Integrated quantum well modulators for very high speed transmission systems

This paper summarises work currently performed within the European program RACE, under contract R2006 WELCOME, Quantum Well Components for High Speed Transmission Systems. The introduction of Integrated Broadband Communication (IBC) services requires solutions that enable high capacity transmission and distribution of information at low cost, including the integration and possible upgrade of existing networks. A currently discussed approach is based on direct detection schemes at very high bit rates on one optical carrier. Optical communication systems based on standard fibres presently achieve data rates of 10 Gbit/s. The most stringent limitation appears to be the dispersion of standard fibres which limits the bridgeable fibre length. Residual chirp which always accompanies intensity modulation has not only to be minimised. For adjustable low negative chirp, however, the maximum fibre length can be even increased above the dispersion limit of chirp-free fibre transmission. In the WELCOME project several approaches for transmission with direct detection and low chirp intensity modulation at bit rates of 10 Gbit/s and above have been successfully demonstrated. Among them, electroabsorption (EA) modulators have shown their potential to fulfil these requirements