Mode separation of a multiplex mode in a mode-division multiplexing system is studied. The clear, desired single-mode pattern, which is separated from the multiplex mode by using a holographic filter, is observed in the experiment.

Phase performance in a temperature sensor using a conventional single-mode step-index fiber is studied. Two modes are excited in a so called single-mode fiber when the wavelength of a laser source is shorter than the one suggested by the specification of a fiber. The phase shift due to the temperature change of a step-index fiber is analyzed. The intensity fluctuation by the interference of two modes is observed in the experiment and estimated in the computer simulation.

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.

Phase performance in a fiber optic temperature sensor using a mode-division multiplex is studied. The phase shift due to the temperature change of a multimode graded-index optical fiber is analyzed. The intensity fluctuation by the interference of two modes is estimated in computer simulation.

A fiber optic temperature sensor using a conventional graded index multimode optical fiber is proposed. The multimode fiber is excited by two selected modes using a computer-generated holographic filter. A clear periodic signal created by interference between two modes is observed in the experiment.

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.

This study investigates a new transmission method of light from a point source in a multimode graded-index fiber. The position of the point source is arranged along with a mode pattern to precisely determine the location of an output point image. Propagation performance is observed in an experiment and estimated by simulation.

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.

Cross talk in mode-division multiplexing system is studied. The mode patterns when the fiber is bent are observed in the experiment.