Measurement of pulse width and amplitude jitter noises of gigahertz optical pulse trains by time-domain demodulation

We propose a technique for measuring both pulse width and amplitude jitter noises of high-repetition-rate optical pulse trains and the cross correlati on between these noises as well. The technique is based on time-domain ampl itude demodulation of three harmonic components of the detected pulse train . We applied this technique to characterize noises of a gigahertz optical p ulse train generated by an actively mode-locked Er-doped fiber laser. Corre lation between pulse width jitter and pulse amplitude jitter was observed a t low frequencies in this laser. Unlike relaxation oscillation noise, low-f requency noise is free from pulse energy jitter. Owing to its ability to me asure pulse width jitter in addition to amplitude and phase jitters, this t echnique is of great interest for characterizing noises of a wide variety o f optical pulse train sources. (C) 2001 Optical Society of America.