Experimental research about a 40 GHz orthogonal frequency division multiplexing radio-over-fiber system based on optical phase modulator

We demonstrate a 40 GHz radio-over-fiber system using an optical phase modulator along with an intensity modulator to generate an optical millimeter-wave with OFDM signals. In the central station, 40 GHz optical millimeter-wave with OFDM signals is generated by using an optical phase modulator which is driven by the 20 GHz RF signals. Then the optical carrier is filtered out by an FBG. 2.5 Gbit/s OFDM signals are modulated on 40 GHz optical mm-wave directly and transmitted to the base station over 50 km standard single-mode fiber (SSMF). In the base station, the optical mm-wave signals are converted to electrical signals after optical-electrical conversion, and the down-converted OFDM signals are detected after mixing with the local oscillators. The experimental results show that at the BER of 10^-3 and without dispersion compensation, the power penalty of the downlink OFDM signals transmitted over 50 km SMF-28 is less than 1 dB, and the constellation figure is still good.