Increase in Capacity of an IM/DD OFDM-PON Using Super-Nyquist Image-Induced Aliasing and Simplified Nonlinear Equalization

Abstract

For long reach passive optical networks, double-sideband intensity modulation and direct detection can offer the advantages of low cost and low complexity. In this paper, we investigate a joint chromatic dispersion (CD) and nonlinearity compensation technique using super-Nyquist image-induced aliasing and a Volterra series-based simplified nonlinear equalizer (SNE) in a decision feedback manner. The SNE employed in our experiments offers signal-to-noise ratio (SNR) performance comparable to the conventional nonlinear equalizers (NE), but with much fewer coefficients. The distribution of the nonlinear coefficients and the memory length of the SNE/NE are also investigated. Experimental results show that with the proposed aliasing-based CD compensation technique combined with SNE used in each down-sampled signal before per-subcarrier maximum ratio combining, the SNR can be significantly improved. The data rate of the 10-GHz optical OFDM signals is increased by 45%, 52%, and 51% after 48.8, 79.2, and 99.6 km of standard single mode fiber transmission, respectively, compared with those without CD/nonlinearity compensation.