Scintillation index of a multiwavelength beam in turbulent atmosphere

We characterize the scintillation index of a multiwavelength plane-wave optical beam that is subjected to a turbulent optical channel. It is assumed that the level of turbulence in the atmosphere ensures a weak-turbulence scenario and that the turbulence is due to the fluctuations in the index of refraction of the medium. It is assumed that the propagation path is nearly horizontal and that the heights of the transmitter and receiver justify a near-ground propagation assumption.