Abstract

While the capacity of optical fiber transmission systems has rapidly increased over the last decade, the signaling technique employed in the majority of realizations has remained binary on-off key (OOK) modulation using direct detection. There has been increasing interest in alternative signaling techniques, including partial response (duobinary) signaling¹ and 4-ary OOK,² but these approaches have not yet resulted in wide deployment. In this work, we outline a new optical signaling format that combines multi-level phase modulation with direct detection. Key advantages compared to conventional OOK are a doubling in spectral efficiency, relaxed dispersion management and a four-fold increase in PMD-limited transmission length. The technique demonstrates the potential to enable cost-reduced 10 Gb/s and 40 Gb/s systems.

© 2002 Optical Society of America