Phase retrieval for coherent detection in short-reach links using self-interference of aggregated optical OFDM subcarriers

Low-complexity coherent detection using self-interference of aggregated optical orthogonal frequency division multiplexing (O-OFDM) subcarriers is proposed. Self-interference among the aggregated O-OFDM subcarriers is employed to recover their relative phase relationships through the variation in the obtained power spectra. The differences in a few preselected principal spectral components are successfully demonstrated based on the phase states of four O-OFDM subcarriers modulated via quadrature phase shift keying (QPSK). We experimentally verified self-interference and bit error rate reaches 10(-3). The number of bits available in the proposed method increases with the number of subcarriers, gradually approaching that in QPSK beyond OOK.