Analysis Of Multiple Laser Beams Propagation Characteristics And BER In Non-Kolmogorov Turbulence

With our in-depth research on lasers, it’s applications also gradually increasedrecently. When the laser propagation in the atmosphere, the turbulence produced byatmosphere will affect the laser beam, and these include the scintillation effect. Thescintillation effect will produce impact for atmospheric laser communication thestability and reliability,the bit error rate in the transmission of information will bechanged. So researches on the scintillation effect and bit error rate which caused byturbulence has a very important significance.This paper describes the basic formation and the statistical properties ofatmospheric turbulence, and put Non-Kolmogorov turbulence spectrum, sea turbulencespectrum as the main content. Firstly, the scintillation effect of Gaussian beam, flat-topped beam and annular beam on Non-Kolmogorov turbulence has been calculate andanalysis.And then discussed the relationship between the radius of the beam waist, thebeam order, source size, wavelength, spectral index and transmission distance onscintillation index and bit error rate. Secondly, we analysis and calculated thescintillation of the marine atmospheric spectrum on the flat-topped beam and annularbeam. And then discussed the influence of source size, beam order on scintillation indexand bot error rate. And studied the influence of several modulation to bit error rate onSNR, which only caused by atmospheric turbulence. Finally, introduced several methodon reducing scintillation index and bit error rate. The results showed that: under weakNon-Kolmogorov turbulence the scintillation index first increases after reaching a peakwith the spectral index increases and then decreases with the spectral index increase.The scintillation index Gaussian beam decreases with the increase of the beam waist;For the flat-topped beam, the scintillation index decrease with beam order, source size,wavelength increase; For the annular beam, the scintillation index is about the size ratioof two source size; The scintillation index under marine atmosphere spectrum is smallerthan on lande,but the fundamental change law is consistent with the land. The bit errorrate increases with the scintillation index. Using these characteristics of flat-toppedbeam and annular beam,the scintillation index and bit error rate can be reducedeffectively, which can optimize the wireless atmosphere communication; PPMmodulation can reduce the error rate effectively,and improve the performance of lasercommunication systems. These studies have great significance in the development of atmospheric lasercommunication systems.