Henry Fernández passes his viva!

Henry Fernandez

Many congratulations to PGR Henry Fernández, who this week passed his viva with minor corrections. Henry’s thesis title was ‘Optical and Electronics Study of Hybrid Light-Matter States’. His supervisors were Bill Barnes and Saverio Russo, with the examiners being Rob Hicken (internal) and Said Rodriguez, from AMOLF in the Netherlands.

During his PhD, Henry also participated in many different events. He joined in the Startup Weekend Exeter in October 2018, where his team Dot_IT was the winner of the competition. He also participated in many outreach events as part of the Exeter University Optics and Photonics Society. He was the president of this society from February 2018 to February 2019. He was also the chair of the IONS Exeter conference, recently held from 9 to 12th July 2019. IONS Exeter was a student-led conference that brought together esteemed keynote and invited speakers, as well as normal contributions from different countries.

Check out our previous post on Henry’s thesis for more information about his achievements. We wish him all the best for the future, as he will move to Finland to work in a postdoctoral position with Prof. Zhipei Sun, at the Department of Electronics and Nanoengineering of the Aalto University.

The abstract of Henry’s thesis is below:


Hybrid light-matter states are quantum states that result from an efficient combination of light and matter. This combination is efficient when the two constituents exchange their energy faster than the overall energy dissipation.

For such efficiency, devices have to be designed and structured to maximise the energy exchange. When an efficient energy exchange between light and matter is achieved, new quasiparticles are formed.
One type of these particles are the exciton-polaritons, which result from an efficient energy exchange between excitons and a confined light field.

Over the past 40 years, exciton-polaritons have been extensively studied in conventional semiconductors integrated with devices that confine a light field.
However, only in the last five years, exciton-polaritons have been realised in semiconductors with a thickness at the monolayer limit, which was first observed at low temperatures, and later extended to observations at room temperature. These devices performing at room temperature and at the nanoscale are promising for future technologies, where exciton-polaritons may play an important role, due to their combined light and matter properties that provide them with the strong non-linearities necessary for quantum communications among other applications.

However, one crucial step for the use of exciton-polaritons in real applications is the control over their formation. Recent reports elucidate ways to control the excitation of exciton-polaritons at room temperature, using semiconductor transistors integrated with light confinement devices. This control over the excitation of exciton-polaritons is the main focus of the work presented in this thesis.

Previous reports have focused their research in controlling either the light confinement or the excitonic properties of the semiconductor material in separate ways. In this work, however, both have been carefully controlled, allowing for an extended manipulation of exciton-polariton states. The results presented here set a substantial advance on the manipulation of exciton-polaritons in devices operating at room temperature and using 2-dimensional semiconductor materials in tuneable optical microcavities.

These results may lead to application in future quantum technologies through switchable quantum states.

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