Columbia Engineering School scientists have developed optical nanostructures that allow them to control dispersion of light and slow down photons.
Chee Wei Wong
The researchers, Chee Wei Wong and Serdar Kocaman, have demonstrated that light can be transmitted from one point to another without any phase accumulation via an artificial medium as if the medium is entirely lost in space. They were the first to observe zero-index and simultaneous phase at the infrared wavelength and on the chip-scale level.
Kocaman commented that the research team developed and investigated a metamaterial with zero refractive index. The team observed that the light transmits via the material as if the whole space is lost and the electromagnetic wave’s oscillatory phase did not move further as in the case of a vacuum, Kocaman added.
An innovative combination of positive and negative refractive indices is the basis to control an optical phase accurately. All naturally available materials demonstrate positive refractive index. The scientists developed artificial subwavelength nanostructures to manipulate the dispersion of light to facilitate the appearance of a negative refractive index in the medium. They then used a positive refractive index medium to cascade the negative index medium which resulted in a nanostructure with zero refractive index.
According to Chee Wei Wong, phase control of photons is vital and the study has provided a better understanding on how to carry data on photonic chips with continuous control over the light phase. Scientists can now manage light flow, which can allow highly directive antennas and self-focusing light beams, he added.
The Defense Advanced Research Projects Agency and the National Science Foundation have awarded grants for this project.