Spectral engineering of bends and branches in microdisk coupled-resonator optical waveguides.

Rigorous simulations of bent and branched sections of coupled resonator optical waveguides (CROWs) composed of side-coupled whispering gallery (WG) mode microdisks are performed. Pre- and post-fabrication tuning capability of the designed structures is explored, and a novel concept of realization of tunable CROW-based routers and switches is introduced. The proposed tuning mechanism exploits the properties of CROW optical modes coupling with avoided crossing scenario rather than the previously used Vernier effect. Applications of spectrally-engineered branched CROW structures for controllable manipulation of coupling between spatially separated nano-emitters are also discussed.