Optical transmission performance analysis of multi-Gbit/s QPSK on microwave subcarrier

Optical transmission of subcarrier multiplexed (SCM) microwave carriers is a powerful approach to the exploitation of the multi-GHz bandwidths of lasers. modulators, and photodiodes which are now commercially available. Although many previous studies have focussed on the use of SCM for the transmission of large numbers of analogue or digital video signals, SCM techniques can also be used to multiplex multi-Gbit/s signals to total data rates much higher than can be attained with commercially available time-division multiplexing (TDM) technology. The authors compare measured and theoretical values of the energy/bit to noise density ratio (E_b/N₀) for the optical transmission of a microwave subcarrier modulated by multi-Gbit/s QPSK signals. Data rates of 2-3 Gbit/s are used in the study.