All-optical ultrafast pulse recording/regeneration

All-optical ultrafast pulse recording/regeneration Institute for Laser Science Associated Professor Hajime NISHIOKA nishioka@ils.uec.ac.jp http://alr.ils.uec.ac.jp/
		Difference between spatial and frequency domain phase- conjugation mirrors.
Because of broad spectrum, an ultrashort pulse changes its temporal phase structure due to Group-Delay-Dispersion (GDD). The frequency-domain phase-conjugation mirror generates a time-reversed replica of the initial pulse shape after pass through again the same GDD medium.
	A femtosecond time-reversed replica generated by time to frequency transformation.
As well known as the photon-echo system, time-reversal operation requires frequency resolved coherent interaction to resonant matters. Introducing nonlinear coherence transformation techniques (frequency to time or frequency to spatial frequency), the time-reversal operation has been demonstrated in a nonresonant medium such as a piece of glasses. The frequency multiplexed nonlinear optics is effective for pulse-to-pulse coherent summation including WDM optical memories and phase-sensitive optical encoder/decoder.