Laser Research

ACU's Undergraduate Research Festival has been in full swing with poster sessions presented by various students from departments all over campus. It will conclude with more student presentations, a banquet, and a key-note speaker Monday. I feel very fortunate to be studying at an institution that strongly supports research at the undergraduate level, its not exactly something that happens at every university. The physics department itself has done a great deal paving the way for the rest of the student body. We've always had an incredibly strong representation at area and regional conferences, doing work in particle physics at national labs that is usually reserved for doctoral candidates.

I never took advantage of the opportunity to do summer research while here at ACU, mostly because I felt like I had a better offer working for the Engineering Department of the Flathead National Forest back home in Kalispell. Thankfully my friend Nathan and I were able to do some work outside of class in the Optics laboratory as part of a Honors Contract. The picture above is us presenting our poster last Wednesday.

Nathan and I, along with 4 others, were in an Optics course together which had a lab component to it. For our final projects in the lab, we had the opportunity to construct tunable, infrared diode lasers over the course of the last 6 weeks of the spring semester 2009. After much toil none of the three groups finished their respective lasers. However, Nathan and I really wanted to finish two lasers for the department so as to facilitate the assembly of a magneto-optical trap (MOT).

You are probably wondering, "What's a tunable, infrared diody-thingy and how does it make a trap?" We purchased diode lasers, which are a little smaller than the size of a pencil eraser, from a manufacturer and built an apparatus to hold it and make it easier to use. The diode uses semiconducting technology to produce light when a current is put across the leads, emitting them from a small aperture. The light coming from this little hole has a big divergence (meaning it spreads out really fast) and a range of frequencies of light, all in the infrared (meaning they're "too red" to see with the naked eye). Our apparatus solves the former by putting a lens to focus the light down to a usable beam and the latter by using a reflection grating to set up some optical feedback thus locking in a desired frequency. Now, I appreciate you've suffered through my "geek speak" here long enough so I won't go into greater detail here. Just think about us having the ability to control the output frequency of light with some external controls.

Our goal was to complete the two lasers and be able to use them in a MOT, another larger assembly of optical components used to trap and "cool" atoms. Some experiments with MOTs have been able to cool atoms very near absolute zero where all atomic motion stops. When it's this cold, "temperature" is essentially the internal vibrational energy of the atom. Although we were unable to finish the lasers and see the MOT constructed ourselves, we laid some important groundwork for students to follow behind us. As I mentioned earlier, many ACU students are able to pursue research at big national labs, but having some optical research capabilities on campus is exciting.