Highly sensitive nano-aerosol detection based on the whispering-gallery-mode in cylindrical optical fiber resonators

Here, we report a fiber optical technique that is capable of detecting trace-level nano-aerosols. Our method is based on monitoring the nano-aerosol-induced resonance shift due to the optical Whispering-Gallery-Mode (WGM) in a cylindrical optical fiber resonator.

A nearly linear relationship between the WGM resonance shift and the aerosol coverage ratio of silica nanoparticles (40–50 nm dia.) on the fiber resonator was identified in the low coverage regime. Our experimental results imply sensitivity at the level of ∼2 nanoparticles per μm 2 deposited on the fiber resonator, which corresponds to pg-level sensitivity in the total aerosol mass within the effective detection area. The response of this fiber optical sensor is further confirmed by using silica nanoparticles deposited on the fiber surface via electrostatic self-assembly.