Multiple Smallsat Downlink
Regardless of whether data is collected over a geostationary orbit (GEO), low earth orbit (LEO) or medium earth orbit (MEO) satellite network, the data will need to be downlinked to a ground terminal for retrieval and dissemination. As traditional satellite RF transmission links are relatively slow compared to FSO links, optical may become the primary backbone to uplink and downlink satellite networks.
New developments in technology have successful demonstrated that converting from traditional RF designs to optical communications will be a tremendous step forward in the application of data downlink capabilities of LEO small satellites. LEO observation smallsats currently provide more data than can be processed by current technology due to limitations in power, the availabilty of the RF spectrum, pass durations and access to ground stations. The amount of data being downlinked is expected to grow as the number of LEO smallsats in-orbit increases. There are many doubts in the capability of RF to handle this vast amount of data; therefore, a new data transmission alternative is required to provide a greater bandwidth while offering a service that is fast and secure. 
NASA: Small-satellite laser communications
Paper: A CubeSat-based optical communication network for low earth orbit
Paper: Survey of inter-satellite communication for small satellite systems