Al-Gailani, Samir AhmedSalleh, Mohd Fadzli MohdSalem, Ali AhmedShaddad, Redhwan QasemSheikh, Usman UllahAlgeelani, Nasir AhmedAlmohamad, Tarik A.2024-09-292024-09-2920212169-3536https://doi.org/10.1109/ACCESS.2020.3048049https://hdl.handle.net/20.500.14619/6094The next generation (NG) optical technologies will unveil certain unique features, namely ultra-high data rate, broadband multiple services, scalable bandwidth, and flexible communications for manifold end-users. Among the optical technologies, free space optical (FSO) technology is a key element to achieve free space data transmission according to the requirements of the future technologies, which is due to its cost effective, easy deployment, high bandwidth enabler, and high secured. In this article, we give the overview of the recent progress on FSO technology and the factors that will lead the technology towards ubiquitous application. As part of the review, we provided fundamental concepts across all types of FSO system, including system architecture comprising of single beam and multiple beams. The review is further expanded into the investigation of rain and haze effects toward FSO signal propagation. The final objective that we cover is the scalability of an FSO network via the implementations of hybrid multi-beam FSO system with wavelength division multiplexing (WDM) technology.eninfo:eu-repo/semantics/openAccessLaser beamsOptical transmittersOptical receiversOptical filtersOptical scatteringVertical cavity surface emitting lasersFresnel reflectionFSOrain attenuationhaze attenuationDWDM multiplexingand scalabilityArticle10.1109/ACCESS.2020.30480492-s2.0-850991123937373Q173539WOS:000608213900001Q2