THz Beam Propagation Measured Through 3D Amplitude Profile Determination

Which was the name of the article which I spent some time today reading about. I spent all of today reading through this article from a group at Oklahoma state from 2003, another article from a Japanese group in 2001, and various online sources.

The 2003 article is an account of how this group tried to measure a THz beam using a 3D amplitude profile determination technique. I found this useful in helping me tie in all of the information that I have been reading about. I reviewed material on Gaussian beams, complex EM wave representation, beam width and radius of curvature. The article was useful most in the sense that I was able to read of exact experimental design, why certain things were used, and what results were found using said methods. Also, the critical angle for GaAs interface which is ~16 degrees, which is consistent with what I have already read/heard.

The method used for this experiement involved measuring r_s and r_p, which are the Fresnel reflection coefficients. Recall the Brewster angle, or the angle at which there is zero reflection for the P waves, which was utilized in this setup. From the article, "beams with arbitrary spatial variations can be described mathematically as a superposition of Hermite-Gauss modes for Cartesian symmetry or Laguerre-Gauss modes for cylindrical symmetry." This 2003 group used the Laguerre-Gauss technique because of beam shape. I think that I will be using this same sort of approach for my work.

The article had much more in it to offer, but for lack of my own comprehension, I will talk about it next week after catching up on reading this weekend.

In terms of reading, Dr. Gallot has lent me a monograph by Mittleman, which is essentially "the" book on THz and also Antoine has leant me a book on photonics. I would like to skim through both of them either by Sunday or Monday. On that same note, we have a cocktail party at ENSTA in Paris on Monday so I will just do work out of the apartment (no point in spending two hours going to and from work to stay there for a few hours).

Finally, one more thing which occurred on Friday was a talk given by Dr. Steven Girvin from Yale about "Quantum Money, Information and Computing". It ended up being a pretty interesting talk (and actually answering some questions I had from last semester).