ALL-OPTICAL SIGNAL REGULARIZING REGENERATION USING A NONLINEAR FIBER SAGNAC INTERFEROMETER SWITCH WITH SIGNAL-CLOCK WALK-OFF/

All-optical signal regularizing/regeneration using a nonlinear fiber S agnac interferometer switch (NSIS) that employs signal-clock walk-off is investigated. The NSIS realizes all-optical signal regeneration, in cluding timing and amplitude regularizing, by switching clock pulses w ith amplified input signals using a walk-off-induced wide, square swit ching window and intensity-dependent transmittance of the device. Firs t, characteristics (in both the temporal and spectral domains) of the all-optical signal regeneration achieved with the NSIS are investigate d theoretically and experimentally. They certify that if clock pulses are within the square switching window obtained with signal-clock walk -off, the clock pulses can be modulated according to the data that the input signals carry and retain their temporal and spectral profiles. This means that if clock pulses can be prepared that meet the system r equirements, the NSIS can convert input signals that may not satisfy s ystem requirements into high-quality output signals. Limitations on th e switching contrast due to the cross-phase modulation of counterpropa gating reference pulses is also discussed. Second, two possible applic ations of NSIS-based all-optical signal regularizing/regeneration, 1) an all-optical multiplexer with an optical clock and 2) an all-optical regenerative repeater, are discussed. Preliminary experiments with si milar to 10-ps pulses at bit rates of similar to 5 Gb / s that use loc ally prepared optical clock pulses, show that the NSIS provides an err or-free regeneration function with a certain tolerance for pulse-perio d irregularity if a proper optical clock is obtained.