Monte Carlo simulation of two-photon induced molecular orientation in solid polymer films

摘要

We present the first Monte Carlo simulations of the mechanism of two-photon induced molecular orientation by photo-isomerization of chromophores in solid polymer films. Two-photon absorption (TPA) occurring at intense laser pulses creates molecular orientation of photo-isomers proportionally to the square of the excitation intensity and the fourth power of the cosine of the angle θ between the TPA-transition dipole moment and the direction of the polarization of the excitation light. Photo-selection in cos~4 θ will result in the orientational redistribution of the chromophores differently from the well-known one-photon absorption process. Kinetic Monte Carlo model is proposed and illustrative "microscopic" results related to diffraction gratings inscription are presented.