Abstract

The advent of high-quality single-frequency injection lasers (e.g., Refs. 1-3) for the 1.55-μm wavelength of minimum loss in single-mode silica fiber has made possible high-data-rate long-distance transmission. High bit rates over long distances were previously not possible in this fiber window because of the significant dispersion at 1.5 μm, and the multifrequency nature of long-wavelength Fabry-Perot lasers. While a number of sophisticated techniques. Including coherent modulation and heterodyne detection, show promise for future lightwave systems,⁴ the relative simplicity of direct modulation and detection continues to make this scheme attractive even as bit rates are pushed into the multigigabit regime.

© 1985 Optical Society of America