Shine a light: material behaves simultaneously as metal and semiconductor

The discovery by engineers at the University of California San Diego is claimed to address one of the biggest challenges in the field of photonics, namely minimising loss of optical signals in plasmonic metamaterials.

Plasmonic metamaterials are materials engineered at the nanoscale to control light and can be used to develop devices ranging from invisibility cloaks to quantum computers. Metamaterials typically contain metals that absorb energy from light and convert it into heat. Consequently, part of the optical signal gets wasted, lowering the efficiency.

In a recent study published in Nature Communications, a team of photonics researchers led by electrical engineering professor Shaya Fainman at the UC San Diego Jacobs School of Engineering demonstrated a way to make up for these losses by incorporating a light emitting semiconductor material into the metamaterial.

"We're offsetting the loss introduced by the metal with gain from the semiconductor. This combination theoretically could result in zero net absorption of the signal - a 'lossless' metamaterial," said Joseph Smalley, an electrical engineering postdoctoral scholar in Fainman's group and the first author of the study.