Image by AFP via @daylife
”Scientists trap a rainbow.” The headline makes it sound like the end result of a series of experiments that began as a hastily made, ill-thought out promise to a small child.
“I’m sorry I missed your play, but don’t worry – daddy will get you whatever you want for your birthday! What do you want?”
“I want a rainbow!”
Or, my preferred alternative, it’s the culmination of an escalating series of boasts by a couple of drunk engineers, as a hasty comedown from “I can build a turbine powered by unicorn horns!”
The actual origins of rainbow trapping are, I admit, probably a bit more mundane. But the end result is cool nonetheless. Here’s the story: a team of researchers at Lehigh University have successfully developed a plasmonic surface capable of trapping a rainbow. That is, it takes the broadband spectrum of light and slows it down so that each individual wavelength (color) of light gets separated–making it easier to process any information contained therein.
And if you read the above sentence thinking to yourself, “What’s ‘plasmonic’ mean?”, you’re not alone — I had to spend a few hours researching it myself. But what I found is fascinating. When light hits a plasmonic surface, it creates a wave of electrons that move at the same frequencies as photons, rather than the much slower frequencies of an electric current. But while photons have to be transmitted over fiberoptic cable — which is too bulky to be a computer component, plamons can be transmitted over wire, just like those used for traditional electronics.
Apart from potential computing applications, plasmonics can be used as biosensors, making it possible to more easily determine what your body is doing, and potentially make it easier for doctors to diagnose disease.
In the case of this rainbow-trapping plasmonic surface, the researchers at Lehigh created “adiabatically graded metallic gratings”, which are basically small, nanosized grooves in a sheet of silver. The gratings themselves were so small that the dimensions had to be confirmed with atomic force microscopy.
However, once the grade depths were confirmed, light was focused on the surface. Each of the individual grooves captured a different color of light — kind of like a prism separating white light into its colors — thereby “trapping” the rainbow on the plasmonic surface. Each color is slowed to a different speed, making it easier to process the data being transmitted. That improved processing means that it can potentially be used to improve current biosensors and make it easier for doctors to monitor the health of their patients.
It will be interesting to see where this area of plasmonics research goes. I may have only learned what plasmonics was a few hours ago, but I’m hooked now. You can look forward on some follow ups to this and other areas of plasmonic research.
Also, a final word of advice to any unicorns who might be reading this: watch your backs. Drunk engineers on a mission are relentless.