Third order nonlinearity examined by pulsed and CW lasers: an organic urea barbituric acid (UBA) single crystal for optical limiting application with DFT study

Abstract

Bulk size of urea barbituric acid single crystal which has not been reported earlier was successfully grown by slow evaporation solution growth method. Single-crystalXRDbrought out the lattice constant and the crystal system is observed to be monoclinic with space group P. Functional group of UBAwere determined by FT-IR.UBAcrystal is entirely visible from 270 to 900 nmwith linear optical energy gap value to be 4.50 eV. The observedHOMO–LUMOenergy gap was 5.21 eV. Thermally, UBAcrystal is found to be stable up to 184°°C. TheCp value ofUBA increases from 1.21 to 1.58 J g−1K−1 with the temperature difference from 30 to 100°°C.UBA shows good photoconductive nature and it found to be positive and Laser Damage Threshold (LDT) value ofUBA crystal is 0.97GWcm−2. Hardness testing confirms thatUBA crystal belongs to soft nature category. Dielectric properties ofUBAcrystal are studied as a function of frequency and temperature. Third orderNLO properties of theUBA crystal were studied underCWand pulsed lasers (ns) regimes using Z-scan technique. Good Optical limiting (OL) response (2.2860 х 1012W/m2) confirms the efficiency ofUBA crystal to be used as optical limiters for protection towards short pulse lasers.