title: Q-factor analysis of nonlinear impairments in ultrahigh-speed Nyquist pulse transmission.
abstract: We present detailed analytical and numerical results of the dispersion and nonlinear tolerances of RZ and Nyquist optical pulses in ultrahigh-speed TDM transmissions. From a Q-map analysis, i.e. by numerically calculating the Q-factor distribution as a function of transmission power and fiber dispersion, we found that Nyquist TDM transmission has a substantially larger Q margin as regards both dispersion and optical power thanks to ISI-free overlapped TDM. We also show that the optimum transmission power for Nyquist pulses is 2 dB lower than for RZ pulses. An analytical model is provided to explain the overlap-induced nonlinear impairments in Nyquist TDM transmission in a high power regime, which agrees well with numerical results.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Hirooka
authors.forename: Masataka
authors.initials: M
authors.lastname: Nakazawa