Plasma Optics for Novel Sources of Bright Light: Expanding the Frontiers of Achievable Light Intensities

Plasma mirrors – microscopically small, momentary light reflectors formed by high-power laser beams irradiating and ionizing solid surfaces – are powerful photonic devices for manipulating light that is too intense to be handled by conventional optics. Not only can plasma mirrors redirect and focus high-power light, they can also serve as ultrafast nonlinear filters suppressing unwanted noise in pulsed laser beams, and as generators of a broad range of frequencies from terahertz to x-rays, potentially with properties that are beyond the reach of current light sources. Among the results obtained by our group in the last six years, the first generation of relativistic high-order harmonics from plasma mirrors at Princeton stands out because of its potential to become a novel compact soft x­ray source providing power as great as much larger accelerator facilities and useful for a vast range of applications that rely on x­ray light and will greatly benefit if more intense and shorter x­ray pulses are available.