JPH0324650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical switch for switching a light transmission path using an electro-optic effect used in an optical communication system or the like.

Conventional optical switches switch optical fibers used as transmission lines by placing a plurality of optical fibers facing each other and mechanically moving the opposing optical fibers to each other. Such optical switches require relatively high voltage and large current to obtain mechanical driving force, resulting in large power consumption.

The present invention has been made in view of the above points, and an object of the present invention is to provide an optical switch that can reliably switch optical paths with low voltage and low power consumption in order to utilize the electro-optic effect. For this reason, the optical switch according to the present invention is formed by diffusing metal in a band shape on an optical crystal or semiconductor substrate and intersecting two waveguides.
Triangular waveguide switching electrodes are provided on both opposing outer sides of the waveguide crossing portion on the surface of the substrate in close contact therewith.

The drawing is a perspective view of an embodiment of an optical switch according to the present invention. Optical crystals that are ferroelectric (e.g.
A metal such as titanium (Ti) is vapor-deposited in a strip shape on a substrate 8 made of a semiconductor (LiNbO ₃ , LiTaO ₃ , etc.) or a semiconductor with a thickness of about 1 mm, and then diffused by heat treatment at 1000°C for 5 hours to form two intersecting strips. For example, waveguides 2, 3 and 1, 4 with a width of 10 μm and a thickness of 4 μm
form. The refractive index of the portion formed by diffusing titanium in this way is larger than that of the substrate material, and light travels within this waveguide while being repeatedly totally reflected on its inner wall surface. By appropriately selecting the intersection angle of the intersection portion 5 of these two intersecting waveguides, the width, thickness, etc. of the waveguides, the light from the waveguide 1 can be adjusted to, for example, an intersection angle of 2°, a waveguide width of 10 μm, etc. Thickness 4μm
can be bent at the intersection 5 and guided to the waveguide 3. A switching electrode 6 is disposed on the outside of the crossover portion 5 in close contact therewith, and a grounding electrode 7 is disposed on the opposite side.
will be provided. Such switching electrodes 6, 7
As shown, are two triangular shapes whose bases are substantially parallel to each other. A suitable DC or AC voltage is applied between these electrodes 6 and 7 from a power source 9 via a switch circuit 10, for example from several volts to several +.
By applying a voltage, the refractive index of the substrate 8 below the switching electrode 6 can be changed to be approximately the same as the refractive index of the waveguide. Therefore, the light also passes through the lower part of this electrode and is expanded to include the lower part of the electrode at the intersection of the waveguides, and by appropriately forming the shape of this electrode (of its total reflection surface), The light from the waveguide 1 can be guided straight to the waveguide 4. In this way, the path of light from waveguide 1 to 3 is switched to path 4, but it is also possible to switch the path of light from waveguide 2 from 4 to 3. Furthermore, the lights from the waveguides 1 and 2 can be simultaneously switched to mutually intersecting waveguides or to waveguides that are separated from each other. Note that the grounding electrode 7 may be provided on the entire lower surface of the substrate 8 or at any other suitable location.

The optical switch with the above configuration has no mechanical drive part, has a simple structure, and almost no current flows between the electrodes, so power consumption is low, and voltage can be applied or stopped by the on/off operation of the electrical switch. By doing so, it becomes possible to reliably switch the optical path by utilizing the phenomenon of total reflection of light. In addition, since the electrodes are placed close to the outside of the waveguide intersection so that they do not overlap with the waveguides and do not form any gaps, the light passing through the waveguides is not affected by the electrodes and propagation loss can be kept low. Furthermore, when a voltage is applied to configure the lower surface of the electrode as part of a waveguide, light can be efficiently propagated using the lower surface of the electrode as part of the waveguide.

[Brief explanation of drawings]

The drawing is a perspective view of an embodiment of an optical switch according to the present invention. 1, 2, 3, 4...Waveguide, 5...Cross section, 6
...Switching electrode, 8...Substrate.

Claims (1)

[Claims] 1 Diffuse titanium in a strip shape onto a LiNbO ₃ or LiTaO ₃ optical crystal substrate to a width of 10 μm and a thickness of 4 μm.
It is formed by intersecting two waveguides at an intersection angle of 2°,
Triangular waveguide switching electrodes are provided on opposite sides of the waveguide crossing portion on the substrate surface, and the substrate portion below the switching electrode is controlled by controlling the voltage application to the waveguide switching electrode. An optical switch characterized in that the refractive index is made approximately equal to the refractive index of a waveguide.