Fiber-dispersion-induced signal fading for measuring high-frequency modulation efficiency of an electrooptic phase modulator

A novel method for measuring the modulation efficiency of electrooptic phase modulators is proposed based on the fiber-dispersion-induced signal fading. The fiber dispersion spectrally alters the relative phasing of the phase modulated signal and leads to the fading of the recovered electrical signal, from which the modulation efficiency is obtained in the case of a given fiber dispersion. The frequency-dependent modulation index and half-wave voltage are experimentally measured for a commercial phase modulator, which agree well with the results obtained using the conventional technique.