Closing the terahertz gap: Tiny laser is an important step toward new sensorsIn a major step toward

Closing the terahertz gap: Tiny laser is an important step toward new sensors

In a major step toward developing portable scanners that can rapidly measure molecules in pharmaceuticals or classify tissue in patients’ skin, researchers have created an imaging system that uses lasers small and efficient enough to fit on a microchip.

The system emits and detects electromagnetic radiationatterahertz frequencies—higher than radio waves but lower than the long-wave infrared light used for thermal imaging. Imaging using terahertzradiation has long been a goal for engineers, but the difficulty of creating practical systems that work in this frequency range has stymied most applications and resulted in what engineers call the “terahertz gap.”

“Here, we have a revolutionary technology that doesn’t have any moving parts and uses direct emission of terahertz radiation from semiconductor chips,” said Gerard Wysocki, an associate professor of electrical engineering at Princeton University and one of the leaders of the research team.

Terahertz radiation can penetrate substances such as fabrics and plastics, is non-ionizing and therefore safe for medical use, and can be used to view materials difficult to image at other frequencies. The new system, described in a paper published in the June issue of the journal Optica, can quickly probe the identity and arrangement of molecules or expose structural damage to materials.

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