Ultrafast Pulse Laser Interference for Submicromachining

Abstract

Submicromachining with ultrafast pulse laser has been demonstrated utilising the phenomenon of laser light interference. This technique has been proven to overcome the feature size limit of conventional laser micromachining. By first interfering the laser light, and then using the central bright fringe of the interfered beam to machine, it has been proven that the effective ablation spot size can be reduced and subsequently, reducing the size of the ablated features. Preliminary results show a 300% reduction in feature size by machining with the interfered laser beam compared to the conventional direct laser beam. 300 nm holes were successfully ablated on a 100 nm thick gold film on a fused silica substrate using the interfered laser beam compared to 1 μm holes ablated using the conventional direct laser beam at the same laser energy and machining parameters.