Emissions of brilliant attosecond pulse in circular polarization by using inclined lasers

We propose a practical approach to produce intense circularly polarized (CP) attosecond pulses using inclined linearly polarized (LP) lasers from relativistic plasma mirrors. Due to the dynamics of the plasma surface currents at the radiation point, the phase difference of high-order harmonics in the two orthogonal transverse directions approaches π/2 by proper inclination angle and incident angle of the driving laser. One- and three-dimensional particle-in-cell simulations show that CP attosecond extreme-ultraviolet pulses with an intensity about 3.1×1020 W/cm2 are obtained by using a LP laser with an intensity of 1.3×1021 W/cm2, both the inclination and incident angles of which are 45°. This approach is more feasible than previous approaches using CP/two-color driving lasers, and such a CP attosecond source provides a unique tool for a variety of chirality-sensitive applications.