Absorption of high-intensity, high-contrast femtosecond laser pulses by a dielectric solid

Abstract

Basic understanding of high-intensity femtosecond laser absorption by a solid is crucial for high-energy-density science. This multidimensional problem has many variables like laser parameters, solid target material, and geometry of the excitation. This study is important for a basic understanding of intense laser-matter interaction as well for applications such as ‘plasma mirror’. Here, we experimentally observe high-contrast femtosecond laser absorption by an optically polished fused silica target at near-relativistic laser intensities (∼1018 W cm−2). Laser absorption as a function of angle of incidence and incident energy is investigated for both p- and s-polarized pulses in detail, providing a strong indication of the presence of collisionless processes. At an optimum angle of incidence, almost 80% of the p-polarized laser energy gets absorbed by the target. We also observed high reflectivity (∼60%) at lower angle of incidence (30∘) for both the polarization of laser, indicating this study is fundamentally important for ‘plasma mirrors’ at near-relativistic intensities.