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 standar...