Magnetic Field–Assisted Manipulation of Polymer Optical Microcavities

Abstract

Manipulation of optical microcavities using a magnetic field is a novel and clean strategy as the molecular structure and its packing are not affected in this technique, unlike in mechanical and light‐based ones. As a proof of principle, herein magnetic field–triggered orientation of polystyrene optical cavities loaded with 1) red‐emitting dye and 2) magnetic iron oxide nanoparticles is demonstrated. Due to the incorporation of the dye, the nonemissive polymer cavities show whispering gallery modes in the fluorescence spectra with the Q‐factor in the range of 400. Further, the integration of iron oxide nanoparticles facilitates the collective alignment of polymer cavities efficiently depending upon the applied magnetic field direction. The presented new method, which combines magnetic field–assisted micromanipulation and organic nanophotonics, is anticipated to offer prospects in the area of biophotonics, biomedicine, and magnetic field sensors.