Optical nonlinearity of Tectona Grandis L.f. (teak) leaf extract under continuous wave and pulsed laser excitation

Abstract

In this work, we investigate the linear and nonlinear optical properties of the natural dye obtained from Tectona Grandis L.f. leaves by solvent extraction. Tectona Grandis L.f. of the Verbenaceae family, which provides high-quality, high-value timber for various uses, is a major strategic element in the forestry economies of many tropical countries. We investigated the nonlinear optical properties at 532 nm using CW and pulsed (5 ns) lasers, employing the techniques of Z-scan and Spatial Self phase modulation (SSPM). Theoretical fits to the measured data under CW excitation give the third-order nonlinear absorption coefficient (β_eff) in the order of 10^-3 cm/W, and the nonlinear refractive index coefficient (n₂) in the order of 10^-6 cm²/W, respectively. The β_eff and n₂ values obtained for pulsed excitation are in the order of 10^-8 cm/W, and 10^-15 cm²/W, respectively. These values are comparable to those of efficient nonlinear optical (NLO) materials previously reported in literature, revealing the applicability of the teak leaf extract natural dye in optical limiting applications for protecting sensitive optical detectors and human eyes from hazardous laser radiation.