Slow-light dispersion in periodically patterned silicon microring resonators

We demonstrate a novel periodically patterned ring resonator evanescently coupled with a coupler waveguide (CWG) on a silicon-on-insulator platform. In order to optimize the coupling, we phase match the ring resonator and the CWG by tuning the width of the CWG. In the transmission spectra, we measure a high extinction ratio of more than 20 dB and achieve a group index of ~20 in the slow-light regime. Beating patterns in the calculated mode profiles suggest strong interference between degenerate modes. This device opens up the possibility of new applications in compact device integration in wavelength-division multiplexing system while reducing the in-band four-wave mixing cross talk.