JP2002006164A - Waveguide and manufacturing method thereof - Google Patents

Abstract

(57) [Problem] To provide a waveguide with improved productivity and a method of manufacturing the same. When the glass transition temperature of a material forming a core portion is Tg1 and the glass transition temperature of a material forming a cladding layer is Tg2, a temperature difference between “Tg1−Tg2” is 6;
The temperature is set to 0 ° C. or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional waveguide will be described below with reference to the drawings.

FIG. 3 is a view for explaining a conventional method of manufacturing a waveguide.

First, as shown in FIG. 3A, GeO ₂ -added SiO ₂ soot or TiO ₂ -added SiO ₂ soot is applied as a core layer 2 on the upper surface of a quartz substrate 1 by a fire deposition method for about 1.5 hours. After being deposited to a thickness of several μm, it is sintered and clarified for about 10 hours.

Next, as shown in FIG. 3B, the core layer 2 is patterned by photolithography and reactive ion etching to form a core 2a.

Finally, as shown in FIG. 3C, P ₂ O ₅ and B ₂ O ₃ were added as an upper cladding layer 3 on the core portion 2a and the quartz substrate 1 again by the fire deposition method. A waveguide was obtained by depositing SiO ₂ and sintering it to make it transparent.

In the waveguide thus manufactured, the upper cladding layer 3 and the quartz substrate 1 serving as the lower cladding layer are integrated by sintering and transparency, so that the core portion is finally included in the cladding layer. 2 is embedded.

[0008]

The above-mentioned prior art has a problem in that the core layer 2 and the upper cladding layer 3 are deposited by a fire deposition method, and therefore a large number of steps and time are required, resulting in poor productivity. Was.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a waveguide with improved productivity and a method for manufacturing the same.

[0010]

According to the present invention, in order to achieve the above object, a core portion embedded in a cladding layer has a glass transition temperature Tg1 of the core portion. Assuming that the glass transition temperature is Tg2, a material having a temperature difference of “Tg1−Tg2” of 60 ° C. or more is selected.

In particular, the lower clad layer and the upper clad layer are integrated by hot pressing to form a clad layer, so that the core portion is embedded in the clad layer.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a waveguide according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a waveguide according to an embodiment of the present invention.

This waveguide is provided with a plurality of linear cores 12 embedded in a cladding layer 11 made of quartz glass. The cladding layer 11 has a glass transition temperature of the core 12 of Tg1,
Assuming that the glass transition temperature of Tg2 is Tg2, "Tg1-Tg
2 "is a fluorophosphate glass which is a fluorine-based glass having a temperature difference of 60 ° C. or more.

With respect to the waveguide configured as described above,
Hereinafter, the production will be described with reference to the drawings.

FIG. 2 is a diagram for explaining a method of manufacturing a waveguide according to an embodiment of the present invention.

First, as shown in FIG. 2A, on the upper surface of a lower cladding layer 21 made of a fluorine-based glass, for example, a fluorophosphate glass, at least one surface of quartz glass that has been optically polished so that one surface is substantially mirror-finished. The core layer 22 is placed so as to be in contact with the optically polished surface of the core layer 22. Then, the lower clad layer 21 and the core layer 22 are integrated by hot pressing at a temperature 50 to 60 ° C. higher than the glass transition temperature of the lower clad layer 21. This integration is performed by intermolecular bonding between the lower cladding layer 21 and the core layer 22.

Next, as shown in FIG.
The surface opposite to the surface in contact with the lower cladding layer 21 is optically polished to a desired thickness of about 5 to 7 μm.

Next, as shown in FIG. 2C, a resist layer 23 is formed by spin coating on the surface of the core layer 22 that has been optically polished in the previous step.

Next, as shown in FIG. 2D, patterning is performed by photolithography so as to form a plurality of linear lines having a desired shape.

Next, as shown in FIG.
2 is etched by a reactive ion etching method,
The core 12 is formed.

Next, as shown in FIG. 2 (f), the core layer 12 is exposed by removing the resist layer 23.

Next, as shown in FIG. 2 (g), an upper clad layer 24 made of a fluorine-based glass, for example, fluorophosphate glass is placed so as to be in contact with the exposed upper surface of the core portion 12.

The contact surface of the upper cladding layer 24 that is in contact with the core portion 12 exposed at this time is a surface that has been optically polished so as to be substantially a mirror surface in advance.

Finally, the upper clad layer 24 is hot-pressed at a temperature 50 to 60 ° C. higher than the glass transition temperature to form the clad layer 11 in which the upper clad layer 24 and the lower clad layer 21 are integrated. This integration is performed by intermolecular bonding between the upper cladding layer 24 and the lower cladding layer 21. At this time, the core 12 is buried in the cladding layer 11, as shown in FIG.

Hereinafter, a waveguide according to a detailed embodiment will be described.

(Example 1) As the lower cladding layer 21,
Glass transition temperature: 430 ° C., refractive index: 1.451 P ₂
A fluorophosphate glass of O ₁ -AlF ₃ -CaF ₂ -BaF ₂ -SrF ₂ having a thickness of 1 mm, and a glass transition temperature of a core layer 22 having one side optically polished and having a thickness of 50 μm: 1
Prepare quartz glass at 060 ° C. and a refractive index of 1.458,
The core layer 22 is placed so that the polished surface thereof is in contact with the lower clad layer 21, and hot pressed at 490 ° C. for 30 seconds.

Next, optical polishing is performed from the exposed surface side of the core layer 22 until the thickness of the core layer 22 becomes 7 μm.

Next, a photoresist layer is formed on the core layer 22, a mask pattern is superposed thereon, and exposure and development are performed to form a patterned resist layer. Thereafter, reactive ion etching is performed using the patterned resist layer as a mask to form a 7 μm square core portion 12.

Subsequently, a fluorophosphate glass having a thickness of 1 mm to become the upper clad layer 24 having the same composition as the lower clad layer 21 is placed on the core portion 12 and hot pressed at 490 ° C. for 30 seconds to obtain a waveguide.

Since the glass transition temperature of the quartz glass which is to be the core 12 of the waveguide is 1060 ° C., even when the glass is hot-pressed at 490 ° C., the quartz glass which is the core 12 does not undergo any thermal deformation, and the shape accuracy is reduced. An excellent waveguide was obtained. Also, no cracking or peeling at the clad-core interface occurred.

(Example 2) BK12 glass (SiO ₂ —B ₂ O ₃ —Na ₂ O—K ₂ O-based glass, glass transition temperature: 573 ° C., refractive index: 1.5187) as the core portion 12, a cladding layer K2 glass (SiO ₂ —B ₂ O ₃ —K ₂₎
O-Na ₂ O-BaO-based glass, glass transition temperature: 51
Using 0 ° C. and a refractive index of 1.5160), a hot press temperature of 570 ° C. was performed in the same manner as in Example 1 to produce a waveguide. The core portion 12 of the waveguide made of BK12 did not undergo thermal deformation due to hot pressing, and had excellent shape accuracy. Also, no cracking or peeling at the clad-core interface occurred. Since the glass transition temperature difference between the BK12 glass and the K2 glass at this time is 63 ° C., in order to form a waveguide by the method of the present embodiment, the glass transition temperature difference between the clad glass and the core glass must be 60 ° C. That is all.

(Comparative Example) BK7 glass (SiO ₂ —B ₂ O ₃ —Na ₂ O—K ₂ O-based glass, glass transition temperature: 565 ° C., refractive index: 1.5163) as the core 12, clad layer 11 As K7 glass (SiO ₂ —B ₂ O ₃ —K ₂ O—
Na ₂ O—BaO glass, glass transition temperature: 515
And the refractive index: 1.5111) in the same manner as in Example 1 and a hot press temperature of 565 ° C. to produce a waveguide. The BK7 glass core layer of this waveguide was slightly thermally deformed by hot pressing, and the shape precision was inferior to Examples 1 and 2. However, neither cracking nor separation at the clad-core interface occurred.

Comparing Example 1, Example 2 and Comparative Example, the difference between the glass transition temperature of the cladding layer 11 and the core 12 in Example 1 was 630 ° C., and the difference between the cladding layer 11 and the core 12 in Example 2 was 630 ° C. Since the glass transition temperature difference is 63 ° C. and the glass transition temperature difference between the clad layer 11 and the core portion 12 of the comparative example is 50 ° C., in order to form a waveguide by the method of the present embodiment, the clad glass and What is necessary is just to make the glass transition temperature difference of the core glass 60 ° C. or more.

[0035]

As described above, according to the present invention, the waveguide can be manufactured by hot pressing, and the apparatus cost is lower than that of the conventional method, the working time is shorter, and the productivity is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a waveguide according to an embodiment of the present invention.

FIG. 2 is a view for explaining the manufacturing method.

FIG. 3 is a diagram illustrating a conventional method for manufacturing a waveguide.

[Description of Signs] 11 Cladding layer 12 Core part 21 Lower cladding layer 22 Core layer 24 Upper cladding layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihisa Kumita 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H047 KA04 PA26 QA04 QA07 TA41 4G062 AA06 BB09 BB17

Claims (8)

[Claims] 1. A semiconductor device comprising: a clad layer; and a core portion embedded inside the clad layer.
When the glass transition temperature of the core portion is Tg1 and the glass transition temperature of the cladding layer is Tg2, “Tg1-Tg
g2 ”is a waveguide made of a material having a temperature difference of 60 ° C. or more. 2. The waveguide according to claim 1, wherein the cladding layer is made of a fluorine-based glass. 3. The waveguide according to claim 2, wherein the cladding layer made of a fluorine-based glass is a fluorophosphate glass. 4. The waveguide according to claim 1, wherein the core is made of quartz glass. 5. A method comprising: integrating a lower cladding layer and a core; patterning the core into a plurality of linear shapes to form a core portion; and placing an upper cladding layer on an upper surface of the core portion. A method of manufacturing a waveguide in which a core portion is embedded inside a clad layer by forming the clad layer by integrating the lower clad layer and the upper clad layer by hot pressing. 6. The method according to claim 5, wherein the step of integrating the lower cladding layer and the core is performed by hot pressing. 7. The step of integrating the lower cladding layer and the core includes polishing the core so as to be substantially mirror-finished, and bringing the polished core surface into contact with the lower cladding layer to form an intermolecular bond. The method of manufacturing a waveguide according to claim 5. 8. The step of forming the clad layer by integrating the lower clad layer and the upper clad layer, wherein the upper clad layer is polished so as to have a substantially mirror surface, and the polished surface of the upper clad layer and the 6. The method for manufacturing a waveguide according to claim 5, wherein the lower clad layer is brought into contact with the lower clad layer to bond the molecules therebetween.