PURPOSE: To cancel the dispersion in an optical fiber in high performance without converting an optical signal to an electric signal and even when the dispersion exists in a difference of optical path lengthes.
CONSTITUTION: In an optical circuit constituting a multistage asymmetrical Mach-Zehnder type interference device constituted so that directional couplers 6, 7, 8, 9 whose lengthes of two pieces of input ports are different from each other and the lengthes of two pieces of output ports are different from each other are cascade connected in multistage among the ports with long lengths and among the ports with short lengthes, and the directional coupler 5 whose lengthes of two pieces of output ports are equal is connected to the prestage, and the diretional coupler 10 whose lengthes of two pieces of input ports are equal is connected to the poststage, the asymmetrical Mach-Zehnder type interference device consisting of two 3dB directional couplers 33, 34, two pieces of arms 29, 30 and heaters 43, 44 is connected to the prestage of the optical circuit as a gain adjuster.
OKAMOTO KATSUNARI
KOMINATO TOSHIMI
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