Single-step maskless nano-lithography on glass by femtosecond laser processing

Femtosecond laser processing is widely adopted today for microfabrication because of its ability to make rapid processing on almost all types of materials in ambient environment. However, it is challenging to apply femtosecond lasers for high-speed large-scale subwavelength nanofabrication, particularly, for two-dimensional nanopatterning on transparent dielectric materials due to their low light absorption. Previous demonstrations of femtosecond laser two-dimensional nanofabrication on dielectrics typically lack structural quality and long-range uniformity. In this work, we report a maskless laser nano-lithographic technique to fabricate high-quality two-dimensional periodic nanodomes on glass. The glass sample is first coated with a thin copper film and then irradiated by femtosecond laser pulses. We show that the period and size of the nanodomes can be controlled using a multi-fluence process. More importantly, a single-fluence technique is developed here, for the first time, for high-quality nanopatterning on glass. The nanopatterning formation mechanism is studied by dynamics experiments and numerical simulations. This introduced technique will provide a simple but highly effective way for dielectrics nanofabrication.