Abstract
The optical gain spectra of inhomogeneously distributed semiconductor Quantum dots (QDs) embedded in a dielectric matrix has been examined theoretically using density matrix treatment. The expression for the threshold field is required to obtain optical gain. We have examined the role of excitons and biexcitons in gain mechanism and found that the gain arising due to excitonic nonlinearity enhances in presence of biexcitons. A comparison of the optical gain spectra of single quantum dot (SQD) and inhomogeneous distribution of quantum dots (IDQ) shows that the exciton peak in SQD gets red shifted in IDQ while biexciton peak in SQD exhibits a blue shift. A detailed numerical analysis establishes a strong dependence of optical gain on size distribution function and it is found that an increased size distribution width yields larger gain and increased gain bandwidth. The nonlinear gain is also found to increase in a matrix possessing larger dielectric constant.
Published Version
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