Optics and Photonics Society of Iran

In this study, nonlinear refractive index of the dication of meso-tetraphenylporphyrin with trifluoroacetic acid was measured in solution using double gratings interferometer and triple gratings moiré techniques. Different concentrations of the diacid were used in the presence of a thermal lens induced in the fluid to investigate the effect of concentration on the nonlinear refractive index of the diacid by fixing other parameters such as the laser beam intensity. For ensuring the accuracy of the results, two methods were used for data recording and analysis the first method is double gratings interferometer and Fourier transform analysis with high accuracy and the second method is triple gratings moiré technique and four-section spatial phase shifting. The results of both methods were in good agreement with each other.