Investigations on Mo dye-doped PPLT single crystals for possible non-linear optical applications

We report pure Piperazinium L-tartrate (PPLT) and methyl orange (MO) dye-doped PPLT for third-order NLO applications. The crystals were grown by slow evaporation solution growth technique at ambient conditions. Both single-crystal and powder XRD evinces the monoclinic system with space group of P21. Formation of PPLT and incorporation of MO dye in PPLT was confirmed through Fourier transform infrared (FTIR) study. Calculated hardness number and stiffness constant with Vicker’s Micro hardness study portrays the soft nature of the title crystals. The decrease in bandgap of PPLT is due to the additional energy levels introduced between the valence band and conduction band which in turn increases the net polarizability of the crystal. The thermal behavior of the PPLT crystal was investigated by thermogravimetric and differential thermal analysis (TG–DTA). The third-order nonlinear optical properties such as nonlinear refractive index (n₂), absorption co-efficient (β) and susceptibility (χ(3)) were studied by Z-scan technique at 632.8 nm using He–Ne laser.