Polaron effect-dependent third-order optical susceptibility in a ZnS/CdSe quantum dot quantum well

The effect of the electron–phonon interaction on the third-harmonic is investigated theoretically for electrons confined in a core–shell quantum dot. The interactions of electrons with different phonon modes in the core–shell system, including the confined longitudinal optical (LO) and the interface optical (IO) phonon modes, are investigated. We carried a detailed calculation of third-harmonic generation (THG) process on a ZnS/CdSe core–shell quantum dot as a function of pump photon energy with different incident photon energy and under different sizes. The results reveal that the polaron effects are quite important especially around the peak value of the third-order susceptibility. By increasing the size of the quantum dots, the peaks of χTHG(3) will shift to lower energy, and the intensities of the peaks will increase.