Baud-rate flexible clock recovery and channel identification in OTDM realized by pulse position modulation

We propose a novel scheme of OTDM utilizing pulse position modulation, where optical null headers (ONH) are inserted between the signal pulses periodically to allow channel identification. The ONH also achieves in-band clock distribution through the generation of high contrast pilot tone on the signal power spectra, enabling baud-rate flexible clock recovery. Using the novel scheme, clock recovery with a timing jitter of less than 200 fs is achieved at different baud rates up to 344 Gbaud. We demonstrate stable clock recovery with channel identification in 344-Gb/s OTDM transmissions over dispersion managed 3-km SMF.