Enhancement of third harmonic generation in air filamentation using obstacles*
Liu Xiao-Longa)†, Lu Xinb), Du Zhi-Guia), Ma Jing-Longb), Li Yu-Tongb), Zhang Jieb),c)
       
(a) Spectral distribution of the fundamental pulse. (b) Intensity of TH emission disturbed by thin copper fibers: no disturbances (solid line); single fiber (dash line); two fibers (dot line); three fibers (dash-dotted line); four fibers (short dot line).