Abstract
The power penalty induced by imperfect phase recovery in PSK homodyne communication systems with balanced phase-locked loop receivers are exactly evaluated. Optimum phase deviations between the mark-state and the space-state bits are used in this study. This study for the first time shows the imperfect-phase-recovery-induced power penalty as a function of laser linewidth with optimum phase deviations considered. It can be estimated from the theoretical result that an optimal balanced PLL receiver requires the laser linewidth as Δν ≤ 1.15 × 10 -6 × (bit rate) in contrast to the previous reported one Δν ≤ 5.88 × 10 -6 (bit rate). We also point out here that the previously reported laser linewidth requirement was wrongly estimated.