Photonic Crystal Surface Emitting Lasers across the Visible Spectrum based on Bulk Nanocrystals

Pieter Geiregat^a, Ivo Tanghe^b, Zeger Hens^a, Dries Van Thourhout^b, Justin Hodgkiss^c, Kai Chen^d, Margarita Samoli^a, Servet Ataberk Cayan^a

^aPhysics and Chemistry of Nanostructures Group, Ghent University, 9000 Ghent, Belgium

^bPhotonics Research Group, Ghent University, Belgium, Technologiepark-Zwijnaarde, 126, Gent, Belgium

^cSchool of Chemical and Physical Sciences,Victoria University of Wellington, New Zealand, New Zealand

^dRobinson Research Institute, Victoria University of Wellington, Wellington, New Zealand, PO Box 600, Wellington, New Zealand

Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS Fall 2024 Conference (MATSUSFall24)

#PhotoQD - Photophysics of colloidal quantum dots

Lausanne, Switzerland, 2024 November 12th - 15th

Organizers: Philippe Green and Jannika Lauth

Invited Speaker, Pieter Geiregat, presentation 128
DOI: https://doi.org/10.29363/nanoge.matsusfall.2024.128
Publication date: 28th August 2024

Combining integrated optical platforms with solution processable semiconductor materials offers a clear path towards miniaturized and robust light sources, including lasers. Semiconducting colloidal quantum dots present a unique platform to realize this by combining tunable properties and high luminescence efficiency with solution processing. A limiting aspect for both red and green emitting materials remains the drop in efficiency at high excitation density due to non-radiative quenching pathways, such as Auger recombination. Next to this, lasers based on such materials remain ill characterized, leaving questions on their ultimate performance.

Here, we show that weakly confined ‘bulk’ colloidal quantum dots offer a unique solution processable materials platform to circumvent the long-standing material issues. First, we demonstrate that optical gain in such systems is mediated by a 3D plasma state of unbound electron-hole pairs which gives rise to broadband and sizable gain across the full red spectrum with record gain lifetimes and low threshold. As proof of concept, the nanocrystals are integrated on a silicon nitride platform enabling high spectral contrast, surface emitting and TE polarized PCSEL – type lasers with ultra-narrow beam divergence across the visible (green, red) spectrum from a small surface area. Our results prime these 'bulk' nano-materials as excellent materials platform to realize highly performant and compact on-chip light sources.

References:

[1] Tanghe, I., Samoli, M., Wagner, I. et al. Optical gain and lasing from bulk cadmium sulfide nanocrystals through bandgap renormalization. Nat. Nanotechnol. 18, 1423–1429 (2023).

Acknowledgements:

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