Surface plasmon resonance and nonlinear optical behavior of pulsed laser-deposited semitransparent nanostructured copper thin films

In this paper, surface plasmon resonance (SPR) and nonlinear optical properties of semitransparent nanostructured copper thin films fabricated on the glass substrate at 400 A degrees C by pulsed laser deposition technique are reported. The thickness, linear absorption coefficient and linear refractive index of the films were measured by spectroscopic ellipsometer. The average particle size as measured via atomic force microscope was in the range of 12.84-26.02 nm for the deposition time ranging from 5 to 10 min, respectively. X-ray diffraction spectra revealed the formation of Cu (111) and Cu (200) planes. All these thin films exhibited broad SPR peak. The third-order optical nonlinearity of all the samples was investigated via modified z-scan technique using cw laser at a wavelength of 632.8 nm. The open aperture z-scan spectra of Cu thin film deposited for 5 min duration exhibited reverse saturation absorption whereas all the other samples displayed saturation absorption behavior. The nonlinear refractive index coefficient of these films showed a positive sign having the magnitude of the order of 10(- 4) cm/W. The real and imaginary parts of susceptibilities were also calculated from the z-scan data and found to be of the order of 10(- 6) esu.