Study Shows Soap Bubbles Can Be Made Into Tiny Lasers

A new study carried out by Slovenian scientists shows that shining light on bubbles made from a mixture of soap water and fluorescent dyes can turn them into tiny lasers that are particularly good at sensing electric fields and pressures and can be used as pressure sensors. The paper in question is published in the latest issue of the journal Physical Review X.
The head of the latest study, Matyaz Huuma of the University of Ljubljana, and his colleagues collaborated to develop the bubble lasers. Huuma explains that soap bubbles are simple but very unique and wonderful objects that exhibit many interesting properties, such as beautiful interference colors. Scientists have studied various optical phenomena in soap films and bubbles, but so far they have not been used as optical cavities.
Bubble lasers require three key components: first, a cavity in which light can be reflected back and forth, which is usually made from mirrors, and in the latest study, the researchers used the internal volume of the bubble; second, the laser must also contain a material that amplifies the light, and for this reason the team added fluorescent dyes, which emit a very bright light, to the bubble mixture; and finally the last component, the light itself. Inside the latest bubble lasers, the light comes from an optical fiber that shines through a focusing lens onto the bubbles.
The bubble laser is so sensitive that it can be used to detect pressure changes as small as 0.001 percent of atmospheric pressure. On a sunny day, they can also sense electric fields in the surrounding air.
The team creatively combined the concept of "micro-ring lasers" with the idea of pushing light through a liquid membrane to create a completely new platform that opens the door to a host of novel applications.
They are already working on handheld pressure and electric field sensing devices based on bubble lasers, and are also experimenting with bubble lasers made from liquid crystals instead of soap, which would make the lasers more stable and "long-lived," according to Huma.