Metamaterial Shows Promise as THz Imager

An imaging approach involving metamaterials could make the terahertz regime more accessible.

Researchers from Boston College, the University of New Mexico and Duke University engineered a low-power multiplex tunable spatial light modulator (SLM) that uses a series of masks to retrieve multiple samples, which are reassembled by a single-pixel detector.

Data obtained from these encoded measurements are used to computationally reconstruct the images as much as six times faster than traditional raster-scan THz devices, the researchers said.

THz waves are received by a metamaterial spatial light modulator, which sends multiple data points to a single-pixel detector, which then computationally reconstructs the image faster, more efficiently and with higher fidelity than conventional THz imaging technology. Courtesy of Nature Photonics.

The new metamaterial SLM modulates THz radiation, allowing it to actively display encoding masks designed to retrieve THz images. One such encoding technique allowed the researchers to access negative encoding values, which allow for higher-fidelity image reconstruction.

Earlier THz camera designs, such as focal-plane-array-based cameras, have relied on expensive and bulky detector arrays to assemble images. A negative encoding value typically requires phase-sensitive sources and detectors, multiple detectors or taking twice the number of measurements in order to create the image.

In the present study, the researchers created masks without additional equipment or measurements, allowing researchers to use a more robust image encoding method that increased image quality while reducing the time needed to acquire the image.

Applications proposed for terahertz imaging include skin cancer screening, airport security, all-weather navigation and biodetection.

The research was published in Nature Photonics (doi: 10.1038/nphoton.2014.139).

For more information, visit: www.bc.edu.