Pulsewidth dependence of laser-induced periodic surface structures using a picosecond fiber laser

Abstract

Ultrafast laser microprocessing is a key and growing technology for a number of industrial applications such as thin-film photovoltaics, scribing very hard materials, and some niche marking applications. Ultrafast lasers are capable of athermal material modification, such as laser-induced periodic surface structures (LIPSS) and black silicon, which opens up interesting marking regimes that are not easily accessed by longer pulse sources. We demonstrate the ability to create LIPSS on metals and semiconductors such as stainless steel and single-crystalline and poly-crystalline silicon. We compare and contrast the results achievable with pulsewidth varying from 3 to over 400 picoseconds. Starkly different regimes of marks become possible with the ability to tune pulsewidth and pulse energy over a wide range. Solid colorization, darkening, and holographic colorization (LIPSS) are all possible and experimentally demonstrated on an array of substrates.