Particle-in-cell analysis of time dependencies of high intensity relativistic transparency thresholds

High-intensity lasers capable of accelerating electrons to relativistic speeds alter the optical properties of a plasma through the phenomenon of relativistic transparency. This phenomenon critically influences the laser-plasma energy coupling efficiency and thus must be taken into consideration when choosing parameters for various applications (laser-plasma acceleration, for example). Here we employ 1D particle-in-cell simulations of a high-intensity pulse incident onto a uniform plasma – inducing relativistic motion of the electrons – while simultaneously probing the target with low-intensity pulses of various frequencies. FFT analysis of transmitted waves reveals the critical frequency throughout time. Additionally, the heating and polarization dependencies are discussed.