Enrich data bit rate and propagation distance performance for free space optical communication (FSOC) via a new dual-diffuser modulation (DDM) technique

A new dual-diffuser modulation (DDM) technique improve the performance of the conventional intensity modulation/direct detection (IM/DD) for On Off Keying (OOK) in term of data bit rate and propagation distance. This new modulation technique employs two transmitters and two receivers to create a robust modulation with optimizing the reduction scintillation index, enhance the power received and improve the threshold signal level. At the transmitters, the laser exits combine with low cost phase screen diffuser to create a `new´ superior laser beam characteristic in order to combat atmospheric turbulence effectively. Meanwhile at the receivers, the signal will be subtracted. The analysis result shows that in comparison various data bit rates at BER10^-9, the DDM is capable to operate excellent under small power launched where the bit rate can achieved above 10Gbps at 5dBm power transmit. Meanwhile for phase screen diffuser effect, the DDM optimizes the performance of diffuser where the data bit rate can reached approximately 1.5Gbps and the conventional IM/DD-OOK only performed at 0.155Gbps.