In 2003 University Roma Tre patented an innovative multiport passive planar lightwave circuit (PLC) with an arrayed-waveguide grating (AWG) configuration, that is able to optically implement the discrete Fourier transform. The device has been used to simultaneously generate and process a large number of optical codes in optical code division multiple access (OCDMA) networks, as well as optical packet switching (OPS) systems.
The Nippon Telegraph and Telecommunications (NTT) Electronics has manufactured several prototypes, in collaboration with the National Institute of Information and Communications Technology (NICT) Tokyo and Osaka University, Japan. The AWG-based device has been used to encode/decode multiple users also at different wavelengths in worldwide record experiments.
Large part of research investigation focused also on the OPTICAL SECURITY of OCDMA-based systems. The same configuration has been used to optically implement the orthogonal frequency division multiplexing (OFDM) in the EU-funded ASTRON project. In this project, a Terabit integrated transceiver has been fabricated that enables the wide and cost-efficient deployment of flexible core and access networks. The photonic device has been also modified for hybrid Time-Frequency Multiplexing to implement the optical fractional Fourier transform within the Japanese STARBOARD project