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Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection

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Two-photon absorption in CdTe quantum dots.

Lázaro Padilha, Jie Fu, David Hagan

|June 6, 2009

Summary

This summary is machine-generated.

We measured two-photon absorption (2PA) in Cadmium Telluride quantum dots (QDs). 2PA strongly depends on QD size, decreasing as dots get smaller. A model predicts 2PA spectra for various QD sizes.

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Area of Science:

Materials Science
Quantum Physics
Nanotechnology

Background:

Two-photon absorption (2PA) is a nonlinear optical process with applications in imaging and materials processing.
Cadmium Telluride (CdTe) quantum dots (QDs) are semiconductor nanocrystals with tunable optical properties.

Purpose of the Study:

To measure and analyze the frequency-dependent 2PA spectra of CdTe QDs in glass matrices.
To investigate the influence of QD size on 2PA properties.
To adapt and validate a theoretical model for predicting 2PA spectra.

Main Methods:

Experimental measurement of degenerate and nondegenerate 2PA spectra of CdTe QDs of varying sizes.
Comparison of QD 2PA spectra with bulk CdTe.
Adaptation of a degenerate 2PA model using effective mass approximation for nondegenerate cases.

Main Results:

2PA in CdTe QDs is strongly size-dependent, decreasing with smaller QD size.
The adapted model accurately describes experimental 2PA data up to approximately 1.4 times the bandgap energy (Eg).
Normalization to dot volume did not eliminate the size dependence of 2PA.

Conclusions:

The size-dependent 2PA behavior of CdTe QDs is a critical factor in their optical response.
The developed theoretical model provides a predictive tool for 2PA spectra of different sized CdTe QDs.
This research facilitates the design and application of QDs in nonlinear optical technologies.