Thermally induced optical nonlinearity and optical power limiting action of 2,4,5-trimethoxy-4′-nitrochalcone under CW laser regime

In the present work, we report the results of thermally induced third-order nonlinear optical (NLO) properties of 2,4,5-trimethoxy-4'-nitrochalcone (abbreviated as 2,4,5TMNC) investigated by Z-scan technique using continuous wave (CW) Argon ion laser at a wavelength of 488 nm with adjusted power ranging from 2.5 mW to 20 mW. The experiments were performed by varying the concentration of the molecules in solution. The sample demonstrated strong reverse saturable absorption (RSA) and self-defocusing effect (negative nonlinear refractive index). The estimated values of the NLO absorption coefficient (beta), nonlinear refraction (n(2)) and absolute nonlinear susceptibility chi((3)) are found to be of the order of 10(-5) m/W, 10(-11) m(2)/W and 10(-5) esu, respectively. The magnitude of the nonlinear absorption coefficient (beta) was found to increase with concentration. The linear absorption spectrum of 2,4,5TMNC was measured using UV-Vis-NIR spectrometer. The optical band gap (Eg) value of title chalcone is obtained from the tauc's plot of (alpha hv)(2) versus hv. The optical limiting performance of 2,4,5TMNCis also investigated for device application. In addition to the above, the computation studies are also carried out to attain the ground state molecular geometry which is found in close to experimental results. Time-Dependent-Density Function Theory (TD-DFT) was used to determine the UV-Vis spectrum at B3LYP/6-31G* level of theory and found to be comparable with experimental data. The HOMO-LUMO energy gap was also determined and discussed. The results promote this chalcone derivative as a promising candidate for optical limiting and optical switching applications.