Abstract

The spectral as well as coherence properties of gain- and index-guided semiconductor lasers are very different for cw operation.¹ Gain-guided lasers exhibit a multimode emission spectrum with a single-longitudinal mode linewidth of typically 5-50 GHz, corresponding to a coherence length of the order of 1 cm. in contrast, index-guided lasers emit a single-longitudinal mode with a few megahertz linewidth, corresponding to a coherence length of ~100 m. It is generally believed that these differences determine possible applications of the respective laser type in optical fiber communication systems, because the loss dispersion and noise performance are governed by the emission spectrum and coherence length of the transmitter.

© 1983 Optical Society of America