Femtosecond studies of the third-order optical non-linearity of nanometre-sized cadmium oxide organosols by the z-scan technique

摘要

Recently there have been extensive investigations on optical nonlinearity, and in particular on the third-order non-linearity of semiconductor nanoparticles, and on their potential practical applications [1-4]. It has been shown that, in certain conditions, the reduction in dimensionality of systems from three dimensional (bulk) to zero dimensional (nanoscale) for semiconductors can lead to an enhanced non-linearity which is determined by the quantum size effect and some other mesoscopic effects of nanoparticles [5], In general, some nanometre-sized materials may have a relatively large third-order optical nonlinearity if its bulk counterpart exhibits a large linear refractive index, ?o, and have a narrow band gap, Es [6]. CdO semiconductor (n0 = 2.49 and Es — 2.3 eV) nanoparticles, therefore, may have a large non-linear refractive index, n2.