Wednesday, May 21, 2008
What's claimed to be the world's first room-temperature terahertz laser harnesses the optical equivalent of heterodyning to bridge the terahertz gap. Today, a terahertz-gap exists where most semiconductor lasers fail to operate--between microwave wavelengths (centimeters) and optical wavelengths (microns). In between are the millimeter wavelengths--terahertz frequencies (1-10 THz). The only semiconductor lasers that run at terahertz frequencies today are supercooled quantum cascade lasers (QCL). Now, the co-inventor of the QCL has demonstrated a heterodyning method cast in nonlinear materials that mixes two easy-to-generate optical frequencies spaced apart at the desired terahertz frequency, resulting in a room-temperature terahertz laser. Terahertz lasers enable scanning like x-rays, but are completely safe to use around people. Using a terahertz scanner, airports could detect hidden weapons under clothing, as well as hazardous and toxic materials inside luggage. Terahertz lasers could also remotely detect hazardous gases floating in the air, offering a potential solution to identifying improvised explosive devices from a distance.
Posted by R. Colin Johnson at 9:07 AM