What if we could control light so precisely that we could develop more efficient light sources and faster quantum technologies? Dr Andreas Stefan Schulz of the University of Twente successfully defended his PhD thesis on the controlled placement of nanoscale light sources last Friday March 14. Professor Manfred Bayer, the rector of TU Dortmund, visited the University of Twente especially for the occasion to serve as member of the thesis jury.
Light normally moves freely through space, but in special nanostructures, so-called photonic band gap crystals, you can control the emission of light or even forbid its presence completely. The exact spot where light particles (photons) are emitted by a source in these crystals is crucial: a small shift can make the difference between extremely strong or, on the contrary, suppressed light emission.
World record in light control
Schulz solved a major outstanding challenge by developing methods to place tiny light sources, so-called quantum dot nanocrystals, in a precisely controlled manner within the tiny nanostructure of the photonic crystal. To do this, he uses polymer brushes, microscopic chemical chains that hold the quantum dots in place.
This original approach allowed Schulz to set a new record during his PhD. He managed to inhibit light sources to emit photons from their ‘excited state’ 50 times compared to free space, thereby exceeding the previous world record. In other words, the quantum dot stores extra excited-state energy but does not emit a photon. This enables revolutionary applications in quantum computers and chemical nano sensors, for example. Moreover, the results fit seamlessly with advanced theoretical models.
His successful PhD defence is not only an important personal milestone for Schulz, but also attracts international attention. Professor Manfred Bayer visited Twente on the occasion of the promotion to take part in Schulz's thesis jury. Bayer is a world leading expert of semiconductor nanostructures and quantum technologies, and since 2020 rector of TU Dortmund, one of the largest German universities.
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Dr Andreas Stefan Schulz conducted his interdisciplinary research as a PhD student in three different chairs: Complex Photonic Systems (COPS), Materials Science and Technologies of Polymers (MTP) and Molecular Nanofabrication (MNF). His supervisors were Prof Dr Willem L. Vos, Prof Dr Jurriaan Huskens and Prof Dr G. Julius Vancso.
