Group velocity dispersion of CdSSe/ZnS core–shell colloidal quantum dots measured with white light interferometry

• We measure the group velocity dispersion (GVD) coefficient of colloidal quantum dots.
• Two different sizes of commercially available CdSSe/ZnS core–shell dots were studied.
• The GVD coefficient decreases with increasing wavelength above the absorption band.
• We can model the dots' GVD coefficient theoretically using the absorption spectrum.

We measure the group velocity dispersion coefficient of CdSSe/ZnS core–shell colloidal quantum dots in liquid suspension in the ∼700–900 nm wavelength range using a white-light Michelson interferometer. Two different sizes of dots are investigated. In both cases, the group velocity dispersion coefficient decreases with increasing wavelength above the absorption edge in the dots. For quantum dots in which the linear absorption spectrum shows clear peaks, the absorption characteristics of the dots can be used to accurately model the wavelength-dependence of the group velocity dispersion coefficient.