Measurement of the amplitude and phase transfer functions of an optical modulator using a heterodyne technique

We present a new technique that measures the full amplitude and phase transfer curves of the modulator as a function of the applied bias, from which the small signal /spl alpha/-parameter can be calculated. The technique measures the amplitude and phase transfer functions simultaneously and directly, compared to techniques where a time-consuming data analysis is necessary to calculate the a-parameter and an additional measurement is necessary to estimate the phase. Additionally, the chirp profile for all operation points can be calculated.