Figure 6.

Resonance characteristics (Q factor and resonance intensity) as a function of inner hole size for three hollow dielectric structures: (i) Asymmetric cylinder pair with the hole size of the shorter cylinder fixed as 0.3D ₀ but the other varied, (ii) Asymmetric cylinder pair with the hole size of the longer cylinder fixed as 0.3D ₀ but the other varied, (iii) Symmetric cylinder pair (i.e., having the same cylinder length) with the hole size of one cylinder fixed as 0.3D ₀ but the other varied. All three cases can be explained based on the degree of effective structural asymmetry. By changing the inner hole size, we can adjust structural asymmetry in hollow dielectric resonators, and then we can control the Q factor and the resonance intensity of Fano resonances. In (iii), the Fano resonance disappears at D = 0.3D ₀, because the structure becomes exactly symmetric. So, the data point is missing at D = 0.3D ₀.