Nonlinear ultrafast laser processing of diamond surfaces for precision microfabrication

Abstract

Ultrafast femtosecond laser processing provides a versatile platform for precision micro- and nanoscale modification of wide-bandgap materials such as diamond. In this work, the formation of microscale and submicron surface features on high-pressure high temperature (HPHT) single-crystal diamond and chemical vapor deposition (CVD) diamond films is investigated using high-repetition rate femtosecond laser pulses. Systematic experiments examined the influence of laser fluence, pulse energy, and spatial pulse overlap on ablation morphology, feature dimensions, and material response. Arrays of craters, microchannels, and reservoir structures were fabricated through localized ablation, demonstrating the capability of femtosecond laser processing for flexible surface microstructuring of diamond. Differences in ablation behavior between HPHT single-crystal and polycrystalline CVD diamond were analyzed in terms of structural and electronic properties. The depth of laser-machined features was determined using an acetate replication technique followed by scanning electron microscopy. Results show a strong dependence of feature geometry and ablation efficiency on processing conditions, with single-crystal diamond exhibiting deeper ablation and sharper features at comparable fluence. These findings highlight the role of nonlinear absorption and defect mediated carrier dynamics in ultrafast laser–diamond interactions and suggest applications in diamond based microfluidic devices, field-emission structures, and advanced electronic and photonic systems.

Keywords: femtosecond laser, laser ablation, diamond micromachining, laser nanomachining, ultrafast laser processing.