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Journal of Nonlinear Optical Physics & Materials

INTERSUBBAND OPTICAL ABSORPTION COEFFICIENTS AND REFRACTIVE INDEX CHANGES OF AN ELLIPSOIDAL FINITE POTENTIAL QUANTUM DOT

G. Rezaei, M.R.K. Vahdani, M. Barati

Published Mar 1, 2010• 8 citations
Publisher

Abstract

Intersubband optical absorption coefficient and refractive index changes of a weakly prolate ellipsoidal quantum dot, using the compact-density matrix formalism and iterative method, are investigated. In this regard, the linear and nonlinear intersubband optical absorption coefficient and refractive index changes of a GaAs / Al x Ga 1-x As ellipsoidal quantum dot, as functions of the dot radius, ellipticity constant, stoichiometric ratio and incident light intensity are calculated. The results indicate that absorption coefficient and refractive index changes strongly depend on the light intensity, size and geometry of the dot and structure parameters such as aluminium concentration in GaAs / Al x Ga 1-x As structures.

DOI
10.1142/s021886351000511x

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Linear, nonlinear, and total refractive index changes are investigated theoretically in asymmetric coupled quantum wells. The analytical expressions for the linear and third-order nonlinear refractive index changes are obtained based on the density matrix method and the iterative approach. Numerical calculations are performed for typical GaAs/Al(subscript x)Ga(subscript 1-x)As asymmetric coupled quantum wells. The calculated results reveal that a large variation of the refractive index near the transition energy can be obtained in asymmetric coupled quantum wells, and that the incident optical intensity and the structure parameters, such as the barrier width and the right-well width, have great effects on the total refractive index changes.