Nonlinear effect on sinc-shaped optical filter demultiplexing all-optical OFDM system

We propose a novel all-optical orthogonal frequency division multiplexing (OFDM) systems without the requirement for discrete fast Fourier transform (FFT). The liquid crystal on silicon (LCOS) programmable wavelength selective switch (WSS) is employed in this all-optical OFDM for filtering, which can generate multiple orthogonal sub-carriers on the modulated optical source of super-continuum spectrum. Based on the proposed all-optical OFDM, the error-free transmission with high spectral efficiency can be achieved in the case of no dispersion and nonlinear effect. Furthermore, we systematically analyze the impact of nonlinear effect on the all-optical OFDM transmission systems, known as the main limiting factor in dense multi-carriers systems. And system simulation indicates that in the absence of local oscillating laser and extra dispersion and nonlinear compensation algorithms, our proposed all-optical OFDM can achieve 5 km single mode optical fiber transmission with less than 5*10⁻³ bit error rate (BER) and 1*10⁻² BER when employing no more than 16 and 64 sub-carriers, respectively. From the perspective of spectral efficiency and system complexity, our proposed all-optical OFDM system shows a huge superiority over single sideband modulation in short distance transmission.