Remote and rapid micromachining of broadband low-reflectivity black silicon surfaces by femtosecond laser filaments.

We report an approach for remote and rapid fabrication of a broadband low-reflectivity black silicon surface by ablating crystalline silicon with femtosecond laser filaments in air. Porous microstructures on the processed silicon surface are formed, resulting in a significantly enhanced light trapping efficiency in a broadband (UV-IR) spectral range. It is found that the air filament can significantly reduce the average number of adopted pulses in a normalized fabrication area and enables the processing remotely, which opens a way toward remote and rapid micromachining of optoelectronic materials by femtosecond laser filaments.