From visible light to radio waves, most people are familiar with the different sections of the electromagnetic spectrum. But one wavelength is often forgotten, little understood, and, until recently, rarely studied. It's called terahertz, and it has important applications in imaging and communications.



Northwestern University researchers have used metamaterials and #3Dprinting to develop a novel lens that works with terahertz frequencies. Not only does it have better imaging capabilities than common lenses, but it opens the door for more advances in the mysterious realm of the terahertz.



The focal length of a lens is determined by its curvature and refractive index, which shapes the light as it enters. Without components to counter intrinsic imperfections, resulting images can be fuzzy or blurred. This new lens, on the other hand, employs a gradient index, which is a refractive index that changes over space to create flawless images without requiring additional corrective components.



There are two major factors that made this new lens possible. First, it is made from a novel metamaterial that exhibits properties not readily available in nature.