Navel Research Labs has developed and patented [U.S. Patent No.
6,154,299, awarded November 2000] the solid state multiple quantum
well (MQW) modulating retroreflectors (MRR). This high bandwidth
(greater than one megabit per second), low power (tens of milliWatts)
device impresses an external modulation onto an interrogating laser
beam. NRL has been pursuing a host of applications in both terrestrial
and spaceborne environments. Initial devices have been developed
for applications near 980 nanometers. More recently devices have
been developed and demonstrated for operation near 1550 nanometers.
web link: http://mrr.nrl.navy.mil/