Tapered racetrack microring resonator for single nanoparticle detection

Abstract

Abstract Rapid detection of a single nanoparticle has always been challenging and demanding. Several methods and approaches have been employed over the last few years. In this work, we have devised an integrated photonic platform to detect a single nanoparticle (NP) such as gold (Au) nanoparticle. The proposed platforms make use of a racetrack micro-ring resonator where a small region in the lower arm (non-coupled) of the resonator has been tapered to enhance the evanescent field strength many folds, which enhances the sensitivity of the device. Numerical simulations have been performed using finite difference time domain that reveal the splitting of a resonant mode in the presence of Au nanoparticle (AuNP) of radius 100 nm. The proposed approach has the capability to distinguish between different sizes and numbers of NPs. We have also studied the effect of assorted NPs in the vicinity of the tapered region. Numerical results also confirm the unique potentiality to detect NPs even if they are not adjacent to waveguide surface as well detection of a single NP of infinitesimally small size. We believe that the proposed architecture may pave a pivotal role in the sensing of biological objects such as novel viruses whose size is similar to the size of AuNP as studied in this work.