I'm writing back-to-back posts, this one about my time at work today. Thankfully, Mélanie has returned and is feeling much better. We had a bit of conference this morning, and I showed her the summary I wrote last Wednesday and the path-length calculations I had finished. She was quite intrigued by the spectra showing an abrupt and dramatic change in the qualitative shape of the spectra for the 160-159um cavity as the pump energy approached the lasing threshold. (The two numbers refer to the widths of the cavity at either end of the strip, so the 160-159um cavity has the smallest angle of all the non-parallel FP's.) The spectra change from looking "typical" for true Fabry-Perots to bumpy and funny-looking right around the threshold energy. My new directive: investigate this region and determine roughly how the spectra depend on pump position and energy. Pump position will likely have a large impact on the spectra with these new cavities, because their width changes from top to bottom.
I haven't quite begun to tackle my new task yet. Today I took more threshold data, and managed to determine the lasing threshold for a true Fabry-Perot, as a reference. Over the past few weeks, I have not been accustomed to seeing what I expect when I plot my data, so I was very pleased to see the quasi-hockey-stick shape that clearly heralded a threshold energy. It takes a while to churn through this data, so I still have three more cavities to analyze before moving on, but I feel purposeful and optimistic. Secrets of non-parallel Fabry-Perots, I'm coming for you!
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