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 1×10-9.