An Investigation on Opto-thermo-mechanical Behaviour of a Borate Family NLO Crystal for Photonic Applications

A borate family crystal, thiourea hydrogen borate, a nonlinear material (NLO), is grown, and its optical and physicochemical properties are investigated. Single-crystal X-ray diffraction study conducted reveals triclinic structure of the crystal. Energy-dispersive X-ray analysis is performed to determine the elemental composition of the material. Fourier transform infrared spectral analysis is done to identify the functional groups. Ultraviolet (UV) characterization is done to figure out the optical properties like the fundamental frequency and optical band gap for nonlinear applications. Second harmonic generation analysis shows the crystal to possess centrosymmetric structure. Third-order analysis is conducted to deduce the third-order susceptibility ( χ 3 ). Thermal gravimetric analysis and differential thermal analysis are performed to determine the decomposition temperature and process of decomposition. Mechanical stability is examined by Vickers microhardness test, and the mechanical properties have been inspected for photonic applications.