High-power femtosecond laser pulses propagating in air form self-guided filaments that can persist for many meters. Characterizing these filaments has always been challenging owing to their high intensity. An apparently novel diagnostic is used to directly measure the fluence distribution of femtosecond laser pulses after they have formed self-guided optical filaments in air. The diagnostic is unique in that the information contained in the filaments is not lost owing to the interaction with the apparatus. This allows filament characteristics such as energy and size to be unambiguously determined for the first time.
© 2005 Optical Society of America
(120.1880) Instrumentation, measurement, and metrology : Detection
(190.3270) Nonlinear optics : Kerr effect
(190.4420) Nonlinear optics : Nonlinear optics, transverse effects in
(320.2250) Ultrafast optics : Femtosecond phenomena
(320.7110) Ultrafast optics : Ultrafast nonlinear optics
Antonio Ting, Daniel F. Gordon, Eldridge Briscoe, Joseph R. Peñano, and Phillip Sprangle, "Direct characterization of self-guided femtosecond laser filaments in air," Appl. Opt. 44, 1474-1479 (2005)