Novel manufacturing processes of single emitter plasmonic patch nanoantennas
The success of advanced quantum communication relies crucially on non-classical light sources emitting single indistinguishable photons at high flux rates and purity. Controlled positioning and fabrication of nanostructures like nanoemitters is necessary to realize such technologies. For this purpose, lithography has to be performed.
However, conventional fabrication methods like scanning electron microscopy or optical lithography involves exposing the emitter directly and destructively to the electrons / laser of the writing beam. So it is necessary to develop novel non-destructive manufacturing processes.
The objective of these new processes is to realize plasmonic (or photonic) nanostructures in which nanoemitters are deterministically placed exactly at the position for which the resonant electromagnetic field is maximum, and thus the interaction between the emitters and the field is as well maximum.
• Deterministic electron-beam lithography using fluorescence microscopy images
The invention uses a combination of optical and electron-beam lithography, and uses fluorescence microscopy images to draw electron-beam exposure patterns. Indeed, fluorescent emitters (individual or aggregates) are imaged by fluorescence microscopy and at the same step alignment markers are created around them by means of optical lithography on a resist bi-layer covering the emitters. This bi-layer prevents the electrons of the beam from damaging the fluorescent emitters.
• Deterministically aligned optical lithography with spatially shaped laser modes
By generating and utilizing spatially shaped laser modes like donut laser modes, the invention circumvents the problem of emitter bleaching and performs optical lithography centered over a single or aggregates of fluorescent emitters without causing any harm to the emitter. This is because the light intensity at the center of a donut laser mode is ideally zero, and during the lithography process, the emitter is placed at the center of the donut laser mode. The optical lithography is performed on a resist above the emitter
The technique has been used to deterministically fabricate single emitter plasmonic patch antennas with a controlled patch size and circular and elliptical shapes.