Permanent tuning of optical resonant modes of chalcogenide-coated microresonators

Chalcogenide materials are promising for optical resonant mode tuning of whispering gallery mode (WGM) microresonators due to their high nonlinearity. In this study, this phenomenon was demonstrated for Ge₂Sb₂Te₅-coated toroidal microresonators using an optical postprocess, which utilizes the intrinsically photosensitive property of the Ge₂Sb₂Te₅ coating. A signal laser was used to illuminate the resonator for permanent tuning of the WGMs in a sensitive manner. 0.01 nm and 0.02 nm permanent tuning of the WGMs was recorded for 5 nm and 10 nm coated resonators, respectively. This technique enables resonance matching of coupled optical resonators, which could pave the way for optoelectronic circuitries employing multiple optical microresonators.