutions hardly change the quality of many polymers, they do not affect the waveguiding characteristics of light. The present invention will be specifically described below with reference to examples.

<Example 1> An example of a method for producing a polymer optical waveguide (single mode optical waveguide) will be described based on the steps shown in FIG.

Here, since the optical waveguide is operated in a single mode at a wavelength of 1.3 μm or more, the relative refractive index difference Δ =
Make it 0.3%. Therefore, the polymer for the clad is a copolymer of deuterated polymethylmethacrylate and fluorinated methacrylate (molar ratio = 96.5: 3.5) (refractive index: 1.4777), and the polymer for the core is Deuterated polymethylmethacrylate (Survival rate: 1.4
821) was used. Each of these polymers was dissolved in a mixed solution of chlorobenzene and xylene to form a solution.

On the silicon substrate, the polymer for cladding is
It was spin-coated to a thickness of about 25 μm. After baking and drying,
The core polymer was spin-coated to a thickness of about 8 μm. next,
Using a dicing saw with a width of 50 μm, both sides of the core portion were cut so that a core portion with a width of 8 μm remained. Finally, a cladding polymer was spin-coated to a thickness of 25 μm so as to cover the core portion, and an embedded waveguide was produced. When the thus-formed optical waveguide was cut into a length of 5 cm and the cross section was observed with a microscope, a rectangular pattern of a core portion having a height of 8 μm and a width of 8 μm was observed. It was confirmed that the waveguide was operated in a single mode by injecting laser light having a wavelength of 1.3 μm. The propagation loss at this time was 0.74 dB, which showed good waveguide characteristics.

Example 2 A polymer optical waveguide (single mode optical waveguide) film is produced based on the steps shown in FIG. In this embodiment, a silicon substrate with 200 nm of copper deposited is used. Further, since the single mode operation is performed at a wavelength of 1.3 μm or more, the relative refractive index difference Δ = 0.
As a polymer for the clad, a copolymer of deuterated polymethylmethacrylate and fluorinated methacrylate (molar ratio = 96.5: 3.5) (refractive index:
1.4777), and deuterated polymethylmethacrylate (refractive index: 1.4821) was used as the core polymer. Each of these polymers was dissolved in a mixed solution of chlorobenzene and xylene to form a solution. Copper is 200nm
Approximately 2 parts of polymer for cladding is deposited on the vapor-deposited silicon substrate.
It was spin-coated to a thickness of 5 μm. After the baking and drying treatment, the core polymer was spin-coated to a thickness of about 8 μm. Then 50
A dicing saw having a width of μm was used to cut both sides of the core so that a core having a width of 8 μm remained. Finally, a cladding polymer was spin-coated to a thickness of 25 μm so as to cover the core portion, and an embedded waveguide was produced. This waveguide was dipped in a 20 mol% hydrochloric acid solution to dissolve copper, peeled off from the silicon substrate, thoroughly washed with distilled water, and dried.
The optical waveguide film thus formed was cut into a length of 5 cm, and the cross section was observed with a microscope.
A rectangular pattern of the core portion having a width of m and a width of 8 μm was observed. It was confirmed that the waveguide operated in single mode by irradiating a laser beam having a wavelength of 1.3 μm. The propagation loss at this time is
It was 0.75 dB, which showed a good waveguide characteristic.

Example 3 A method for producing a polymer optical waveguide (multimode optical waveguide) will be described based on the steps shown in FIG. As the polymer for the clad, an epoxy ultraviolet (UV) curing resin (refractive index: 1.511),
An epoxy UV curable resin (refractive index: 1.560) having a different refractive index was used as the core polymer. The clad polymer was spin-coated to a thickness of about 50 μm and irradiated with UV to cure it. Next, the core polymer was spin-coated to a thickness of about 50 μm and irradiated with UV to cure it. Then 100
A dicing saw having a width of μm was used to cut both sides of the core so that a core having a width of 50 μm remained. Finally, a clad polymer was spin-coated to a thickness of 50 μm so as to cover the core, and was irradiated with UV to be cured to prepare an embedded waveguide.

The optical waveguide thus formed was cut into a length of 5 cm and the cross section was observed with a microscope.
A rectangular pattern of the core portion having a width of 50 μm and a width of 50 μm was observed.
Propagation loss when a laser beam with a wavelength of 1.3 μm was incident was 2.5 dB, which showed good waveguiding characteristics.

Example 4 A method for producing a polymer optical waveguide (multimode optical waveguide) array film will be described based on the steps shown in FIG. 2 copper as substrate
A silicon substrate with a thickness of 00 nm was used. An epoxy-based ultraviolet (UV) curable resin (refractive index: 1.511) is used as the clad polymer, while an epoxy-based UV curable resin having a different refractive index (refractive index: 1.11) is used as the core polymer. 560) was used. First, the clad polymer was spin-coated to a thickness of about 50 μm and irradiated with UV to be cured. Next, the core polymer was spin-coated to a thickness of about 50 μm and irradiated with UV to cure it. Then 20
Four cores having a width of 47 μm were formed by cutting the core layer portion five times at a pitch of 250 μm using a dicing saw having a width of 0 μm. Finally, 5 to cover the core
UV-coated with a cladding polymer to a thickness of 0 μm
Was irradiated and cured to prepare an embedded waveguide. This waveguide was dipped in a 20 mol% hydrochloric acid solution to dissolve copper, peeled off from the silicon substrate, thoroughly washed with distilled water, and dried. The optical waveguide array film thus formed was cut into a length of 5 cm, and its cross section was observed with a microscope. As a result, four rectangular patterns of a core portion having a height of 50 μm and a width of 47 μm were seen. The propagation loss of each waveguide when a laser beam having a wavelength of 1.3 μm was incident was 2.5 dB on average, and good waveguide characteristics were exhibited.

<Example 5> A method for producing a polymer optical waveguide (single mode optical waveguide) will be described based on the steps shown in FIG. Since the single mode operation is performed at a wavelength of 1.3 μm or more, the polymer for the clad has deuterated polymethylmethacrylate and fluorinated methacrylate (molar ratio = 9) so that the relative refractive index difference Δ = 0.3%.
6.5: 3.5) copolymer (refractive index: 1.477)
7), deuterated polymethylmethacrylate (refractive index: 1.4821) was used as the core polymer. Each of these polymers was dissolved in a mixed solution of chlorobenzene and xylene to form a solution.

On the silicon substrate, the polymer for cladding is
It was spin-coated to a thickness of about 30 μm. After baking and drying,
Next, a groove having a depth of 8 / m was prepared using a dicing saw having a blade having a width of 5 μm. The groove actually made has a width of 8
The depth was 8 μm. The core polymer was spin-coated so that the groove was filled, and the excess core polymer was removed by plasma etching with oxygen. Finally, 25μ
A cladding polymer was spin-coated to a thickness of m to prepare a buried waveguide. When the optical waveguide thus formed was cut into a length of 5 cm and the cross section was observed with a microscope, a rectangular pattern of a core portion having a height of 8 μm and a width of 8 μm was found. It was confirmed that the waveguide was operated in a single mode by injecting a laser beam having a wavelength of 1.3 μm, and the propagation loss at this time was 0.81 dB, showing a good waveguide characteristic.

Example 6 A method for producing a polymer optical waveguide (single mode optical waveguide) will be described based on the steps shown in FIG. Aluminum is used as the substrate.
A 0 nm evaporated silicon substrate is used. Wavelength 1.3μ
Since the single mode operation is performed at m or more, the relative refractive index difference Δ
= 0.3%, the polymer for cladding should be
A copolymer (refractive index: 1.4777) of deuterated polymethylmethacrylate and fluorinated methacrylate (molar ratio = 96.5: 3.5) was used, while deuterated polymethylmethacrylate was used as the core polymer. (Refractive index: 1.48
21) was used. Each of these polymers was dissolved in a mixed solution of chlorobenzene and xylene to form a solution. On a silicon substrate on which aluminum is deposited to a thickness of 200 nm,
The clad polymer was spin-coated to a thickness of about 30 μm. After the bake drying treatment, a dicing saw having a blade with a width of 5 μm was used to form a groove having a depth of 8 μm. The groove actually formed had a width of 8 μm and a depth of 8 μm. The core polymer was spin-coated so that the groove was filled, and the excess core polymer was removed by plasma etching with oxygen. Finally, the cladding polymer was spin-coated to a thickness of 25 μm to prepare a buried waveguide, and
The polymer optical waveguide part was peeled from the silicon substrate, thoroughly washed with distilled water and dried. The optical waveguide film thus formed was cut into a length of 5 cm, and the cross section was observed with a microscope to find that the height was 8 μm and the width was 8 μm.
A rectangular pattern of the core portion of μm was observed. Wavelength 1.3μ
It was confirmed that the waveguide operates in a single mode by injecting m laser light. The propagation loss at this time is 0.85.
It was dB and showed good waveguiding characteristics.

Example 7 A method for producing a polymer optical waveguide (multimode optical waveguide) will be described based on the steps shown in FIG. As the polymer for the clad, an epoxy ultraviolet (UV) curing resin (refractive index: 1.511),
An epoxy UV curable resin (refractive index: 1.560) having a different refractive index was used as the core polymer. The clad polymer was spin-coated to a thickness of about 100 μm and irradiated with UV to cure it. Then, a dicing saw having a blade with a width of 50 μm was used to form a groove having a depth of 50 μm. The actually formed groove had a width of 53 μm and a depth of 50 μm. The core polymer was spin-coated so as to fill the groove, and was irradiated with UV to be cured, and then the excess core polymer was removed by oxygen plasma etching. Finally, a clad polymer was spin-coated to a thickness of 50 μm, and was irradiated with UV to cure the polymer, thereby producing an embedded waveguide. When the thus-formed optical waveguide was cut into a length of 5 cm and the cross section was observed with a microscope, a rectangular pattern of a core portion having a height of 50 μm and a width of 53 μm was found. Propagation loss when a laser beam with a wavelength of 1.3 μm was incident was 2.7 dB, which showed good waveguiding characteristics.

<Embodiment 8> A method for producing a polymer optical waveguide (multimode optical waveguide) will be described based on the steps shown in FIG. An epoxy-based ultraviolet (UV) curable resin (refractive index: 1.51) was used as the clad polymer, and an epoxy-based UV curable resin (refractive index: 1.560) having a different refractive index was used as the core polymer. . The clad polymer was spin-coated to a thickness of about 100 μm and irradiated with UV to cure it. Then, a dicing saw having a blade with a width of 50 μm was used to form a groove having a depth of 50 μm. The actually formed groove had a width of 53 μm and a depth of 50 μm. The core polymer was spin-coated so as to fill the gap, and a plastic spatula was used to remove excess polymer for the core other than that filled in the groove portions, followed by UV irradiation to cure the polymer. Finally, a clad polymer was spin-coated to a thickness of 50 μm, and was irradiated with UV to cure the polymer, thereby producing an embedded waveguide. The optical waveguide thus formed was cut into a length of 5 cm and the cross section was observed with a microscope.
A rectangular pattern of the core portion having a width of m and a width of 53 μm was observed. Propagation loss when a laser beam with a wavelength of 1.3 μm was incident was 2.8 dB, indicating good waveguiding characteristics.

[0034]

As described above, in the method for producing a polymer optical waveguide according to the present invention, (1) a polymer material that is low in cost and easy to process is used,
(2) A large-scale device is not required in the process of making a waveguide that constitutes an element, (3) The core part of the waveguide that guides light is directly made by mechanical cutting with a dicing saw, etc. Is characterized by. Further, in the present invention, preferably, attention is paid to the positional accuracy of the dicing saw and the controllability of the thickness of the blade, and the dicing saw is used for producing an optical material using a polymer material. Therefore, the optical waveguide manufactured according to the present invention exhibits good optical waveguide characteristics, and it is possible to easily and inexpensively manufacture the polymer optical waveguide regardless of a large amount or a small amount.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view for explaining a method for producing a polymer optical waveguide according to the present invention, FIG. 1 (a) is a diagram for explaining a step of laminating a polymer layer on a substrate, and FIG. FIG. 4A is a diagram for explaining a step of forming a core having a desired shape, and FIG. 7C is a diagram for explaining a step of forming a cladding layer again.

FIG. 2 is a diagram for explaining a second example of a method for producing a polymer optical waveguide according to the present invention, in which (a) is a core having a polymer clad layer laminated on a substrate and then having a desired shape; For explaining the step of forming the core, (b) for explaining the step of applying a core polymer having a refractive index higher than that of the polymer for the clad layer, and (c) for explaining the clad material after forming the core. It is a figure for demonstrating the process of apply | coating.

[Explanation of symbols]

 1 Substrate 2 Polymer for Clad 3 Polymer for Core 4 Core 5 Dicing Saw 6 Polymer for Clad 7 Substrate 8 Polymer for Clad 9 Dicing Saw 10 Polymer for Core 11 Core 12 Polymer for Clad

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Saburo Imamura 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (6)

[Claims] 1. A step of forming a first layer made of a polymer, which serves as a cladding, on a substrate, a step of forming a second layer made of a polymer having a refractive index higher than that of the first layer, and the second step. A step of forming a core portion by mechanically cutting and removing a part of the layer, and a step of forming a third layer covering the core portion with a polymer material having a refractive index lower than that of the core portion. A method for producing a characteristic polymer optical waveguide. 2. The method according to claim 1, further comprising a step of removing the substrate after the step of forming a third layer covering the core portion with a polymer material having a refractive index lower than that of the core portion. A method for producing a polymer optical waveguide characterized by the above. 3. The method according to claim 1, wherein in the step of mechanically cutting and removing a part of the second layer to form the core portion, the cutting is performed using a dicing saw. A method for producing a characteristic polymer optical waveguide. 4. A step of forming a first layer made of a polymer serving as a clad on a substrate, and a step of mechanically cutting and removing a part of the first layer to form a groove portion in the first layer. A step of pouring a polymer material for core having a refractive index higher than that of the first layer into the groove portion, a step of removing an unnecessary portion of the polymer material for core to produce a core portion, And a step of forming a second layer covering the core portion with a polymer material having a low refractive index. 5. The method according to claim 4, further comprising a step of removing the substrate after the step of forming the second layer covering the core portion with a polymer material having a refractive index lower than that of the core portion. A method for producing a polymer optical waveguide characterized by the above. 6. The method according to claim 4 or 5, wherein in the step of mechanically cutting and removing a part of the first layer to form a groove in the first layer, the cutting is performed using a dicing saw. A method for producing a polymer optical waveguide, which is characterized by being performed.