Narrow-linewidth discrete-mode laser diodes for coherent communication applications

Lasers with narrow-linewidth emission are a key component for higher-order modulation formats. We report on discrete-mode laser diodes designed for narrow-linewidth emission and demonstrate linewidths less than 80 kHz. Using these devices in quadrature phase shift keying and 16-quadrature amplitude modulation transmission setups, similar performance to that of an external cavity laser is demonstrated.