Performance analysis of QPSK FSO system with various operating wavelengths and adaptive optics over fog channel

We report the effect of fog over a free space optical (FSO) communications system employing quadrature phase-shift keying (QPSK) and operating within three carrier wavelengths (0.65 μm, 1.55 μm, and 10 μm). We analyze the power losses on the receiver side and the link performance in terms of the received power level and the Q factor under clear and fog-attenuated atmosphere conditions. Moreover, we present a new approach to applying adaptive optics correction in fog-attenuated atmosphere conditions where fog-induced scattering is significant. This simulation experiment introduces field tracing based numerical simulation techniques and ray tracing techniques. We simulate and compare collimation of the laser beam for all three wavelength-based FSO systems, with and without objective lenses.