An 112 Gbit/s real-time coherent passive optical network downlink transmission experiment over 100 km standard single mode fiber with 1∶128 splitting ratio is demonstrated. Adaptive dispersion compensation digital signal processing in the real-time receiver has compensated 100 km dispersion and 50 km dispersion difference with almost no power penalty and 43.5 dB power budget has been achieved.
DWDM networks have been evolving to higher spectral efficiency. To make optical duobinary format,
which is considered as a suitable modulation format in MAN DWDM networks, can work in 50GHz
channel spacing 43Gb/s DWDM networks is very significant. In this paper, it is pointed out that the
delay time in delay-and-add optical duobinary system is one of key factors which affect system
performance. The suitable delay time for 43Gb/s systems compatible 50GHz with 100GHz channel
spacing is obtained by system simulation. The simulation results show that 0.8 bit delay time is more
suitable for 43Gb/s ODB DWDM system at compatible 50 with 100GHz channel spacing than 1 bit delay
time because of its higher Q value and bigger dispersion and nonlinearity tolerance.
Transmission performances of 10Gbps DWDM NRZ, RZ and CSRZ system are compared by both theoretical simulation and experiment. Simulation shows the NRZ, RZ and CSRZ have different duty cycle, spectrum and chirp characteristics, which are the main reasons for different transmission performances. Simulation also shows that NRZ has the largest dispersion tolerance. The chirp of RZ brings out more jitter than the other two modulation formats do during transmission. CSRZ has less pulse distortion induced from dispersion due to its chirp characteristics.
Our simulation is verified by experiments with a multi-channel 10Gbps ultra long haul system. The experiments of our transmission system show that both NRZ and RZ system can transmit above 3200km, and CSRZ can transmit as far as 5490km.