Abstract

Electroabsorption intensity modulators offer the potential for a low cost source for high bit rate, long haul transmission when they are integrated with a semiconductor laser. The presence of positive frequency chirp in the modulator generally results in poor transmission performance over standard-dispersion fiber. Previous chirp-characterization methods have used the measurement of the linewidth enhancement factor a from the relative sideband strength¹ and the fiber-response technique² Although a is useful for comparing devices, the system performance is determined by the temporal distribution of the various frequency components in the transmitted light, which cannot be found from knowledge of a alone. This paper reports a novel technique for determining the influence of operating wavelength on the chirp of the transmitted light under digital modulation and shows how it may be used to achieve negative chirp, pulse narrowing, and an extended transmission distance.

© 1995 Optical Society of America