Chromatic dispersion monitoring technique based on chirped pilot tones

We report on a chromatic dispersion monitoring technique using a direct detection of high-speed chirped pilot tones. Unlike the previously proposed monitoring technique using amplitude-modulated (AM) and phase-modulated (PM) pilot tones, the proposed technique can discriminate the sign of accumulated dispersion. The results show that the performance of this technique could not be seriously deteriorated by polarization-mode dispersion (PMD) and self-phase modulation (SPM) since the tone frequency was small (∼2 GHz).