JPH05165067A - Optical switch - Google Patents

Abstract

PURPOSE:To perform high speed changing-over by furnishing two light wave- guide paths intersectingly on a glass board, wherein the paths are made of a glass material having a higher refractive index than the glass board, providing an activation layer of a glass with additives of semiconductor particulates in the middle of the intersection of paths, and impressing a voltage on this activation layer. CONSTITUTION:Two light wave-guide paths 2-1, 2-2 made of a crystal glass to which germanium is added for increasing the refractive index, are provided intersecringly on a base board 1 prepared by laying a crystal glass layer on a silicon wafer. In the middle of the intersection 3 of the two paths, an activation layer 4 is provided consisting of crystal glass to which particles of lead sulphide are added, and thereupon an aluminum electrode 5 is installed to form an optical switch, wherein the particle size is 40Angstrom . The energy gap at this time is 1.5eV, and the wave-length of the light corresponding to this energy is 0.83mum. If an electric field of 10MeV/cm is applied to the activation layer, the refractive index drops by 10% for the light of wave-length 0.8mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch, and more particularly to an optical switch in which a waveguide and an electrode are formed on a glass substrate and a voltage is applied to a part of the waveguide to switch light.

[0002]

2. Description of the Related Art Among optical waveguides, a waveguide containing silica glass as a main component has a low optical transmission loss and can be connected to a silica-based optical fiber with a low loss. (Japanese Patent Laid-Open No. 63-175808). As part of the development in this field, an optical switch was devised by forming a waveguide on a glass substrate, providing a heater on a part of the waveguide, and utilizing the temperature dependence of the waveguide (1989, Institute of Electronics, Information and Communication Engineers). Autumn National Convention: C. 266, 4-206). That is, when the temperature of the glass waveguide in this portion rises by applying power to the heater, the refractive index is generally lowered due to the thermo-optic effect.

[0003]

The response speed of the switch utilizing the thermo-optic effect depends on the heating speed of the heater or the cooling speed of the waveguide. These temperature characteristics are determined by the heat capacity or heat transfer characteristics of the material forming the optical switch, but there is a limit to increase the response speed. The response speed of this type of optical switch is several msec.
It is about several + msec. On the other hand, the speed required for an optical switch in the field of optical communication is μsec to nsec, and it has been difficult to put it into practical use unless the switch has a new idea.

[0004]

The present invention is an optical switch for solving the above problems, and is characterized in that it has a higher refractive index than a substrate provided on a glass substrate in a crossed manner. An optical switch comprising two optical waveguides made of glass, an active layer made of glass added with semiconductor fine particles disposed at the intersections, and an electrode attached to the active layer for applying an electric field. is there. Here, the size of the energy gap of the added semiconductor fine particles is preferably within ± 10% of the size of the energy corresponding to the wavelength of the light transmitted through the optical waveguide.

[0005]

The function of the semiconductor is to absorb light having a larger energy than its energy gap. This is because the electrons occupying the valence band transition to the conductor. Placing a semiconductor in a high electric field changes the electronic structure that forms this energy gap. Therefore, the phenomenon of absorbing light with energy smaller than the energy gap appears. As described above, in the semiconductor, the characteristics of light absorption change depending on whether or not an electric field is applied, and the absorption spectrum changes. Due to this change, absorption increases on the low energy side (long wavelength side) and decreases on the high energy side (short wavelength side) based on the energy gap of the semiconductor when no electric field is applied. To do. When the characteristics of light absorption change, the refractive index also changes according to the Kramers-Kronig relational expression.

By utilizing this property, an optical modulator, an optical switch, etc. can be constructed. The characteristics of such a semiconductor have hitherto been known for a bulk semiconductor, but the present inventors have found that similar characteristics can be obtained even when the semiconductor is made into fine particles and added to glass. The glass to which a fine-particle semiconductor is added also exhibits excellent optical characteristics inherent to glass, so that a large bulk can be easily produced, it is chemically and thermally stable, and the amount of semiconductor particles to be added is The refractive index can be easily changed by changing it, which is advantageous in producing an optical component.

Further, since the size of the energy gap can be changed by changing the type of the added semiconductor, it is preferable to select it according to the wavelength of the light used. For example, PbS in IV-VI group, GaAs, I in IV-V group
CdS and the like are effective in the genus I-VI. Furthermore, the size of the energy gap also depends on the particle size of the semiconductor particles to be added. Therefore, if the particle diameters are made uniform, efficient characteristics can be obtained. Here, the energy gap depending on the particle diameter is preferably within ± 10% with reference to the absence of an electric field. This is because the ratio of change in the refractive index with respect to the applied voltage is remarkably reduced in the case of more than this. Hereinafter, the present invention will be described more specifically with reference to examples, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0008]

1 is a view showing an embodiment of an optical switch according to the present invention, FIG. 2 is a sectional view taken along line XX of FIG. 1, and FIG.
3 is a sectional view taken along line YY of FIG. In the figure, a substrate 1 in which a quartz glass layer is provided on a silicon wafer, and a quartz glass 2 on which germanium is added to increase the refractive index 2
The optical waveguides 2-1 and 2-2 of the book are arranged so as to cross each other. At the center of the intersection 3, an active layer 4 made by adding particles of lead sulfide to quartz glass was placed, and an aluminum electrode 5 for applying a voltage was provided thereon to form an optical switch. The particles of lead sulfide were made into 40 Å fine particles. The energy gap at this time is 1.5 eV. The wavelength of light corresponding to this energy is 0.83 μm. When an electric field of 10 MeV / cm was applied to this active layer, the wavelength was 0.8 μm.
The refractive index decreased by about 10% with respect to the light of m.

In FIG. 1, when 0.8 μm of light was made incident from port 1, the light went straight and was emitted to port 2. Then, when a voltage of 10 V was applied to the electrodes, the refractive index of the active layer was lowered, and the light was totally reflected on this surface and the
Emitted from. The semiconductor applied to the active layer is a material in which lead sulfide, cadmium sulfide, gallium arsenide, and the like are effective. Although the optical switch has been described above, the modulator can be formed by appropriately designing the crossing angle and the active layer.

[0011]

As is apparent from the above description, according to the present invention, the optical path can be switched in a short time by applying a voltage to the active layer provided at the intersection of the optical waveguides. There is an effect that it is possible to provide an optical switch that has excellent connectivity with an optical fiber and has a low loss and a simple configuration.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical switch according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view taken along line YY of FIG.

[Explanation of symbols]

 1: substrate 2, 2-1 and 2-2: optical waveguide 3: intersection part 4: active layer 5: electrode

Claims (2)

[Claims] 1. Two optical waveguides made of glass having a higher refractive index than the substrates provided on the glass substrate so as to cross each other,
An optical switch provided with an active layer made of glass to which semiconductor particles are added, disposed at the intersection, and an electrode attached to the active layer for applying an electric field. 2. The energy of the added semiconductor fine particles
2. The optical switch according to claim 1, wherein the size of the gap is within ± 10% with respect to the size of energy corresponding to the wavelength of light transmitted through the optical waveguide.