Nonlinear optical characteristic curve of protein (BSA)

The third-order nonlinear optical property, nonlinear refractive index ( $$n_2$$ ) of Bovine Serum Albumin has been measured with the reagent Coomassie Brilliant Blue (R-250) by varying the incident laser intensity at the wavelength 514 nm. The closed aperture Z-scan technique, with a chopped laser, has been used to measure $$n_2$$ and the obtained results are of the order of $$\sim 10^{-7}$$ esu. A variation of one order is also observed with the increase in the dye (R-250) concentration. An approach to determine the optical biomarker is also described with the help of a characteristic curve.