Stability and Efficiency of Ionization-Based Diffraction Gratings*

High-power ultrashort-pulse lasers require large optics, making further increases in laser power prohibitively expensive. Plasma optics offer a solution to this problem because their damage thresholds are orders-of-magnitude higher than those of traditional solid-state optics, allowing compact plasma-based high-power optical devices. Diffractive ionization gratings, a type of plasma optic, can be created by crossing two laser beams within a neutral gas; the interference between the beams causes fringes of varying intensity that produce alternating layers of plasma and neutral gas, resulting in a modulated index of refraction. We present experimental measurements of a stable ionization grating with a high average diffraction efficiency of 34%. The pump wavelengths used to generate the grating were varied and the duration of the diffracted pulse was measured with frequency-resolved optical gating. The presented results indicate that ionization gratings may be applicable for use in future high-power laser systems.