A metamaterial that consists of a two-dimensional array of U-shaped gold structures (square background in the picture) efficiently emits terahertz frequency electromagnetic waves (red axis) when illuminated by a wavelength tunable near-infrared pump laser (blue axis). Credit: Ames Laboratory
Metamaterials allow design and use of light-matter interactions at a fundamental level. An efficient terahertz emission from two-dimensional arrays of gold split-ring resonator metamaterials was discovered as a result of excitation by a near-infrared pulsed laser.
Terahertz waves are used in non-invasive imaging and sensing technology, in addition to information, communication, processing, and data storage technologies. Despite their widely recognized importance, however, there are few terahertz sources presently available due to the limitations of natural materials. This discovery opens new ways to use metamaterials for these important applications.