Polarization characteristics of gold-coated microdisk resonators

The transmission properties and electric-field distribution characteristics of crescent-shaped and fully gold-coated silica microdisk resonators are studied under different polarizations. The transmissivity of the crescent-shaped gold-coated microresonator under TE polarization shows a shift in resonance wavelength relative to that of the resonator without a gold coating, whereas the weakening and elimination of resonance are observed under TM polarization. For the microresonators with a full gold coating, the transmissivity under TE polarization demonstrates a nearly horizontal line and the spectrum under TM polarization displays a stronger resonance. Additionally, the electric-field distributions display properties of both types of structure: the resonance for the TE polarization shows the electric-field confinement, while the hybrid dielectric-surface plasmon polaritons modes are observed for TM polarization. Furthermore, the slow propagation effect observed in the crescent-shaped gold-coated microresonator is discussed and the dependence of transmission on gold thickness is investigated.