Metamaterial Flexible Sheets Could Transform Optics

A new metamaterial design that aims to replace bulky optical devices could improve IR thermal cameras, energy harvesting, and security screening and radar systems.

Polarization is one of the basic properties of electromagnetic waves, which convey valuable information in signal transmission and sensitive measurements. Conventional methods to advance polarization control impose demanding requirements on material properties and fabrication methods and attain only limited performance.

Now, Los Alamos National Laboratory researchers have demonstrated ultrathin, broadband and highly efficient metamaterial-based terahertz polarization converters that can rotate a linear polarization state into an orthogonal one. The metamaterial structure was created using flexible sheets capable of realizing near-perfect anomalous refraction.

Researchers at Los Alamos National Laboratory have developed a metamaterial design that could replace bulky optics, improving IR thermal cameras, energy harvesting, and security screening and radar systems. Members of the metamaterials team include (from left): Nathaniel K. Grady, Hou-Tong Chen and Jane E. Heyes. Images courtesy of LANL.

The investigators say the design could be exploited to make flat lenses, prisms and other optical elements such as high-performance spatial light modulators. The wavefront shaping also can result in a helical phase dependence, forming Laguerre-Gauss modes carrying an orbital angular momentum that could be useful in quantum entanglement or telecommunications.

The device could be scaled to work in the microwave to IR range, the researchers said. However, fabrication challenges and metal losses can become issues when approaching visible frequencies that significantly degrade the device performance.

(a) An ultrathin (72-µm thick) metamaterial sample. (b) An illustration of how the metamaterial redirects an electromagnetic wave, which would not happen for a normal thin film. The structure is not drawn to scale.

Part of the work was performed at the Center for Integrated Nanotechnologies, a Department of Energy Office of Science User Facility and Nanoscale Science Research Center.

The research — funded in part by the Los Alamos National Laboratory Directed Research and Development program — was reported in Science (doi: 10.1126/science.1235399).

For more information, visit: www.lanl.gov