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Updated: Feb 5, 2026

Compact Quantum Dots for Single-molecule Imaging
Published on: October 9, 2012
Ultrafast spectroscopic studies of composition-dependent near-infrared-emitting alloyed CdSeTe quantum dots
Wenzhi Wu1, Shiwei Ren, Qiuju Han
1School of Electronic Engineering, Heilongjiang University, Harbin, 150080, China. victorkonghu@hotmail.com.
Abstract:
In this study, optical and structural characterizations of near-infrared-emitting alloyed CdSeTe quantum dots (QDs) are measured after the dissolution in toluene. Luminescence spectra are obtained from alloyed CdSeTe QDs under 800 nm femtosecond laser excitation. With increasing pump fluence, the line width or full width at half maximum (FWHM) of photoluminescence (PL) spectrum becomes larger than 10 nm due to increasing temperature. Ultrafast spectroscopic properties of CdSeTe QDs are investigated by means of time-resolved PL, transient absorption (TA) and Z scan techniques. Moreover, open-aperture (OA) Z scan measurement is used to clarify the composition and pump fluence dependence of optical nonlinearity under femtosecond laser excitation. With increasing pump fluence, evolution from saturable absorption to reverse saturable absorption in CdSeTe QDs is observed. The transition process is analyzed via a phenomenological model based on nonlinear absorption coefficient and saturation intensity, which indicates that CdSeTe QDs have potential for applications in all-optical switching devices.
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