Microwave-assisted extraction of betanin from beta vulgaris and their characterization and applications to nonlinear optics

Herein, we report the third-order nonlinear optical (NLO) features of the natural pigment betanin extracted from beta vulgaris (beet root) using microwave-assisted extraction (MAE) technique. The natural pigment betanin is examined via, UV–visible absorption, photoluminescence, FT-IR and 1H NMR spectroscopic techniques, respectively. Third-order NLO features of the extracted natural pigment are scrutinized by low-power CW diode laser at 532 nm wavelength. Betanin shows negative nonlinear index of refraction (n2) and positive nonlinear coefficient of absorption (β) owing to self-defocusing and reverse saturable absorption (RSA) behavior. The order of magnitude of n2 and β of betanin is measured to be 10−11 (m2/W) and 10−4 (m/W), respectively. The results firmly suggest that the natural pigment betanin extracted from red beet root is a novel optical candidate for future photonics and optoelectronics optical applications.