Second-order hyperpolarizability and all-optical-switching of intensity-modulated spatial self-phase modulation in CsPbBr1.5I1.5 perovskite quantum dot

The averaged second-order hyperpolarizability of pervoskite (CsPbBr1.5I1.5) quantum dots (QDs) was characterized using the intensity-dependent spatial self-phase modulation (SSPM). The radial intensity variation of the Gaussian beam displayed the diffraction profile of concentric rings at the far-field due to the coherent superposition of transverse wave vectors with characteristic spatial nonlinear phases. The number of concentric rings as a function of input-intensity revealed the nonlinear refraction coefficients of the QDs. The nonlinear refraction coefficient or the real part of third-order nonlinear susceptibility as a function of concentration of QDs characterized the averaged second-order hyperpolarizability which is the nonlinear refraction coefficient of a single perovskite QD. The vertically asymmetric diffraction ring of SSPM indicates the phase distortion of the optical field due to the heat convection. All-optical switching characteristics of perovskite QDs is attributable to the intensity-modulated SSPM. The input intensity of optical switching by the SSPM was estimated to be similar to 1.05 MW/m(2).

Automated summary

The study characterized the averaged second-order hyperpolarizability of pervoskite quantum dots using intensity-dependent spatial self-phase modulation (SSPM), revealing the nonlinear refraction coefficients of the QDs and the all-optical switching characteristics. The input intensity of optical switching was estimated to be around 1.05 MW/m(2).