A novel multi‐ary PolSK modulation for downstream signal in wavelength reusing wavelength division multiplexing passive optical network

A novel modulation, that is, multi‐ary polarization shift keying (PolSK) modulation is proposed for wavelength division multiplexing passive optical networks (PONs) to achieve colorless optical network units. The downstream signal applies the proposed multi‐ary PolSK to eliminate the induced crosstalk to the remodulated amplitude shift keying upstream signal. Different from traditional PolSK, there are more than two polarization states in the proposed multi‐ary PolSK, so it provides higher bit rates and spectra efficiency. Four‐ary and 6‐ary PolSK are demonstrated and evaluated by simulation. The results show the proposed multi‐ary PolSK supports high‐speed downstream signal in future PONs with very low crosstalk induced to the remodulated upstream signal.