Free Space Optical Communication and Laser Beam Propagation through Turbulent Atmosphere: A Brief Survey

In this survey paper, a brief survey has been performed about the free space optical communication (FSO), which has emerged as an innovative hot topic in the field of research. This paper inspected about the features and challenges faced by FSO communication. Here, it is focused about atmospheric turbulence, one of the main challenge FSO has to encounter during the propagation of laser beams through free space. The survey has also been undergone regarding the various modulation schemes, and various laser optical beam profile that can be used in FSO as optical source of propagation. The analysed techniques employed for the process of modulation are Amplitude shift keying(ASK), Binary phase shift keying(BPSK), Quadrature phase shift keying(QPSK), Pulse position modulation(PPM), Pulse amplitude modulation(PAM), Pulse width modulation(PWM). Also, investigated about the effect of different types of aberrations such a tilt, astigmatism, coma, and spherical aberrations present in a turbulent atmosphere on different laser beam profiles such as Bessel Gaussian (BG) beam, Laguerre-Gaussian (LG) beam, Hermite-Gaussian (HG) beam, Helical beam.