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Proceedings Paper

Two-photon absorption in direct bandgap semiconductors quantum dots
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Paper Abstract

We present degenerate and nondegenerate two-photon absorption spectra in a series of CdSe and CdTe quantum dots. The measurements show that the two-photon absorption (2PA) spectrum is strongly dependent on the quantum dot size and that the 2PA coefficient decreases as the quantum dot size decreases, and it is larger for the frequency nondegenerate process. Previously we had shown a theoretical analysis of these results based on a simple model using the effective mass approximation. Although this model works well for larger quantum dots, it fails for the smaller ones. Here we use the more (formula available in manuscript) model for the band structure and consider the hole band mixing in quantum dots to describe our data. This theory better describes the spectral structures for smaller quantum dots and also predicts the decrease of the 2PA coefficient with the decrease of quantum dot size. This is due to the reduction of the number of possible transitions and the blue shift of the optical bandgap from quantum confinement. This theory predicts the reduction of the 2PA coefficient with size, although our experimental results show an even stronger reduction.

Paper Details

Date Published: 31 August 2006
PDF: 9 pages
Proc. SPIE 6327, Nanoengineering: Fabrication, Properties, Optics, and Devices III, 63270M (31 August 2006); doi: 10.1117/12.681160
Show Author Affiliations
Lazaro A. Padilha, College of Optics and Photonics, CREOL & FPCE, Univ. of Central Florida (United States)
Univ. Estadual de Campinas (Brazil)
Jie Fu, College of Optics and Photonics, CREOL & FPCE, Univ. of Central Florida (United States)
G. Nootz, College of Optics and Photonics, CREOL & FPCE, Univ. of Central Florida (United States)
David J. Hagan, College of Optics and Photonics, CREOL & FPCE, Univ. of Central Florida (United States)
Univ. of Central Florida (United States)
Eric W. Van Stryland, College of Optics and Photonics, CREOL & FPCE, Univ. of Central Florida (United States)
Univ. of Central Florida (United States)
D. Buso, Univ. di Padova (Italy)
A. Martucci, Univ. di Padova (Italy)
Carlos L. Cesar, Univ. Estadual de Campinas (Brazil)
Luiz C. Barbosa, Univ. Estadual de Campinas (Brazil)
Carlos H. B. Cruz, Univ. Estadual de Campinas (Brazil)


Published in SPIE Proceedings Vol. 6327:
Nanoengineering: Fabrication, Properties, Optics, and Devices III
Elizabeth A. Dobisz; Louay A. Eldada, Editor(s)

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