Giant enhancement of optical nonlinearity in multilayer metallic films.

The local electric field has been derived analytically inside multilayer metallic films with weak nonlinearity, and hence the effective linear dielectric constant and third-order nonlinear susceptibility of the layered structures are calculated. As the number of layers increases, the comparison with the previous results of graded metallic films shows a gradual transition from sharp peaks to a broad continuous band. These results give further evidence of the emerging absorption band reported recently [J. P. Huang and K. W. Yu, Appl. Phys. Lett. 85, 94 (2004)]. Thus, multilayer metallic films can serve as optical materials with a giant enhancement of optical nonlinearity and a large figure of merit. [ABSTRACT FROM AUTHOR]