Transient Plasma Photonic Crystals - A Route Towards Slow Ultra-intense Light?

Abstract: Periodic electron and ion density modulations in near critical density plasmas induced by counterpropagating femtosecond pulses of intensities on the order of 10¹⁵ to 10¹⁶ Wcm⁻² are described in a linear and stationary regime and investigated using particle-in-cell simulations in one and two dimensions. The periodic gratings produce transient plasma photonic crystals lasting up to several picoseconds with ultra-wide angle-selective band gaps on the order of Δω/ω₀ ≈ 10-20%. The slow light effects and transmission of ultra-short pulses of intensities up to 10¹⁷ Wcm⁻² near the band gap are studied both as a function of frequency and angle of incidence, demonstrating group velocities which are consistently below those in a uniform plasma of the same average density. The velocities are found to approach zero near the gap at the cost of high reflection and dispersion. Furthermore, the effect of ion mass and driving pulse chirp on the transient structures are studied. Finally, the band gaps may be used to repeatedly reflect a short intense pulse in a waveguide-like fashion with effective propagation velocity as low as ~10% of the speed of light.