Third-harmonic generation in a laser-pre-excited gas: the role of excited-state neutrals
نویسندگان
چکیده
The generation of the third harmonic of 150-fs 4-mJ Ti:sapphire laser pulses in the atmospheric air preliminary excited by 15-ns 100-mJ pulses of the second harmonic of a Nd:YAG laser is investigated. Preliminary laser excitation of a gas is shown to considerably increase the efficiency of frequency tripling of femtosecond pulses. Characteristic times corresponding to the maximum intensity of third-harmonic generation are shown to substantially exceed the characteristic plasma decay times, indicating the important role of excited-state neutrals in the enhancement of THG efficiency. q 2000 Elsevier Science B.V. All rights reserved. PACS: 42.50.Hz; 42.65.Ky
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