Fig. 1: Intensity vs polarization grating excitation.
a PP beams generate an intensity grating with period ΛTG and constant polarization. b OP beams generate a modulated polarization with the same periodicity and constant intensity. c Diffraction from an intensity TG resulting from surface modulations uz and refractive index variations. The first typically dominates the backward-diffracted signal and the latter the forward diffraction. d Diffraction from a polarization TG, where the thermal modulation depends on the dichroic absorption Δβ, reducing \({{{\bf{u}}}}_{z}^{\star }\). The signal can still originate from refractive index variations associated with the chiral dispersion Δδ.
