Open AccessSimultaneous clock recovery and dispersion, OSNR monitoring for 112-Gbit/s NRZ-DQPSK using frequency down-conversion electro-optical phase-locked loop
Author(s) -
He Wen,
Lin Cheng,
Jinxin Liao,
Xiaoping Zheng,
Hanyi Zhang,
Ye Guo,
Bingkun Zhou
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.00b687
Subject(s) - optics , clock recovery , phase shift keying , phase locked loop , phase noise , physics , polarization mode dispersion , symbol rate , clock signal , bandwidth (computing) , bit error rate , dispersion (optics) , computer science , telecommunications , jitter , channel (broadcasting)
A cost effective clock recovery scheme simultaneously providing signal performance monitoring is proposed for high speed electrical time domain multiplexing (ETDM) transmission systems to release the bandwidth requirement on the involved electrical devices. In the scheme, we first convert the clock frequency down in the optical domain using electroptic modulation, and then extract the clock with a phase locked loop (PLL) after photo-detection. All the devices involved are operated at frequencies lower than half of the symbol rate. Furthermore, we use a quadrature phase detector in the PLL to create a monitor signal which characterizes the transmitted signal performance in terms of optical-to-noise ratio (OSNR) and accumulated chromatic dispersion (ACD). This scheme is applied to a 112-Gbit/s none-return-to-zero (NRZ) differential quadrature phase shift keying (DQPSK) system. Experimental results show that the clock can be recovered in a dispersion range of -40 to 40 ps/nm, and the evaluated OSNR, over a range of 18~36 dB, has a deviation smaller than 1 dB compared to the measured one based on the optical spectrum method. The bit error ratio remains below 10(-9) for 12 hours in the back-to-back case and 2 hours after transmission over 100-km standard single mode fiber (SSMF).