Scintillation index of modified Bessel-Gaussian beams propagating in turbulent media

Abstract

The scintillation index is formulated for modified Bessel-Gaussian beams propagating in weakly turbulent media. Numerical calculations applied directly to the derived triple integral show that, for off-axis positions, the modified Bessel-Gaussian beams of higher than zero order scintillate less than Gaussian beams at large input beam sizes and low beam orders with the increasing width parameter initially contributing positively to this phenomenon of less scintillation. As the beam order exceeds two, this advantage is diminished. The modified Bessel-Gaussian beam of order zero is a special case, however, exhibiting lowest scintillation at small input beam sizes. When considered against the propagation length, higher-order modified Bessel-Gaussian beams continue to offer less scintillation than those of order zero. At various radial positions, the scintillation index of modified Bessel-Gaussian beams with orders higher than zero attains small values toward the beam edges but rises sharply when approaching the beam axis. The effect of inner and outer scales of turbulence is also studied, and it is found that while increasing the inner scale of turbulence seems to cause increases in scintillation, the influence of the outer scale is hardly noticeable.