Researchers developed a gear-shaped photonic crystal microring that strengthens light-matter interactions without compromising optical quality. As a result, an on-chip microresonator with an optical quality factor 50 times higher than the previous record in slow light devices has been developed, which could improve microresonators used in various photonics applications such as sensing and metrology, nonlinear optics, and cavity quantum electrodynamics.
Optical microresonators improve light-matter interactions by combining long temporal confinement (high-quality factor) with strong spatial confinement of an electromagnetic wave.
The light devices developed by the researchers combine the best features of two types of optical microresonators — a photonic crystal and a whispering gallery mode resonator — into a single device. While combining the two has previously been attempted, previous microring devices that were successful in slowing light to increase interactions (as a result of the photonic crystal) had to sacrifice quality factor. Researchers observed modes with group velocity slowed down by ten times compared to conventional microring modes in this new “microgear” photonic crystal ring with no degradation in quality factor.
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