Abstract
A theoretical assessment of the performance of a new modulation format which is of interest for both submarine and terrestrial optical transmission is presented. It consists in increasing the extinction ratio of a standard phase-shaped binary transmission (PSBT) signal in order to obtain a high tolerance to both chromatic dispersion and signal-to-noise ratio degradation. This enables the optical power to be reduced and also therefore nonlinear effects, or the amplifier spacing to be increased. Furthermore, this modulation format yields a high spectral efficiency for wavelength division multiplexing applications.