T-rays at room temperature

INNOVATIONS IN LASER technology have led a team of Harvard boffins to create the world’s first electrically-pumped semiconductor source of coherent Terahertz (THz) radiation at room temperature.

Previously, electrically-pumped, Terahertz semiconductor lasers were impractical to use, due to the significant amounts of cryogenic cooling needed to make them work properly, but the new findings could prove to be a breakthrough in the field of Terahertz (THz) radiation, or T-rays.

The research was carried out by Mikhail Belkin and Federico Capasso, who worked with Professor Robert L. Wallace, a Vinton Hayes Senior Research Fellow in Electrical Engineering at Harvard.

The boffins tackled the heat problems of contemporary lasers by building their own mid-infrared Quantum Cascade Laser (QCL), which was able to give out two different light frequencies at the same time. T-rays were formed at room temperature when difference frequency occured inside the laser at 5THz.

“There is the potential of increasing the terahertz output power to milliwatt levels by optimising the semiconductor nanostructure of the active region and by improving the extraction efficiency of the terahertz radiation", gushed Belkin.

What this means in a practical sense is that T-Ray devices could eventually be used for sniffing out biological or chemical substances through sealed packages, exposing hidden weapons, finding hard to see flaws in things like the Space Shuttle's foam insulation, and even being able to spot tumours without causing any nasty side effects.

The full findings will be published today in the journal of Applied Physics Letters. µ

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