Optics

A one-two approach to air-lasing

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Science  23 Jan 2015:
Vol. 347, Issue 6220, pp. 385
DOI: 10.1126/science.347.6220.385-b

Standoff spectroscopy involves the excitation and detection of chemical species at a distance. From security screening to environmental monitoring, there is a need to obtain accurate readings, which usually entails getting as much of a signal back as possible. Powerful laser pulses can excite pockets of air at great distances, allowing the remote sensing of the surrounding atmosphere, but their utility is limited by the small amount of light that gets back to the detector. Laurain et al. provide a solution to this problem, in the form of a two-color sequence of intense laser pulses. The first pulse, at infrared wavelengths, efficiently dissociates the air molecules; it is followed by a second ultraviolet pulse that excites the dissociated molecules and induces lasing. The induced laser light is emitted directionally, providing the possibility of greatly enhanced detection efficiency.

Phys. Rev. Lett. 113, 253901 (2014).

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