ABSTRACT
Nanohole optical tweezers have been used by several groups to trap and analyze proteins. In this work, we demonstrate that it is possible to create high-performance double nanohole (DNH) substrates for trapping proteins without the need for any top-down approaches (such as electron microscopy or focused-ion beam milling). Using polarization analysis, we identify DNHs as well as determine their orientation and then use them for trapping. We are also able to identify other hole configurations, such as single, trimers and other clusters. We explore changing the substrate from glass to polyvinyl chloride to enhance trapping ability, showing 7 times lower minimum trapping power, which we believe is due to reduced surface repulsion. Finally, we present tape exfoliation as a means to expose DNHs without damaging sonication or chemical methods. Overall, these approaches make high quality optical trapping using DNH structures accessible to a broad scientific community.
ABSTRACT
Single-photon sources are required for quantum technologies and can be created from individual atoms and atom-like defects. Erbium ions produce single photons at low-loss fiber optic wavelengths, but they have low emission rates, making them challenging to isolate reliably. Here, we tune the size of gold double nanoholes (DNHs) to enhance the emission of single erbium emitters, achieving 50× enhancement over rectangular apertures previously demonstrated. This produces enough enhancement to show emission from single nanocrystals at wavelengths not seen in our previous work, i.e., 400 and 1550 nm. We observe discrete levels of emission for nanocrystals with low numbers of emitters and demonstrate isolating single emitters. We describe how the trapping time is proportional to the enhancement factor for a given DNH structure, giving us an independent way to measure the enhancement. This shows a promising path to achieving single emitter sources at 1550 nm.
