Characterization of AM-to-PM Conversion in Silicon p-i-n Photodiodes

We have measured the amplitude-to-phase modulation (AM-to-PM) conversion in a silicon p-i-n photodiode for the first time and found that it behaves qualitatively similar to III-V detectors previously reported in the literature. One or more minima in the AM-to-PM conversion gain as a function of average photocurrent was seen and the minima were found to depend on the reverse bias, suggesting that space charge fields produced by the separating carriers interact with the applied reverse bias and modulate the drift velocities and hence the transit times.