Growth and characterization of novel Curcuma longa natural dye-doped sodium p-nitrophenolate dihydrate single crystals for nonlinear optical applications

The strategic inclusion of dopant materials is crucial for altering the properties of single crystals. This study explores the integration of natural dyes, specifically curcumin pigment from Curcuma longa extract, as dopants in the growth process of sodium para nitrophenolate dihydrate (SPND) single crystals. Comparative analyses between Curcuma longa dye-doped (CL-SPND) and undoped (SPND) crystals reveal significant enhancements in their growth period (24 days for SPND and 17 days for CL-SPND), optical transmittance (67% for SPND and 78% for CL-SPND), thermal stability (132 °C for SPND and 144 °C for CL-SPND) and mechanical properties. The single-crystal X-ray diffraction confirms the crystalline nature of both SPND and CL-SPND crystals. FT-IR and FT-Raman spectroscopic analyses confirm the presence of functional groups and validate dye integration into the crystal lattice. The SHG conversion efficiency of the SPND crystal was found to be 4.9 times higher than that of KDP, while the CL-SPND crystal exhibited a 5.68 times higher efficiency, making it 1.15 times more efficient than SPND. The enhanced third-order nonlinear response of CL-SPND crystals was observed using the Z-scan technique with an Nd:YAG laser.