Towards ultrahigh-contrast ultraintense laser pulses-complete characterization of a double plasma-mirror pulse cleaner

The effects of small amounts of energy delivered at times before the peak intensity of ultrahigh-intensity ultrafast-laser pulses have been a major obstacle to the goal of studying the interaction of ultraintense light with solids for more than two decades now. We describe implementation of a practical double-plasma-mirror pulse cleaner, built into a f = 10 m null telescope and added as a standard beamline feature of a 100 TW laser system for ultraintense laser-matter interaction. Our measurements allow us to infer a pulse-height contrast of 5 × 10¹¹ - the highest contrast generated to date - while preserving ∼50% of the laser intensity and maintaining excellent focusability of the delivered beam. We present a complete optical characterization, comparing empirical results and numerical modeling of a double-plasma-mirror system.