Novel optical line codes tolerant to fiber chromatic dispersion

A novel family of optical line codes to counteract the effects of a dispersive fiber is presented. The performance of the first code in the family, referred to as order-1 code, is analytically evaluated and compared to that of the duobinary and phased amplitude-shift signaling (PASS) codes, which are a modified form of duobinary proposed by Stark et al. (1999). The order-1 line code turns out to be very robust to chromatic dispersion and, for a given penalty, allows the bridging of a distance 1.5 times (or more) greater than duobinary. The novel family of codes was conceived by exploiting the finding that, approximately, a very dispersive fiber turns an input pulse into the form of its Fourier transform seen in the time domain. Higher-order codes allow the bridging of larger distances if combined with appropriate chirping.