NEWS | Feb. 7, 2017

Physical Chemist at U.S. Naval Research Laboratory Moves Technology at the Speed of Light

By Jonathan B. Holloway

A physical chemist at U.S. Naval Research Laboratory (NRL) had an article he co-authored with several scientists, “Polaritons in Layered Two-Dimensional (2-D) Materials” published in the science journal Nature Materials.

In the article, Dr. Joshua Caldwell and fellow scientists explain the technological potential of a new breed of one atom thick materials known as 2-D materials. In their research, they make clear the interaction between light and matter within atomically thin 2-D materials.

The authors review what is known and can be predicted, and investigates new properties in other 2-D materials. Their study observes the discovery of new 2-D materials properties and functions that enable faster, more efficient, and compact optical components. The research also identifies the most recent developments, and provides insight into best practices for technological advances.

Caldwell says he’s thankful to NRL’s long term training program for connecting him with Nobel Laureate Prof. Kostya Novoselov of the University of Manchester in the United Kingdom, which led to his study of 2-D materials.

According to Caldwell graphene is the first-generation of a new class of materials.

“Graphene is single-atom thick layer of ‘honey-combed’ carbon atoms that can be exfoliated from graphite, commonly found in pencils,” said Caldwell. “Graphite has individual layers of these carbon atoms with strong covalent bonds between atoms in each layer, with adjacent layers held together by a weak attractive force called the van der Waals force. Breaking the van der Waals bond between layers through exfoliation is what causes layers to separate, and allow the (graphite) pencil to write, or isolate single layers of graphene.”

The presence of van der Waals bonded layers are common to all 2-D materials. It lets 2-D materials be isolated into single, or few to several atomic-thick layers, as well as the ability to stack different 2-D materials on top one another to create what is called a heterostructure. This approach provides the ability to make arbitrary stacks to permit the application of 2-D materials in present day innovations.

On his own Caldwell is studying 2-D materials with properties that reduce and focus light past the diffraction limit.

“Imagine sunlight passing through a magnifying lens, creating a concentrated spot of light,” Caldwell said.

Caldwell’s research highlights how 2-D materials can focus a spot of light 1,000 to 10,000 times smaller than the diameter of a human hair through the process of forming polaritons.

“Polaritons are short-lived ‘quasi-particles’ formed by mixing a photon (light) and an oscillating charged particle, like an electron,” said Caldwell. “Mixing these particles retain the characteristics of the photon, while compressing that wavelength of light to sizes approaching that of the charged particle.”

Caldwell’s research offers new possibilities for numerous applications. It also redefines current ideas towards technological devices using nano-photonics instead of standard optics and electronics, meaning technology will be able to operate at the speed of light.

“A photon of light moves and modulates much faster compared to electrons in modern day electronics,” said Caldwell. “Using light will make everything orders of magnitude faster.”

As Caldwell continues his work, he says he looks forward to new discoveries and applications for nano-photonics and 2-D materials.

Click Here to read the full research article and visit the Nature Materials Website.