Laser Smackdown: The Most Amazing Use of a Laser?

Chad asks the question in general, but I am going to personalize it. I’ve had the opportunity to do some neat things with lasers, mostly related to laser cooling and trapping. I’ve trapped K-37, K-38(m), K-40, K-41, Rb-85, Rb-87, and Cs-133 (the first two of those being radioactive isotopes with half-lives of around one second) and in each case, made a slow atomic beam to send the atoms somewhere else so we could use them for whatever reason depending on the experiment. Making state-of-the-art atomic clocks? Pretty cool. I’ve made holograms, which are a not-too-shabby use.

But the neatest thing I ever did happened in grad school, while we were still building up to cooling and trapping. There was a science summer school in session, and our lab set up a demonstration: we took our home-built lasers and modulated the current being sent to them by tapping in to the output jack of a boombox. Then we sent the beam across the lab and onto a photodiode, and sent the AC output into another boombox. Music sent across the room on a beam of light! Essentially fiber-optic data transmission without the fiber, so we could show the students that blocking the beam stopped the music, and while this is standard (even boring) today and wasn’t really new even then, I thought it was the coolest thing I had ever done (to that point, anyway).