A promising nonlinear optical feature in natural green dye for optical limiting applications

Third-order nonlinear optical (NLO) features of chlorophyll, a natural green dye is obtained from Coleus amboinicus is reported herein for the first time. The natural dye is characterized by UV-Visible, FT-IR and gas chromatography mass spectrum. Third-order NLO parameters such as nonlinear refractive index (n2) and nonlinear absorption coefficient (beta) are measured by facile Z-scan method using closed aperture and open aperture (OA) technique, respectively. A low power laser working at 650 nm wavelength with continuous output of 5 mW is used for the experiments. The self-defocusing nonlinear refractive index and reverse saturable absorption based nonlinear absorption coefficient is presented. The measured values of n2 and beta are found to be - 1.96 x 10-7 cm2/W and 6.06 x 10-3 cm/W. Third-order NLO susceptibility of chlorophyll extracted from C. amboinicus is measured to be 6.75 x 10-7 esu. Furthermore, the optical limiting (OL) study is conducted, and the sample shows a low OL threshold of 2.15 mW. The overall results suggest that the natural dye extracted from C. amboinicus seems to have a significant material for photonics and optoelectronics applications.