Programmable multiple ion beams based on a magneto-optical trap ion source

Abstract

We report a programmable multiple ion beam system developed by combing a magneto-optical trap ion source with a spatial light modulator (SLM). Neutral rubidium atoms are trapped into a magneto-optical trap and cooled to 700 μK. An excitation laser beam, the intensity distribution of which is shaped into a square array by the SLM, selectively excites the cold atoms, which are subsequently ionized by an ionization laser beam. The ions are then extracted by an electric field to produce multiple ion beams. A 3×3 ion beam array has been generated. The size of each beams is 180 μm, and the transversal reduced emittance of multiple ion beams at the source is evaluated to be 1.65 × 10−9 m radeV. We also demonstrate the generation of ion bunches with a user-defined spatial pattern. In the future, by integrating this programmable multiple ion beam system with high reduction ion optics, it is possible to generate nanoscale multiple focused ion beams for the potential applications in maskless patterning and direct writing lithography.