Ultrafast laser nanoprocessing with nondiffracting beams

Abstract

During nanopatterning of material surfaces by ultrashort laser pulses, the nano-damage depends critically on the laser fluence compared to the fluence threshold. The positioning of the sample surface with respect to the focal point is a strongly demanding factor when patterning large surfaces. We demonstrate the application of nondiffracting Bessel beams to reproducible nanometric-scale feature femtosecond laser patterning. A specific setup producing femtosecond pulse zero-order Bessel beam with a central spot radius of 360 nm was developed. We exhibit femtosecond laser processing of near identical nanocraters in glass over a longitudinal positioning range of more than 20 µm. The use of Bessel beams significantly reduces constraints on critical sample positioning in the nanoscale writing regime, enabling the use of femtosecond laser pulses for fast inscription of nanometer-scale features over large sample areas.