Patent Number: 6,434,286

Title: Optical signal switching apparatus

Abstract: Variable (coupling ratio) optical couplers 3-0 and 6-0 each have ports of two inputs and two outputs, and the coupling ratio of inputted light is variably controlled by drive circuits 4-1 and 7-1. In the optical 1+1 switching structure, the coupling ratio of the variable (coupling ratio) optical coupler 3-0 is controlled to be 50%:50%. The variable (coupling ratio) optical coupler 6-0 is controlled to have the coupling ratio of 100%:0% or 0%:100%. In the optical 1:1 switching structure, the coupling ratios of the variable (coupling ratio) optical couplers 3-0 and 6-0 are controlled to be 100%:0% or 0%:100%. When a performance monitor (0) 9-0 detects signal degradation, signal interruption, and the like, the system controller 1-0 sends an instruction signal and the control circuits 20-0 and 21-0 output control signals for controlling coupling ratios of the variable (coupling ratio) optical couplers 3-0 and 6-0, respectively.

Inventors: Hayashi; Yukio (Fujisawa, JP), Kakizaki; Sunao (Kawasaki, JP), Tsushima; Hideaki (Komae, JP), Kuwano; Shinichi (Yokohama, JP)

Assignee: Hitachi, Ltd.

International Classification: H04Q 11/00 (20060101); G02B 006/26 ()

Expiration Date: 08/13/2010