We report a magneto-optic bistable device using a magnetic thin film waveguide modulator. Because of a discontinuous transmission curve of this waveguide, optical bistable operations can be obtained with a wide range of bias field at room temperature.

This letter describes transformation of an elliptical emission region of a semiconductor laser into a triple mode pattern of a graded-index optical fiber by a holographic filter. As a result of comparison of experiment with computer simulation, it has been shown that this method is effcient for the above transformation.

In this letter, the temperature properties of laser speckle pattern generated from a multimode optical fiber are studied. It is shown that the power spectral width of speckle intensity variation induced by the temperature change is proportional to the fiber length and the rate of temperature change.

An optical logic operation is reported which can perform by means of a spatial filtering. As the data encoding for the spatial filtering, the methods which used the diffraction grating is studied.

Splice Loss of LP modes in multimode graded-index optical fibers is investigated. It becomes clear that splice loss of particular mode and the excitation rate of the other modes by mode conversion is predicted from the factor, e.g. fiber axis misalignment, fiber and face gap, end fiber end face inclination.

Mode excitation of multimode optical fibers by using a computer generated hologram (CGH) is studied. The excellent field pattern of the multiplex mode, which is transmitted through the fiber, is observed in the experiment.

We report a magneto-optic analog-to-digital converter for a 2-digit case with a ternary code and a unit distance code using a multiple-reflection Kerr effect in Permalloy thin films. In our experiment, a sampling frequency could be extended up to 30 kHz.