Novel training symbol structure for transmitter IQ mismatch compensation for PDM CO-OFDM at 100Gb/s

We propose a novel training symbol structure for polarization division multiplexed (PDM) coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. We deduce the mathematical model for the scheme. Based on the given model, a novel compensation method is introduced to compensate the IQ imbalance. The theoretical analysis is validated by numerical simulation, in which we apply the Quadrature Phase Shift Keying (QPSK) modulation at a data rate of 75.211Gb/s over 50 km and data rate of 100Gb/s over 320 km transmission. Compared with the commonly used approach, the proposed scheme demonstrates better system BER performance against IQ imbalance.