Multiple scattering effects on coherent bandwidth and pulse distortion of a wave propagating in a random distribution of particles

Abstract

In this paper, integral and differential equations are derived for the two‐frequency mutual coherence function in a random distribution of stationary and moving particles. The differential equation is then solved for a plane wave case, and the coherent bandwidth is obtained for both the weak and strong fluctuation cases. Using the two‐frequency correlation function, the output pulse shape is calculated for different particle densities. When the optical distance is small compared with unity, the pulse shape is substantially unchanged, but a long tail develops. When the optical distance is large, the coherent bandwidth is reduced and considerable pulse spread and delay occur. Numerical calculations are given for a nanosecond optical pulse propagating through cloud. It is shown that in dense cloud (density 0.5×10 9 m −3 ), the pulse delay and spread are 3 and 1.28 μsec respectively over a distance of 5 km. This agrees with available experimental data.