Patent ID: 8837948

Claim:
An apparatus for processing a signal light from free-space to amplify said signal light for free-space optical communication comprising: a wave division multiplexer connected to a multimode er-doped fiber carrying the signal light; a multimode circulator connected to the wave division multiplexer wherein the multimode circulator is driven by a diode driver and a diode; a band pass filter coupled with the wave division multiplexer wherein the band pass filter is connected to the multimode circulator which in turn is connected to the wave division multiplexer; a tap coupler wherein the tap coupler connects the band pass filter to a receiver subsystem detector and also directs the signal light to an automatic gain control detector; an automatic gain control circuit connected to the automatic gain control detector; a counter-pumped diode driver connected to the automatic gain control circuit; and a counter-pumped diode connected to the counter-pumped diode driver, wherein the counter-pumped diode counter pumps the amplified signal light to the wave division multiplexer.