Three-dimensional fs-laser subtractive nanolithography of crystals

Nanoscale structuring of hard, brittle, and high-quality cm-scale optical crystals has remained a two- dimensional surface process until the recent report that 3D architectures can be sculpted inside laser crystals (YAG and sapphire) with feature sizes on the 100 nm level and nanoscale precision. The mechanism by which these phenomena can occur is a giant wet-chemical etching selectivity of around a million (similar to 10(6)) between photomodified and unmodified crystal volumes, which enables nanopores (similar to 200 nm) to reach mm-scale lengths, discovered and recently reported by A. Rodenas et al. [1]. We report here recent results that expand the state-of-the-art on this new 3D nanolithographic technique for undoped YAG optical crystals, a potentially disruptive future manufacturing technology for photonics and nanotechnology in general.