The National Science Foundation announced that associate professor of electrical and computer engineering at Michigan Technological University, Elena Semouchkina, has used magnetic resonance to capture rays of visible light. By controlling the path of light around objects, it is scientifically possible to make them appear invisible to the human eye. Professor Semouchkina and her colleagues reported on their research in the journal Applied Physics Letters, published by the American Institute of Physics.
Groundbreaking British transformation optics pioneers
Professor Semouchkina’s work relies on approaches to transformation optics that were developed and applied to investigating invisibility by British scientists John B. Pendry and Ulf Leonhardt in 2006. The simple explanation is that beams of light can flow around objects and meet again on the other side, so anyone looking directly at the object would not be able to see it. Professor Semouchkina explained, “You would see the light source directly through the object this effect could be achieved if we surround the object by a shell with a specific distribution of such material parameters as permittivity and permeability.”
Cloak of invisibility?
The type of invisibility described by writer H.G. Wells in 1897, or Harry Potter author J.K. Rowling is still some way off, as the research is at an early stage. Professor Semouchkina and her team at Pennsylvania State University, where she is also an adjunct professor, have however designed a non-metallic ‘invisibility cloak’ using arrays of glass resonators made of chalcogenide glass, an insulator that does not conduct electricity.
Computer simulations to test for practical invisibility
Computer simulations have established that the experimental cloak could make objects hit by infrared waves disappear from view. Although this has yet to be demonstrated under laboratory conditions, the team are optimistic. “We want to move experiments to higher frequencies and smaller wavelengths,” said Professor Semouchkina. “The most exciting applications will be at the frequencies of visible light.”
Potential applications of invisibility
The value of this research could be significant, with potentially important military uses. Developments in ‘stealth technology’ have long been used to making aircraft invisible to RADAR, but Professor Semouchkina considers that it may also be possible in the future to conceal people or objects.
The science of ‘metamaterials’
The type of multi-resonator devices used to create Professor Semouchkina’s ‘invisibility cloak’ are called “metamaterials”. These are artificial materials that can bend and refract light in unexpected ways. Instead of the familiar atoms and molecules of natural materials, metamaterials have what are called ‘lattices’ that provide the range of relative permittivity needed. These metamaterials have been identified by the American Physical Society as one of the top three physics discoveries of the decade.
In the past, there were no materials known to science that had the relative permeability of less than one that is needed for the invisibility cloak to bend and accelerate light beams. The concept of metamaterials was first suggested by Russian scientist Victor Veselago and first tested in the year 2000 at Imperial College in London.
The National Science Foundation (NSF)
The research into this use of metamaterials is funded by the National Science Foundation (NSF), which has provided a grant of $318,520.
Professor Semouchkina, who has been a U.S. citizen since 2005, has a Master’s Degree in Electrical Engineering and a Doctorate in Physics and Mathematics from Tomsk State University in Russia. She also has a second Doctorate in Materials from Penn State University. Scientists are experimenting with magnetic resonance to capture rays of visible light and bend them around objects, making them invisible.