tailieunhanh - Báo cáo hóa học: " Excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots | Florez and Camacho Nanoscale Research Letters 2011 6 268 http content 6 1 268 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots Jefferson Florez and Angela Camacho Abstract We study the excitonic effects on the second-order nonlinear optical properties of semi-spherical quantum dots considering on the same footing the confinement potential of the electron-hole pair and the Coulomb interaction between them. The exciton is confined in a semi-spherical geometry by means of a three-dimensional semiparabolic potential. We calculate the optical rectification and second harmonic generation coefficients for two different values of the confinement frequency based on the numerically computed energies and wavefunctions of the exciton. We present the results as a function of the incident photon energy for GaAs AlGaAs quantum dots ranging from few nanometers to tens of nanometers. We find that the second-order nonlinear coefficients exhibit not only a blue-shift of the order of meV but also a change of intensity compared with the results obtained ignoring the Coulomb interaction in the so-called strong-confinement limit. Introduction Nonlinear optical properties of semiconductor quantum dots have attracted considerable interest due to their several potential applications 1-4 . In particular second-order nonlinear optical properties such as nonlinear optical rectification OR and second harmonic generation SHG have received special theoretical 5-8 and experimental 9 10 attention due to their magnitudes being stronger than those of high-order ones making them the first nonlinear optical effects experimentally observed. The confinement of carriers provided by a quantum dot is well described by a parabolic potential when only the lowest excited states of the carriers are considered. However self-assembled quantum dots growth in the .