The thin shells of bubbles interact with light in fascinating ways; that is, of course, the source of their brilliant colors. In this recent study, researchers discovered that bubbles can serve as tunable lasers. A laser has three major components: an energy source, an optical resonator, and a gain medium that amplifies light in the resonator. For bubble lasers, an external pump laser provides energy and the bubble’s thin shell acts as a resonator. Fluorescent dye in the bubble serves as the gain medium.
Once formed, the bubble lasers are incredibly sensitive to electric fields and pressure changes, making them excellent sensors. For added stability, the team is using smectic liquid crystal bubbles, which, unlike soap bubbles, don’t evaporate easily. (Video, image, and research credit: Z. Korenjak and M. Humar; via APS Physics)