Femtosecond nonlinear optical properties of Ti-doped In₂Te₃ thin films grown by magnetron co-sputtering

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Herein, we successfully prepared Ti-doped In 2 Te 3 and pure In 2 Te 3 films by magnetron co-sputtering at room temperature. The film structure was measured using x-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS), while the linear optical constant of the films was measured using a spectroscopic ellipsometer (SE). The nonlinear optical properties of the films were examined using the Z-scan technique, wherein the samples were irradiated with 140 fs laser pulses at a wavelength of 800 nm and a repetition rate of 80 MHz, with an input intensity of 1.2GW/cm 2 . Ti incorporation led to decreased crystallinity and a reduction (redshift) in the optical bandgap ( E g ). All films exhibit reverse saturation absorption (RSA) and self-focusing effect. A ninefold increase in the nonlinear refractive index ( n 2 ) and a fourfold increase in the nonlinear absorption coefficient ( β ) were observed for the Ti-doped S40 sample in comparison to the pure S0 sample. Adjusting the phase transition between amorphous and crystalline states in Ti-doped In 2 Te 3 films further modulated their nonlinear optical properties. The optical limiting (OL) behavior of pure In 2 Te 3 and Ti-doped In 2 Te 3 thin films was investigated, and the results demonstrated that Ti-doped In 2 Te 3 films show great promise as optical limiter devices in nonlinear photonics.