ABNORMALITY DETECTION CIRCUIT FOR OPTICAL MODULATION ELEMENT, OPTICAL TRANSMISSION DEVICE UTILIZING THE SAME AND ABNORMALITY DETECTION METHOD FOR OPTICAL MODULATION ELEMENT

摘要

PROBLEM TO BE SOLVED: To enable determination of disconnection of a line L and to prevent light transmittance from being left increased and from resulting in failure of blocking light.SOLUTION: In one or more detection points P provided on a line L between a drive circuit 15 that drives an optical modulation element EAM and the optical modulation element EAM, drive current that drives the optical modulation element EAM passing through the line L is detected and whether the detected drive current is within or beyond a normal range is determined to determine disconnection of the line L.