Simplified adaptively modulated optical OFDM modems using subcarrier modulation with added input/output reconfigurability

Three novel designs of adaptively modulated optical orthogonal frequency division multiplexing modems using subcarrier modulation （AMOOFDM-SCM） are proposed, for the first time, each of which requires a single inverse fast Fourier transform/fast Fourier transform （IFFT/FFT） operation. These designs not only significantly simplify the AMOOFDM-SCM modem configurations, but also offer extra unique network features such as input/ output reconfigurability. Investigations show that these three modems are capable of supporting more than 60 Gb/s AMOOFDM-SCM signal transmission over 20, 40 and 60 km single mode fibre （SMF）-based intensity modulation and direct detection （IMDD） transmission links without optical amplification and chromatic dispersion compensation.