Cost-efficient, polarization-insensitive and widely-tunable AOWC of OFDM signal based on FWM in SOA

In this paper, we propose a cost-efficient, polarization-insensitive and widely-tunable wavelength conversion scheme for orthogonal frequency division multiplexing (OFDM) signal based on four-wave mixing (FWM) in semiconductor optical amplifier (SOA). In this scheme, electrical OFDM signal directly drives directly modulated laser (DML) to achieve intensity modulation, then the modulated signal lightwave and pump are coupled and injected into a polarization-diversity structure for performing FWM in SOA. The analytical results show that the proposed scheme is polarization-insensitive and has a wider conversion range compared with the parallel pump scheme and orthogonal pump scheme. We have also numerically demonstrated wavelength conversion of 16QAM-OFDM signal by employing the proposed scheme. The results can be agreed with the theoretical analyses. In addition, the impact of input optical power, line-width of external cavity laser (ECL) and injection current of SOA on the system performance are also studied.