JPH04131809A - Production of quartz optical waveguide - Google Patents

Abstract

PURPOSE:To facilitate production by the quartz optical waveguide which exhibits functional characteristics by forming a glass waveguide film in a part of the low-refractive index part of a core part, i.e. the part where light is guided and near this core part by a sputtering method. CONSTITUTION:A buffer layer 12 consisting of a quartz glass film is first formed by a flame hydrolysis deposition method on a silicon wafer 11. A resist film 13 is then formed in the part exclusive of the part to serve as a core by a photoresist method and an Er doped glass film 14 is formed thereon by a sputtering method. This resist film 13 is removed to form the core part 15 consisting of the Er doped glass film. Finally, the clad layer 16 consisting of a glass film is formed by the flame hydrolysis deposition method so as to embed the core part 15. The functional waveguide having the functional characteristics is formed by the sputtering method in this way and the functional waveguide 17 is easily produced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a silica-based optical waveguide exhibiting functionality such as laser amplification and nonlinear optical effects.

<Conventional technology> Among optical waveguides, silica-based optical waveguides, which are mainly composed of silica glass, are attracting attention because they have low optical transmission loss and can be connected to silica-based optical fibers with low loss. are collecting. The method for manufacturing this silica-based optical waveguide is the flame deposition method (FHD).
is deposition) and reactive ion etching (RIE).
The most common method is a combination of glass film microfabrication using ion etching. (See Masao Kawachi, 1. Quartz-based optical guide, bribery and its application to integrated optical components, Optics Vol. 18, No. 12 (December 1989), pp. 681-686).

An example of manufacturing a silica-based optical waveguide using this method will be described with reference to FIG. 3. As shown in the figure, in this method, glass raw materials such as 5iCj, TiCj, etc. are first supplied to a burner 1, and glass fine particles 3 are obtained through a hydrolysis reaction and an oxidation reaction in an oxyhydrogen flame 2. Glass fine particle films 5a, 5 are deposited on a substrate 4 such as an 81 wafer.
C (a)] which sequentially forms b. Here, it is assumed that the glass fine particle films 5a and 5b have different compositions. Then, by heating this to a high temperature, a glass fine particle film 5a is formed.

5b is made into transparent glass to form a buffer layer 6a and a core layer 6b.
C (b) ). The above is the flame deposition method. Next, by reactive etching, unnecessary portions of the core layer 6b are removed to leave a ridge-shaped core portion 6C (Ctc+').

Then, a cladding layer 6d is formed again by the flame deposition method so as to cover the core portion 6C, thereby forming a buried silica-based optical waveguide 7.

<Invention tries to solve! ! Topic: The flame deposition method described above is most commonly used to fabricate silica-based optical waveguides because it is possible to fabricate quartz films with low optical transmission loss and has a high film formation rate. Most of the silica-based optical waveguides used are passive optical devices that perform optical multiplexing, demultiplexing, and branching.

However, there is a desire for a functional waveguide having functions such as laser amplification and switching using nonlinear optical effects.

Incidentally, in order to exhibit such a function, it is necessary to add rare earth elements that exhibit a laser oscillation effect, semiconductor particles that exhibit a nonlinear optical effect, etc. to the waveguide, but the flame deposition method described above Since glass synthesis is performed in an oxyhydrogen flame at a high temperature of ℃ or higher, it is difficult to produce glass containing rare earth elements or semiconductors that are unstable at high temperatures.

SUMMARY OF THE INVENTION In view of these circumstances, an object of the present invention is to provide a manufacturing method that can easily manufacture a functional silica-based optical waveguide.

Means for Solving the Problems> A method for manufacturing a silica-based optical waveguide according to the present invention that achieves the above object includes depositing glass particles on a substrate by a flame deposition method and heating the glass particles to a high temperature to make a transparent material. In a method for manufacturing a silica-based optical waveguide including a step of forming a glass fine particle layer, a glass waveguide film is formed by sputtering on a core portion where light is guided and a part of a low refractive index portion near the core portion. It is characterized by

The present invention will now be described in detail.

The sputtering method used in the present invention is a method in which gas molecules ionized by glow currents in a vacuum container collide with a target material to evaporate atoms constituting the target material, and these atoms are attached to a substrate and formed into a thin film. This is a method of In this sputtering method, atoms constituting the target material are ejected with ions, so a thin film having almost the same composition as the target material can be formed without going through a high-temperature process. Therefore, a functional thin film can be formed by preparing Bergglass as a target material to which a functional substance has been added in advance. In addition, since the target material in the present invention is an insulator, the sputtering method referred to in the present invention is of a high frequency excitation type.

In the present invention, a functional waveguide film having functionality is produced by a sputtering method, while other parts are produced by a flame deposition method, which can produce glass with very few impurities and has a high film formation rate. Functional waveguides can be easily manufactured.

Here, the functional waveguide film refers to a waveguide film that also has functions other than optical waveguide, such as laser amplification and nonlinear optical effects.For example, rare earth elements such as Er and Nd, which have laser amplification effects, and nonlinear optical effects CdS, Ss, , PbS, indicating
A quartz-type waveguide film containing semiconductor fine particles such as CuC1.

In addition, when forming a functional waveguide film on a part of the core part and the low refractive index part in its vicinity using the sputtering method, a photoresist method in which a resist film in the form of a waveguide pattern is formed on the substrate, It is preferable to select and form only the desired portions of the functional waveguide film by applying reactive etching or the like to chemically remove unnecessary portions of the glass.

Note that in the present invention, a silicon wafer, a quartz glass plate, or the like can be used as the substrate.

Example of implementation Hereinafter, the present invention will be explained based on examples.

(Example 1) FIG. 1 shows the manufacturing process of a silica-based optical waveguide according to this example. As shown in the figure, first, a silicon wafer 11 was prepared [(a)], and a buffer layer 12 made of a 20 μm silica-based glass film was formed on the silicon wafer by flame deposition method [(
b)].

Next, a resist film 13 was formed by a photoresist method on a portion excluding a portion that would become the outer core [fo+:]. Then, by sputtering, an Er-doped glass film 14 containing 3vt% Er was formed with a thickness of 8 μm [(mountain)].Then, by removing the resist film 13, the Er-doped glass film 14 was formed by sputtering. A core portion 15 was formed (te+).Finally, a cladding layer 16 made of a 40 μm glass film was formed by flame deposition so as to embed the core portion 15, thereby producing a functional optical waveguide 17.

The functional leading wave @17 produced as described above has a core part 1
Since 5 is made of an Er-doped glass film, it has a laser oscillation function, and has a laser oscillation function of, for example, 1.47 to 1.55 μm along with a signal light of 1.55 μm.
By introducing a 1.49 μm amplification laser beam, 1
．． The 55 μm signal light is amplified.

(Example 2) FIG. 2 shows the manufacturing process of a silica-based optical waveguide according to this example. As shown in the figure, first, a silicon wafer 21 is prepared [C(a)], and a 20 μm film is deposited on it by flame deposition method.
A buffer layer 22 made of a quartz-based glass film of [(
Further, on this buffer layer 22, an 8 μm thick CdS-doped glass film 23 containing 1 wt% of semiconductor fine particles CdS was formed by sputtering ((C)').

Next, a resist film 24 was formed only on the core portion by a photoresist method, and then unnecessary glass portions except the core portion 25 were removed by reactive ion etching using dlE and C2F as an etching gas. (el).Finally, a cladding layer 26 made of a 40 μm glass film was formed by a flame deposition method so as to embed the core portion 25, thereby producing a functional optical waveguide 27.

The functional optical waveguide 27 manufactured as described above has a core portion 2
Since 5 is made of a CdS-doped glass film, it has a nonlinear effect and can be used for switching, etc.

In the above embodiments 1 and 2, an example was shown in which the core portion 15.degree. 25 was doped with a functional substance, but the core portion 15.
For example, doping only the bottom layer or the top layer of 25,
Alternatively, the buffer layer 12 below the core jl15, 25.
22 and the cladding layer 1 above the core layers 15 and 25
Even if only the bottom layer of 6.26 is doped, the functional waveguide according to the present invention can be obtained, and these can also be easily manufactured according to the manufacturing examples of Examples 1 and 2 described above. can.

<Effects of the Invention> As explained above, according to the present invention, it is possible to relatively easily manufacture a silica-based optical waveguide having functions such as laser oscillation and nonlinear optical effects, which was difficult to manufacture in the past. can do.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the manufacturing process of a silica optical waveguide according to one embodiment, FIG. 2 is a process diagram showing the manufacturing process of a silica optical waveguide according to another embodiment, and FIG. 3 is a process diagram showing the manufacturing process of a silica optical waveguide according to another embodiment. FIG. 3 is a work process diagram showing such a quartz-based optical waveguide. In the drawing, 11.21 is a silicon wafer, 12.22 is a buffer layer, 13 is a resist film, 14 is an Er-doped glass layer, 15.25 is a core part, 16.26 is a cladding layer, 17.27 is a functional light guide. 23 is a CdS-doped glass layer, and 24 is a resist layer.

Claims (3)

[Claims] (1) In a method for manufacturing a silica-based optical waveguide, which includes the step of depositing glass particles on a substrate by a flame deposition method and heating them to a high temperature to form a transparent glass particle layer, the part where light is guided A method for manufacturing a silica-based optical waveguide, comprising forming a glass waveguide film on a certain core part and a part of a low refractive index part near the core part by sputtering. (2) A method for manufacturing a silica-based optical waveguide according to claim 1, wherein the glass waveguide film formed by sputtering contains a rare earth element that exhibits a laser oscillation effect. (3) A method for manufacturing a silica-based optical waveguide according to claim 1, wherein the glass waveguide film formed by sputtering contains semiconductor fine particles exhibiting a nonlinear optical effect.