Self-clocking based on in-band pilot for ultra-high bit rates OTDM system

We demonstrated a novel self-clocking based on in-band phase-modulated pilot insertion and extraction for ultra-high speed optical time-division multiplexing (OTDM) signals. The clock recovery function is realized by inserting at the transmitter and extracting at the receiver an in-band phase-modulated pilot that is located in the data spectrum, which eliminates the need for an ultra-fast phase comparator and a phase-locked loop in the receiver. Experimental results show the clock can be successfully extracted from 160 Gbit/s OTDM data signal and employed for demultiplexing of 40Gbit/s tributaries. The self-clocking leads to fast synchronization, low timing jitter and highly stable recovered clock, which introduces 1.5 dB of power penalty with an error-free performance. The proposed method simplifies the design of an OTDM receiver and requires minor modifications of the standard OTDM transmitter.