LEVEL CONTROLLER OF A PLURALITY OF SYSTEM OF OPTICAL SIGNAL

PROBLEM TO BE SOLVED: To efficiently and properly adjust levels of optical signals of the respective systems by simple structure. SOLUTION: This level controller of a plurality of system of optical signals is provided with a level changing part 1 capable of changing the levels of a plurality of systems of the inputted optical signals according to a control signal, an optical switch 2 capable of selecting any of branched optical signals formed by branching output of the level changing part 1 for the respective systems, an optical sensor 3 that detects a level of the selected optical signal and a level control part 4 that switches selection of the optical switch 2 by a prescribed sequence and adjusts the control signal so that the level of the optical signal detected by the optical sensor 3 approaches a prescribed reference value REF. COPYRIGHT: (C)2004,JPO