Abstract

Droplet morphology influences the internal field of the incident plane wave in several major ways: (1) The spatial distribution of the internal field is either confined near the circumference or focused toward the forward portion of the droplet, depending on whether the incident wavelength λ_i does or does not correspond to one of the many morphology-dependent resonances at λ_n,_i. (2) The intensity within the droplet can be greatly enhanced, particularly when λ_i = λ_n,_i. (3) A spread in the propagation vector results when λ_i ≠ λ_n,_i and a standing wave results when λ_i = λ_n,_i. For four-wave mixing nonlinear processes, these modifications affect the effective interaction length, the local nonlinear polarization, and the phase-matching conditions. Examples of CARS and coherent Raman mixing from individual droplets are presented. For threshold- dependent nonlinear phenomena, such as laser emission and stimulated Raman scattering, the droplet morphology acts as an optical cavity for specific wavelengths (λ_s = λ_n,_i within the fluorescent or Raman gain profile. Examples will be presented on laser emission and stimulated Raman scattering which exhibit multiple order Stokes emission (without anti-Stokes emission) and asymmetric broadening for CS₂ droplets due to phase modulation.

© 1985 Optical Society of America