Nonlinear Optical Spectroscopy of Cadmium Chalcogenide Nanocrystals

Abstract

We report on the nonlinear optical properties of cadmium telluride (CdTe) semiconductor colloidal quantum dots. Transmission electron microscopy measurements revealed that the size of CdTe nanocrystal quantum dots, dependent on the growth reaction time, was ∼2-10 nm or near the exciton Bohr radius. The strong blue-shifts of the CdTe, CdSe and CdS nanocrystal absorption spectra and the atomic-like discrete energy states of exciton indicate an exciton quantum confinement. These are completely different optical properties from the bulk crystals. The energy transition for exciton absorption was assigned as h1→e+, h2→e+, h1+→e-, and h2+→e- for the 1st, 2nd, 3rd and 4th exciton absorption peaks. Z-scan and I-scan nonlinear spectroscopy revealed that the CdTe nanocrystal quantum dot in toluene (∼8 × 10-5 mol/L) has the negative nonlinearity (self-defocusing) with ∼ -1 × 10-13 m2/W and a high nonlinear figure of merit of ∼200. For the optical power self-limiting experiment, the CdTe nanocrystal was almost opaque above ∼0.8 MW/cm2 at the position of z∼6.9 cm.

Manifested luminescence and magnetic responses of stoichiometry dependent Cd1− xMnxSe quantum dots

“…The absorption maximum of pure CdSe QDs is found to be located at $430 nm (2.8 eV) (Fig. 3(b)); which is strongly blue-shifted from its corresponding bulk CdSe value (l = 714 nm) [23]. The comparatively broad, subsidiary peak, observed at a relatively lower energy (2.4 eV) is believed to have arisen owing to the Urbach tailing as a result of carrier transition between the extended and the localized states.…”

Strain-Induced Modulations of Electro-Optic and Nonlinear Optical Properties of ZnO: A First-Principles Study

“…CdTe has been proven to be a good nonlinear optical material previously [17,18]. The electro-optic constants of telluride are approximately one half of that for ZnO, while the corresponding values for sulfide and selenide are much smaller than other materials.…”