Openbare verdediging doctoraatsproefschrift Pieter Geiregat

02/10/2015 16:00

'Colloidal Quantum Dots for Guided Wave Photonics:
From Optical Gain to Ultrafast Modulation'

The public defense will take place on Tuesday, 10th of February at 16h00 in the Rector Vermeylen room of het Pand (Onderbergen 1, 9000 Gent) (see map, parking nearby in the Sint-Michiels parking).

The use of light instead of electricity as information carrier is replacing classical micro-electronics due to increased bandwidths and lower energy cost. Just as electronics moved from bulky components to integrated circuits, photonics is moving in the same direction. In the Photonics research group (Department of Information Technology), we use the same material , silicon, and fabrication methods as in micro-electronics to realize densely integrated 'photonic' circuits for generating, guiding and modulating light on small chips. A disadvantage of using silicon however is its limited optical functionalities when it comes to generation (e.g. for integrated lasers) and modulation of light. As such, novel materials are investigated to enhance the silicon photonics platform.

In this doctoral thesis, we investigated the possibility for colloidal quantum dots (or nanocrystals) to realize these enhanced functionalities. As nanometer (a millionth of a millimeter) sized pieces of crystalline semiconductor, these quantum dots offer size tunable optical properties (such as emission color) and are at the extreme of quantum confinement with no dimension left macroscopic. This leads to intriguing new physics at the nanoscale. In the research group Physics and Chemistry of Nanostructures, these quantum dots can be synthesized in large volumes.
The goal of this research was to combine colloidal quantum dots with silicon photonics to realize new and more performant optical functions on micro-chips such as amplification and modulation of light, functionalities difficult to realize on silicon until now.