Design and evaluation of a low complexity all-optical OFDM system applied to passive optical networks

Abstract

Over the year the demand for fast connections and the capacity to transmit great loads of data is one argument responsible for driving the development of new technologies and techniques to enhance the actual telecommunications networks. This work focused on studying the effects of applying an all-optical orthogonal frequency division multiplexing (AO-OFDM) process on passive optical networks (PON) for the next generation of telecommunications systems. The PON has been pointed as one solution to address the growing demand of the fast and bandwidth-hungry applications and services which are emerging from the advent of the 5G and the ever-growing popularity of smart devices. This work has shown that changing the Fourier transforms from the electrical to the optical domain not only avoid a significant data flow bottleneck, also that it is possible to enhance the actual grid further. This research had shown that it is possible to transmit over 1.28 Tbps over 90 km of standard single mode fibre (SSMF) or even it is possible to transmit over 640 Gbps over 240 km of SSMF, without any active device to amplify or repeat the signal. Additionally, aiming to minimise the number of active devices used by placing an optical flat comb (OFC) source to generate multiple wavelengths from a single continuous wave (CW) light source. The OFC is based on the recirculating frequency shifting (RFS), from which this work achieve the generation of over 128 new wavelengths timely stable and with a power peak difference of 0.3 dB. Thus, this work had shown one possible scenario where a PON was applied with OFC generating 128 optical channels, where each channel was capable of transmitting 12.5 giga-symbols per second over 240 km of SSMF.