(IPC) A Photonic Correlation Scheme Using FWM With Phase Management to Achieve Optical Subtraction

In this paper, a photonic correlation scheme that allows accumulation of negative signals is presented. The scheme uses four-wave mixing of pairs of signal and pump wavelengths, which are chosen such that they create idler wavelengths at a common wavelength. The total optical power at this target idler wavelength depends on the relative phase of each pump and signal wavelength. This concept has been applied to form a correlator where signal wavelengths are modulated by an input bit stream and mixed with pump wavelengths representing a reference bit pattern. This approach provides a correlation function with smaller unwanted noise peaks due to cancelation in the subtraction process. Simulation of the proposed correlation technique has been used to verify the concept using both intensity and phase modulation of the signal wavelengths.