Optical cubic nonlinearity of copper oxide thin films synthesized by reactive pulsed laser deposition

The article presents results of the parameters of optical cubic nonlinearity (OCN) of thin amorphous Cu2O films under 532 and 1064 nm pulsed laser excitation. The films were synthesized on SiO2 (silica) substrates by reactive pulsed laser deposition technique at 293 or 800 K under a different oxygen pressure of 1, 3, or 5 Pa. The bandgap of the films was determined from the absorption spectra. The films synthesized under 1 and 3 Pa oxygen pressure at 293 K demonstrated at 1064 nm positive OCN, whereas the films obtained at 293 K, 5 Pa, and 800 K, 1 Pa demonstrated negative OCN. The largest nonlinear refractive index of n2 = + 1.35 × 10−6 cm2/W was obtained for the film synthesized at 293 K, 1 Pa. Under 532 nm excitation, the films also revealed positive or negative OCN, depending on the synthesis parameters, with the absolute value of |n2| on the order of 10−7 cm2/W. The largest |n2| = 5.16 × 10−7 cm2/W was obtained for the 293 K, 3 Pa film. Depending on the manufacturing conditions, the films exhibited saturated absorption or reversed saturated absorption.