Measuring the Optical Properties of Ionization Gratings in Air for Control of Femtosecond Lasers

Abstract

Interference between crossed femtosecond lasers can drive spatially varying ionization, producing a high-flux plasma optic. We measure the plasma and optical properties of an ionization grating in air as it redirects a millijoule-scale probe beam.

Holographic Plasma Lenses

“…Both schemes rely on two co-propagating pump beams whose interference pattern imprints a three-dimensional (3D) refractive index structure acting as a diffractive lens. SVI uses ionization of a background gas in the high-intensity fringes of the interference pattern while areas of destructive interference remain as neutral gas, leading to an index modulation n gas − n plasma ≈ 10 −2 [27][28][29][30]. For ponderomotively driven structures, electrons are ponderomotively forced out of high-intensity regions; the resultant space-charge force pulls ions down the intensity gradients as well.…”