Femtosecond nonlinear optical investigations of nitro chalcones-doped PMMA thin films for optical limiting and photonic applications

Herein we present the linear and third-order nonlinear optical properties of two nitro substituted chalcone derivatives [3-(4-fluorophenyl)-1-(3-nitrophenyl) prop-2-en-1-one and (2E,4E)-1-(3-nitrophenyl)-5-phenylpenta-2,4-dien-1-one; abbreviated as F3NC and Ci3NC, respectively] doped PMMA polymer thin films. The chemical spray pyrolysis method was adopted to prepare the films at three different doping concentrations (5 wt%, 10 wt%, 15 wt%). The linear optical studies were performed using UV-Visible-NIR spectra, and surface roughness using AFM technique. Hirshfeld surface analysis was adopted to understand the intermolecular interactions. The third-order nonlinear optical properties were investigated using Z-scan method under Ti:Sapphire femtosecond (fs) laser pulses (~150 fs, 80 MHz, 800 nm). Open aperture and closed aperture Z-scan curves indicated the presence of two-photon assisted reverse saturable absorption and self-defocusing effect, respectively. The calculated nonlinear refraction (n2), nonlinear absorption (β) coefficients and third-order susceptibility [χ(3)] were found to be 10-12 cm2 W-1, 10-8 cm W-1 and 10-11 e.s.u., respectively. We observed increase in nonlinearity of the films with increased chalcone doping concentration. F3NC doped films exhibit a higher nonlinearity than Ci3NC doped films. The observed results reveal that chalcone-doped PMMA thin films are possible materials for optical limiting and photonic applications.