Bulk crystal growth and characterization of imidazolium l-tartrate (IMLT): a novel organic nonlinear optical material with a high laser-induced damage threshold

Bulk transparent organic nonlinear optical (NLO) single-crystals of imidazolium L-tartrate (IMLT), with a low near-UV cutoff wavelength at 235 nm and a large powder second harmonic generation (SHG) efficiency, being 4.5 times larger than that of KH2PO4 (KDP), have been successfully grown by the slow cooling method. Kurtz and Perry powder test reveals that IMLT is a phase-matchable NLO material with good optical transmittance in the entire visible region. The laser-induced damage threshold experiments show that the grown IMLT bulk crystals possess an excellent resistance to laser radiation with a high threshold up to 7.45 GW cm−2, much larger than those of several known inorganic and organic NLO materials. Furthermore, the thermal properties associated with its high laser-induced damage threshold, including the specific heat and thermal expansion coefficients, have been investigated thoroughly as a function of temperature. The intrinsic origin of the laser-induced damage was also analyzed based on studying the surface morphologies triggered with the laser-induced damage using an optical microscope. All the findings in the present work indicate that IMLT has a potential application as a useful NLO candidate.