Demultiplexed detection of ultrafast optical signal using interferometric cross-correlation technique

A novel demultiplexing method using the interferometric cross-correlative technique is described and experimentally demonstrated for detecting ultrahigh-speed optical signals. In the proposed technique, cross correlation between the local pulse is observed through the first-order mixing of lightwaves to detect the existence of signal pulses. The only factor limiting the bit rate is the pulse width of the local oscillator´s light: the responses of all other phenomena including detector´s electrical circuits do not affect the maximum signal detection speed. Several characteristic of the detection method are clarified through the theoretical investigation. In an experiment, the demultiplexed detection of a 25 Gb/s pulse train is successfully demonstrated, for the first time to the author´s knowledge, using the proposed method