耦合微盘及带输出波导的单微盘腔的耦合模式特性

Abstract

The optical microresonators with high Q factor and ultra-small mode volume have attracted great attentions for applications in optoelectronic devices. For a coupled-microdisks and a single microdisk connected with an output waveguide, coupled mode characteristics resulting from the structure asymmetry are investigated by the finite-difference time-domain(FDTD) method and the Pade′ approximation. Mode field patterns and mode Q factors are calculated, and the relative energies of mode-field components with different angular wave numbers are estimated from the coupled mode-field distribution. For coupled microdisk resonator, the higher-order modes introduced by the mode coupling usually reduces the mode Q factor of the coupled mode greatly. For a single microdisk resonator with a radius of1μm and a refractive index of3.2 connected with a0.2-μm-wide output waveguide, a coupled mode at the wavelength of1.52μm is observed with the mode Q factor of268 and a triangle mode-field pattern, which is the coupled mode between whispering-gallery modes TE9,1 and TE6,2 with a wavelength difference of6.6 nm.