Interband optical Raman gain in a strained oxide quantum dot with Hylleraas co-ordinates

Abstract

Exciton Raman scattering of a three-level system is observed in a CdO/ZnO quantum dot using the size dependent Smorodinsky–Winternitz potential. Resonance Raman excitation for the fundamental optical transition is concentrated in the present work. The differential cross section of Raman optical intensity associated with the exciton is computed with the incident photon energy and the geometrical confinement effect. Raman differential cross section is found by the third-order harmonic generation. The built-in internal fields are incorporated in the heterostructure. They arise between the interior and outer core/shell materials in the heterostructure which contains the spontaneous polarization and piezoelectric polarization. The Hamiltonian of the exciton is included with the dielectric mismatch effect and the variational approach with Hylleraas co-ordinates are employed to obtain the energy eigen values numerically. The energy dependent effective mass of electron and the size related strain-induced potentials for the conduction and valence bands are incorporated in the Hamiltonian. The nonlinear optical properties are obtained with the density matrix approach. The results show that the Raman intensities are more influenced in the strong confinement region. The resonance peak Raman intensity is observed as 6.84 (arb.units) for a 60 A spherical dot. The Raman gain is optimized by varying the dot size. And, the Raman optical gain as high as 240/cm is achieved for the dot radius, 22 A of CdO/ZnO spherical quantum dot. This can be employed for the potential applications in optical devices.