Plasma polarization grating for circularly polarized high-order harmonic generation

Abstract

Polarization grating (PG) is a kind of optical element based on the Pancharatnam-Berry phase, providing a unique capability of manipulating the polarization properties of output beams [Bomzon et al., Opt. Lett. 27, 1141–1143 (2002) and Oh and Escuti, Opt. Lett. 33, 2287–2289 (2008)]. Here, we extend this concept into the nonlinear domain of high-order harmonic generation from the laser-solid interaction. Through theoretical analysis and numerical simulations, we proposed a scheme of two non-collinear relativistic lasers of opposite handedness interacting with a solid target to generate angularly isolated, circularly polarized harmonics of both left and right handedness simultaneously. The physical mechanism was described as the confluence of PG and relativistically oscillating mirror, which can be defined as a new mechanism: “relativistically oscillating polarization grating mechanism.” This work provides a useful method for developing bright, near-monochromatic, short-wavelength radiation sources with desirable polarization for a broad range of applications.