2012-08-09

Reflection: 2012 Summer UROP

The long-term reviews I have been doing this summer have been on the desktop that I have been using for my UROP work this summer. Most of my thoughts about that have basically been along the lines of "UROP work went fine today". But I've realized that I haven't properly discussed what I've done this summer, I figured that I should share a little bit about that today because tomorrow is my last day here for the summer before I go home for a few weeks' break.

Let us start with the basics. A dielectric is essentially any material medium that changes the average speed at which light propagates due to the interaction of the electromagnetic field with the atoms and molecules constituting the dielectric. A photonic crystal is a periodic array of dielectric, and this periodicity can be found in 1, 2, or 3 dimensions. The photonic crystals that I was modeling this summer are in 2 dimensions; specifically, they are rectangular slabs of dielectric material with cylindrical holes of air/vacuum punched through the center along one axis. These sorts of periodic structures are special because they have certain bands of natural resonant frequencies at which the electromagnetic field is very well supported and other bands of frequencies where the field basically can't exist in the structure at all. This allows for very efficient manipulation of light at various frequencies. For instance, last fall, I was looking at optimizing photonic crystals to absorb the most light at various angles of incidence given a range of frequencies. This summer, I have been characterizing the electromagnetic energy flux from the photonic crystal structure that I mentioned before as a function of frequency and wavevector; the energy flux comes from localized current sources embedded in the dielectric material, and this models spontaneous emission. Such spectra should and do show peaks near the resonant frequencies. I was working closely with a postdoctoral associate and graduate student who had previously determined the functional dependence of the flux spectrum analytically and verified it experimentally. I was essentially providing a third method of verification through numerical analysis in MEEP. I have also asked the graduate student with whom I work about the ultimate applications of these flux spectrum modeling techniques, and the closest thing I have gotten to a good answer is that many macromolecules look like photonic crystals locally, so knowing the resonant frequencies and wavevectors for the flux spectrum makes imaging said macromolecules much easier.

In the process, I've become much more accustomed to using MEEP. I'm no longer scared of Scheme despite my C++/JAVA programming background; in fact I'm almost used to using Scheme. I've gotten a better handle on the tricks of the Linux terminal. And this was the first time that I was able to have a good level of appreciation for what I was doing, because this was the first full term that I was able to UROP after the lecture in my 8.04 (Quantum Physics I) class in 2012 May about photonics. Overall, I would say that my UROP was a success in that I really enjoyed every bit of it!

2 comments:

  1. Scheme is great! You must read SICP if you haven't already: http://mitpress.mit.edu/sicp/

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    1. @Chenyu Zhao: I've briefly looked through the beginning, but if I need to, I'll probably go through it in detail soon. Thanks for the tip!

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