Free Space Optical Quantum Communication Channel Modelling to Predict Losses under Diverse Weather Conditions

One of the most rapidly developing communication technologies is quantum communication. Quantum Free-Space Optical Communication (FSO) provides unlimited bandwidth for data transmission. A key barrier to FSO links is associated with the losses caused by atmospheric absorption and scattering of molecules and aerosols. In the present study, we analyze the performance of a free-space classical link for 650 nm, 785 nm, 850 nm and 1550 nm wavelengths for a link range of 0.5 Km and 50 Km. The losses due to atmospheric components such as rain, fog, snow and turbulence are predicted for different wavelengths. Also, we presented similar analysis for free space quantum link using difference frequency generation(DFG) method for both short range (0.5 Km) and long-range link (50 Km) under diverse weather conditions. It is done by combining weak wavelengths of 650 nm, 785 nm, 850 nm and 1550 nm, along with a tunable pump LASER (Krypton) to generate IR B waves (1400 nm - 3000 nm). The total atmospheric losses with DFG is compared with the losses generated without using DFG.