MESA+ University of Twente
Research Business & Innovation About MESA+ Education

Philip Harding (promotion date: 13 June 2008)

Photonic crystals modified by optically resonant systems

Promotion date: 13 June 2008

Thesis advisor: prof. dr. Willem L. Vos

Assistant thesis advisor: dr. Allard P. Mosk

We investigate light propagation in periodic, nanoscale structures, i.e., photonic crystals. Some photonic crystals can be made to include a defect, or a cavity. This cavity can lock up light.

During my PhD I investigated how the resonant frequency of such a cavity can be changed on ultrafast (ps) timescales. Also, we wanted to find out whether the light that is locked up in a cavity changes its color, i.e., whether we can change the color of light.

My thesis clearly shows that this is indeed the case, although the mechanism is entirely different to the mechanism discussed in literature. We also find that the width of the cavity resonance increases, which is disadvantageous if you want to use these cavities for, e.g., optical networks. Our findings are of interest to designers working on the next generation of light switches in optical networks.

What is, in your view, essential for successfully obtaining results in this research area?

First of all you have to trust your data, and find a way of thinking and arranging them in a logical way. Then you can think of new directions of researching and experimenting that are promising and fruitful.

How did your colleagues adapt to new ideas and approach, coming from your side?

Well, you never start from scratch. My predecessor had built an extremely powerful setup, which I then modified. From an experimental side, my research was more an evolution than a revolution. The obtained results however were unique, novel and also remarkable. We also gained surprising insights into the propagation of light.

New ideas developed during the PhD in discussions with colleagues and supervisors. I think that's one of the key points of MESA+, and, more in general, the Dutch way researchers are at work in Dutch universities. The discussion atmosphere is very good. You can praise people openly, as well as criticize them, in a background that is free of time consuming patent background issues. That is very important to make real scientific progress.

Do you have clear future plans already?

Although I find academic research exciting, I am looking into two career paths at the moment: teaching and working in industry.

Working in industry appeals to me because of the applied nature of the work. I am excited by the prospect of working in a more commercial setting, for example in businesses dealing with optics and nanophotonics.

As a second career path, I could imagine teaching general physical subjects to students at `hogeschool' or university level.

What, you think, is important for MESA+ to bear in mind in the near future?

The production of samples should be connected in a direct way to more fundamental research topics, I believe. That can be a unique selling point of an institute like MESA+.

If you can quickly build new, breakthrough structures and perform experiments on them in an innovating way, this can lead to scientific results in an efficient way. Without excellent samples, you are lost in this type of experimental research.