Abstract

The nonlinear optical properties of semiconducting quantum dots have attracted much attention because of the enhancement of nonlinear susceptibilities and the fast response time. The origin of the nonlinearities in such systems, however, is not thoroughly understood. In cuprous halide microcrystallites such as CuCl and CuBr the translational motion of Wannier exciton is confined, since the crystallite radius is larger than the exciton Bohr radius. The resonance effect of confined exciton gives rise to the large enhancement of the third-order nonlinear susceptibility ,^[1,2,3] Here, we report on measurements of figures of merit χ⁽³⁾/α and χ⁽³⁾/ατ in CuCl microcrystallites in glasses in the wide range of the sizes. We clearly demonstrate the mesoscopic enhancement of the nonlinearity due to the crystallite size-dependent oscillator strength of the confined excitons.

© 1992 IQEC