Quadratic nonlinear-optical properties of a new transparent and highly efficient organic–inorganic crystal: 2-amino-5-nitropyridinium-dihydrogen phosphate (2A5NPDP)

• DOI: 10.1364/josab.9.000534
• Publication Date: 2008-11-13T15:00:35Z
• Authors: Z. Kotler; R. Masse; R. Hierle; D. Josse; J. Zyss
• Keywords: 01 natural sciences; 0104 chemical sciences

Linear and quadratic nonlinear-optical (NLO) properties of a new organic–inorganic crystal, 2-amino-5-nitro-pyridinium-dihydrogen phosphate (2A5NPDP), are reported. 2A5NPDP was designed to display high NLO efficiency by incorporating highly polarizable organic molecules arranged in a polar order between phosphate polyanion sheets. The material is transparent in the visible and the near-IR (from 0.42 to 2 μm) with favorable phase-matching (PM) conditions for second-harmonic generation in the 1-μm region. Crystal nonlinear coefficients responsible for PM were determined by the Maker fringe method, leading at 1.06 μm to d15 ≅ 7.2 pm/V and d24 ≅ 1.3 pm/V. The measured crystal coefficients significantly depart from oriented gas model calculations based on molecular hyperpolarizability values measured in an aprotic solution, thus suggesting important crystal-field effects and protonation contributions. Thermal sensitivity of the PM angle at 1.34 μm is found to be 155″/°C, which is considerably larger than typical values of inorganic NLO crystals and opens the way to efficient thermal tuning of phase-matched processes.