Effect of external stresses on the optical and electronic properties of potassium dihydrogen phosphate crystals

Potassium dihydrogen phosphate (KDP) has been extensively used in electro-optic switches and laser spectroscopy in modulating the frequency of laser radiation. When making refined optical KDP components for such applications, the external stresses in the manufacturing process can introduce changes in their optical and electronic properties. With the aid of the ab initio density functional theory analysis, this paper investigates the effect of stresses on the absorption coefficient, band gap, refractive index, dielectric function and Plasmon energy. It was found that the stress-induced variations in these properties are due to a change of KDP molecular structures. The microstructural changes induced by the uniaxial (along the < 110 > direction) or by the biaxial (< 100 > and < 010 > directions) or by the triaxial (< 100 >, < 010 > and < 001 > directions) tensile stresses bring about significant changes in the optical and electronic properties of KDP.