Abstract
We propose and demonstrate an all-optical phase noise reduction scheme that uses optical nonlinear mixing and tunable optical delays to suppress the low-speed phase noise induced by laser linewidth. By utilizing the phase conjugate copy of the original signal and two narrow-linewidth optical pumps, the phase noise induced by laser linewidth can be reduced by a factor of similar to 5 for a laser with 500-MHz phase noise bandwidth. The error-vector-magnitude can be improved from similar to 30% to similar to 14% for the same laser linewidth for 40-Gbit/s quadrature phase shift keying signal. (C) 2014 Optical Society of America