Two-Photon Absorption Measurements: Establishing Reference Standards.

Abstract : Two-Photon Absorption "TPA" is an important phenomenon taking place at high light intensities and consisting in simultaneous absorption of two low energy photons to generate a higher energy excited state of a material. Materials showing efficient two-photon absorption are required for a number of applications including information storage, photonic signal processing, optical power limiting, nonlinear microscopy of biological systems etc. This report contributes to the knowledge of parameters influencing the two-photon cross section values obtained by direct absorption measurements and provides representative data for comparison with other techniques.