Intersubband Refractive Index and Optical Absorption Coefficients Changes in Lens-Shaped Quantum Dots

Intersubband transitions between the conduction subbands of quantum dots dramatically alter the real index of refraction (n(r)) and the absorbtion coefficient (alpha) of the host matterial. We use the density matrix formulation to calculate the linear and third order nonlinear changes in refractive index, and the absorption coefficient caused by such transitions in the Symmetric Lens-Shaped Quantum dots. The numerical results on GaAs indicate that absorption coefficient and refractive index change strongly depend on the size of the dot. There is a large increase in the absorption coefficient and refractive index values as the size of the dot decreases. Also by increasing the incident optical intensity, the absorption coefficient and refractive index changes decrease.