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Authors: I. Tanghe, M. Samoli, I. Wagner, S. A. Cayan, A. H. Khan, K. Chen, J. Hodgkiss, I. Moreels, D. Van Thourhout, Z. Hens, P. Geiregat
Title: Solution processed bulk colloidal nanocrystals as gain material in photonic crystal surface emitting lasers across the green-red spectrum
Format: International Conference Proceedings
Publication date: 1/2024
Journal/Conference/Book: SPIE Photonics West
Editor/Publisher: SPIE, 
Volume(Issue): p.paper 12864-34 (4 pages)
Location: San Francisco, United States
DOI: 10.1117/12.2692651
Citations: Look up on Google Scholar
Download: Download this Publication (448KB) (448KB)


Colloidal quantum dots (QDs) are heavily investigated for their applications in light emission such as light emitting diodes and, more challenging, lasers due to their appealing processing conditions, compared to e.g. epitaxy, lowering cost and enabling patterning, and tunable optical properties. Using quantum confined Cd-based QDs, several groups have shown light amplification and ensuing lasing action in the red part of the spectrum. Although impressive milestones were achieved, there is to date no single material that can provide the demanding combination of gain metrics to be truly competitive with existing epitaxial growth approaches.
In this work, we take a look at CdS/Se nanocrystals in the regime of vanishing quantum confinement, so-called ‘bulk nanocrystals’. We show that these unique materials display disruptive optical gain metrics in the green optical region. Indeed, while showing similar gain thresholds compared to state-of-the-art QD materials, the gain window (440-600 nm, … ), amplitude (up to 50.000/cm) and gain lifetime (up to 3 ns) vastly outpace other QD materials.
Using these novel gain materials, we demonstrate lasing in the highly demanded green spectral region (480 – 530 nm) and in the red (650 – 740 nm) both with pulsed and quasi-CW optical excitation. These lasers are made using a Photonic Crystal Surface Emitting Laser (PCSEL) type cavity. As a final step, we attempt to further optimize the lasing properties, be it either narrow linewidth lasers, or high power output, based on in-depth understanding of the hybrid QD-PCSEL laser system.

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