JPH0735935A - Production of optical branching and coupling device - Google Patents

Abstract

PURPOSE:To easily produce the optical branching and coupling device by substrate waveguides having a property to preserve the plane of polarization. CONSTITUTION:A stress imparting layer 2, a core layer 3 and a stress imparting layer 4 are successively and continuously deposited from a gaseous phase on a substrate 1 by a gaseous phase deposition stage. The stress imparting layer 2, core layer 3 and stress imparting layer 4 formed on the substrate 1 are then etched according to Y-branch type waveguide patterns and thereafter both ends of the substrate where the patterns are not formed are etched. Optical fiber housing grooves 11 are formed in the positions corresponding to the ends of the Y branch type waveguide patterns.

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 an optical branching / coupling device, and more particularly to manufacturing an optical branching / coupling device suitable for branching / coupling a single mode optical fiber having polarization plane conservation. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, optical branching / splitting used for branching / coupling single-mode optical fibers having polarization-preserving properties.
As the coupler, a coupler formed of a fiber type waveguide is known.

[0003]

However, the productivity of the optical branching / coupling device composed of the fiber type waveguide is poor,
There is a problem that the characteristics are not stable. Therefore, it is conceivable to configure the optical branching / coupling device by using the substrate type waveguide, but in the case of the substrate type waveguide, it is difficult to provide polarization plane conservation.

In view of the above, it is an object of the present invention to provide a method of manufacturing an optical branching / coupling device which can easily manufacture an optical branching / coupling device using a substrate waveguide having a polarization plane preserving property. To do.

[0005]

In order to achieve the above object, in a method of manufacturing an optical branching / coupling device according to the present invention, first, a stress applying layer and a core layer are formed on a substrate by a vapor deposition process. The stress-applying layer and the stress-applying layer are successively and sequentially deposited from the vapor phase, and then the stress-applying layer, the core layer and the stress-applying layer formed on the substrate are etched according to a Y-branch waveguide pattern, and then, It is characterized in that both ends of the substrate on which the pattern is not formed are etched to form optical fiber accommodating grooves at positions corresponding to the ends of the Y-branch waveguide pattern.

[0006]

By the vapor deposition process, the stress-applying layer, the core layer and the stress-applying layer are successively and successively deposited on the substrate from the vapor phase, and then the stress-applying layer formed on the substrate is formed. When the core layer and the stress-applying layer are etched according to the Y-branch waveguide pattern, the waveguide having the sandwich structure in which the core layer is sandwiched by the two stress-providing layers becomes the Y-branch waveguide pattern. It is possible to easily manufacture an optical branching / coupling device having a polarization preserving property by using the substrate type waveguide. Furthermore, after that, etching both ends of the substrate,
Since the optical fiber accommodating groove is formed at a position corresponding to the end of the Y-branch type waveguide pattern, if the optical fiber is fixed in this groove, good coupling between the optical fiber and the waveguide can be obtained. Since the groove is formed by the continuous etching process as described above, the manufacturing is easy.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the drawings. Each step of the manufacturing method according to the embodiment of the present invention is as shown in FIGS. 1A to 1G, and specifically, for example, the CVD as shown in FIG.
This is done using the device 6. The optical branching / combining device produced by this is as shown in FIG.

For convenience of explanation, the completed optical branching / combining device will be described first with reference to FIG. 3. Stress is applied on a quartz or silicon substrate 1 in a direction perpendicular to the surface of the substrate 1. Layer 2, core layer 3, and stress imparting layer 4
It has a structure in which and are sequentially stacked. The stress applying layer 2, the core layer 3, and the stress applying layer 4 are formed in a Y-branch pattern as shown in FIG. Two V-grooves 11 are formed on each end of the substrate 1,
A constant polarization single mode optical fiber 12 is provided in each of the V grooves.
Are arranged. Two stress applying layers 2,
Stress is applied to the core layer 3 in a direction perpendicular to the substrate surface by 4, and a difference occurs in the propagation constant in the axial direction of the optical signal propagating in the core layer 3 to preserve the plane of polarization. Thus, an optical branching / coupling device having a polarization plane preserving property for the constant polarization single mode optical fiber is constructed. Although not shown in FIG. 3, a protective layer of a SiO ₂ thin film (see 5 in FIG. 1G) that covers and protects the stress applying layer 2, the core layer 3, and the stress applying layer 4 is provided.

Next, the manufacturing method will be described. The stress applying layers 2 and 4 and the core layer 3 are formed by continuously forming three glass films of different materials on the substrate 1 by the CVD method (chemical vapor deposition method), and the glass film forming step is completed. rear,
It is formed by etching to form a Y-branch type waveguide pattern as shown in FIG. By being manufactured by such a method, the manufacturing process can be simplified, and the interface state between the stress applying layers 2 and 4 and the core layer 3 can be kept good.

Specifically, for example, C as shown in FIG.
The VD device 6 is used. The CVD device 6 is a reaction container 61.
And a heating device 62 arranged around it, and the reaction vessel 61 is provided with a source gas supply port 63 and an exhaust port 64. The substrate 1 holds the holder 6 inside the reaction container 61.
Held by 5.

In this embodiment, a silicon wafer with a thermal oxide film is used as the substrate 1, and SiCl ₄ is used as a source gas;
60cc / min, GeCl ₄ ; 2cc / min, BBr; 12cc / mi
n was sent together with O ₂ ; 2000 cc / min into the reaction vessel 61 heated to 1400 ° C., and as shown in FIG. 1A,
SiO ₂ —B ₂ O ₃ —G which is the stress applying layer 2 on the substrate 1
An eO ₂ based glass layer was grown at 2 μm / min. This Si
O ₂ -B ₂ O ₃ -GeO ₂ based glass layer, SiO _2; 90
%, B ₂ O ₃ ; 2%, GeO ₂ ; 8%, and the refractive index is 1.4585.

After the stress applying layer 2 has grown to a thickness of 18 μm, SiCl ₄ ; 60 cc / min, GeC
l ₄ ; 12 cc / min, O ₂ ; 2000 cc / min, temperature 145
At 0 ° C., the core layer 3 of the SiO ₂ —Ge—O ₂ based glass layer
1B, the stress applying layer 2 is continuously grown to a thickness of 9 μm as shown in FIG. 1B. This SiO ₂ -Ge
The —O ₂ type glass layer is composed of SiO ₂ ; 87%, GeO ₂ ; 13
% Composition had a refractive index of 1.464.

Next, as shown in FIG. 1C, a stress-applying layer 4 made of a SiO ₂ —B ₂ O ₃ —GeO ₂ -based glass layer similar to the above was formed to a thickness of 18 μm under the same conditions as above.

These three layers of glass films 2, 3 and 4 by the CVD method are continuously grown in three layers, and after this is finished, a photoresist 71 is applied as shown in FIG. 1D, and then UV exposure is performed. Then, the window 72 is formed according to the Y-branch waveguide pattern. Metallic titanium is deposited as a mask layer 73 on the window 72 by sputtering, and then the photoresist 71 is removed (see FIG. 1E). Next, CF ₄ is used as an etching gas, and the glass films 2, 3 and 4 other than the waveguide pattern are removed by RIE (reactive ion etching) (see FIG. 1F). Next, as shown in FIG. 1G, a SiO ₂ layer having a thickness of 1 μm is provided as a protective layer 5 by decomposing an organometallic compound, Si (OC ₂ H ₄ ) in this embodiment, so as to cover them. It was Then, both ends of the silicon substrate 1 are provided with V grooves 11 for fixing the optical fiber 12 by anisotropic etching as shown in FIG. The dimensions of each part in the embodiment are shown in FIG.
As written in.

[0015]

As described in the above embodiments, the method of manufacturing an optical branching / coupling device according to the present invention is very easy because it can be manufactured by the vapor deposition process and the two etching processes performed thereafter. In addition, it is possible to manufacture an optical branching / coupling device having a polarization preserving property by using the substrate type waveguide. Further, in the optical branching / coupling device produced by this manufacturing method, if the optical fiber is fixed in the optical fiber housing groove, good coupling between the optical fiber and the waveguide can be obtained.
In this way, an optical branching / coupling device using a substrate-type waveguide that can be easily coupled with an optical fiber can be easily manufactured. Therefore, according to the present invention, an optical branching / combining device that can be easily connected to a single-mode optical fiber having a polarization-preserving property and that can be branched / coupled while preserving the polarization plane of light propagating through the optical fiber, It can be easily manufactured by the substrate type waveguide.

[Brief description of drawings]

FIG. 1 is a sectional view in each of the manufacturing steps according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a CVD apparatus used in the same example.

FIG. 3 is a schematic perspective view of an optical branching / coupling device according to the embodiment.

[Explanation of symbols]

 1 substrate 2, 4 stress imparting layer 3 core layer 5 protective layer 6 CVD apparatus

Claims (1)

[Claims] 1. A vapor deposition step of sequentially depositing a stress-applying layer, a core layer and a stress-applying layer from a vapor phase on a substrate, and the stress-applying layer and the core layer formed on the substrate. And an stress applying layer are etched according to the Y-branch waveguide pattern, and then both ends of the substrate on which the pattern is not formed are etched to correspond to the ends of the Y-branch waveguide pattern. A method of manufacturing an optical branching / coupling device, which comprises a step of forming an optical fiber accommodation groove at a position.