Saturday, February 13, 2016

Terahertz wave comb- National Science Foundation

An artist's conception of a terahertz wave comb developed in the lab of California Institute of Technology chemist Geoffrey Blake.
More about this image
California Institute of Technology (Caltech) chemists have developed a precise ruler of terahertz light that will aid in the study of organic molecules in space and the soft interactions between molecules in water. The new device is an example of what is known as a frequency comb (due to its resemblance to a hair comb), which uses ultrafast pulsed lasers, or oscillators, to produce thousands of unique frequencies of radiation distributed evenly across a spectrum like the teeth of a comb.

Light can come in many frequencies, only a small fraction of which can be seen by humans. Between the invisible low-frequency radio waves used by cell phones and the high frequencies associated with infrared light lies a fairly wide swath of the electromagnetic spectrum occupied by what are called terahertz -- or sometimes called submillimeter waves. 

Exploitation of these waves could lead to many new applications in fields ranging from medical imaging to astronomy, but terahertz waves have proven tricky to produce and study in the laboratory.

The new device created by Caltech chemists generates and detects terahertz waves over a wide spectral range with extreme precision, allowing it to be used as an unparalleled tool for measuring terahertz waves. The new device uses ultrafast pulsed lasers, or oscillators, to produce thousands of unique frequencies of radiation, distributed evenly across a spectrum like the teeth of a comb. Scientists can then use them like rulers, lining up the teeth like tick marks to very precisely measure light frequencies.

The research was supported by a grant from the National Science Foundation.

To learn more about this research, see the Caltech news story Chemists create 'comb' that detects terahertz waves with extreme precision. (Date image taken: April 2015; date originally posted to NSF Multimedia Gallery: Feb. 12, 2016)
Credit: Lance Hayashida/Caltech, NASA/ESA/ and the Hubble Heritage Team (STScI/AURA) - ESA/Hubble Collaboration
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