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Wico Hopman (Cum Laude) (promotion date: 20 April 2007)

Light-Flow Characterization and Manipulation in 1 and 2 Dimensional Photonic Crystals

Promotion date: 20 April 2007 Cum Laude

The project I mainly worked for was a project dealing with the development of a nanomechanical actuated light switch based on photonic crystals. The optical design of the light switch (switching light from one port to the other), is being developed in the Integrated Optical MicroSystems group (IOMS), whereas the nanomechanical part and the integration of both technologies are being developed in the Transducers Science and Technology (TST) research group. Furthermore, modelling of the optical design is being supported by a third group involved: the Applied Analysis & Mathematical Physics group (AAMP).

After the 2-years time I worked on the project, we were able to show on/off switching using a nano-probe1 and we discovered a new method for measuring and visualizing standing waves in resonator with the highest resolution so far. In addition, I worked on slow light (a highly reduced speed of light), which can be a property of periodic media. During my PhD I have developed a new a simple method for measuring slow light in waveguide gratings, details can be found in the Optics Express article2.

What is your thesis about?

The project I mainly worked for was a project dealing with the development of a nanomechanical actuated light switch based on photonic crystals. The optical design of the light switch (switching light from one port to the other), is being developed in the Integrated Optical MicroSystems group (IOMS), whereas the nanomechanical part and the integration of both technologies are being developed in the Transducers Science and Technology (TST) research group. Furthermore, modelling of the optical design is being supported by a third group involved: the Applied Analysis & Mathematical Physics group (AAMP).

After the 2-years time I worked on the project, we were able to show on/off switching using a nano-probe1 and we discovered a new method for measuring and visualizing standing waves in resonator with the highest resolution so far.

In addition, I worked on slow light (a highly reduced speed of light), which can be a property of periodic media. During my PhD I have developed a new a simple method for measuring slow light in waveguide gratings, details can be found in the Optics Express article2.

Why would you want this novel light switch?

Well, besides the challenging research that is needed to realize such a switch, we think this switch can find its demand in the telecom or sensor industry market, because of the potential cost reduction the extremely small size of this switch can establish. In other words, you can put a higher number of chips on one wafer and since it uses so little material the optical switches will eventually be cheaper. Besides the small size of the switch, which also allows a fast switching rate, we anticipate the nanomechanical actuation can be beneficial for its power consumption.

What did you achieve?

After the 2-years time I worked on the project, we were able to show on/off switching using a nano-probe1 with a minimum tip radius of less than 20 nm, and we discovered a new method for measuring and visualizing standing waves in resonator with the highest resolution so far.

In addition, I worked on slow light (reducing the speed of light), which can be a property of periodic media. During my PhD I have developed a new a simple method for measuring slow light in waveguide gratings, details can be found in the Optics Express article2.

Are applications thinkable integrating such small structures?

Yes, the structures can be used in telecom devices, as a sort of routing device. Or it might also find an application in sensor chips, where the switch is used to read out a specific sensor in a network of optical sensing elements. However, the integration of the piezo actuator (tip and cantilever that influences the light) still needs a lot of development.

You have been very successful by the sounds of it.

Yes, but I like to mention that the mayor part of my results where obtained in close co-operation with other (colleague) experts. The way in which the light in the resonator can be characterized is completely new. It resulted in quite a few publications and even more to come.

What did you enjoy most about your research?

In short: the versatility and the freedom of it. Of course, I had to operate within the limits of the project, but I was free to investigate what I thought was relevant and important.

I worked with a lot of students and skilled colleagues and could determine my own working hours. Sometimes you don’t do a full week and sometimes you work 60 hours (or more) per week and there is nobody who says anything of it as long as you deliver.

In my project, I was allowed to attend conferences frequently. I have been to several, and not so very long ago to Salt Lake City in Utah (July 2007).

Did you encounter any problems?

Of course, I am certain that every PhD student will experience a period in which everything seems impossible.

How did you deal with the problems?

By doing sports exercises (swimming, running, cycling) almost every day of the week, which helped a lot to maintain a clear mind and get rid of possible frustrations. Especially, the first 2 years when I could work part time at IOMS, I was aiming at an international sports career (Olympic distance Triathlon). When I found out that I could not achieve this level (in a short time), I gradually reduced my exercise hours and focussed more on my PhD.

What will you do next?

I will start work at Sensata Technologies in Almelo as a design engineer. They develop sensors for the automobile industry. Despite, the nice time I spend in the academic world, I decided to leave the academic world for a while in favour of industry. Once I have had that experience I will decide where my future lies.

For the summary of the thesis, click here

Voor de samenvatting van het proefschrift, click hier

1 http://www.utwente.nl/nieuws/pers/en/archive%20press%20releases/cont_06-041_en.doc/

2 http://vjbo.osa.org/abstract.cfm?id=127255