Ultrafast-laser driven micro-explosions in transparent materials

TLDR

These experiments probe light propagation at intensities near 10^21 W/m², studying electron ionization and the material response to extreme pressure and temperature. We initiate micro‑explosions inside fused silica, quartz, sapphire, and other transparent materials using tightly focused 100 fs laser pulses, ejecting material from the center to form a cavity surrounded by compacted material, and examine the resulting structures with optical microscopy, diffraction, and atomic force microscopy of internal cross sections. The micro‑explosions produce structures 200–250 nm in diameter, attributed to strong self‑focusing of the laser pulse, and provide a novel technique for internal micro‑structuring of transparent materials.

Abstract

We initiate micro-explosions inside fused silica, quartz, sapphire, and other transparent materials using tightly focused 100 fs laser pulses. In the micro-explosions, material is ejected from the center, forming a cavity surrounded by a region of compacted material. We examine the resulting structures with optical microscopy, diffraction, and atomic force microscopy of internal cross sections. We find the structures have a diameter of only 200–250 nm, which we attribute to strong self-focusing of the laser pulse. These experiments probe a unique regime of light propagation inside materials at intensities approaching 1021 W/m2, the electron ionization that accompanies it, and the material response to extreme pressure and temperature conditions. The micro-explosions also provide a novel technique for internal microstructuring of transparent materials.