Title

Optimization Of Band Structure And Quantum-Size-Effect Tuning For Two-Photon Absorption Enhancement In Quantum Dots

Keywords

band structure; lead salt; Nonlinear optics; nonlinear spectroscopy; quantum dots; two-photon absorption

Abstract

The two-photon absorption, 2PA, cross sections of PbS quantum dots, QDs, are theoretically and experimentally investigated and are shown to be enhanced with increasing quantum confinement. This is in contrast to our previous results for CdSe and CdTe QDs where the reduced density of states dominated and resulted in a decrease in 2PA with a decrease in QD size. Qualitatively this trend can be understood by the highly symmetric distribution of conduction and valence band states in PbS that results in an accumulation of allowed 2PA transitions in certain spectral regions. We also measure the frequency nondegenerate 2PA cross sections that are up to five times larger than for the degenerate case. We use a k•p four-band envelope function formalism to model the increasing trend of the two-photon cross sections due to quantum confinement and also due to resonance enhancement in the nondegenerate case. © 2011 American Chemical Society.

Publication Date

3-9-2011

Publication Title

Nano Letters

Volume

11

Issue

3

Number of Pages

1227-1231

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/nl1042209

Socpus ID

79952609332 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/79952609332

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