High-order nonlinearity of silica-gold nanoshells in chloroform at 1560 nm

The nonlinear response of silica - gold nanoshells (SGNs) in chloroform was studied using laser pulses of 65 fs at 1560 nm. The experiments were performed using the thermally managed Z - scan technique that allows measurements of the electronic contribution for the nonlinear response, free from thermal influence. The results were analyzed using an analytical approach based on the quasi - static approximation that allowed extraction of the nonlinear susceptibility of a SGN from the data. High third - order susceptibility, chi((3))(sh) = - 1.5 x 10(-11) m(2)/V-2, approximately four orders of magnitude larger than for gold nanospheres in the visible, and large fifth - order susceptibility, chi((5))(sh) = - 1.4 x 10(-24) m(4)/V-4, were obtained. The present results offers new perspectives for nonlinear plasmonics in the near - infrared. (C) 2010 Optical Society of America