Plasma-based polarizer and waveplate at large laser intensity.

A plasma photonic crystal consists of a plasma density grating which is created in underdense plasma by counterpropagating laser beams. When a high-power laser pulse impinges the crystal, it might be reflected or transmitted. So far only one type of pulse polarization, namely the so-called s wave (or TE mode) was investigated (when the electric field vector is perpendicular to the plane of incidence). Here, when investigating also so-called p waves (or TM modes, where the magnetic field vector is perpendicular to the plane of incidence), it is detected that the transmission and reflection properties of the plasma photonic crystal depend on polarization. A simple analytic model of the crystal allows one to make precise predictions. The first conclusion is that in some operational regime the crystal can act as a plasma polarizer for high-intensity laser pulses. Also, differences in phase velocities for grazing incidence between s and p polarization are found. Thus, secondly, the crystal can be utilized as a waveplate, e.g., transforming linearly polarized laser light into circular polarization. All these processes extend to laser intensities beyond the damage intensities of so far used solid state devices.