AbstractWavelength division multiplexing-based free space optics (WDM FSO) has emerged as a potential communication network candidate for last-mile access among other applications. FSO has received much attention in the last few years as a complement as well as an alternative to radio frequency-based communication due to spectrum crisis among other reasons. On the other hand, WDM has been considered as one of the next-generation optical access network candidates for bandwidth efficiency and increased data rates. A hybrid network of these two technologies thus has emerged as another research direction. In this article, we present the background, progress and the current state of WDM FSO.