Photonic Crystal Surface Emitting Lasers Across the Visible Spectrum Based on Colloidal Quantum Dots

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, high luminescence efficiency. 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. Here, we first show 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 QS materials as excellent materials platform to realize highly performant and compact on-chip light sources.