Isolated attosecond pulse in the water window from many-cycle laser-driven plasma mirrors without pulse engineering

Abstract

High-order harmonic generation from relativistic laser-driven plasma mirrors is an attractive route to produce highly energetic attosecond pulses in the extreme ultraviolet to x-ray regime. To achieve an isolated attosecond pulse (IAP) driven by many-cycle intense laser pulses, pulse engineering techniques such as polarization modulation and wavefront rotation, are usually needed. Here we show that it is possible to generate an IAP without pulse engineering. Through particle-in-cell simulations, it is found that plasma mirrors can be rapidly heated and deformed in a relatively long preplasma regime. Intense IAP in the high-frequency spectral region is given rise once when the mirror parameters are suitable. The results may offer a new route to generate a bright IAP source for various applications such as bio-imaging and electronic dynamic studies.