Showing papers by "Koichi Asatani published in 1981"

Speckle Noise Reduction in Fiber Optic Analog Video Transmission Using Semiconductor Laser Diodes

Abstract: This paper investigates the effects of speckle noise on analog video transmission systems using semiconductor laser diodes. The system linearity degradation due to speckle noise is examined using different fiber types. Then this paper proposes a new modulation technique employing a superimposed pulse scheme to reduce speckle noise. It is experimentally confirmed that the proposed modulation method is effective in reducing speckle noise. Based on the above investigations, analog video transmission experiments are performed using single-mode fibers, step-index multimode fibers, and graded-index multimode fibers in the 0.8 and 1.3 μm wavelength regions. The results of the transmission tests have confirmed the feasibility of analog video transmission using semiconductor laser diodes.

Optical broadcast communication network

Abstract: PURPOSE:To avoid the echo produced by a coupling line and to expand an optical broadcast communication network in an easy way, by expanding the constitution of the said communication network with connection of plural star couplers CONSTITUTION:The n units of terminals 1-1-1-n are connected to n pieces of output optical fibers of a star coupler 1' as well as to n pieces of input optical fibers of a coupler 1 of a star coupler pair 1 The terminal 2-1-2-n of a star coupler 2 are connected in the same connecting way as mentioned above The pair of 1 and 1' are connected to the pair of 2 and 2' by supplying the output optical fiber of the coupler 1 to the coupler 2' and supplying the output optical fiber of the coupler 2 to the coupler 1' respectively