We show that optical receivers operated impulsively are more sensitive
than for nonreturn-to-zero (NRZ) operation. Impulsive sensitivity imp
rovements of 5.8 and 4.7 dB are measured for two pin-FET receivers usi
ng a modelocked laser transmitter, and compared to theoretical express
ions for the NRZ and impulsive Q-factors. We also show that the optimu
m detection bandwidth for impulsive coding is larger than for NRZ, in
contrast to previous models.