Ultralow-loss silicon ring resonators

We experimentally demonstrate silicon ring resonators with internal quality factors ofQ0 2.2 × 107, corresponding to record 2.7 dB∕m propagation losses. Importantly, we show that these propagation losses are limited by bend loss, indicating that the propagation loss limit for silicon has not yet been reached. © 2012 Optical Society of America OCIS codes: 230.4000, 230.5750, 230.7370. Waveguide loss is a key parameter for many important microphotonic devices and systems, ranging from high-quality filters to delay lines, high-fidelity sensor systems [1], and systems addressing many key challenges in com-puting and communication architectures [2]. Addition-ally, silicon is quickly proving to be the waveguide material of choice for microphotonics, enabling active componentry, such as modulators, switches, and photo-detectors [3–5]; passive components, such as microring resonators and polarization transparent devices; and compact polarization splitters and rotators [6–8], as wel