Abstract

Recently, we demonstrated a technique for optically guiding intense laser pulses, in which a plasma refractive index channel was produced through the hydrodynamic evolution of a laser breakdown spark in an ambient gas¹. Here, we present measurements and calculations showing that our plasma light pipe can support, at high intensity, distinct electromagnetic mode propagation, as well as "leaky mode" propagation. As a reminder of the plasma dynamics involved, Fig. 1 shows a calculation of the response of 30 torr Xe to a pulse of peak intensity I=7x10¹³ W/cm², spot size r₀=1 μm, and duration τ_p=100 ps, pulse conditions typical of the ≲ 1 cm long axicon focus of our experiment¹. Results from 2.2 cm long channels will be presented in a future paper. It is seen that a shock forms after some delay, after which an electron density minimum develops on axis.

© 1994 Optical Society of America