Ultimate-fast all-optical switching of a microcavity

Promotion date: September 4.

Promotor: Prof.dr. Willem Vos

Semiconductor microcavities store light for a given amount of time in a small volume and thereby increase the interaction between light and matter to the point of manipulating quantum states of matter. The dynamic manipulation of a cavity is thereby of major interest to control light matter interactions in time.

Integrated photonic circuits are demonstrated to increase the clock speed of communication to tens of GHz. This increase is achieved by using semiconductor microcavities that form the backbone of optical modulators. However, even this increase will not be sufficient to meet the future computational demands since the data produced by humans grows exponentially at a rate of tenfold every five years. For this reason, switching speed of cavities should be increased to meet the growing need for speed in computation.

We have repeatedly and reproducibly switched a semiconductor microcavity operating in the “original” telecom band by exploiting the virtually instantaneous electronic Kerr effect. We achieve for the first time ever repeated switching of a cavity beyond THz rates. The results offer opportunities for fundamental studies of cavity quantum electrodynamics and optical information processing in the sub-picosecond time scale.

Was your research fundamental in nature or more application oriented?

Application features inspired me but the fundamental aspects were dominant during my research project. This part of research I learned to appreciate even more during my thesis project. It is the fundamental breakthroughs, which will allow the big application changes of the future to happen.

Do you recall some special moments during your PhD period?

Well, several happened along the way, differing one from the other. There are quite a few key moments I can think of during my research. When you can come up with good news from the lab, there is a certain excitement, to start with. Also understanding the results, bringing them together and then publishing them are all exciting moments, which stimulate you even more along the way. In general, being able to understand, control and even change a physical phenomenon as you wish, is an exciting job and very fulfilling. The harder the problem to be solved is, the greater is the excitement that you feel in the end.

Can you mention some main publications?

The article in Applied Physics Letters was highlighted in Nature, Nature Photonics and Nature Physics, showing the great impact of the work. Also Optics Letters, Applied Optics, Physical Chemistry Chemical Physics, and the Journal of the Optical Society of America B, did publish articles along the way of research.

In what way did you develop as a scientist and researcher?

The biggest difference, I suppose, is the way my mindset changed about scientific literature. As a bachelor student one is studying the books and learning from it. As a master student, you look at literature, refer to it and create literature yourself, thereby relying on the literature already existent. As a PhD-student however, I learned in what way to question literature and use it as an inspiration for further research. In this way creating literature is quite different from what I published as a master student.

What are your future plans?

First of all I am going to work as a post-doc on a similar topic here. Also I would like to finish some thought-of experiments and publish some more nice results. This is very rewarding.

In a future job I am looking for new things to explore. The precise setting doesn’t matter that much to me. I hope to continue to explore, understand, and improve to eventually contribute to the people I am going to work for in a useful way.

Did you feel part of the Mesa+ community during your PhD period?

Yes, we had some nice collaborations within Mesa+, for example with the Applied Nanophotonics program (ANP), led by dr. Pepijn Pinkse. I enjoyed the presentations and poster sessions at the Mesa+ Days and monthly meetings of ANP. Also collaborations started with LPNO group during one of the ANP meetings. I have experienced in MESA+ that learning is not the most important here, but getting to know your colleagues and their expertise is the way to expand your capabilities.

What in your opinion is important for Mesa+ to stay successful in future?

Apart from the scientists and the technicians, the support personal should be of high level, I believe.

Similar to evaluation of the scientific groups the support departments such as purchasing, human resources, and computer support departments should be evaluated on a regular basis. Good expertise of the support personnel can save valuable research time, preventing unnecessary delay of work.