Dual frame OFDM with optical phase conjugation for MIMO system in multimode fiber

For nonlinearity and dispersion mitigation in optical fiber, the authors propose a dual frame OFDM transmission, based on optical phase conjugation. The proposed dual frame OFDM is modification of asymmetrically clipped OFDM (ACO-OFDM) frame. The proposed OFDM frame consist of two positive frames, first one is time compressed ACO-OFDM frame and second one is optical phase conjugated version of first frame. This increases the bandwidth efficiency and total transmitted power for the system. For electronic dispersion compensation (EDC) in conventional OFDM, signal pre-processing is applied at transmitter side where it requires channel information. In case of OFDM and multiple input multiple output (MIMO) system setup for multi mode fiber, channel becomes almost unpredictable. The proposed dual frame OFDM does not require EDC at transmitter side. For received optical power \(-12\) dbm conventional ACO-OFDM records bit error rate (BER) \(4.48*10^{-1}\) and proposed dual frame ACO-OFDM with OPC records BER \(2.58*10^{-4}\). Simulation results for variable fiber length show BER \(2.20*10^{-1}\) for phase conjugated subcarrier coding and \(2.24*10^{-3}\) for proposed ACO-OFDM with OPC for multi-mode fiber length 500 m. It also allows different multiframe transmission based on time and wavelength diversity.