Modified terahertz optical asymmetric demultiplexer for the extinction ratio enhancement of all-optical NRZ-to-inverted-RZ converter

Abstract

In future all-optical networks, it is likely that both WDM and OTDM will be incorporated, and there will be a need for all-optical data format conversion/reconversion between WDM and OTDM [1]. Nonretum-to-zero (NRZ) and retum-to-zero (RZ) formats are mostly used among a variety of data formats. NRZ format has the merit of lower bandwidth requirement and higher timing jitter tolerance than RZ format, while RZ format Is preferred in ultra-fest OTDM networks to make use of bit-interleaving technique. Some previous works have demonstrated NRZ-to- (inverted)-RZ converters using nonlinear optical loop mirror (NOLM) and cross-gain compression of semiconductor optical amplifier (SOA) [1]. NRZ-to-inverted-RZ converter based on cross-gain compression of SOA has the merit of simplicity in construction, though its extinction ratio (ER) is poor. To improve ER, we have serially added a modified terahertz optical asymmetric demultiplexer (TOAD) [2] to the converter. In this paper we propose and demonstrate ER enhanced NRZ-to-inverted-RZ converter.