Edwin L. Aguirre
Imagine being able to “see” structures or organisms, such as individual viruses or DNA molecules, measuring only billionths of a meter in size. Or watch live interactions between biological cells in real time and in their natural environment.
That’s the goal of researchers worldwide in developing a so-called superlens, or “perfect” lens
. They are using a new class of engineered synthetic materials — called negative refractive index metamaterials
— in trying to achieve resolution beyond the diffraction limit of ordinary optical microscopes.
One of the scientists working in this field is electrical and computer engineering Assoc. Prof. Alkim Akyurtlu, who recently received a three-year grant totaling about $650,000 from the Air Force Office of Scientific Research to study such metamaterials.
“Super-resolution imaging is also sometimes called subwavelength imaging because we can view details of an object below the wavelength of visible light,” explains Akyurtlu.
She says the metamaterials that she and her research group are working on will possess the desired properties to make a perfect lens.
“Not only can you see things much smaller than with a standard optical microscope but you can also apply the technique to improve photolithography and nanolithography, which are essential for manufacturing even smaller computer chips and other microelectronics,” she says. “This technology is also very useful in medical imaging, biological security screening, military surveillance and homeland security.”
Some of the main drawbacks of the current designs of negative refractive index metamaterials are the large amount of losses in resolution that exist in these materials.
“To minimize the losses, we have designed our metamaterials using conventional materials, such as magnetic semiconductors and transition metals, which exist in nature,” she says. “Since there are no inhomogeneities in the raw materials, we believe the losses will be less.”
In addition to this novel approach, Akyurtlu and her team plan to reduce the losses even further by shifting the frequency at which the maximum losses occur.
“Hence, we will operate in the low-loss frequency regime for our metamaterials,” she says. “No one has proposed such an idea. We accomplish this by using bichromatic irradiation, that is, two laser sources.”