  The basic understanding of high-intensity femtosecond laser absorption in 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 is important for a basic understanding of intense
laser-matter interaction as well for applications such as `plasma mirror'.
Here, we have experimentally observed high-intensity, high-contrast femtosecond
laser absorption by an optically polished fused silica target at
near-relativistic laser intensities ($\sim$10$^{18}$ W/cm$^2$). The 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 as large as 80% of the laser ($p$-polarized) energy
gets absorbed in the target. Such a high percentage of absorption at
near-relativistic intensities has not been observed before. At smaller angles
of incidence the high reflectivity (e.g. about 60 - 70% at 30$^\circ$
incidence) indicate that, this study is fundamentally relevant for plasma
mirrors at near-relativistic intensities.
