Livio Paradiso

Electrical spectral technique for measuring cross-phase modulation impact in WDM optical systems

An electrical spectral technique to correctly evaluate cross-phase modulation behavior in intensity modulation-direct detection systems is proposed. Intrinsic advantages of the technique, in terms of high accuracy, are discussed in comparison with the classical time-domain method, which requires precise receiver noise characterization. Measures have been performed with a pump-and-probe scheme on different standard optical communications fibers (i.e., G.652, G.655). The employed pump has been intensity modulated by a nonreturn-to-zero alternate pattern at different bit rates (from 1 to 10 Gb/s), with 0.8- and 1.6-nm pump-probe wavelength spacing. The experimental results are compared with the time-domain technique when accurate calibration is performed.

40-Gb/s RZ-DQPSK time-polarization interleaving

Time-polarization interleaving 40-Gbit/s RZ-DQPSK with 100-ps symbol-slot is received with integrated equipment designed for 10-Gsymbol/s DPSK detection without polarization demultiplexing. BER comparison with other 40 Gbit/s equivalent modulation formats is experimentally investigated in back-to-back configuration.

Effect of Optical Filtering on 20-Gbit/s RZ-DQPSK Transmission over 2000 km in a 64-Channel DWDM System

We analyze 20-Gb/s RZ-DQPSK transmission in a 33-GHz spaced 64-channel DWDM system over a 2000-km laboratory straight line. In particular filtering impact on DQPSK modulation format due to optical filter and a de-interleaver at the receiver and pre-filter at the transmitter are experimentally evaluated and commented.

Separate Evaluation of Nonlinearity-Due Q Penalties in Long-Haul Very Dense WDM Optical Systems

Nonlinearity-due Q penalties are experimentally evaluated on a 2000-km, 33-GHz spaced DWDM system, dependently on system length and channel spacing. SPM, FWM and XPM, which is found to be the major constrain, are separately addressed.