JPS62174708A - Optical waveguide and its production - Google Patents

Abstract

PURPOSE:To obtain an optical waveguide of a low loss by having projecting parts to limit a light propagation region on a substrate and providing a core layer and clad layer to the upper part thereof. CONSTITUTION:The substrate 1' having a flat surface is prepd. and the waveguide part is covered by, for example, a photoresist 5. The part except the waveguide part is etched and thereafter, the resist is removed to form the substrate 1 having the projecting parts which are the optical waveguide part. The clad layer 2, core layer 3 and clad layer 4 are successively deposited on such substrate 1 and the substrate is cut out by which the optical waveguide is obtd. A quartz or silicon substrate is used for the substrate 1. The projecting parts which are the light propagation region are formed on the substrate 1 by cutting the part except the light propagation region to a groove shape by etching or the like. Known methods such as, for example, thermal CVD method and flame hydrolysis deposition method are used as the method for successively depositing the clad layers and core layers on the substrate 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a manufacturing method for optical components useful in optical communication systems, optical information processing systems, etc., particularly planar optical waveguides, which is simple and advantageous in terms of mass production. It is.

[Conventional technology]

Conventional optical components consist of microscopic optical components such as prisms and lenses, and alignment and assembly of optical axes are difficult. In order to solve these complications, we created a waveguide on a plane and combined the light,
Various waveguides including demultiplexing and modulation elements have been proposed. Materials used for optical waveguides include, for example, semiconductors,
There are dielectric materials, glass, polymer materials, etc. In order to create an optical waveguide using these materials, a process as schematically shown in FIG. 4 is generally used. That is, a substrate 1 with a flat surface
'Clad on top? tJ2, the core layer 5 is sequentially deposited [steps (a) and (b) in FIG. 4]. Next, the core layer is patterned by etching [step (C) in FIG. 4]. Furthermore, a cladding layer 4 is deposited [step (d) in FIG. 4].

Through the above steps, a planar waveguide is created.

[Problem that the invention seeks to solve]

As mentioned above, the conventional method requires many steps as it involves the steps of deposition → etching → deposition, which causes problems such as the deposited film peeling off due to contamination of the substrate, and difficulty in controlling the pattern width due to side etching during etching. was there.

Therefore, the purpose of the present invention is to solve such problems,
An object of the present invention is to provide an optical waveguide that is simple and easy to mass-produce, and a method for manufacturing the same.

[Means for solving problems]

The present invention achieves the above object by first forming a desired waveguide pattern on a substrate by etching so as to leave it in a convex shape, and then successively depositing a cladding layer, a core layer, and a cladding layer. be.

That is, the present invention provides an optical waveguide having a convex portion on a substrate that defines a light propagation region, and a core layer and a cladding layer on top of the convex portion, and after forming a convex portion serving as a light propagation region on the substrate, , relates to a method of manufacturing an optical waveguide characterized by continuously forming a cladding layer.

An example of the leading waveguide of the present invention is shown in FIG. A cladding layer 2, a core layer 3, and a cladding layer 4 are sequentially laminated on a substrate 1 having a convex portion that defines a light propagation region.

FIG. 2 schematically shows an example of a method for forming the optical waveguide of the present invention having the structure shown in FIG.

First, a substrate 1' having a flat surface is prepared [step (a) in FIG. 2], and the optical waveguide portion is covered with, for example, photoresist 5 [step (b) in FIG. 2]. A substrate 1 having a convex portion serving as an optical waveguide portion is formed by etching the portion and then removing the resist (Step (C) in FIG. 2). Next, on the substrate 1, a cladding layer 2,
A core layer 3 and a cladding layer 4 are deposited [Fig. 2(d) to (f)
) step], by cutting out this, the optical waveguide shown in FIG. 1 is obtained.

The substrate used in the present invention may be an ordinary quartz or silicon substrate, and is not particularly limited.

In order to form a convex portion that becomes a light propagation region on a substrate, it is sufficient to remove the area other than the light propagation region in the form of a groove as described above, and etching such as dry etching such as reactive ion etching or ion beam etching or wet etching , laser processing, ultrasonic processing, etc. may be used.

Methods for sequentially depositing the cladding layer and the core layer on the substrate having the convex portion include, for example, a chemical vapor deposition method such as a thermal CVD method, a flame hydrolysis deposition method, a plasma CVD method, a sputtering method, and an evaporation method. Well-known means such as the following can be used.

In steps ('b) to (C) in Figure 2, for example, IF/NH, F
When wet etching is performed using a substrate, the cross section of the substrate becomes as shown in FIG. 3, and in this case, the same result as the substrate with the cross section shown in FIG. 2(c) can be obtained.

(Function) By simplifying the waveguide production process, it is possible to prevent peeling and the like caused by substrate contamination as in the conventional method, and the width can be easily controlled, making mass production possible. In the present invention, first, after forming a desired waveguide pattern so as to remain in a convex shape on a substrate, a cladding layer, a core layer,
Since the cladding layer can be formed in a series of continuous steps and the refractive index can be changed simply by changing the type of additive or the amount supplied, a planar waveguide can be easily formed. Furthermore, pattern width control is easy.

〔Example〕

The optical waveguide of the present invention and its manufacturing method will be explained in more detail below using Examples. However, the scope of the present invention is not limited in any way by the following examples.

First, a flat quartz substrate was prepared, and a waveguide pattern was formed using photoresist (AZ-1350, T) IC.

At this time, the resist covers the substrate that will become the waveguide portion. Co') Reference.

Next, CF4 (10scc
m) + H2 (2sccm) was mixed and introduced and RF
After etching the substrate by 50 μm under the conditions of power 200W and vacuum level 10” torr, and peeling off the resist,
The substrate was organically cleaned. As a result, a substrate was formed in which the waveguide portion remained in a convex shape. In order to successively form the cladding, core, and cladding layers on this substrate using a thermal CVD device, the substrate is first heated to 1000°C and Si
c 500.1000 each of the mixed gases of t4 and 0□
It was introduced at a flow rate of cc/min, and the cladding layer was 510 cc/min.
2 was deposited on a 5 μm substrate.

As a next K core layer, a 5iCL4;TiC4,02O mixed gas was introduced at flow rates of 500, 30, and 1000 cc/min, respectively, and a 50 μm thick SiO□ layer containing T1 was deposited.

Furthermore, a mixed gas of 8 i C14 and o 2 was introduced as a cladding layer at a flow rate of 500.1000 cc/min, and an 8102 layer was deposited to a thickness of 20 μm.

By cutting out this, an optical waveguide having the structure shown in FIG. 1 was easily obtained.

When the waveguide thus obtained was used as a branching waveguide, it branched 1=1 and the propagation loss was extremely good at 0.25 dB. (Example 1) In addition, wet etching was performed using HF(1):NF4F(7), and an optical waveguide was created in the same manner as above on the substrate having the structure shown in FIG. 3, and was used as a branching waveguide. Results similar to those above were obtained. (Example 2) [Effects of the Invention] The guiding waveguide and manufacturing method of the present invention first form a cladding layer, a core layer, and a cladding layer using a chemical vapor deposition method to obtain an optical waveguide with extremely low loss. Furthermore, by limiting the light propagation region with the convex structure, the manufacturing process can be simplified and the optical waveguide can be miniaturized.

Therefore, the present invention is an optical waveguide having various shapes and patterns that are useful in various optical application equipment such as optical communication systems and optical information processing systems, and an advantageous manufacturing method thereof. This is an extremely useful technique.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining an embodiment of the optical waveguide of the present invention, FIG. 2 is a diagram explaining the manufacturing method of the optical waveguide of the present invention in order of steps, and FIG. 3 is a diagram explaining another embodiment of the present invention. Figure, 4th
The figure is a diagram explaining the manufacturing method of the conventional product step by step.

Claims (4)

[Claims] (1) An optical waveguide having a convex portion on a substrate that defines a light propagation region, and a core layer and a cladding layer on top of the convex portion. (2) A method for manufacturing an optical waveguide, which comprises forming a convex portion serving as a light propagation region on a substrate, and then continuously forming a core layer and a cladding layer. (3) A method for manufacturing an optical waveguide according to claim (1), in which the core layer and cladding layer are formed by chemical vapor deposition. (4) The method for manufacturing an optical waveguide according to claim (3), wherein the core layer and the cladding layer are formed by a chemical vapor phase reaction of a mixed gas of a glass-forming raw material gas and an additive.