Digital coherent detection with bandpass sampling in multiband phase-modulated radio-over-fiber links

Abstract

The performance of using bandpass sampling technique in optical phase-modulated and coherent detection (PM-CD) radio-over-fiber (RoF) links is analyzed. Additionally, a method to select aliasing-free bandpass sampling frequency is derived. This method is suitable for subcarrier multiplexing (SCM) scenario with the presence of independent free-running optical local oscillator (LO) caused frequency offset. Analytical assessment and simulations are used to determine the ultimate performance with respect to ADC bits resolution and laser linewidth. The simulation result shows that 8 bit resolution and narrow laser linewidth (less than 100kHz) are expected to achieve high performance link for undersampling applications in the PM-CD RoF links.