Optical Frequency Comb?

I just stumbled upon this, a type of laser I have never heard about being used for a pretty awesome purpose. Does the laser they describe actually exist? Is it a laser at all? :thinking:



"Since 1954, troopers have used breathalyzers to determine whether drivers have imbibed--and just how much. Jun Ye, a physicist at the University of Colorado, has transported the concept into an entirely new realm: medical diagnostics. The device he's designed detects thousands of different biological molecules in a single exhalation, creating a snapshot of the breath's contents that could signal the presence of illnesses, from cancer to cystic fibrosis. This split-second diagnosis is powered by a laser called an "optical frequency comb," which emits a wide spectrum of lightwaves that interacts with airborne compounds. "You have this rainbow of light coming out in a regularly spaced comb pattern," Ye says. "When breath molecules fly through the rainbow, they set off resonant frequencies that make the comb look like it has missing teeth." If the resulting pattern shows the presence of carbon monoxide, hydrogen peroxide and nitric oxide, for example, the exhaler may be suffering from asthma. "You don't have to wait days for test results," Ye says. "Within a minute, you know what's going on."

Original Article: 10 High-Tech Health Breakthroughs Coming Soon to Your Body - Popular Mechanics

An optical frequency comb consists of a femtosecond laser, which spectrum has many sharp lines separated by the repetition rate. The spectrum can be broadened using a nonlinear fiber, to get a rainbow of all colors.
The optical frequency comb allows for absolute frequency meaurements of optical frequencies by measuring the beat frequency to the comb lines.
This technique was invented by Hänsch in Munich end of the 90s and he got the Nobel price for it in 2005.

It's the first time, I see this medical application of the frequency comb. But it sounds very reasonable to identify the different molecules by their specific absorption of the lines of the frequency comb. With the broad spectrum of the comb, it is possible to measure the absorption of many different molecules at the same time. Cool.

Check wikipedia for Ti:Saphire laser and gainwidth (or in Encylopedia of Laser Physics and Technology)!