Researchers at the University of Cambridge have developed a way to produce high quality liquid crystal lasers with nothing more than a custom inkjet printer. The team believes that the new technique will enable us to churn out lasers with existing printing equipment, which will enable low-cost mass production of things like labs on a chip and smart surfaces like laser-enabled wallpaper.
"Until now, no one has been able to print lasers"
Liquid crystal lasers are a pain to build. You need a clean room environment and precise alignment of the glass plates that form the ends of the laser’s resonant cavity, the part that traps the photons emitted by the active laser medium (in this case a special dye in the liquid crystal), and keeps them clanging around as they coax more photons out of other nearby atoms. The team’s new approach, which has been published in the journal Soft Matter, uses inkjet printing to lay hundreds of dots of 200ºF liquid crystal on a glass substrate, or base layer, that’s been coated with a liquid polymer.
As the polymer dries, the combination of a chemical reaction with the liquid crystal and the mechanical force of the drops hitting the glass perfectly aligns the liquid crystal molecules, leaving you with hundreds of tiny lasers-to-be. The approach also exploits a property of the crystal to get rid of the need for the mirrors at the ends of the resonant cavity altogether, said one of the paper’s authors, W-K Hsio to the BBC. As an example of a future application of the low-cost technology Hsiao discussed smart, laser-dotted wallpaper. "Blind people who walk around the museum with a low-power scanner can this way know which room they’re in, what exhibition is displayed, and where they have to turn to find an emergency exit," he explained.