Squeezing Light Into Infinitesimally Thin Lines

Fabricated surfaces that support line waves at the interface.

Fabricated surfaces that support line waves at the interface.

December 18, 2017 | Source: University of California, San Diego, jacobsschool.ucsd.edu, 19 Sept 2017, Liezel Labios

Researchers have demonstrated a new mode of electromagnetic wave, called a "line wave," which travels along an infinitesimally thin line along the interface between two adjacent surfaces with different electromagnetic properties. The scientists expect that line waves will be useful for the efficient routing and concentration of electromagnetic energy, such as light, with potential applications in areas ranging from integrated photonics, sensing and quantum processes to future vacuum electronics.

"Line waves are the first electromagnetic waves that are found to be guided by an infinitesimal, one-dimensional object," said Daniel Sievenpiper, a professor of electrical and computer engineering at the University of California San Diego and the study’s senior author. “The waveguide is nothing more than a line, which leads to a very high field concentration. This can be used to enhance nonlinear processes, leading to things like higher speed modulators for optical communication, or more sensitive chemical detectors.”

“What’s remarkable is how squeezing waves into a simple line could give rise to essentially infinite energy concentration and near-perfect energy transmission,” said Dia’aaldin Bisharat, a visiting graduate researcher from the City University of Hong Kong who is the first author of the study and conducted the work at the UC San Diego Jacobs School of Engineering. The researchers published their work in a recent issue of Physical Review Letters.

The new electromagnetic line waves are analogous to what are known as electromagnetic surface waves, which occur at the surface interface between two different materials laid one on top of the other. Surface waves can be used to strongly confine and guide light, making them useful for energy transmission and communication applications.