Influence of surrounded metallic layers on whispering-gallery modes in circular microresonators

Influences of surrounded metallic layers (Au, Al, Ag, Cu, and Ti) on whispering-gallery modes (WGMs) are numerically investigated by solving eigenvalue equation for multiple-layer two dimensional circular microresonators. For TM modes, metal layer can provide good optical confinement as its thickness is larger than 0.03 μm. For TE modes, an isolation layer should be introduced to reduce the dissipation loss of metallic layers. Al and Ag layers can provide better optical confinement than Au layer, and Ti layer which is usually a layer of p-electrode will result in a large dissipation loss.