Monday, August 15, 2005

"QUANTUM: Ultrasensitive quantum lasers sniff toxins"

Less than two years after Lucent Technologies Bell Labs pioneered the quantum cascade laser and predicted more-sensitive spectroscopy, Georgia Tech researchers say they've validated the concept of single-chip spectra analysis. By integrating all the components in one device, such a spectrometer could enable lab-on-a-chip applications reminiscent of the handheld "tricorder" popularized by Star Trek. No one has yet integrated all the components onto a single chip, but Boris Mizaikoff, an associate professor at the Georgia Institute of Technology, said he has proven the concept using available laboratory quantum cascade lasers, waveguides and detectors. Now he is testing the device as an ultrasensitive spectrometer. By using the midinfrared signatures for molecules that have the characteristics of known explosives, toxins and other agents of interest, Mizaikoff has shown that a single chip can identify through spectroscopy almost any substance of interest after "sniffing" scant parts per billion of that substance. Ultimately, the single-chip lab would be housed in a handheld device. In his initial tests, Mizaikoff coupled a hollow waveguide to a frequency-matched quantum cascade laser to irradiate a 1-milliliter gas sample. Conventional spectroscopy, by contrast, samples hundreds of milliliters. Yet sensing inside the photonic-bandgap material enabled the detection of levels down to 30 parts per billion.