The development of integrated approaches for optical trapping, based on photonic or plasmonic structures fabricated on a chip, offers several compelling advantages. First, chip-based optical traps enable the trapping platform to be miniaturized. Second, the chip-based configuration lends itself naturally to the incorporation of sensing modalities. Third, optical nanostructures can generate strong near-fields, boosting the trapping performance.
In this presentation, works by the author and his team in the field of optical trapping with silicon photonics and with plasmonics are described. We will describe the use of silicon microring resonators for trapping and sensing particles. We will furthermore describe silicon photonics for sorting particles, as well as for sensing proteins. Finally, we will describe experiments in which a silicon photonic crystal cavity trapped a silver nanoparticle on whose surface molecules had been formed. We carried out Raman spectroscopy of these molecules, with the silver nanoparticle held in position via the photonic crystal cavity.
Plasmonic nanostructures are compelling for optical trapping due to the large gradient forces they can generate, a consequence of their ability to generate highly confined optical fields. Yet deleterious thermal effects can also occur. We describe the use of a plasmonic nanotweezer with an integrated heat-sink. If time permits, we will also describe recent work in which fluorescence microscopy was used to track the position of a nanoparticle trapped by a double nanohole aperture.