Abstract In this demonstration, we propose and investigate experimentally a bidirectional wavelength-division-multiplexed (WDM) free space optical communication (FSO) system integrated with fiber access network for wireless traffics. Here, there are four 10 Gbit/s on–off keying (OOK) WDM-FSO signals would propagate through a 25 km single-mode fiber (SMF) transmission and a 6 m free space transmission length for the bidirectional downstream and upstream FSO traffics. Moreover, an accurately simulation of detected powers of FSO wavelength under different free space transmission lengths can be estimated based on the proposed WDM-FSO system architecture. Therefore, according to the experimental and simulated results, the bidirectional WDM-FSO transmission can achieve 1000 m free space transmission length based on the obtained power sensitivity of each FSO signal.