JPH08160240A - Silica-based optical parts and their production - Google Patents

Abstract

PURPOSE: To make it possible to plot optical circuits with high accuracy by forming a silica glass layer on a silica glass surface for plotting having a specific loss to a specific radiation and irradiating the silica glass layer with the specific radiation from above the layer, thereby plotting the optical circuits. CONSTITUTION: These silica based optical parts are formed by forming the silica glass layer having a low defect concn. on the silica glass surface for plotting having the loss of at least 1dB/m with the radiation of a wavelength 165nm and irradiating the silica glass layer with the radiation of a wavelength <=330nm from above the layer, thereby plotting the optical circuits. The silica glass surface for plotting which is cut from a glass body of a preform and is subjected to polishing is irradiated with the light via the mask having transparent parts at the time of plotting the optical circuits in the silica glass. The preform 1 of the silica glass is produced by a sol-gel method, etc., and the production thereof is executed under conditions selected in such a manner that the SiSi defect concn. associated with the desired loss at 165nm of >=dB/m is generated. After the layer 1" of the low defect density is formed, the layer is irradiated with the light 4 from the mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silica glass waveguide type optical component used in optical communication equipment and the like.

[0002]

2. Description of the Related Art Conventionally, as a technique for producing an optical waveguide, one using a fine processing technique (Nishihara et al.), One using ion diffusion (Nishihara et al.), And local refraction by light irradiation are used. There was one using the rate change (V.Mizrahi et.al.).

[0003]

Among the conventional optical waveguide fabrication techniques, one using a fine processing technique is to produce a transparent multilayer thin film whose refractive index is controlled with high precision, and to perform fine processing with higher precision. Since it requires technology, there are many processes,
Therefore, there is a problem that the stability of the product is not good. Further, the method utilizing the diffusion of ions utilizes the diffusion phenomenon from the solution to the inside of the solid, and therefore has a very slow process speed and is not suitable for mass production. Also,
The method of locally changing the refractive index by light irradiation requires exposure to high-pressure hydrogen gas for a long time to diffuse the hydrogen gas, and the treatment takes about 20 days. Therefore, as a problem in producing the optical waveguide, how to reduce the number of process steps and how to shorten the processing time have been problems.

[0004]

SUMMARY OF THE INVENTION The present invention provides a wavelength of 165n.
For a radiation of m, a silica glass layer having a low defect concentration is formed on the surface of the writing silica glass having a loss of at least 1 dB / m, and the radiation having a wavelength of 330 nm or less is drawn on the silica glass layer. It is a silica-based optical component that is drawn by irradiating silica glass for use in drawing, and has a transparent portion on the drawing silica glass surface cut and polished from the glass body of the base material when drawing an optical circuit in the silica glass. A method for manufacturing a silica-based optical component, characterized by irradiating light through a mask.

A specific method for reducing the number of steps in manufacturing an optical waveguide and shortening the time required for the process will be described below. First, FIG. 1 shows a procedure for manufacturing an optical component. In FIG. 1, the silica glass is the base material 1
Formed as. The base material 1 can also be manufactured by an inner surface deposition method, an outer surface deposition method, or a sol-gel method. In each case, the production of silica glass involves processing steps performed under conditions selected to produce a relatively high SiSi defect concentration associated with the desired loss at 165 nm of at least 1 dB / m or higher.

The silica glass for drawing thus produced is cut and polished into a desired size to form a glass piece 1 ', and a silica glass layer 1 "having a low defect concentration is formed on the glass piece 1', and then the glass piece 1'is formed. Higher strength from the top 330
Light 4 having a predetermined wavelength of not more than nm is irradiated through the mask 5 for a predetermined time. Here, the mask 5 is composed of a portion that transmits the light 4 and a portion that does not transmit the light 4, and
It goes without saying that by irradiating with the predetermined light 4 for a predetermined period of time, as shown in FIG. 2, it is possible to specify the change in the refractive index, that is, the depth of drawing on the silica glass.

If the drawn optical circuit has a portion called a "lattice", a so-called mask-based equal-magnification exposure method may be used, which is called a "lattice" in the drawn optical circuit. The refractive index of the optical waveguide part is n
_Iteratively varies between _max and n ₀ as a function of distance along the path, n _max is the maximum effective index, n ₀ is the minimum effective index, and n _max and n ₀ are (n _max -N ₀ )
It is a silica-based optical component having a relationship represented by / n ₀ > 10 ⁻⁵ . In addition, in order to provide a portion called "interferometer" or "amplifier" in the optical circuit for drawing, a light transmitting portion may be provided on the mask in advance. The main part of the optical component is manufactured in this manner, and the optical component is completed by incorporating it into the casing.

[0008]

[Action]

1. Since the optical circuit can be formed only by irradiating the light through the mask, the processing time can be significantly shortened. 2. By changing the defect concentration, the sensitivity to light irradiation can be changed arbitrarily. 3. Since elements other than silicon and oxygen are not used, the non-uniformity of doping elements does not matter.

[0009]

Example As a base material of silica glass, a base material 1 was produced by a normal VAD method as shown in FIG. In the dehydration step, in order to increase the loss at 165 nm, the treatment was performed in an atmosphere in which 50% chlorine was mixed in He, and in the sintering step, the treatment was performed in He containing no chlorine.
The produced silica glass base material 1 was cut and surface-polished as shown in FIG. 1 (b) to prepare a glass piece 1 '.
Further, as shown in FIG. 1 (c), a silica glass layer 1 "having a low defect concentration at 165 nm and a small loss was formed by the flame deposition method through the burner 3. As shown in FIG. As shown in FIG. 1D, the silica glass plate 6 having a double structure was irradiated with vacuum ultraviolet light 4 of 165 nm for 3600 seconds through a mask 5 to obtain a waveguide type optical component.

[0010]

As described above, according to the present invention,
Compared to the conventional waveguide-type optical component manufacturing process, the processing time can be significantly shortened, and the wavelength of the irradiation light is also
Since short wavelengths can be used, it is possible to draw an optical circuit with high accuracy. The silica glass of the present invention is
At 165 nm, it has a loss above background. That is, it has a loss of at least 1 dB / m.
This indicates that there is a high concentration of SiSi defects in the silica glass. High concentrations of SiSi defects have been generally unachievable without Ge doping until now (.DELTA.n> 10 at 488 nm, for example).
^-4 ) is enabled and used in the optical waveguide creation process,
It becomes possible to create a highly accurate optical waveguide in a short time.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a configuration of an optical component manufacturing process of the present invention.

FIG. 2 shows how the refractive index change Δn value greatly changes due to the introduction of SiSi defects in this example.

[Explanation of symbols]

 1: Base material of silica glass 2, 3: Burner 4: Vacuum ultraviolet light 5: Mask 6: Silica glass

Claims (7)

[Claims] 1. With respect to radiation having a wavelength of 165 nm, a silica glass layer having a low defect concentration is formed on a drawing silica glass surface having a loss of at least 1 dB / m, and a wavelength of 330 nm or less is formed on the silica glass layer. Irradiating the above-mentioned drawing silica glass with the above-mentioned radiation to perform drawing. 2. The silica-based optical component according to claim 1, wherein the drawing silica glass does not incorporate elements such as Ge other than silicon and oxygen. 3. A drawn optical circuit has a portion called a "lattice", and the refractive index of the optical waveguide portion is n _max and n _0.
Between n _max and n ₀ is (n _max −n ₀ ), where n _max is the maximum effective refractive index, n ₀ is the minimum effective refractive index, and it varies repeatedly as a function of the distance along the path. / N ₀ > 1
0 Silica-based optical component according to claim 1 having a relationship represented by ^-5. 4. The silica according to claim 1, wherein the drawn optical circuit has a portion called an “interferometer”, and the portion branching the optical path and the portion joining are integrated. Optical components. 5. The silica according to claim 1, wherein the drawn optical circuit has at least one light amplification section, and an element other than silicon and oxygen is introduced into the amplification section. Optical components. 6. Silica characterized in that, when an optical circuit is drawn in silica glass, light is irradiated through a mask having a transparent portion on the surface of the drawing silica glass cut and polished from the glass body of the base material. Method for manufacturing optical components. 7. When drawing an optical circuit in silica glass,
7. The silica-based structure according to claim 6, which has a structure of two or more layers of a light absorbing layer made of silica glass having a loss of at least 1 dB / m with respect to radiation of 165 nm and a layer having a low defect concentration and not absorbing light. Optical component manufacturing method.