In-plane polarization anisotropy of ground state optical intensity in InAs/GaAs quantum dots

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Date
2011
Authors
Usman, Muhammad
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AIP Publishing
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Abstract
The design of optical devices such as lasers and semiconductor optical amplifiers for telecommunication applications requires polarization insensitive optical emissions in the region of 1500 nm. Recent experimental measurements of the optical properties of stacked quantum dots have demonstrated that this can be achieved via exploitation of inter-dot strain interactions. In particular, the relatively large aspect ratio (AR) of quantum dots in the optically active layers of such stacks provide a two-fold advantage, both by inducing a red shift of the gap wavelength above 1300 nm, and increasing the TM001-mode, thereby decreasing the anisotropy of the polarization response. However, in large aspect ratio quantum dots (AR > 0.25), the hole confinement is significantly modified compared with that in lower AR dots-this modified confinement is manifest in the interfacial confinement of holes in the system. Since the contributions to the ground state optical intensity (GSOI) are dominated by lower-lying valence states, we therefore propose that the room temperature GSOI be a cumulative sum of optical transitions from multiple valence states. This then extends previous theoretical studies of flat (low AR) quantum dots, in which contributions arising only from the highest valence state or optical transitions between individual valence states were considered. The interfacial hole distributions also increases in-plane anisotropy in tall (high AR) quantum dots (TE110 not equal TE-110), an effect that has not been previously observed in flat quantum dots. Thus, a directional degree of polarization (DOP) should be measured (or calculated) to fully characterize the polarization response of quantum dot stacks. Previous theoretical and experimental studies have considered only a single value of DOP: either [110] or [-110]. (C) 2011 American Institute of Physics. [doi:10.1063/1.3657783]
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Quantum dots , Polarization , Valence bands , Wave functions , Anisotropy
Citation
Usman, M. (2011) 'In-plane polarization anisotropy of ground state optical intensity in InAs/GaAs quantum dots', Journal of Applied Physics, 110(9), 094512 (9pp). doi: 10.1063/1.3657783
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© 2011, American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Usman, M. (2011) 'In-plane polarization anisotropy of ground state optical intensity in InAs/GaAs quantum dots', Journal of Applied Physics, 110(9), 094512 (9pp). doi: 10.1063/1.3657783 and may be found at http://aip.scitation.org/doi/10.1063/1.3657783