<i>In situ</i> growth of an ethyl <i>p</i>-hydroxybenzoate single crystal by the vertical Bridgman technique: a potential nonlinear optical material for third-harmonic generation

Abstract

Optically transparent single crystals of ethyl p -hydroxybenzoate (EPHB) were successfully grown by the vertical Bridgman technique. The crystalline phase and unit-cell dimensions were obtained from powder X-ray diffraction using Rietveld analysis. The presence of defects and grain boundaries was investigated by high-resolution X-ray diffraction. The optical quality of the grown single crystal was assessed by UV–Vis and photoluminescent spectroscopies. A blue emission, with a bi-exponential decay time, was obtained from time-resolved photoluminescence upon laser excitation at 266 nm. The mechanical strength of the EPHB single crystal was studied by Vickers hardness testing. A decrease in the laser-damage threshold was observed with a nanosecond Nd:YAG laser source for increased pulse repetition rates. The third-order nonlinearity, nonlinear absorption coefficient and nonlinear refractive index were measured using the Z -scan technique with a femtosecond Ti:sapphire laser. The third-order nonlinear coefficient values for the grown crystal were compared with those of a potassium dihydrogen phosphate single crystal.