Abstract

The increasing in capacity of WDM transmission systems demands higher spectral efficiency. Several techniques, such as narrow-band modulation¹ and bandwidth limitation,^2,3 have been proposed. However, the principle is the same: minimize the overlap between neighboring channels and separate one channel by an optical filter completely. A power penalty arises when the channel spacing is close to the modulation bandwidth due to coherent closstalk of overlapped spectra or due to intersymbol interference when a narrow optical filter is used.¹ As the result, the spectral efficiency has been limited. In this paper, we propose and experimentally demonstrate a novel scheme for WDM systems to overcome the spectral efficiency limitation.

© 2002 Optical Society of America