Computation of Nonlinear Optical Scattering by Droplets.

Abstract

Abstract : Nonlinear interactions of optical waves with droplets can be important in optical propagation through the atmosphere and in optical characterization of droplets. (1) We developed a detailed model of optical bistability in spheres which are illuminated with an intense optical plane wave. For the analysis we used the linear relation between the shift in the location of a morphology-dependent resonance (MDR) of the sphere and the change in the refractive index of an inhomogeneous sphere (when the change in index is real and small). (2) We applied the volume current method, a first-order perturbation solution for scattering, to inhomogeneous spheres. The scattering results obtained for a small off-axis sphere inside a sphere compare well with results computed using separation of variables. For a near-resonance sphere the results do not agree as well. (3) We modeled linear time-dependent internal fields in droplets illuminated with pulses that are Gaussian in space and time. (4) We completed the analysis of spheres which contain two-photon absorbers, and hence become inhomogeneous when illuminated with light. (5) We calculated scattering by droplets having the type of radially inhomogeneous refractive index that can occur in high-temperature combustion environments. Scattering, Nonlinear optics, Droplets.