Speaker
Description
Plasma-based optical elements can withstand laser intensities several orders of magnitude higher than traditional optical elements, making them highly promising for manipulating relativistic intensity laser pulses. In this work, we propose and demonstrate a novel microstructured plasma target, inspired by the design of traditional Fresnel zone plates (FZP). The specific target structure causes diffraction of the input laser at each zone, resulting in constructive interference and facilitating effective focusing and amplification of the input laser pulse. Three-dimensional particle-in-cell simulation results show that the microstructured plasma target can focus Gaussian laser pulses with an intensity on the order of $10^{22}~\rm W/cm^2$ to an intensity exceeding $10^{24}~\rm W/cm^2$ with the laser focus spot size approaching the diffraction limit of approximately 0.73 $\mu$m and laser fluence enhancement by 46 times. It is also found that, when the microstructured plasma target is modified into a reflective element, laser intensities up to $10^{25}~\rm W/cm^2$ may be achieved. This extremely-high-intensity tightly-focused laser pulse can trigger intense photon radiation when interacting with targets, e.g., a wire plasma target, offering opportunities to explore vacuum birefringence, quantum electrodynamics (QED) cascades, laboratory astrophysics, etc.
