Durdu Güney stands in his lab where he and his team work on creating a ‘perfect lens’.
Credit: Michigan Tech
Imagine if we could see nanometer-sized viruses with the naked eye. That’s a real possibility with a “perfect lens.” It is a theoretical perfected optical lens made out of metamaterials, engineered to change the way the materials interact with light. MTU researchers have found a way to possibly solve one of the biggest challenges, getting light waves to pass through the lens without getting consumed. “These findings open the possibility of reviving the early dreams of making ‘magical’ metamaterials from scratch.”
Metamaterials go beyond the limits of natural materials such as glass, plastic, metal or wood. To do that, the base used for making a metamaterial- like the thin silver films Güney’s group uses- that are tweaked at the subwavelength scale so that light waves interact with the material in new ways. The metal base Güney tests would look more like a traditional glass lens; light would pass through instead of reflecting off the metal.
“Aluminum and silver are the best choices so far in the visible light spectrum, not just for a perfect lens but all metamaterials,” . “Loss -or the undesired absorption of light -is good in solar cells, but bad in a lens because it deteriorates the waves.” Solution for a sharper image then is to offer up a sacrificial light wave.
To create their sci-fi light-bending properties, a perfect lens relies on negative index metamaterials. + and – refer to how a material responds to propagating and decaying light waves, which are like the yin and yang of optics. Most materials, +ve index materials, allow only propagating light waves to pass through. -ve index metamaterials on the other hand pass through propagating light waves + amplify the decaying light waves.
“In order for the perfect lens to work, you have to satisfy a lot of electromagnetic constraints,” Güney explains. “We don’t know how exactly the required optical modes [light waves in the material] need to be excited and protected in the lens for the perfect construction of an image.” In their plasmon-injection scheme (π-scheme), the researchers take advantage of knowing which light wave crumbles as it passes through the negative index lens. They use this wave -destined to fail in the lens -to shield the desired light wave, allowing it to pass through unscathed. “With this approach, you can engineer this sacrificial wave,”
APPS: future accessible medicalimaging technology and lightweight field equipment etc: “see with your own eyes” http://www.mtu.edu/news/stories/2015/july/bringing-back-magic-metamaterials.html
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