Linear and nonlinear propagation of optical Nyquist pulses in fibers

We present an analytical and numerical description of optical Nyquist pulse propagation in optical fibers in the presence of dispersion and nonlinearity. An optical Nyquist pulse has a profile given by the sinc-like impulse response of a Nyquist filter, which has periodic zero-crossing points at every symbol interval. This property makes it possible to interleave bits to an ultrahigh symbol rate with no intersymbol interference in spite of the strong overlap between adjacent pulses. We analyze how this periodic zero-crossing property is maintained or affected by the fiber dispersion and nonlinearity, and show that it is better maintained against nonlinearity in the presence of normal dispersion.