Short- to Long-Reach WDM Access Network With Free Space Optical Traffic Link

In this paper, we demonstrate a free space optical (FSO) wavelength-division-multiplexing passive optical network (WDM-PON) architecture with short-reach to long-reach fiber transmission to overcome different environments and geographical restrictions. Based on the periodic nature of the 2×N arrayed waveguide grating (AWG), the downstream and upstream wavelengths in the proposed fiber access network are offset by one channel to enable symmetric FSO data transmission. Thus, the Rayleigh backscattering (RB) beat noise can be mitigated fully. Four WDM channels are selected to transmit wireless FSO signals over the proposed PON architecture, each utilizing different modulation rates and fiber transmission distances for demonstration. In addition, the corresponding bit error rate (BER), detected power sensitivity and power budget of each WDM FSO signal are also analyzed and discussed.