Group velocity delay in coupled-cavity waveguides based on ultrahigh-Q cavities with Bragg reflectors

摘要

Optical waveguides formed by coupled ultrahigh- Q cavities have been investigated byfinite-difference time-domain (FDTD) simulation. The flexible control of group velocity andbandwidth are demonstrated by adjusting the coupling strength. An ultrahigh group velocitydispersion (GVD) of 3 x 106 psI em-1 together with a group velocity as low as 3 x 10-5c(c is the speed of light in vacuum) is obtained at the band edge, creating a potential applicationin dispersion compensation. In a coupled-cavity waveguide (CCW) consisting of cavities withquality factor (Q) of 106, slow light at c 1100 with a useful bandwidth as wide as 230 GHz isdemonstrated, in which the calculated propagation loss is only 1.3 dB cm-1 . A design for acascaded CCW with inverse dispersion is proposed for the further improvement of bandwidth.