Multiband Phase-Modulated RoF Link With Coherent Detection and Bandpass Sampling

Bandpass sampling-based coherent detection of multiband subcarrier multiplexed signals was experimentally demonstrated over phase-modulated radio-over-fiber links. Theoretical analysis and experiments are conducted to evaluate the transmission performance. In addition, for multiband transmission, an effective method for determining the valid analog-to-digital converter sampling frequency ranges is derived to ensure no aliasing in the presence of frequency offset. Two quadrature phase-shift keying subcarrier signals were successfully transmitted and recovered over 50.6-km fiber transmission. The experimental results demonstrate that the bandpass sampling performs error free transmission with ~9 dB the sensitivity penalty when the sampling rate decreases from 10 to 1 GSa/s. The hardware independence and computational complexity reduction is worth of this performance loss.