Angular Dependences of Third Harmonic Generation from Microdroplets

Abstract

We present experimental and theoretical results for the angular dependence of third harmonic generation of water droplets in the micrometer range (size parameter $62<\mathrm{ka}<248$). The third harmonic generation signal in $p$ and $s$ polarization obtained with ultrashort laser pulses is compared with a recently developed nonlinear extension of classical Mie theory including multipoles of order $l\ensuremath{\le}250$. Both theory and experiment yield over a wide range of size parameters remarkably stable intensity maxima close to the forward and backward direction at ``magic angles.'' In contrast to linear Mie scattering, both are of comparable intensity.