Silicon MMI-Coupled Slotted Conventional and MZI Racetrack Microring Resonators

We experimentally demonstrate two types of silicon-on-insulator microring devices: 1) a slotted conventional microring resonator (MRR) using a multimode interferometer (MMI) coupler as the coupling element; and 2) an MMI-coupled slotted Mach-Zehnder interferometer (MZI) racetrack microring. We achieved a high bandwidth of 1.1 nm and a quality factor Q of ~ 1300 at the wavelength of 1510 nm for the conventional MRRs with a radius of 20 μm. A high extinction ratio (17-25 dB) is exhibited over a wavelength range from 1490 to 1520 nm. At the 1515-nm resonance wavelength, the MMI-coupled MZI racetrack microring demonstrates a quasi-free spectral range of 22.6 nm with a high extinction ratio of 25 dB. The demonstrated devices have many applications such as biochemical and gas sensing and modulation in communication systems.