Abstract

Chromatic dispersion in conventional single-mode fiber can cause serious degradations in the performance of optical communication systems operating in the low-loss region around a wavelength of 1.5-μm. Direct on-off keying of single-frequency semiconductor lasers results in linewidth broadening, or “chirp”, due to modulation-induced changes in the carrier density [1]. This broadening, when combined with fiber dispersion of 15–20 psec/km · nm, causes intersymbol interference in the received optical pulses and limits the bit rate and distance of operation. Low-chirp, 1.5-μm lasers have been used in laboratory systems operating at up to 4 Gbit/s over 100 km of conventional fiber [2].

© 1990 Optical Society of America