JPH0153762B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel optical waveguide that is excellent as an optical branching/coupling circuit element, etc., which is a component of an optical transmission system. Conventional optical waveguides of this type include those in which optical fibers are combined, or optical waveguides in which a light-transmitting glass portion having a higher optical refractive index than the surrounding area is provided on the surface of a glass substrate by means such as vacuum evaporation or sputtering. ing. However, the former requires high assembly precision and is susceptible to mechanical vibration, while the latter has the disadvantage that the surface precision of the interface between the light-transmitting glass portion and the substrate glass is poor and the scattering loss of light is large. The purpose of the present invention is to provide an optical waveguide that eliminates the above-mentioned drawbacks, and its gist is
A chalcogen characterized by locally irradiating a chalcogen compound having a composition of 65 to 97% Se and 3 to 35% Ga to create a difference in optical refractive index between the irradiated part and the non-irradiated part. Located in the optical waveguide. The chalcogen compound used in the present invention was previously filed as Japanese Patent Application No. 170653/1986. When this chalcogen compound is irradiated with light at a temperature below 240°C, it crystallizes and its visible light transmittance decreases (darkening). phenomenon), the darkened product is heated to 240℃.
It is a substance that has the property of vitrifying when heated to a higher level, increasing its visible light transmittance, and returning to its original state (referred to as a bleaching phenomenon). As a result of further research on the physical properties of the present chalcogen compound, the inventors of the present application found that the optical refractive index was higher during the darkening than during the bleaching, and by causing local darkening, it was possible to easily form an optical waveguide. Invent something that can be manufactured,
It is disclosed here. When the chalcogen compound used in the present invention is heated to a temperature of 240° C. or lower and irradiated with light, the optical refractive index in the darkening state increases as shown in Table 1, depending on the compounding ratio of Se and Ga in the compound. The larger the difference in refractive index is, the better it is for an optical waveguide, but if Δn is 0.003, it is practical. In addition, this chalcogen compound absorbs a considerable amount of light in the visible wavelength range during bleaching or darkening, but it absorbs little near-infrared light with a wavelength of around 800 nm, making it suitable for near-infrared light optical waveguides. ing.

[Table] The shape of the optical waveguide of the present invention does not matter, but since the light for darkening does not reach too deep from the surface layer of the chalcogen compound, it is preferable that the chalcogen compound be formed in the form of a thin film on the substrate surface. . In addition, the substrate is preferably a light-transmitting plate glass in order to cause darkening by irradiation with light, and the chalcogen film is preferably a vapor-deposited film from the viewpoint of controlling the thickness of the chalcogen film and adhesion strength. In addition, since chalcogen compounds tend to deteriorate when exposed to moisture, it is desirable to coat the surface with paraxylylene.

[Formula] is particularly preferably vacuum-deposited to a thickness of about 1.5 μm from the viewpoint of light transmittance, heat resistance, film strength, water resistance, etc. The wavelength of light for darkening is preferably in the range of 300 to 800 nm; light with a wavelength longer than 800 nm takes a long time to darken, and light with a wavelength shorter than 300 nm does not cause darkening. In addition, from the viewpoint of shortening the darkening time, refining the crystal grains in the darkening state, and preventing scattering at the interface, it is preferable that the light be strong. In order to prevent overheating above .degree. C., monochromatic light sources that do not include light in the infrared wavelength range, such as He--Ne lasers and Ar lasers, are particularly preferred. When the chalcogen compound used in the present invention is heated to 240° C. or lower, the darkening time due to light irradiation can be shortened as the temperature increases. However, if the temperature exceeds 240°C, bleaching occurs instantaneously, so it is necessary to darken at a temperature below 240°C, and for safety reasons, it is preferable to darken at a temperature of 200 to 230°C. In addition to components that are unintentionally mixed in as impurities in the chalcogen compound used in the present invention, Al,
Si, P, S, Ge, As, In, Sn, Sb, Te or Tl
10mol of one or more elements selected from
% or less will not adversely affect the performance of the chalcogen optical waveguide of the present invention. Example 1 Ga powder and Se powder (each with a purity of 99.999%) were mixed in atomic percentages of 0:100, 3:97, 5:95,
Mix at a ratio of 10:90, 20:80, 30:70, 35:65, 40:60, seal each mixture in a quartz ampoule, heat and melt in vacuum at 1100℃ for 10 hours, and then rapidly cool. Five types of Ga-Se compounds with different component ratios were obtained. Next, this was taken out and pulverized, and five types of powder obtained were sequentially used as vapor deposition sources to form Ga--Se chalcogen compound thin films with different component ratios on glass substrates using a vacuum vapor deposition apparatus. The deposition conditions at this time were: substrate temperature: 30°C, deposition rate: 50A/min, degree of vacuum: 2×10 ^-5 torr, and the thickness of the obtained Ga-Se chalcogen compound thin film was 5000A. Furthermore, the glass substrate on which these thin films were deposited was transferred to another vacuum evaporation apparatus, the substrate temperature was maintained at 25 to 30°C, and 1
Paraxylylene was used as a deposition source at a vacuum level of ×10 ^-3 torr, and a protective film of paraxylylene was coated on the thin film. The thickness of paraxylylene at this time is approximately
It was 1.5 μm. 8 types with different component ratios adjusted as above.
Figure 1 shows an investigation of the refractive index change of a Ga-Se chalcogen compound thin film, and the refractive index of the thin film is approximately
It is changing from 3.6 to 2.7. Next, the Ga-Se chalcogen compound thin film with the above eight component ratios was heated with a xenon lamp (intensity
It was heated to 210° C. while irradiating with 100 mw/cm ² ). It was observed that the transmitted color of the thin film changed from orange to blackish brown due to this irradiation and heating. This phenomenon is darkening, which is common in chalcogen materials. At the same time, the refractive index of the thin film obtained also changes. Table 1 shows the changes in the refractive index of the eight types of Ga--Se chalcogen compound thin films before and after light and heat treatment. Furthermore, among the Ga-Se chalcogen compound thin films with eight different component ratios in the bleaching state,
A chalcogen glass thin film sample with a composition of Ga0.1Se0.9 and laminated with paraxylylene was exposed to a He-Ne laser beam (λ=
6328Å) is focused on a minute area with an aperture (spot diameter of 100μ) and irradiated onto an arbitrary optical circuit pattern, a crystallization phenomenon due to darkening appears in this minute area, and the refractive index of this minute area changes the light. Compared to the refractive index of the unaffected part,
It increased with the range of change shown in Table 1. It can also be seen that by performing such operations, any optical circuit pattern waveguide can be easily formed. From the above, the chalcogen optical waveguide of the present invention can be formed into an optical waveguide with a freely patterned pattern by simply irradiating it with light, and has better boundary surface precision than conventional vacuum evaporation methods, so it is an optical waveguide with less light scattering loss. It turns out that it is a wave path.

[Brief explanation of drawings]

Figure 1 shows the chalcogen compound used in the present invention.
A graph showing changes in refractive index when changing the content ratio of Se:Ga. FIG. 2 is a diagram showing a method of forming a waveguide of the present invention by irradiating light onto a chalcogen thin film formed on a substrate, in which 1: chalcogen compound thin film layer, 2: paraxylylene protective film, 3: glass substrate, 4: Laser beam, 5: Condensing lens,
6: It is a light condensing spot.

Claims (1)

[Claims] A chalcogen compound having a composition of 65 to 97% Se and 3 to 35% Ga at 1 mol% has a wavelength that changes locally.
1. A chalcogen optical waveguide, characterized in that it is irradiated with light of 300 to 800 nm at a temperature of 240° C. or lower to create a difference in optical refractive index between the irradiated portion and the non-irradiated portion. 2. The chalcogen optical waveguide according to claim 1, wherein the chalcogen compound is a chalcogen compound formed in the form of a thin film on a substrate surface. 3. The chalcogen optical waveguide according to claim 2, wherein the chalcogen compound is a chalcogen compound deposited in the form of a thin film on a plate glass surface.