Remote Upconversion of Radio Over Fiber by Band-Pass Filtering of Ultra-Short Pulse

A novel remote frequency upconversion of a radio-over-fiber (RoF) signal is proposed and demonstrated. The traditional RoF signal at transmitter is replaced with frequency chirped optical pulse modulated by base-band data. During fiber transmission, the optical pulse evolves into an ultra-short pulse under the effect of fiber dispersion. The upconversion is completed at the remote antenna unit (RAU) by just selecting out the target signal spectrum, which is shifted to the wanted high order harmonics with a band-pass filter. Thereby, the RoF system is simplified by removing the mixer and high-frequency local oscillator at the central office, still keeping RAU as simple as possible. With this approach, a 2-Gbit/s data up-converted to 16 GHz is received with a BER below 10^-9 and spectrum efficiency of 1-bit/s/Hz after transmission of 45-km SMF and 7-m air without optical in-line, pre-amplificiation, dispersion compensation, and optical filtering.