Novel orthogonal wavelength division multiplexing (OWDM) scheme: Theory and experiment

The continuous increase of the transmission capacity demand reveals particularly interesting new modulation and multiplexing techniques targeting at high spectral efficiency (bit/s/Hz) DWDM systems. Several approaches to augment the spectral efficiency have been proposed such as vestigial sideband demultiplexing, orthogonal polarisation multiplexing and bandwidth limitation. In the meantime, the orthogonal spectrum packaging of electrical carriers has proven its high spectral efficiency and resistance to transmission channel impairments in its electrical counterpart modulation, OFDM (Orthogonal Frequency Division Multiplexing). The electrical OFDM modulation is implemented using digital inverse Fourier-transform (FT) operation in the transmitter and straight FT operation in the receiver. This approach cannot be performed at the optical domain as the digital signal processors are not available at core network line rates