We experimentally demonstrate a 4-Gb/s radio-over-fiber (RoF) system with 40-km fiber and 2-m wireless distance downstream at 100-GHz carrier.To the best of our knowledge,this is for the first time in China to realize optical wireless link at 100 GHz.In this letter,simple intensity modulator with direct detector (IM-DD) modulation is employed and optical power penalty after 40-km single mode fiber (SMF)-28 and 2-m air link is 3.2 dB with bit-error-rate (BER) at 1 x 10-9.