All-optical periodic code matching by a single-shot frequency-domain cross-correlation measurement

Optical single-short measurement of the cross-correlation function between periodic sequences is demonstrated. The sequences are encoded into the broadband ultrashort phase-shaped pulses which are mixed in the nonlinear medium with additional amplitude-shaped narrowband pulse. The spectrum of the resulted four wave mixing signal is measured to provide the cross-correlation function. The high contrast between the values of cross-correlation and auto-correlation (the latter includes also the information of the sequence period) has potential to be employed in the optical implementation of CDMA communication protocol.