Spöcker H, Portuné M, Woggon U. Biexcitonic fingerprint in the nondegenerate four-wave-mixing signal of weakly confined cadmium sulfur quantum dots.
OPTICS LETTERS 1998;
23:427-429. [PMID:
18084533 DOI:
10.1364/ol.23.000427]
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Abstract
Nondegenerate four-wave mixing is analyzed with respect to biexcitonic contributions in the third-order nonlinear susceptibility x((3)) . The presence of biexcitons causes a distinct asymmetry in the frequency dependence of self-diffraction. By measurement of the dependence of the intensity of the self-diffracted signal on detuning between the two incident laser beams, the biexciton binding energy is determined to be E(XX)=7.8 meV for cadmium sulfur quantum dots of R=7.5 nm embedded in glass. Thus, even for weakly confined II-VI quantum dots with R~2.7a(B) , a confinement-induced enhancement of E(XX) was found.
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