Structural and Third Order Nonlinear Optical Properties of PbS:La Thin Films

The present study examines the third order NLO and electrochemical properties of spray deposited lanthanum doped PbS (PbS:La) thin films. FCC crystallization was confirmed by XRD patterns along the plane (2 0 0). The crystallite size of PbS increases with La doping concentration and ranges from 25 to 34 nm.PbS:La thin films demonstrate self-defocusing due to temperature effects caused by absorption of single photons or free carriers. As a result of the low cationic field strength and high polarizability of La³⁺ ions, PbS exhibits a higher nonlinear refractive index. The nonlinear susceptibility and refractive index were found to be in the range 3.12 x 10^-6 to 5.23 x 10^-6esu and 2.65 x 10^-9 to 3.52 x 10^-9 cm²/W, respectively. The PbS:La thin films improve the structural properties and therefore, it becomes suitable candidature for the applications in nonlinear optical devices.