Cavity modes modulation using photonic molecules

Interaction of whispering gallery modes (WGMs) in two coupled microcavities, referred to as a photonic molecule, was investigated experimentally. The study involved a systematic examination of the modes of the coupled cavities by manipulating the cavity gain coefficients and coupling strength. The cavity gain coefficients were adjusted by using dye-doped and un-doped microcavities, while the coupling strength was varied by altering the separation between the microcavities. The resulting observations include splitting and merging of the eigenmode frequencies. These experimental findings were corroborated by the predictions of an extended coupled mode theory (CMT) and numerical simulations. Additionally, it was discovered that coupled microcavities offer advantages over single cavities in certain applications where tunability of cavity modes is required.