Double-laser differential signaling for suppressing background radiations in FSO systems

In order to reduce the impact of background radiations on the performance of terrestrial FSO systems, we propose to use two laser wavelengths and to perform the data detection at the receiver in a differential mode. We consider first the case of simple OOK modulation and show the performance improvement by using the proposed technique. We also extend our study to the case of PPM modulation while proposing special signaling schemes that allow an increase in data transmission rate at the same time of reducing the background noise effect.