Hybrid WDM free space optical system using CSRZ and Rayleigh backscattering noise mitigation

Abstract

Abstract Hybrid wavelength-division-multiplexing (WDM) and free space optical (FSO) access networks are getting great attention due to numerous advantages. In this work, hybrid WDM-FSO system is demonstrated for 55 km at capacity of 5 × 10 Gbit/s using compressed spectrum return to zero (CSRZ) WDM-FSO in downstream and nonreturn to zero (NRZ) in upstream for demonstrating transmitter diversity which inturn decrease the interchannel interference. For the suppression of Rayleigh backscattering (RB) interferometric beat noise, bidirectional cyclic multiplexer is employed. Cyclic multiplexer provide λ 1 to λ 5 wavelengths for optical line terminal (OLT) to ONU transmission and λ 2 to λ 6 for ONU to OLT transmission. Insertion losses of each component are considered and in the end, power budget is also calculated. Results revealed that FSO length of 780–1050 m are obtained using various WDM-FSO downstream signals and their power budget, redundant budget, maximum distance, and insertion losses also calculated.