Time-dependent scintillations of pulsed Gaussian-beam waves propagating in generalized atmospheric turbulence

Expressions for both the temporal first- and second-order intensity moments of pulsed Gaussian-beam waves passing through generalized atmospheric turbulence are derived under the near- and far-field approximations, respectively. With the help of these expressions, the time-dependent scintillation behavior of optical pulses during propagation in generalized atmospheric turbulence is examined by numerical calculations. The effects that the spectral index of the spatial power spectrum of refractive-index fluctuations has on the temporal dependence of pulse scintillations are analyzed under the condition that the generalized plane-wave Rytov variance is specified as a constant for various spectral indices. It is shown that both the near- and far-field scintillations of an optical pulse are less dependent on time as the spectral index becomes smaller, indicating that there does exist a significant difference between the time-dependent scintillation behavior of an optical pulse in non-Kolmogorov turbulence and that in the Kolmogorov one. The obtained results are helpful for understanding the time-dependent scintillations of optical pulses propagating in generalized atmospheric turbulence and hence are useful for practical applications.