Temperature-dependent refractive index of potassium acid phthalate (KAP) in the visible and near-infrared

We report an investigation of the temperature-dependence of the refractive index of potassium acid phthalate (KAP) crystal. Refractive index measurements are based on a refractometer setup operating in a temperature range from 25 degrees C to 200 degrees C and using five different laser wavelengths in the visible and near-infrared. Temperature-dependent dispersion relations are proposed, with an average fitting quality that exceeds experimental accuracy, and compared to previous room-temperature Sellmeier equations. Consequently, the new relations are employed for the calculation of various linear and nonlinear optical properties of KAP. (C) 2011 Elsevier B.V. All rights reserved.