A simple method for measuring the RF halfwave voltage of phase modulators

We propose a simple and straight-forward method for measuring the RF half-wave voltage of electrooptic phase modulators based on the gain compression of phase-modulated photonic link with interferometric demodulation. By using network analyzer, we measured the RF half-wave voltage of the phase modulator with two MZI differential delay times of 486 ps and 35 ps. The measurement results approximate the typical value of the phase modulator under test. Moreover, the gain of link calculated by measured RF half-wave voltage fits well with the gain directly measured by network analyzer. Our experiment shows that this measurement method is easy to operate and has a high accuracy.