Mode Coupling Between Coupled First and Second Order Whispering-Gallery Modes in Coupled Two Microdisks

We investigate the mode characteristics for the two coupled microdisks by finite-difference time-domain (FDTD) technique. The numerical results show that the coupled first order whispering-gallery modes (WGMs) can couple with the coupled second order WGMs when their wavelengths approach each other. Q-factors of the coupled first order WGMs greatly decrease due to such mode coupling. The simulated time variation of mode field pattern also verifies the mode coupling between the first and the second coupled WGMs.