Novel plasma mirrors for petawatt (PW)-class lasers using ultrathin films of liquid crystal

Plasma mirrors are nonlinear optical components that, in their “off” state, have low reflectivity and high transmission. A high-intensity laser pulse will excite a plasma on the component surface triggering the “on”, high reflectivity state. Plasma mirrors are used to dynamically remove laser pre-pulse from ultrashort, ultrahigh intensity laser pulses, greatly increasing temporal pulse contrast. We have shown that free standing, ultrathin (<30 nm) films of the liquid crystal 8CB can serve as excellent, renewable plasma mirrors that can support pulses at powers up to 1 PW. The 8CB films have low vapor pressure and can be formed at high repetition rate inside a vacuum chamber at relatively low cost. More than conventional plasma mirrors using standard optical substrates, ultrathin films can facilitate versatile beam geometries for experiments via dynamic beam redirection. We have also introduced new computational models using both particle-in-cell simulations and empirical models. In this work, we describe both how free standing, ultrathin liquid crystal films can serve as excellent plasma mirrors and consider pathways to multi-PW operation, including use of liquid crystal mixtures.