Increasing Q-Factor of Planar Dielectric Resonators with Whisper Gallery Modes

Increasing the Q-factor of thin planar dielectric resonator with whispering gallery modes

“…From the point of view of forming the resonant fields of WGMs, the importance of an air gap in the design of the thin planar DR is also obvious. As was shown in the paper [7], the fields of WGMs deeply penetrate into the air gap. Therefore, the efficient value of the dielectric constant of the resonator is determined by the height of an air gap.…”

“…1). Earlier, we have proposed using the coupling slot formed by a narrow end of a rectangular metal waveguide for exciting the HE-polarized WGMs in thin planar DRs [7]. The coupling slot was placed in the plane of one of the metal mirrors which covered the flat bases of a thin dielectric disk.…”

“…As noted in [7], the reason for this behavior of the unloaded Q -factor of the tunable thin planar DR is the change in its eigen loss. At creating an air gap in the design of a thin planar DR, the maximum amplitude of the electric component of WGMs fields is shifted from the thin dielectric disk to an air gap (Fig.…”

“…At low heights of an air gap ( H / h = 0.8 ÷ 1.0), the regime of strong coupling with p > 1 is realized. It is determined by the high “concentration” of the resonant field in the region between the metal mirrors [7]. At increasing the height of an air gap, decreasing the coupling parameter is explained by the shift of the resonant field from a dielectric to an air gap.…”

“…However, the possibility of using the planar DRs with lower heights has not been fully investigated. We have previously shown that in such resonators on the basis of thin dielectric disks with shielded flat surfaces, the fields of WGMs can be formed [7]. Coating the flat bases of thin dielectric disks by reflective surfaces solves the problem of complete internal reflection of waves from the flat bases of thin dielectric disks.…”