OPTICAL FREQUENCY-DOMAIN DIFFERENTIAL PHASE-SHIFT KEYING IN FEMTOSECOND-PULSE SPECTRAL MODULATION SYSTEMS

We propose a novel scheme of differential phase shift keying (DPSK) in the optical frequency domain, We take advantage of the intrinsic cohe rence among spectral elements derived by spectrum slicing a femtosecon d optical pulse, introducing differential phase modulation between adj acent spectral elements with a femtosecond-pulse shaper, Detection of the differential phase is achieved by a Mach-Zehnder (MZ) or Sagnac in terferometric receiver without requirement of any external phase refer ence.