Surface-enhanced optical nonlinearity of a gold film

Abstract The enhancement of optical nonlinearities in a gold film with random roughness were measured by Z -scan technique with 0.71 ns, 532 nm laser pulses. The values of the nonlinear absorption coefficient β and nonlinear refractive index coefficient γ were obtained through open- and close-aperture Z -scan, β =−1.3×10 −5 m/W, γ =1.32×10 −12 m 2 /W, correspondingly, the imaginary part χ (3) Im and the real part χ (3) Re of the third-order nonlinear susceptibility χ (3) were obtained, respectively. The thermal effect and the enhancement of optical nonlinearities due to the surface plasmon resonance in metal film were discussed.