Identification of Analytical Singularity in a Non‐Plasmonic Nanosensing System

Optical sensing works most efficiently around the singularity of resonances. In pursuit high quality-factor and sensitivity, non-plasmonic nanosensors are desired as metallic materials intrinsically lossy. However, standalone resonant systems dielectric nanoparticles (NPs) generally do not possess a pole or its identification has proven to be hard across complex frequency domain. To solve this problem, an active external cavity is designed NP put inside it formulate cavity-NP (C-NP) system. The dimensions comparable with effective wavelength in particle material coupled resonance shown exhibit when singular optimum gain applied, overcoming no-pole-limitation NPs. underlying physics system studied pseudo-orthonormal eigenmode method (POEM), which can treat such non-Hermitian quickly pinpoint from real frequencies. POEM study generates set guidelines that facilitate device design experimental optimization. Through dynamic finite-difference time-domain simulations, all-dielectric gain-assisted structure thus identified reach at small optical gain. When used sensor, accommodates nanoscale volume giant sensitivity operated pole.