Theoretical Study On Single Photon Source Of Semiconductor Quantum Dot Coupled Microcavity

High quality and high efficiency single photon source is the core component of quantum information and communication technology.Semiconductor quantum dots,also known as "artificial atoms",have the advantages of high quantum efficiency,high brightness and easy integration and become the ideal solid-state system for the preparation of single photon source.The performance of semiconductor quantum dots single photon source coupled with cavity is greatly improved by the influence of cavity quantum electrodynamics.In this paper,we aim to produce a high efficiency single photon source of microcavity coupled quantum dots,calculate and analyze the energy level structure of quantum dots,discuss the transition mechanism of quantum dots,and propose a scheme to optimize the single photon source efficiency of semiconductor quantum dots based on cavity quantum electrodynamics.The main research contents of this topic are as follows:1.The energy levels and transitions of AlxGa1-xAs/GaAs cylindrical quantum dot were analyzed using the effective mass approximation based on the Schrodinger equation.We derive the longitudinal and radial electron and hole eigenenergies from the continuous wave function at the boundary conditions.The results show that the smaller the size of the quantum dots,the larger the composition of the surrounding AlxGa1-xAs materials,and the more discrete the energy levels of the quantum dots.We also propose that AlxGa1-xAs in the radial direction can be replaced by different passivating materials,and the surface scattering of cylindrical QD can be eliminated by the good insulation of the passivating materials.The effects of different passivating materials on the energy levels of QD are theoretically calculated,the transverse size of GaAs quantum dots in the infinite deep potential well is less than 7.35 nm.Finally,the mechanism of the transition emission of the carriers in quantum dots at discrete energy levels is discussed.This provides theoretical guidance for the preparation of single photon source of high-quality quantum dots.2.Based on the cavity quantum electrodynamics,the efficiency of a quantum dot-single photon source coupled with an arbitrary detuned single mode cavity is calculated by considering the pure dphasing process and the internal and external cavity loss ratio.The results show that there is an optimal loss ratio between inner and outer cavities in the detuning system to maximize the efficiency of the single photon source.Pure phase elimination can improve the efficiency of the device in the proper range of internal and external cavity loss ratio.The relationship between efficiency and temperature is further studied.It is found that the efficiency at high temperature can be higher than that at low temperature by proper design.This provides an important theoretical basis for the preparation of high efficiency single photon source.