New terahertz devices could strengthen security

Scientists have developed gen-next devices that use terahertz waves to detect explosives, chemical agents and dangerous biological substances from safe distances.
Current terahertz sources are large, multi-component systems that sometimes require complex vacuum systems, external pump lasers and even cryogenic cooling.
The devices are heavy, expensive, and hard to transport, operate, and maintain.
"A single-component solution capable of room temperature and widely tunable operation is highly desirable to enable next generation terahertz systems," said Manijeh Razeghi, Walter P Murphy Professor of Electrical Engineering and Computer Science at Northwestern University's McCormick School of Engineering and Applied Science.
Razeghi and her team have been working to develop such a device.

In a paper in the journal Applied Physics Letters, they have demonstrated a room temperature, highly tunable, high power terahertz source.
Based on nonlinear mixing in quantum cascade lasers, the source can emit up to 1.9 milliwatts of power and has a wide frequency coverage of 1 to 4.6 terahertz.