Structural, photoinduced optical effects and third-order nonlinear optical studies on Mn doped and Mn-Al codoped ZnO thin films under continuous wave laser irradiation

We report the photoinduced optical effects, third-order nonlinearity, and optical power limiting of Mn doped and Mn-Al codoped ZnO thin films. The thin films were prepared by the spray pyrolysis technique. The structural properties of the deposited films were examined by x-ray diffraction studies. Z-scan measurements were conducted to evaluate the nonlinear optical parameters using a He-Ne laser operating in continuous wave mode at 633 nm wavelength. The present study reveals that the introduction of Mn and Mn-Al into ZnO leads to significant changes in the third-order nonlinear susceptibility. Photoinduced second-harmonic generation studies also reveal the dependence of the nonlinear optical properties on the Mn content. Switching over from saturable absorption to reverse saturable absorption was observed. The optical limiting studies show that the films possess a lower limiting threshold and clamping level, which is essential for use in eye and sensor protection applications. Hence, the Mn doped and Mn-Al codoped ZnO thin films investigated here emerge as promising candidates for future optoelectronic and photonic device applications such as optical power limiters.