Nonlinear absorption and optical limiting properties of the 2-amino-5-nitropyridinium dihydrogenophosphate hybrid crystal

Abstract

We report on the nonlinear absorption properties of a hybrid organic–inorganic crystal: 2-amino-5-nitropyridinium dihydrogenphosphate (2A5NPDP). Nonlinear transmission measurements with nanosecond pulses are interpreted in terms of a three photon absorption that results from a two-step process: two-photon absorption (TPA) followed by excited state absorption. The absorption properties and their polarization dependence have been studied for several crystal orientations in the visible range (450–650 nm). Optimum effects were obtained when propagation was along the crystallographic axis a → and polarization was set parallel to b → . This is in agreement with the orientation of the molecules in the crystal. In an f/5 optical system, the optical limiting properties of the crystal allow the transmitted energy to be clamped below 15 μJ on the whole visible range.