Focusing High-Power Laser Pulses with Diffractive Plasma Lenses*

The construction of compact high-power laser systems requires the manipulation of light at intensities above the ionization threshold of optical materials. Diffractive plasma optics, based on spatial patterns of either ionization or ion-displacement driven by interfering pump beams, provide damage-resistant control of high intensity light that is relatively resistant to plasma inhomogeneity and nonlinearity. We describe here how two pump lasers can be overlapped to produce zone-plate-like diffractive plasma lenses that focus and collimate high-intensity light. Results from analytic models are supported by particle-in-cell simulations, nonlinear pulse propagation calculations, and experimental measurements of ionization gratings. Simulations suggest that femtosecond pulses can be focused by experimentally feasible plasma lenses with greater than 70% efficiency at up to sub-relativistic unfocused intensities. The development of plasma replacements for key components of short-pulse lasers will allow continued advancement towards higher-power light sources.