NASA and the US Army have tested 100 megabit per second laser communication with a cubesat. This is 50 times better than 2 megabit per second radio communication to cubesats that are currently used.
Optical Communications and Sensor Demonstration (OCSD) CubeSat could be improved to 2.5 gigabits per second with relatively simple upgrades to the attitude control system and a few other systems. This would open the possibility of using small satellites in applications, such as synthetic aperture radar or hyperspectral Earth imaging, that produce volumes of data far beyond the capacity of radio-frequency downlink systems. It is also possible to use these satellites as data relay nodes in low-Earth orbit. Having several small satellites has the potential to provide low-latency, high-rate communications as a service for other satellites in orbit around Earth.
The OCSD cubesats are small and simple and do not have adjustable mirrors to aim their laser beams. Instead, the whole satellite rotates. It uses a sophisticated steering system — complete with tiny star trackers that takes bearings off the constellations — to aim itself within 1/40th of a degree of the intended target