JPH07104139A - Production of glass waveguide and its apparatus for production - Google Patents

Abstract

PURPOSE:To produce the low-loss glass waveguide by forming a homogeneous bubbleless clad glass film. CONSTITUTION:A smooth silicon substrate 6 is placed on an SiC jig 5 in a quartz furnace core tube 7 and further a quartz glass substrate 3 deposited with a porous glass layer 4 is placed thereon. The heat from a heater 8 is effectively transmitted through the SiC jig 5 and the silicon substrate 6 to the quartz glass substrate 3 and the porous glass layer 4 is efficiently heated from the substrate 3 side. The heat radiation from the upper part of the quartz furnace core tube 7 to the porous glass layer 4 is suppressed by an opaque quartz glass plate 9. The porous glass layer 4 is vitrified to transparent glass from the substrate 3 side in such a manner, by which the homogeneous bubbleless transparent clad glass film is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass waveguide and a method for manufacturing the same, in which a porous glass layer serving as a clad glass covering a quartz glass substrate on which a core waveguide is formed is sintered to form a transparent glass. In particular, the present invention relates to a method for manufacturing a glass waveguide and a manufacturing apparatus for the same, in which sintering is improved in order to obtain a uniform transparent clad glass film having no bubbles.

[0002]

2. Description of the Related Art In order to reduce the loss of a glass waveguide, it is necessary to form a uniform core film on a quartz glass substrate and then form a fine and uniform core waveguide by photolithography and etching techniques. . Furthermore, it is necessary to form a uniform transparent glass film having no bubbles when the core waveguide on the substrate is filled with the clad glass. In forming the transparent clad glass film, generally, a porous glass is deposited by a flame deposition method on a substrate on which a core waveguide is formed, and the deposited porous glass layer is sintered to obtain a clad film. As shown in FIG. 3, this sintering is performed in the quartz furnace tube 7 of the electric furnace, and the quartz glass substrate 3 on which the porous glass layer 4 is deposited is formed.
Is placed on a quartz glass jig 10 and heated by a heater 8 around the quartz furnace tube 7.

[0003]

However, due to the above-mentioned conventional sintering, bubbles remain in the clad glass film obtained by making the porous glass layer 4 transparent and vitrification, which causes an increase in transmission loss of the glass waveguide. Was there. In particular, as shown in FIG. 2, the bubbles 2 were likely to remain in a narrow portion surrounded by the fine core waveguide 1.

An object of the present invention is to provide a glass waveguide manufacturing method and a manufacturing apparatus therefor capable of forming a uniform clad glass film without bubbles and manufacturing a low loss glass waveguide.

[0005]

A method of manufacturing a glass waveguide according to the present invention comprises forming a core waveguide on a quartz glass substrate or a silicon substrate with a quartz glass film, and depositing porous glass on the core waveguide. A method for producing a glass waveguide by forming a clad glass by heating the deposited porous glass layer into a transparent glass by heating, wherein the porous glass layer is transparentized from the substrate side. .

Further, the glass waveguide manufacturing apparatus according to the present invention heats the porous glass layer deposited so as to cover the core waveguide on the silica glass substrate or the silicon substrate with the silica glass film to form a transparent glass. In the apparatus for manufacturing a glass waveguide having a heating furnace, a supporting member having good thermal conductivity for supporting the substrate from the back surface side is provided in the heating furnace.

In the glass waveguide manufacturing apparatus, a shield for reducing heat radiation from the porous glass layer side on the substrate may be provided in the heating furnace.

[0008]

In the method of manufacturing a glass waveguide of the present invention, since the porous glass layer is made into transparent glass from the substrate side, even if bubbles occur in the transparent glass, they immediately escape to the outside and the bubbles remain. do not do. On the other hand, conventionally, since transparent glass is formed from the surface side of the porous glass layer, the generated bubbles are difficult to escape and remain in the clad glass film. Also,
In the glass waveguide manufacturing apparatus of the present invention, since the substrate is supported from the back side of the substrate by using the supporting member having good thermal conductivity in the heating furnace, the heat of the heated supporting member is transferred from the substrate side to the porous glass. Heat is satisfactorily transferred to the layer, and the vitrification of the porous glass layer proceeds from the substrate side. Further, by blocking the heat radiation from the surface side of the porous glass layer by the shield, a temperature distribution in which the temperature of the surface side of the porous glass layer is lower than that of the substrate side is more clearly realized, and the surface of the porous glass layer is It is possible to reliably prevent transparent vitrification from the side.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a glass waveguide and a manufacturing apparatus therefor according to the present invention will be described below with reference to the drawings.

First, a transparent quartz glass substrate having a thickness of 1 mm and a size of 3 inches is used as a substrate for a glass waveguide, and a TiO ₂ —SiO ₂ type glass film having a thickness of 8 μm is formed on this substrate by an electron beam evaporation method. did. Next, a 1 μm thick dungsten silicide (WSi) film is formed on this glass film by sputtering, the core pattern is transferred by photolithography, and a core waveguide with a width of 8 μm is formed by reactive ion etching. did. afterwards,
A core waveguide formed quartz glass substrate, a flame deposition method to deposit _{P 2 O 5 -B 2 O 3} -SiO 2 based porous glass, to form a porous glass layer with a thickness of 320 .mu.m.

Next, the porous glass layer 4 on the quartz glass substrate 3 was heat-treated in the electric furnace (manufacturing apparatus) shown in FIG. 1 to form a transparent clad glass film having a thickness of 25 μm. As shown in the figure, the electric furnace is provided with a heater 8 on the outer circumference of a quartz furnace core tube (heating furnace) 7, and the inside of the quartz furnace core tube 7 is in a He gas atmosphere. The quartz glass substrate 3 is placed on a jig 5 made of SiC via a silicon substrate 6 having a thickness of 1 mm and placed in a quartz furnace tube 7. An opaque quartz glass plate 9 for blocking heat radiation is provided in the upper portion of the quartz furnace tube 7 where the quartz glass substrate 3 is placed.

The heater 8 is energized to bring the temperature of the electric furnace to 10 ° C.
per minute and the temperature is raised to 1320 ° C., and the porous glass layer 4
Was sintered. The heat from the heater 8 is effectively transmitted to the entire back surface of the quartz glass substrate 3 through the SiC jig 5 having good thermal conductivity and the silicon substrate 6 having a smooth surface and a thermal conductivity about 100 times better than that of quartz glass. The porous glass layer 4 is efficiently heated from the quartz glass substrate 3 side.

Further, since heat radiation from the upper part of the quartz furnace tube 7 to the porous glass layer 4 is blocked by the opaque quartz glass plate 9, heating from the upper surface of the porous glass layer 4 is suppressed. Therefore, the porous glass layer 4 on the quartz glass substrate 3
Gradually becomes transparent glass from the side of the quartz glass substrate 3. In this way, the clad glass layer obtained by sintering the porous glass layer 4 was a homogeneous transparent glass film without generation of bubbles.

In the method shown in the above embodiment, 1 × shown in FIG.
A 16-splitter was prepared and the loss was measured. The insertion loss including the optical fiber was 12.8 dB, and the variation between the ports was within ± 0.3 dB, which was good. On the other hand, although the conventional method shown in FIG. 3 was also used to produce a 1 × 16 splitter, as shown in FIG. 2 (b), bubbles remained in the narrow portion of the core waveguide 1 and the insertion loss including the optical fiber was 14%. .5
The variation between dB was as large as ± 1 dB.

Although the quartz glass substrate 3 is used as the substrate of the glass waveguide in the above embodiment, a silicon substrate with a quartz glass film may be used. In this case, since the silicon substrate has good heat conductivity, among the jig 5 and the silicon substrate 6 as the supporting member, the silicon substrate with the quartz glass film is replaced with the SiC substrate without using the silicon substrate 6.
You may make it mount directly on a jig.

[0016]

【The invention's effect】

(1) In the method for producing a glass waveguide according to claim 1, when the porous glass layer on the substrate is sintered, the porous glass layer is made into transparent glass from the substrate side. It is possible to form a homogeneous clad glass film that does not remain, and to manufacture a low-loss glass waveguide.

(2) In the glass waveguide manufacturing apparatus according to the second aspect, the porous glass layer is formed on the substrate with a simple structure in which a supporting member having good heat conduction is used to efficiently transfer heat from the substrate side. It realizes a temperature distribution for vitrification from the side and is extremely practical.

(3) In the glass waveguide manufacturing apparatus according to the third aspect, the porous glass layer is provided on the substrate side with a simple structure in which a shield for reducing thermal copying from the porous glass layer side is added. From this, the temperature distribution for transparent glass formation is surely realized, which is extremely practical.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing one embodiment of a glass waveguide manufacturing apparatus according to the present invention.

2 shows a 1 × 16 splitter as an example of a glass waveguide, FIG. 2 (a) is a plan view, and FIG.
FIG. 2B is a partially enlarged view of FIG.

FIG. 3 is a vertical cross-sectional view showing a conventional glass waveguide manufacturing apparatus.

[Explanation of symbols]

 1 Core Waveguide 2 Bubble 3 Quartz Glass Substrate 4 Porous Glass Layer 5 SiC Jig 6 Silicon Substrate 7 Quartz Furnace Tube 8 Heater 9 Opaque Quartz Glass Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Otsuki Inventor Hide 1-1 Otsuki 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Hitachi Cable Ltd.

Claims (3)

[Claims] 1. A clad is formed by forming a core waveguide on a quartz glass substrate or a silicon substrate with a quartz glass film, depositing porous glass on the core waveguide, and heating the deposited porous glass layer into transparent glass. A method for producing a glass waveguide by forming glass, wherein the porous glass layer is made transparent glass from the side of the substrate. 2. A glass waveguide manufacturing apparatus having a heating furnace for heating a porous glass layer deposited so as to cover a core waveguide on a quartz glass substrate or a silicon substrate with a quartz glass film to form a transparent glass. An apparatus for manufacturing a glass waveguide, characterized in that a supporting member having good thermal conductivity for supporting the substrate from the back side thereof is provided in the heating furnace. 3. The production of a glass waveguide according to claim 2, wherein a shield for reducing heat radiation from the side of the porous glass layer on the substrate is provided in the heating furnace. apparatus.