Zero-index waveguide enables researchers to directly observe infinitely long wavelengths: Page 3 of 3

October 10, 2017 //By Jean-Pierre Joosting
In 2015, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) developed the first on-chip metamaterial with a refractive index of zero, meaning that the phase of light could be stretched infinitely long. The metamaterial represented a new method to manipulate light and was an important step forward for integrated photonic circuits, which use light rather than electrons to perform a wide variety of functions.

This may be the first time a standing wave with infinitely-long wavelengths has ever been seen.

"We were able to observe a breath-taking demonstration of an index of zero," said Reshef, who recently accepted a position at the University of Ottawa. "By propagating through a medium with such a low index, these wave features, which in light are typically too small to detect directly, are expanded so you can see them with an ordinary microscope."

"This adds an important tool to the silicon photonics toolbox," said Camayd-Muñoz. "There's exotic physics in the zero-index regime, and now we're bringing that to integrated photonics. That's an important step, because it means we can plug directly into conventional optical devices, and find real uses for zero-index phenomena. In the future, quantum computers may be based on networks of excited atoms that communicate via photons. The interaction range of the atoms is roughly equal to the wavelength of light. By making the wavelength large, we can enable long-range interactions to scale up quantum devices."

The paper was co-authored by Daryl I. Vulis, Yang Li and Marko Loncar, Tiantsai Lin Professor of Electrical Engineering at SEAS. The research was supported by National Science Foundation and was performed in part at the Center for Nanoscale Systems (CNS).


Real-time, unprocessed video of standing waves of light in a 15-micrometer-long, zero-index waveguide taken with an infrared camera. The perceived motion is caused by atmospheric disturbances to the free- standing fibers that couple light onto the chip, changing the relative phase between the two incoming beams. Image courtesy of Harvard SEAS.

www.seas.harvard.edu