Researchers from the University of St Andrews have developed a flexible and ultra-thin membrane-based organic laser that can shoot out a beam of photons while embedded in a contact lens.
But before anyone gets carried away with ideas of cutting through walls à la Cyclops from X-Men, we must note that is not quite how this form of laser technology works.
The team’s “optically pumped” organic laser uses a semiconductive polymer that is excited by exposure to light – in this case, blue light – and subsequently emits a narrow band of light in the visible spectrum that can be tuned to carry binary coded information; essentially, the visual version of a barcode.
In recent years, engineers have revolutionized the field of optoelectronics – electronic devices that manipulate light – by adopting organic polymers as semiconductors. Yet organic lasers, which have the potential to drive new data communications technology and chemical detection devices, have been restricted by the need for rigid backing material.
As described in the journal Nature Communications, the St Andrews physicists invented a new process wherein the laser’s organic semiconductor polymer and diffraction grating are printed into the correct configuration onto a piece of glass, then subsequently freed by submerging the whole assemblage in a water bath.
“The resulting 200-nm thick membrane lasers were operated freestanding in air or readily transferred onto a new substrate, on which direct fabrication of a laser may otherwise be impossible or impractical,” the authors wrote.
Hoping to demonstrate the functionality and versatility of their breakthrough membrane lasers, the authors picked two of the most exciting applications: security stickers for bank notes and wearable identification tags.
Two hundred days after placing a laser sticker on the transparent window of a £5 bill, the correct security signature was still being transmitted in response to light, showing "how membrane lasers that were designed to produce a well-defined and unique lasing spectrum can be used as counterfeit-resilient, barcode-type security labels on bank notes.”
In the other proof-of-concept experiment, a membrane laser inside a contact lens was tested in a cow eye that had been removed. Exposure to levels of blue light that would be tolerable to a living person caused the emission of a green laser beam onto a screen 50 centimeters (20 inches) away. This success demonstrates that wearable organic lasers could be used to complement existing iris-scanning biometric systems in the future.
Though that particular application may seem unappealing due to its distinctly dystopian vibe (and the fact that the prototype adds an unsightly yellow tint to the eye), the authors are quick to assert that it appears safe.
“The intensity of the laser beam and the amount of energy it requires is so low that you can put it in the eye without damaging the eye,” senior researcher Malte Gather told New Scientist. “I would be willing to try it.”
If that's still not your thing, Gather and his colleagues also found promising results from sticking the laser on a fingernail, meaning that one's ID would literally always be at hand.
3
