JP2002196165A - Glass waveguide and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass waveguide in which the generation of bubbles is suppressed, when a clad glass film is formed and a core waveguide is formed uniformly without deformation, and a method for manufacturing the same. SOLUTION: In the glass waveguide for which a core glass film is formed on a quartz glass base plate 1, the core waveguide 7 is formed in photolithographic processes of and an etching or the like, and a clad glass film is formed on a substrate, on which the core waveguide is formed, the core glass film is formed from at least two layers of core glass films which are a first core glass film 3 and a second core glass film 5, and the core waveguide 7 is formed by at least two layers 7A and 7B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIGS. 3 and 4 show a conventional glass waveguide.
You. 11 is Si or SiO_TwoThis shows a substrate consisting of
First, a core glass film 12 is formed on a substrate 11. About
Then, as shown in FIG. 3, photolithography and etching
The core glass film 12 is treated and cut through a
A plane rectangular core waveguide 13 is formed, and then shown in FIG.
Thus, the refractive index is SiO_TwoAlmost equivalent to
Or P_TwoO_Five−P_TwoO _Three-SiO_TwoSystem clad gala
A film 15 is formed.

When the substrate 11 is made of Si, an oxide film is first formed on the substrate 11 and a clad glass film 15 is formed thereon.
A glass film having a refractive index equivalent to that of the above is formed, and thereafter, a core glass film 12 is formed. Substrate 11 is made of SiO ₂
In this case, the core glass film 12 is formed directly on the substrate 11.

In each case, the core glass film 12 is made of TiO.
_{2 -SiO 2, GeO 2 -SiO 2} , GeO 2 -P 2 O 5 -S
It is composed of any one of iO ₂ -based glass and the like.

[0005] In the above configuration, the core waveguide 13 is formed by the cladding glass film 15 without changing the shape of the core waveguide 13.
The cladding glass film 15 is formed by a fire deposition method or a plasma CVD method in order to embed uniformly.

[0006]

However, in the conventional configuration, if the mutual interval (gap) W of the core waveguides 13 becomes narrow (about 4 μm or less), the clad glass film 15 is not uniformly embedded, and bubbles are generated. There's a problem.
Therefore, in the fire deposition method, a high temperature (for example, 1350 ° C. or higher) treatment is performed at the same time as the amount of the dopant is increased in order to reduce the viscosity when the porous glass is vitrified. However, when this process is performed, the core waveguide 13 tilts toward the gap W side, deteriorating the optical characteristics, and causing a problem that the polarization characteristics are increased due to the large amount of the dopant.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to suppress the generation of bubbles at the time of forming the clad glass film, and to change the shape of the core waveguide without changing the shape of the core waveguide. It is an object of the present invention to provide a glass waveguide which can be formed uniformly and a method for manufacturing the same.

[0008]

According to the first aspect of the present invention,
A core glass film is formed on a quartz glass substrate, a core waveguide is formed through photolithography and an etching process, and a clad glass film is formed on the substrate on which the core waveguide is formed. Glass film is first
The core waveguide is formed of at least two layers of a core glass film and a second core glass film, and the core waveguide is formed of at least two layers.

According to a second aspect of the present invention, a core glass film is formed on a quartz glass substrate, a core waveguide is formed through photolithography and an etching process, and a cladding is formed on the substrate on which the core waveguide is formed. In a glass waveguide forming a glass film, the core glass film is formed of a TiO ₂ —SiO ₂ based glass film formed on the quartz glass substrate, and a first core glass film formed on the first core glass film. GeO ₂ -SiO ₂ based glass formed, GeO ₂ -P ₂ O ₅ -
It is assumed that the core waveguide is formed of at least two layers of a core glass film with a second core glass film made of SiO ₂ -based glass or a P ₂ O ₅ -SiO ₂ -based glass film. Features.

A third aspect of the present invention is characterized in that, in the first or second aspect, the first core glass film and the second core glass film have the same refractive index.

According to a fourth aspect of the present invention, in the first aspect, the first core glass film has a higher viscosity than the second core glass film in a temperature range at the time of forming the clad glass. It is characterized by the following.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the thickness of the second core glass film is 1/3 or less of the thickness of the first core glass film. It is characterized by being.

According to a sixth aspect of the present invention, a core glass film is formed on a quartz glass substrate, a core waveguide is formed through photolithography, an etching process, and the like, and a cladding is formed on the substrate on which the core waveguide is formed. In the method of manufacturing a glass waveguide for forming a glass film, the core glass film is manufactured with at least two core glass films of a first core glass film and a second core glass film when forming the core glass film. I do.

According to a seventh aspect of the present invention, a core glass film is formed on a quartz glass substrate, a core waveguide is formed through photolithography, an etching step, and the like. In the method of manufacturing a glass waveguide for forming a glass film, the core glass film is formed of at least two core glass films of a first core glass film and a second core glass film when the core glass film is formed; As a glass film, TiO ₂ −
After forming the SiO ₂ -based glass film, GeO ₂ -SiO ₂ -based glass, GeO ₂ -P ₂
An O ₅ —SiO ₂ -based glass or P ₂ O ₅ —SiO ₂ -based glass film is formed.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the first core glass film and the second core glass film have the same refractive index.

According to a ninth aspect of the present invention, in any one of the sixth to eighth aspects, the first core glass film has a higher viscosity than the second core glass film in a temperature range at the time of forming the clad glass. It is characterized by the following.

The invention according to claim 10 is the invention according to claims 6 to 9
The thickness of the second core glass film is not more than 1/3 of the thickness of the first core glass film.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a glass waveguide according to the present invention will be described.
And an embodiment of a manufacturing method thereof with reference to the attached drawings.
Will be explained. 1 and 2 show a glass waveguide according to the present embodiment.
Is shown. 1 is a transparent quartz glass base of 4 mm square and 1 mm thick
FIG. 1 shows a plate, on which an electronic device is provided as shown in FIG.
5μm thick TiO by beam evaporation_Two-SiO_TwoSystem
A lath film (first core glass film) 3 is formed, and a fire
GeO by disaster deposition method_Two−P_TwoO _Five-SiO_TwoGlass film
(Second core glass film) 5 is formed.

Thereafter, a 0.6 μm thick W
Si (not shown) is deposited by sputtering, a resist (not shown) is formed on the surface with a thickness of 1 μm, and a Mach-Zehnder optical circuit is formed through a photolithography process.
The core waveguide 7 composed of the two layers 7A and 7B is formed through a reactive ion etching process. This substrate 1 is 1300 ° C.
At high temperature in an O ₂ atmosphere.

The refractive index of the first core glass film 3 is equal to the refractive index of the second core glass film 5, and the refractive index is 0.8%. The viscosity of the first core glass film 3 is set higher than the viscosity of the second core glass film 5 at a temperature at the time of forming a clad glass described later, for example, in a range of 1250 to 1350 ° C.

When the SEM photograph of the core waveguide 7 in this case is analyzed, the 1 μm portion of the shoulder 7C of the upper layer 7B in the 6 μm × 6 μm core waveguide 7 has a smooth curvature. In order to provide the shoulder 7C with a smooth curvature, the ratio of the thickness t1 of the first core glass film 3 to the thickness t2 of the second core glass film 5 is set to about 3: 1. Desirably, the thickness t2 of the second core glass film 5 is not more than 1/3 of the thickness t1 of the first core glass film 3. When the thickness t2 of the second core glass film 5 becomes higher than this ratio, the shape of the core waveguide 7 is deformed at the time of forming the clad glass in a later step, and optical characteristics such as multiplexing / demultiplexing characteristics are obtained. This is because there is a risk that the quality will deteriorate.

Finally, as shown in FIG.
Porous glass is deposited on the substrate 1 by a fire deposition method.
At a high temperature of 1330 ° C. to form a transparent glass,
m P _TwoO_Five-B_TwoO_Three-SiO_TwoSystem clad glass film 9
Form.

The glass waveguide made of the Mach-Zehnder optical circuit manufactured by the above-described manufacturing method has no bubbles in the gap W between the core waveguides 7. Moreover, good results of the demultiplexing characteristics were obtained. This good result was obtained because the TiO ₂ —Si
The viscosity of the O ₂ -based glass film (first core glass film) 3 is high,
This is because the shape of the gap W is kept as it was when the core waveguide was formed.

When the second core glass film 5 is not formed, it is considered that the density of the porous glass between the gaps W changes depending on the shape of the gap W. According to this, for example, when 100 devices are manufactured, bubbles are generated in 20 devices, and the loss is increased by 0.5 to 1 dB as compared with a device without bubbles, and 1.3 μm wavelength and 1.5 μm wavelength are reduced due to bubbles. Has degraded the demultiplexing characteristics. Further, when the second core glass film 5 was formed with a thickness of 3 μm, the core waveguide 7 was deformed at the temperature at the time of forming the clad, and the demultiplexing characteristics were deteriorated.

Although the present invention has been described based on one embodiment, it is apparent that the present invention is not limited to this.

The present invention is also effective when a clad glass film is formed by a plasma CVD method. Plasma C
In the VD method, glass particles having directivity are deposited and formed at the time of glass formation, and the deposition of the gap W changes depending on the formation state of the gap W of the core waveguide 7. In the conventional manufacturing method, 75 bubbles out of 100 elements are generated. In the present invention, generation of air bubbles was not recognized in 100 elements.

[0027]

According to the present invention, since the core glass film is formed of at least two core glass films of the first core glass film and the second core glass film, a uniform clad glass film is formed and the optical characteristics are improved. A good glass waveguide is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of a core waveguide according to the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a core waveguide according to the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of a conventional core waveguide.

FIG. 4 is a cross-sectional view showing a conventional core waveguide.

[Explanation of symbols]

 Reference Signs List 1 substrate 3 first core glass film 5 second core glass film 7, 7A, 7B core waveguide 7C shoulder W gap

Claims (10)

[Claims] 1. A core glass film is formed on a quartz glass substrate, and subjected to photolithography, an etching process, and the like.
In a glass waveguide in which a core waveguide is formed and a clad glass film is formed on a substrate on which the core waveguide is formed, the core glass film has at least two layers of a first core glass film and a second core glass film. A glass waveguide formed of a film, wherein the core waveguide is formed of at least two layers. 2. A core glass film is formed on a quartz glass substrate, and subjected to photolithography and an etching process.
In a glass waveguide in which a core waveguide is formed and a clad glass film is formed on a substrate on which the core waveguide is formed, the core glass film is a TiO ₂ —SiO ₂ based glass film formed on the quartz glass substrate And a GeO ₂ − film formed on the first core glass film.
A core glass film of at least two layers including a second core glass film composed of SiO ₂ glass, GeO ₂ —P ₂ O ₅ —SiO ₂ glass, or P ₂ O ₅ —SiO ₂ glass; A glass waveguide, wherein the core waveguide is formed of at least two layers. 3. The glass waveguide according to claim 1, wherein the first core glass film and the second core glass film have the same refractive index. 4. The glass waveguide according to claim 1, wherein the first core glass film has a higher viscosity than the second core glass film in a temperature range when the clad glass is formed. 5. The method according to claim 1, wherein said second core glass film has a thickness of said first core glass film.
The glass waveguide according to any one of claims 1 to 4, wherein the thickness is not more than 1/3 of the thickness of the core glass film. 6. A core glass film is formed on a quartz glass substrate, and subjected to photolithography, an etching process, and the like.
In a method of manufacturing a glass waveguide, wherein a core waveguide is formed and a clad glass film is formed on a substrate on which the core waveguide is formed, the core glass film includes a first core glass film and a second core glass when the core glass film is formed. A method for manufacturing a glass waveguide, wherein the glass waveguide is manufactured using at least two layers of a core glass film. 7. A core glass film is formed on a quartz glass substrate, and subjected to photolithography, an etching step, and the like.
In a method of manufacturing a glass waveguide, wherein a core waveguide is formed and a clad glass film is formed on a substrate on which the core waveguide is formed, the core glass film includes a first core glass film and a second core glass when the core glass film is formed. A TiO ₂ —SiO ₂ -based glass film is formed on the quartz glass substrate as the first core glass film, and GeO ₂ − is formed as the second core glass film. SiO ₂ glass, GeO ₂ −
P ₂ O ₅ -SiO ₂ -based glass, or method of manufacturing a glass waveguide, and forming a P ₂ O ₅ -SiO ₂ type glass film. 8. The method of manufacturing a glass waveguide according to claim 6, wherein the first core glass film and the second core glass film have the same refractive index. 9. The glass waveguide according to claim 6, wherein the first core glass film has a higher viscosity than the second core glass film in a temperature range when the clad glass is formed. Production method. 10. The glass conductor according to claim 6, wherein the thickness of the second core glass film is one third or less of the thickness of the first core glass film. Waveguide manufacturing method.