JPH0158492B2 - - 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 an optical switch requires relatively high voltage and large current to obtain driving force, resulting in large power consumption. Furthermore, especially in communication devices and the like, if the switching of an optical switch is uncertain, light leaks into an optical path other than the optical path to be transmitted, resulting in a so-called crosstalk problem.

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 capable of switching optical paths while reliably preventing crosstalk at low voltage and low power consumption in order to utilize the electro-optic effect. Therefore, in the present invention, metal is diffused in a strip shape onto a substrate made of an optical crystal or a semiconductor, and two waveguides are crossed to form an entrance waveguide and an exit waveguide directed from one side to the other. A waveguide switching electrode is provided on or around the waveguide intersection on the surface, and at least one electrode is provided on the extension of the entrance waveguide.
Crosstalk prevention electrodes are provided on each exit waveguide.

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 band shape on a substrate 5 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 layers. For example, waveguides 1, 4 and 2, 3 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. A switching electrode 6 is provided at the center of the crossing portion 9 of the waveguide, and a grounding electrode 7 is provided adjacent to this. In this example, the optical entrance waveguide is 1, the exit waveguide is 3 or 4, and 2 is used as a backup waveguide. In this case, a crosstalk prevention electrode 8 is provided on the exit side waveguide 4.

In the optical switch configured as described above, if a voltage of the same potential is applied to the switching electrode 6 and the crosstalk prevention electrode 8, the refractive index of the lower part of these electrodes changes and light is reflected there. Therefore, waveguide 1
The light incident on the switching electrode 6 is reflected at the lower part of the electrode 6 and switched to the waveguide 3 due to a change in the refractive index within the waveguide caused by the DC or DC voltage applied to the switching electrode 6. In this case, the electrode 6 is located at the center of the intersection, and its size is, for example, 600 μm x 10 μm.
It is strip-shaped. At this time, the light that leaks without being reflected at the lower part of the switching electrode 6 travels straight to the waveguide 4, but since this light is reflected at the lower part of the crosstalk prevention electrode 8, the light that enters the waveguide 4 is Almost completely gone. Therefore, when the light traveling straight from the waveguide 1 to the waveguide 4 is reflected by the switching electrode 6 to change its course and is switched to the waveguide 3, the light will leak into the other exit side waveguide 4. The light is gone;
Crosstalk phenomena are thus prevented. Incidentally, the ground electrode 7 may be provided on the entire lower surface of the substrate 5 or at any other suitable location.The light from the waveguide 2 can also have the same effect as in the case 1 with the same structure.

The optical switch with the above configuration has no mechanical drive part, has a simple structure, and almost no current flows between the electrodes, resulting in low power consumption, and the voltage is applied by the on/off operation of an electrical switch. Alternatively, by not stopping the optical path, the optical path can be switched reliably, and the occurrence of crosstalk can be completely prevented.

[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... Substrate, 6...
...Switching electrode, 7...Earth electrode, 8...Crosstalk prevention electrode.

Claims (1)

[Claims] 1 Diffuse metal in a band shape on a substrate made of an optical crystal or a semiconductor to cross two waveguides to form an entrance waveguide and an exit waveguide going from one to the other, and cross the waveguides on the upper surface of the substrate. An optical switch comprising a waveguide switching electrode provided on or around the part, and further a crosstalk prevention electrode provided on at least one exit waveguide as an extension of the entrance waveguide.