(Solved): A \( 500 \mathrm{Mb} / \mathrm{s} \) return to zero data transmission system uses a GaAlAs laser d ...

A \( 500 \mathrm{Mb} / \mathrm{s} \) return to zero data transmission system uses a GaAlAs laser diode that has a \( 1 \mathrm{~nm} \) spectral width. The rise time of the laser transmitter output is \( 0.2 \mathrm{~ns} \). Over the transmission distance of \( 30 \mathrm{~km} \) using a graded-index fibre, the bandwidth- distance product is \( 1800 \mathrm{MHz} . \mathrm{km} \). (i) If the receiver bandwidth is \( 1 \mathrm{GHz} \) and the mode-mixing factor \( q=0.7 \), determine the system rise time if the material dispersion is \( 0.07 \mathrm{~ns} /(\mathrm{nm} . \mathrm{km}) \). [5] (ii) With respect to the Return to Zero (RZ) data requirement, discuss whether the rise time obtained in (i) is acceptable or not.