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.

Integrated detection optics for magnetooptical (MO) disk pickup are proposed. The pickup consists of a waveguids device, external lenses, a beam splitter and a laser diode. The detection optics is constructed by integrating a trifocal focusing grating coupler and five photodiode elements in a glass-film waveguide on a Si substrate. The design considerations and fabrication are described, and experimental results are reported. The wavelength bandwidth of the devices are discussed in relation to the wavelength instability of laser diode. Although the obtained performances are not sufficient for practical application, the elementary functions, i.e., MO signal readout, focusing error detection and stabilization by multimode LD, were successfully demonstrated in the simulation experiments.

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.

We fabricated high-quality domain-inverted MgO: LiNbO$_3$ structures with 3.0 and 2.0~$mu$m periods using applying votage to the corrugation electrode. We found that keeping the crystal temperature at 150$^{circ}$C for 12 hours before applying voltage was effective for obtaining good uniformity. We also demonstrated an application of the structures with 3.0~$mu$m period to electro-optic Bragg deflection modulator for the first time.

A tunable external-cavity InGaAs/AlGaAs quantum-well laser using a grating coupler monolithically integrated in a selectively disordered waveguide is demonstrated. The laser consists of an amplifier with a narrow channel for lateral single-mode guiding and a tapered section, a grating coupler for output beam collimation and wavelength dispersion, and an external half mirror. Selective quantum-well disordering technique using SiO2 caps of different thicknesses and rapid thermal annealing was employed to reduce the passive waveguide loss in the grating coupler region. Loss reduction from 40 cm-1 to 3 cm-1 was accomplished. Resultant increase of the grating coupler efficiency and expansion of the effective aperture length led to significant improvement of the laser performances. The maximum output power of 105 mW and wide tuning range of 21.1 nm centered at 997 nm were obtained. The well collimated output beam of full diffraction angles at half maximum of 0.16 0.18 was obtained.