Linearity performance of optoelectronic frequency down-conversion by using dual-series polarization modulator

We proposed and demonstrated a RF-to-Digital photonic link for relaying microwave signals over an optical fiber and linear converting the microwave signal to digital domain. The system uses two cascaded polarization modulators to achieve microwave-optoeletronic mixer. Two parallel polarization controllers (PC) and polarization beam splitter (PBS) are connected to the output of receiver PolM in order to realize I/Q intensity demodulation. We further show that by simply merging the coherent demodulation with DSP, the dynamic range of the system is significantly improved to 112dB-Hz^2/3 at 14 GHz. In this scheme, the fluctuation of optical phase noise has no impact on the stable performance of the system.