Optical Nonlinear Properties and Optical Limiting Effect of Congo red dye under CW Laser


Nonlinear optical properties of congo red dye in tetrahydrofuran (THF) solvent are studied employing different optical techniques. Experiments are performed using the diode laser beam at 532 nm wavelength and 40mW power. The effect of nonlinearity of congo red dye in broadening the laser beam is observed. The optical limiting behavior is investigated by measuring the transmission of the samples. The nonlinear absorption coefficient is calculated using the open aperture Z-scan data, while its nonlinear refractive index is measured using the closed aperture Z-scan data. The nonlinear refractive index and absorption coefficient are found to be in the order of 4.14×10-8cm2/Watt , 1.99×10-3 cm/Watt, respectively. The results indicate that congo red dye is a potential candidate for low-power optical limiting application. The optical limiting behavior of the solvent of azo dye is also demonstrated.