Design of nonlinear optical response of multipole-type excitons by film   thickness and incident pulse width
  We theoretically investigate the nonlinear optical pulse responses of excitons in a thin film where the excitonic center-of-mass motion is confined. A large interaction volume between excitons and radiation yields particular coupled states with radiative decay times reaching several femto-seconds. By considering two polarization directions of light, we reveal that these fast-decay modes dominantly survive in an optical Kerr spectra even under a massive nonradiative damping $\Gamma=30$ meV. The results clearly show that there is an optimal combination of the incident pulse width and the film thickness for maximizing the integrated intensity of nonlinear signals. 
Takashi Kinoshita and Hajime Ishihara
cond-mat.mtrl-sci