Abstract

Coherent optical transmission systems require a semiconductor laser diode with narrow linewidth and stable operation. For example, DPSK or CPFSK modulation schemes in the Gbit/s region require a linewidth of 1 MHz or less. The linewidth has usually been reduced by various external cavity configurations. A fiber-external-cavity configuration¹ is one of the most promising for practical use, since it can offer a compact optical source insensitive to mechanical vibration. From this viewpoint, we have developed compact and stable DFB-LD modules using a fiber external cavity.

© 1988 Optical Society of America