Timing restoration for a series of input pulses is performed optically in a transmission or switching system, using a nonlinear material with negligible walk-off that also receives an essentially orthogonally polarized series of reference pulses. In the nonlinear material, the input pulses are frequency...http://www.google.fr/patents/US5224194?utm_source=gb-gplus-shareBrevet US5224194 - All-optical timing restoration
