Abstract

Future communication networks will increasingly require alloptical functions to overcome the speed and architectural limitations of electronics. Clock-recovery is one such potential function that could benefit from an all-optical approach and several groups have demonstrated all-optical clock-recovery by a variety of techniques. This includes using self-pulsating laser diodes,¹ the Kerr nonlinearity in fiber,² and mode-locked fiber lasers.^3,4 In all of these cases, however, the return-to-zero (RZ) data format has been used. RZ data contains a clock-component at the data ring making clock-extraction relatively-easier than for the case of non-return-to-zero (NRZ) data. NRZ data, however, having a better bandwidth efficiency, is widely used in current lightwave systems. The only study to date of NRZ all-optical clock recovery is work by Barnsley.⁵ However, in that work it was necessary to use a regular (i.e., non-random) data pattern. In this paper, we demonstrate for the first time the feasibility of all-optical clock-recovery using NRZ pseudorandom data.

© 1996 Optical Society of America