Femtosecond Laser Nanomachining of High-Aspect-Ratio Channels in Bulk Fused Silica

Thee-dimensional nano-structuring of bulk fused silica glass remains a challenging issue due to limitations of traditional fabrication methods. In the present work the fabrication of hollow mm-length channels is demonstrated in bulk fused silica by femtosecond laser irradiation followed by chemical etching, achieving feature sizes of 300 nm. The tight focusing and threshold energy conditions allow to reveal unexplored fabrication regimes. The robustness and repeatability of the process are demonstrated through the fabrication of fused silica diffraction gratings, made of parallel hollow channels with variable pitches even in the sub-wavelength regime.