Universe’s fingerprints

The device, which Gao developed together with colleagues of MIT and the Netherlands Institute for Space Research, could prove highly valuable for astronomers. By studying the infrared light emitted by atoms and molecules in space, astronomers can learn a lot about the formation of stars. Stars and star-forming clouds heat up atoms in interstellar space causing these atoms to emit infrared light. The kind of light and the amount depends on the lifecycle stage of the star forming clouds.



“Because of its long wave lenght in comparison with visible light, this light hardly gets distorted while traveling through space”, says Gao, whose article entitled ‘Terahertz laser frequency combs’ was published earlier this month in Nature Photonics. “The spectral lines we detect are the fingerprints of the universe.”



If all follows as planned, NASA will send the instrument up in the stratosphere at forty kilometres altitude above Antarctica with a balloon at the end of 2015. “At that altitude the amount of water, that could absorb the infrared light, is negligible”, says Gao.

At the heart of the technology are so called optical frequency combs. These are light sources whose spectrum consist of a series of discrete, equally spaced lines at optical wavelengths. Because frequency combs allow a direct link from radio frequency standards to optical frequencies, they have revolutionized high-precision metrology and spectroscopy.