Today was the first work day of our stay, though it was more of an introduction day. Emmanuelle Marquis helped us all find our labs; Chau and I are the only ones working at the ENS Cachan. After a very tasty lunch with our advisers and the program leaders, we were given brief tours of some of the labs and shown around the buildings. Dr. Melanie Lebental, my adviser, explained that the sample of Fabry-Perot cavities that I was to have tested wasn't ready yet - the lab that was to prepare it had been shut down temporarily due to a power outage. It looks like I'll be investigating the spectral line widths of these microcavity lasers instead. The lasing modes have much narrower line widths than the theory predicts, and no one knows quite why. Though I still have some reading to do before I understand well enough, I was able to follow her introduction fairly well. There are at least two competing hypotheses for the line width: it may be determined by the...er...Someone-Somebody Limit, which describes a sort of misfiring of the excited atoms that are lasing, or possibly it's Fourier-limited, since the spectral width depends on the shape of the laser pulse in the time domain.
I should be able to distinguish between these hypotheses by determining the response of the line width to the intensity of the pump laser. If the two are inversely proportional, the Someone-Somebody Limit is possibly limiting the width, while if they are directly proportional, Fourier-limiting is more likely.
The next few days will probably be spent reading and catching up on background, but I should be able to start work in the lab soon. And I'm (hopefully) going to spend a few days learning to prepare samples in the clean room! That should be fun to learn.
After work, Chau and I stopped at a market and a bakery that are right next to our RER stop at Cachan. I bought a baguette that was still hot. It was very very tasty. Chau showed me how to buy and activate phone credit, so now I don't have to worry about being unable to communicate with the others.
Here are a few pictures of Kierstin's and my room in the House of Armenian Students:
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