Structural, linear, and nonlinear optical properties of radio frequency-sputtered nitrogen-doped ZnO thin films studied using z-scan technique

Abstract

The third-order nonlinear optical properties of undoped and nitrogen-doped ZnO thin films were evaluated using the z-scan technique. The films were sputter-deposited on glass substrates using radio frequency power. The He-Ne continuous wave laser operating at 633 nm was used as an irradiation source. A change in the growth mode in the nitrogen-doped films was observed. The grain size and roughness were found to be dependent on the nitrogen concentration, as shown by atomic force microscopy analysis. The optical band gap was determined and found to increase with nitrogen concentration in the films. Both nonlinear absorption and refraction nonlinearities were exhibited by the deposited films. The nonlinear refractive index n 2 , the nonlinear absorption coefficient β eff and the third-order nonlinear optical susceptibility χ (3) were determined and found to be largest. Multiple diffraction ring patterns were observed when the samples were made to interact with the laser beam and were attributed to refractive index change and thermal lensing. Further, optical power-limiting experiments were performed to determine the optical-limiting threshold and clamping values for undoped and nitrogen-doped ZnO films.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation

“…Other authors 325 estimated the third-order optical susceptibility χ (3) to be of the order of 10 −3 esu using the Zscan technique under CW He−Ne laser irradiation at 633 nm wavelength. Doping of ZnO thin films with a variety of dopants of different nature has also been pursued, including nitrogen 326 and manganese. 327,328 Again, very good optical nonlinearities were achieved, with χ (3) values being generally in the order of 10 −3 esu.…”

“…Doping of ZnO thin films with a variety of dopants of different nature has also been pursued, including nitrogen and manganese. , Again, very good optical nonlinearities were achieved, with χ (3) values being generally in the order of 10 –3 esu.…”

Third-harmonic optical process in Zn:NiO thin films under the influence of femtosecond and continuous wave laser excitation

“…The high third-order susceptibility may be attributed to the greater presence of nickel and oxygen defect states within the films, as confirmed by photoluminescence studies. Additionally, the increased nonlinear susceptibility in the NiO film doped with 1% Zn may result from its smaller crystallite size and reduced surface roughness [49]. Samples with higher surface roughness tend to scatter light, leading to a decrease in nonlinear optical response.…”