Self-channeling of high-peak-power femtosecond laser pulses in air

Abstract

The self-channeling of ultrashort laser pulses through 20 m of air was demonstrated. The channeled pulse was measured to have 0.75 mJ of energy, a diameter of 80 microm FWHM, and a modulated spectrum. All these values were measured to be fairly constant during the propagation of the pulse. A preliminary model is shown to explain these results.

Triggering, guiding and deviation of long air spark discharges with femtosecond laser filament

“…2 Despite the first real scale demonstration of triggering in 1996, 3 this path was progressively abandoned because of the discontinuous profile of the plasma generated with such long pulses through avalanche breakdown. 4 Following the development of femtosecond CPA (chirped pulse amplification) laser systems, the study of ultrashort filaments in air 5 and their ability to generate a thin uniform plasma channel over very long distances opened new perspectives in the field. [6][7][8][9][10] Laser filamentation is a nonlinear propagation regime affecting femtosecond laser beams provided their peak power exceeds a critical value (5 GW at 800 nm in air).…”

Femtosecond Filamentation in Air

“…A peculiar propagation of intense femtosecond laser pulses is observed in air without apparent diffraction or dispersion, during which the pulse is severely reshaped in the spatial, temporal and spectral domains [4]. The beam first shrinks upon itself to form a narrow intense core of about 100 µm diameter, surrounded by extended region of laser radiation which constitute an energy reservoir able to feed the intense core and sustain its propagation over long distances reaching several hundreds of meters..…”

Spectroscopic analysis of high electric field enhanced ionization in laser filaments in air for corona guiding

“…Filamentation (FIL) induced by ultrashort intense laser pulses in air has attracted much scientific interest since it was first predicted theoretically in 1990 [1] and first observed experimentally in 1995 [2] . The main physical mechanism of femtosecond laser FIL is well known to be a dynamic equilibrium between self-focusing by the optical Kerr effect and defocusing by a self-generated plasma produced by multiphoton/tunnel ionization [3][4][5] .…”

“…Email: tiejunwang@siom.ac.cn Triggering and guiding lightning using lasers was proposed by scientists in 1974 [25] . Four years later in 1978, Greig et al [26] utilized high-energy CO 2 and YAG lasers to investigate laser-guided discharges. Much effort was devoted to understanding the fundamental mechanism of lasertriggered lightning in the 1980s [27][28][29] .…”