Laser-induced optical satellite line profiles in a helium plasma

Abstract

We have observed several different satellite transitions among HeI excited states. These satellites were induced by large, near-resonant, spatially inhomogeneous electric fields. A simple theory was proposed to explain the line shape of both the satellite and the allowed line based on the rotating-wave approximation. The plasma was contained in a dielectric waveguide and the laser mode pattern inside the guide was calculated and incorporated into the line-shape function. It was shown that excellent agreement between theory and experiment could be obtained over a wide range of experimental parameters. Agreement was very good in regimes where perturbation theory fails. We also observed that at high field strengths the Stark shift of the allowed component was less than the three-level theory predicted. We attribute this error to the fact that we have ignored all of the remaining levels of the HeI system.