Exploring the Third-Order Non-linear Optical Responses and Optical Limiting Properties of p-Nitroaniline Picrate: A Theoretical and Experimental Study

The current study investigates the nonlinear optical behaviour of p-nitroaniline picrate, which has been synthesized and characterized. Its third-order non-linear optical properties were investigated via Z-scan studies. p-Nitroaniline picrate demonstrates a reverse saturable absorption, as indicated by a positive absorption coefficient (b), which is of the order 10–12 m/W. Closed aperture data indicate a positive refractive non-linearity due to self-focusing, with non-linear refractive index (n2), third-order susceptibility (χ(3)) and second-order hyperpolarizability (g) in order of 10–19 m2/W, 10–13 esu and 10–34 esu, respectively. Theoretical calculations corroborated the experimental findings, emphasizing the significant third-order non-linearities of p-nitroaniline picrate. An optical limiting property is demonstrated with a threshold of 16.32 J/cm2. Low HOMO-LUMO energy gaps, intermolecular hydrogen bonding and intramolecular charge transfer interactions are the properties that are related to these qualities according to DFT research. Therefore, p-nitroaniline picrate is highly recommended for the optical limiting applications.