Self-guided propagation of laser pulses reflected at high intensity from plasma mirrors

The reflectivity and optical quality of laser pulses reflected off 125\, Kapton™ tape was investigated for use as a repeatable plasma mirror. Reflectivities of around 70% were measured at ≈2 × 10 ^21\, Wm^-2 while maintaining the quality of the laser beam. The ability of the reflected pulse to drive a laser wakefield accelerator was investigated. Self-guided propagation of the reflected beam through a gas cell was observed and shown to depend on the plasma density. Particle-in-cell simulations showed that a wakefield would have been generated, driven solely by the energy within the central high intensity feature of the focal spot. The use of plasma mirrors at these elevated intensities would open up the possibilities of extremely compact configurations for laser wakefield accelerator stages.