Lasing in quantum rods - colloidal nanocrystals and the coffee stain effect

Exciting discoveries in the field of nanophotonics have been made by Margherita Zavelani-Rossi and colleagues of the National Laboratory for Ultrafast and Ultraintense Optical Science, Milan, and the Italian Institute of Technology, Genova.

The results summarised in this video strongly enhance the potential of colloidal quantum rods (QR) and represent the first example of a nanocrystal laser prepared by pure self-assembly.

Core/shell QRs comprising spherical CdSe quantum dots embedded in thick rod-shaped CdS shells were shown to self-organise upon solvent evaporation, forming structures with greatest thickness at the edges the so-called coffee stain effect.

This coffee stain ring contains ordered and close-packed QR assemblies, and displays amplified stimulated emission, with one of the lowest input energy thresholds ever reported.

This lasing from self-assembled microcavities of asymmetric core/shell QRs, without the need for an external resonator to minimise scattering losses, provides a way to fabricate lasers using simple solution-based techniques. Further developments could provide a new generation of photonic devices.

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Science & Technology

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• Nanoscale
• video
• abstract