LASER PHYSICS

Two different combs from a single source

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Science  16 Jun 2017:
Vol. 356, Issue 6343, pp. 1134-1136
DOI: 10.1126/science.356.6343.1134-n

Combs of light divide the optical frequency spectrum into closely spaced tines that can measure molecular absorption spectra with exceptional precision. One appealing method to extend this precision down into the microwave regime is to simultaneously use two slightly distinct combs that differ in spacing by the magnitude of a microwave frequency. The challenge is ensuring that the combs remain synchronized. Link et al. solve this problem by generating both combs from the same semiconductor laser source. The resultant dual comb delivers highly accurate spectra of water vapor, and the approach could be generalized across the optical spectrum by tuning the semiconductor source.

Science, this issue p. 1164

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