Engineers at Northwestern University's McCormick School of Engineering and Applied Science in Illinois have built a compact version of a device that uses terahertz waves for the purpose of imaging, to identify explosives, chemical agents and dangerous biological substances from safe distances.

The problem associated with the technology has always been with the source of large waves, multi-component systems that often require complex vacuum systems, external pump lasers and cryogenic cooling.

The team, led by Manijeh Razeghi, demonstrated the more compact, room temperature, tunable, high-power terahertz source in a paper published in Applied Physics Letters.

The system is based on nonlinear mixing in quantum cascade lasers. Use of the technology allows it to emit up to 1.9 milliwatts of power and a frequency range covering 1 to 4.6 terahertz. Additionally, this multi-section, sampled-grating distribution feedback and distributed Bragg reflector waveguide has a tuning range of 2.6 to 4.2 terahertz at room temperature.

The device can be used for security screening purposes, as well as medical and deep space imaging.

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