Noise Characterization in Free Space Polarization Modulation   Communication Using Simulated Atmospheric Conditions in Laboratory
  We present a practical scheme for measurement-device-independent polarization shift keying using two state polarization encoding. Most of the previous work on optical free space laser communications through the atmosphere was concentrated on intensity modulated systems. However, polarization modulated systems may be more appropriate for such communication links, because the polarization seems to be the most stable characteristic of a laser beam while propagating through the atmosphere. Thus, a detailed comparison between intensity and polarization modulated systems is of much interest. We analyse the noise in presence of simulated smoke and fog conditions within laboratory and propose a practical scheme for extracting message from the received data. The proposed method uses only two detectors to analyse the polarizations and the practical definition of state of polarization enables a higher signal-to-noise ratio even in presence of depolaration elements in atmosphere such as fog and smoke. The system also takes into account existing imperfections within the experimental setup and hence is more robust. 
Ram Soorat and Ashok Vudayagiri
physics.ins-det