A series of avoided crossings of resonances in the system of several different dielectric resonators results in giant Q-factors

TL;DR

This paper demonstrates that optimizing the parameters of multiple dielectric disks leads to giant Q-factors through resonance avoided crossings, significantly enhancing radiation suppression.

Contribution

It introduces a method to achieve unprecedented Q-factors in dielectric resonator systems by exploiting resonance avoided crossings and multipole interference.

Findings

Q-factors up to one billion for six disks

Resonance avoided crossings cause large Q-factor enhancements

Destructive interference of multipole radiation reduces radiation losses

Abstract

We perform optimization of Q-factor in the system of freestanding three/four/five/six coaxial subwavelength dielectric disks over all scales. Each parameter contributes almost one order of magnitude of the Q-factor due to multiple avoided crossings of resonances to give totally the unprecedented values for the Q-factors: $6.6\cdot10^4$ for the three, $4.8\cdot10^6$ for four, $8.5\cdot10^7$ for five and one billion for six freestanding silicon disks. By multipole analysis of the resulting hybridized resonant mode we observe that such extremely large values of the $Q$-factor are attributed to strong redistribution of radiation that originates from almost exact destructive interference of dominating complex multipole radiation amplitudes.