Measurement of the thermo-optic coefficient and Ring surface profile of sulfadiazine azo dye by using milli watts cw laser beams

Abstract

Abstract We report on the observation of thermal lens as well as multiple diffraction ring patterns due to the irradiation of the azo dye “1.8-Dihydroxy-naphthalin-3, 6 disulfonic acid [2-(4-Azo)]-N-(5-methyl-3-isoxazolyl)-benzene sulfonamide” at same time by three continuous wave, green (λ=532 nm), red (λ=635 nm) and blue (λ=473 nm), laser beams. This effect we observed at power input less than 10 mW for the pump 532 nm green laser and as low as 50 μW of beams from other two wavelengths. The number of rings for all three beams is totally controlled by the level of pump input power. The optical limiting of the azo dye solution using the 532 nm green laser beam is also demonstrated. The change in the material refractive index, Δn, the nonlinear refractive index, n 2, and the thermo-optical coefficient dn/dT are calculated based on thermal lens and diffraction ring techniques. The three quantities are found to be in the range of 10−4, 10−7 cm 2/W and 10−5 K −1 respectively by both techniques.