Wavelength shift keying technique to reduce four-wave mixing crosstalk in WDM

In low dispersion fibers, the four-wave mixing (FWM) spectrum is symmetric with respect to the zero-dispersion wavelength. This thesis analyzes a wavelength shift keying (WSK) technique, a modification of the standard wavelength division multiplexing (WDM) system. WSK uses symmetric wavelength assignment and balanced detection to cancel FWM crosstalk to first order. Error probabilities for both dispersion shifted fiber and non-zero dispersion shifted fiber were calculated using Gaussian approximation. WSK out-performs standard on-off WDM at all signal power levels and allows a larger bit rate-distance product for a given BER requirement. Four-Wave mixing in a long-haul transmission scenario was simulated in an experimental testbed. BER measurements compared well with the calculations and proved that WSK is indeed noise tolerant