Editing Optical ring resonators (section)

{{Short description|Set of waveguides including a closed loop}}
[[File:RingResonatorCW.png|thumb|350px|A computer-simulated ring resonator depicting continuous wave input at resonance.]]

An '''optical ring resonator''' is a set of [[waveguides]] in which at least one is a closed loop coupled to some sort of light input and output. (These can be, but are not limited to being, waveguides.) The concepts behind optical ring [[Optical cavity|resonator]]s are the same as those behind [[Whispering gallery|whispering galleries]] except that they use light and obey the properties behind [[constructive interference]] and [[total internal reflection]]. When light of the [[resonant]] [[wavelength]] is passed through the loop from the input waveguide, the light builds up in intensity over multiple round-trips owing to [[constructive interference]] and is output to the output bus waveguide which serves as a detector waveguide. Because only a select few wavelengths will be at resonance within the loop, the optical ring resonator functions as a filter. Additionally, as implied earlier, two or more ring waveguides can be coupled to each other to form an add/drop optical filter.<ref>{{Cite book|title=Photonic Microresonator Research and Applications|date=2010|publisher=Springer US|isbn=9781441917430|editor-last=Chremmos|editor-first=Ioannis|series=Springer Series in Optical Sciences|volume=156|location=Boston, MA|doi=10.1007/978-1-4419-1744-7|bibcode=2010pmra.book.....C |editor-last2=Schwelb|editor-first2=Otto|editor-last3=Uzunoglu|editor-first3=Nikolaos|url = https://cds.cern.ch/record/1339098}}</ref>