A Series of Avoided Crossings of Resonances in the System of Several Different Dielectric Resonators Results in Giant Q-Factors

Pichugin, K., Sadreev, A., Bulgakov, E.// Photonics//

https://doi.org/10.3390/photonics10090973

On an example of a system of three/four/five/six different coupled coaxial silicon disks, we realize a series of avoided crossings of resonances (ACRs) with respect to the different morphologies for the different scales of each disk. Each next step of ACR accompanied by the optimization processes of all previous ACRs contributes almost one order of magnitude to the Q-factor. As a result, we achieve unprecedented values for the Q-factors: $6.6$ · $10^{4}$ for three, $4.8 \cdot 10^{6}$ for four, $8.5 \cdot 10^{7}$ for five and several billions for six free standing silicon disks. Comparisons to such prominent methods as whispering gallery modes or quasi bound states in the continuum to boost the Q-factor demonstrate the tremendous advantage of the present approach not only in terms of Q-factor values but also in terms of mode volumes. Multipole analysis of the final hybridized resonant mode explains such extremely large Q-factor values. The analysis shows a strong redistribution of radiation owing to the almost-exact destructive interference of the dominating complex multipole radiation amplitudes.