Analysis of mode characteristics for microcircular resonators confined by different metallic materials^*

Mode characteristics of metallically confined microcircular resonators are theoretically studied by solving eigenvalue equations for two-dimensional multilayer structures. The influences of conventional metals including Au, Ag, Cu, Al, and Ti, on the mode wavelengths and Q factors of whispering gallery modes (WGMs) are analyzed and compared. The results show silver has the best optical confinement among these metals, and aluminum presents similar behavior to Au. However, Ti, which is usually applied to enhance the adhesion of p-electrode to semiconductors, results in a great dissipation for confined modes. Furthermore, circular microlasers with Al as both p-electrode and optical confinement medium are fabricated, and continuous-wave operations are realized at room temperature for the microlasers with a radius of 15 μm.