Doctoral Thesis: A Hybrid Approach Towards On-Chip Visible Lasers

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Event Speaker: 

Thomas Mahony

Event Location: 

via Zoom, see details below

Event Date/Time: 

Thursday, May 14, 2020 - 3:00pm

Abstract:
In recent years, the world of nanostructured optically active materials has expanded to include organic molecules; colloidal nanocrystals such as quantum dots, quantum rods, and quantum wells or nanoplatelets; perovskite semiconductors; and perovskite nanocrystals. A key feature of these materials is the capability to engineer their energy levels, e.g., via chemical composition or size, allowing for their absorption and emission spectra to be tuned throughout the visible and near- infrared electromagnetic spectrum. Many of these materials are deposited from solution, which makes them suitable for large-area technologies such as solar cells and light-emitting devices (LEDs) for displays. However, nanopatterning these materials and integrating them into photonic devices has proven difficult due to fabrication constraints.

In this work, we demonstrate strategies for processing and nanopatterning organic molecules, colloidal quantum dots, and cadmium selenide nanoplatelets. We created nanobeam photonic crystal cavities that incorporate organic gain media resulting in an ultracompact low-threshold organic laser. We combined colloidal quantum dots with polymethylmethacrylate (PMMA) to create sus- pended polymeric cavities that showed enhanced spontaneous emission from the quantum dots. By functionalizing surfaces, we achieved orientation control of nanoplatelet films. We also achieved the first demonstration of lithographically patterned nanoplatelet films, and we integrated them into silicon nitride photonics. We developed these processing and nanopatterning strategies while building architectures for on-chip lasers; nevertheless, these techniques have broad applicability to other technologies.

Thesis Committee:

Vladimir Bulović, Professor of Electrical Engineering and Computer Science (Thesis supervisor)
Rajeev Ram, Professor of Electrical Engineering and Computer Science 
William Tisdale, Professor of Chemical Engineering

To attend this thesis defense, please contact the doctoral candidate, tsmahony at mit dot edu