PURPOSE: To reproduce an optical clock signal from a NRZ(Non-Return-to Zero) signal and to reproduce an optical clock signal not only from an inputted light intensity modulated or amplitude modulated but also from an inputted light phase modulated.
CONSTITUTION: This circuit comprizes an asymmetric Mach-Zehnder interferrometer 12, composed of a branching device 22 for branching the input light 21 into two, two delay lines 23, 24 having different lengths from each other connected to the branching device 22 and a joining device 25 for joining two delay line outputs, and an optical self-exciting oscillator 14, composed of an external resonator type semiconductor laser including an element for changing the polarization direction of light within the resonator to which the output light 26 of the joining device 25 is inputted, a means for inputting the output of the joining device to the semiconductor laser and an analyser for extracting specified polarization light and an optical clock signal synchronized with the input signal is outputted from the amplitude modulated or phase modulated input light by means of NRZ.
HABARA TAKASHI
HIMENO AKIRA
