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Authors: K. Molkens, I. Tanghe, Dhruv Saxena, Wai Kit Ng, Riccardo Sapienza, P. Geiregat, D. Van Thourhout
Title: Localized and extended states in colloidal quantum dots-based microring lasers.
Format: International Conference Presentation
Publication date: 9/2021
Journal/Conference/Book: EMRS fall meeting
Editor/Publisher: EMRS fall meeting, 
Citations: Look up on Google Scholar
Download: Download this Publication (4MB) (4MB)


Colloidal quantum dots (CQD) are a very versatile material since they are solution processable and have a tuneable bandgap. They are thus a good candidate for light sources in integrated photonics. Here, we use a silicon nitride on oxide platform, enriched with these CQDs. The CQDs are embedded via spin-coating between two nitride layers to get a high stability and good confinement. Complex waveguide structures can be fabricated from this stack in a very precise way. The CQDs make these waveguides optical active components and thus enable demonstration of various on-chip laser cavities To characterize the precision of the processing, we studied the lasing characteristics of an array of 10 coupled ring resonators. A numerical model suggests that supermodes are formed over all the resonators with distinguishable characteristics. This only happens if the difference in resonant frequency of two resonators due to processing errors is smaller than the splitting in resonant energy due to the coupling. We demonstrate a proof-of-concept of this characterization and show that the resonator energy does not differ more than 5 meV. On the other hand, when disorder is deliberately added to the system, light localization can occur. This is induced by the disorder of the system. The material system we provide here is well suited for the study of this kind of phenomena because of the many geometries that are possible and the temperature stability of CQDs. To conclude, we studied arrays of ring resonators both numerically and experimentally within a silicon nitride CQD platform and studied disorder in this system, both intentional and due to fabrication error.

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