Practical design of a high-efficiency relief-type waveguide hologram is demonstrated for the future integration of holograms in optical IC. The hologram is recorded in light-sensitive layer on a thin film waveguide. After the exposure and the subsequent etching, one can obtain a waveguide hologram of relief type. It is shown analytically that, when the parameters are optimized, the relief type provides a high efficiency and an aperture size suitable for storing pictorial informations. Waveguide holograms were fabricated by chemical etching technique in amorphous As2S3 (recording medium)/sputtered glass film (wave-guiding layer) structure. From the intensity distribution of the diffracted light in the hologram plane, the total diffraction efficiency (the sum of the efficiencies in the air side and in the substrate side) was estimated to be 92%. This result compares favourably with the theoretical prediction, and the efficiency of 92% is remarkably higher value than that of a hologram of coventional type storing a pictorial information. Very little deterioration of the image quality owing to the etching was observed. The applicability of the method to the design of a waveguide hologram to be reconstructed by ir light was also confirmed. The high efficiency would make the waveguide hologram of this type promising also as an advancement of holographic circult couplers.

The light emitted from the exit end of an optical fiber can be used as the reference wave in recording a hologram and/or the illuminating wave in reconstructing it. The fundamental problems associated with such an application have been investigated. First, the radiation characteristics of a step-index fiber was analyzed and a simple scalar description, suitable for the holography application, of the far radiation field was derived. It was found that the wavefront of the radiation field is identical with that of a spherical wave radiating from the center of the fiber end. The rough estimation for the size of the far field pattern was given and the orthogonality property of the radiation field was proved. Then the wavefront reconstructing characteristics of the hologram were discussed. The resolution capability of the system was determined by using the point spread function. A reduction coefficient concept has been introduced to describe the effects of the reference and illuminating wavefronts on the diffraction efficiency. It was deduced that recording with a spherical reference wave and illuminating with light derived from a fiber result in negligible reduction of the efficiency. The feasibility of the method was proved experimentally and some theoretical predictions were also confirmed.

Two-dimensional Gunn devices are suitable for integrating many logic devices on an epitaxial GaAs layer grown on a semi-insulating substrate. In this paper, a planar Gunn device with two separated cathodes is proposed and the fundamental logic operations, such as the exclusive OR, the inclusive OR and the inhibitor functions, are discussed theoretically and experimentally. The domain dynamics in this planar device has been examined by the computer simulation. The regions of the reliable operations are also shown by a diagram. Our experimental results confirmed the above logic operations.