Use of Same WDM Channels in Fiber Network for Bidirectional Free Space Optical Communication With Rayleigh Backscattering Interference Alleviation

In the paper, we present and demonstrate experimentally a 10 Gbit/s on-off keying (OOK) bidirectional wavelength-division-multiplexing (WDM) free space optical (FSO) communication architecture integrated in fiber network together with 5 m free space transmission length and 25 km fiber link, respectively. To achieve bidirectional FSO link, the all WDM wavelengths can be used simultaneously to serve as the downstream and upstream traffics in the proposed FSO-WDM system. Here, four pairs of line terminations (LTs) and optical wireless units (OWUs) are integrated arbitrarily in fiber access network for confidential and bidirectional FSO connection based on the requirement of practical environment. In the measurement, the relationship of FSO signal performance and detected tolerance are also discussed and analyzed. Moreover, the WDM-FSO transmission can also avoid the Rayleigh backscattering (RB) beat noise in fiber connection.