Plasmonic metamaterials are materials engineered at the nanoscale to control light but they typically contain metals that absorb energy from light and convert it into heat. As a result, part of the optical signal gets wasted, lowering the efficiency.
In a recent study, a team of photonics researchers demonstrated a way to make up for these losses by incorporating a semiconductor which emits light.
"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 postdoctoral scholar Joseph Smalley.
"This is the first material that behaves simultaneously as a metal and a semiconductor. If light is polarised one way, the metamaterial reflects light like a metal, and when light is polarised the other way, the metamaterial absorbs and emits light of a different 'colour' like a semiconductor.”
Researchers created the metamaterial by growing a crystal of indium gallium arsenide phosphide on a substrate.
They then etched narrow trenches into the semiconductor, creating 40nm-wide rows, which they filled with silver to create a pattern of alternating nano-sized stripes of semiconductor and silver.
"Rather than creating a stack of alternating layers, we figured out a way to arrange the materials side by side, keeping the semiconductor material defect-free," explained Smalley.