Optical waveguides – Integrated optical circuit
Patent
1990-03-20
1993-03-09
Lee, John D.
Optical waveguides
Integrated optical circuit
385 2, 385 8, G02B 612
Patent
active
051931303
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a control device for changing the direction of light or displacing the focusing point of the light.
BACKGROUND PRIOR ART
The prior art will be explained on the basis of e.g. an acoustooptic Bragg cell using an LiNbO.sub.3 waveguide path disclosed in "HIKARI SHUSEKI KAIRO" by H. Nishihara et al., published by OHM Co., page 328, and an SAW light deflecting device disclosed in the lecture of the 35-th OYO BUTSURI GAKU KANKEI RENGO KOENKAI 28a-ZQ-4. FIG. 1 shows the construction of the prior art light deflecting device. In FIG. 1, a Ti diffused waveguide layer 28 is formed on an LiNbO.sub.3 substrate 27. Laser light 30 incident on an input prism 29 becomes waveguide light 31 propagating through the waveguide layer 28. The waveguide light 31 is separated into transmitted waveguide light 33 and diffracted waveguide light 34 by a SAW light deflecting device 32. Both waveguide lights 33 and 34 are radiated from an output prism 35 as transmitted light 36 and diffracted light 37. The diffraction angle of the diffracted waveguide light 34 depends on the pitch of an elastic wave 38 produced by the SAW light deflecting device 32, and the diffraction angle of the diffracted waveguide light 34 and hence the radiation direction of the diffracted light 37 can be changed by an electric signal applied to the SAW light deflecting device 32.
The prior art light deflecting device, however, has the following disadvantages. A change of the diffraction angle caused by the SAW light deflecting device 32 is slight, so that it has been impossible to deflect the diffracted light greatly by the SAW light deflecting device 32. Further, what is deflected is diffracted light, so that the efficiency of the use of energy of the input light 30 has been low.
SUMMARY OF THE INVENTION
An object of the invention is to overcome the disadvantages of the prior art and to provide a light deflecting device capable of causing a large degree of light deflection and having high efficiency of energy utilization.
In order to attain the above object, in accordance with the present invention, there is provided a light deflecting device comprising a conductive thin film formed on a substrate, a waveguide layer formed on the conductive thin film via an intervening transparent layer, and a transparent substrate having a transparent conductive thin film formed on its surface with a liquid crystal layer intervening between the transparent conductive thin film and the waveguide layer, the waveguide layer having a cyclical structure formed on its surface along the direction of propagation of the waveguide light, whereby the waveguide light is radiated by the cyclical structure as radiated light, and the direction of the radiated light is changed by applying a voltage signal between the conductive thin film and the transparent conductive thin film. Further, the light deflecting device of the present invention is characterized in that aligning means for aligning molecules of the liquid crystal layer is provided on the surface of the waveguide layer or the transparent conductive thin film so that the aligning direction is parallel or perpendicular to the propagation direction of the waveguide light. As another characteristic aspect of the device of this invention, the cyclical structure is formed in the shape of a concentric circle and the waveguide light is propagated perpendicularly to the cyclical structure and the radiated light from the waveguide layer is focused on one or more focusing points outside the waveguide layer, whereby the focusing point can be displaced by applying an electric signal between the conductive thin film and the transparent conductive thin film. Additionally, the conductive thin film or the transparent conductive thin film may be divided into a number of sections so that the focusing point can be changed by applying an individual voltage signal to each of the sections.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a prior art light deflecting device;
FIG.
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Asada Jun-ichi
Nishiwaki Seiji
Taketomi Yoshinao
Tomita Takaaki
Uchida Shinji
Barns S. W.
Lee John D.
Matsushita Electric - Industrial Co., Ltd.
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