Ultrafast technologies in 160 Gbit/s transmission systems

Abstract

Today, commercial fiber optical transmission systems are operated at a data rate of 10 or 40 Gbit/s per wavelength channel. The optical time division multiplexing (OTDM) technique allows for the investigation of the next generation TDM data rate of 160 Gbit/s while electrical signal processing at 160 Gbit/s is not yet available. In an OTDM transmission system, the key functions of the transmission system are realized using ultrafast all-optical or electro-optical network elements. In this paper, the recent progress in ultrafast technologies for 160 Gbit/s OTDM transmission systems is reviewed. The focus will be on techniques to realize optical pulse sources and ultrafast optical gates which operate on a time scale of a few picoseconds to a few hundred femtoseconds. They are the key elements of a 160 Gbit/s OTDM transmission system and are applied for various functions in the system. The paper focuses in particular on the application of ultrafast optical technologies for measurement purposes. In an optical communication system the quality of the data signal can be inferred from the optical eye diagram of the data signal. Presently, the measurement of optical eye diagrams at a data rate of 160 Gbit/s is inhibited by the limited bandwidth of photodetectors and electrical sampling oscilloscopes. By realizing an all-optical sampling system using the ultrafast technologies discussed before, the bandwidth of such an optical sampling system exceeds 400 GHz and allows for eye diagram measurements up to 320 Gbit/s.