The Observation of Mode-splitting in Asymmetrical Photonic molecules via Whispering gallery modes

This Letter investigates mode splitting via whispering gallery modes (WGMs) in asymmetrical photonic molecules (PMs) composed of size-mismatched dual microspheres fabricated from fused silica. The characteristics of asymmetrical PMs were analyzed both numerically and experimentally, focusing specifically on the separation and intensity differences of splitting peaks. The splitting spectra exhibited a redshift, and the separation of two splitting peaks reached a maximum in symmetrical PMs, with a minimal difference in intensity also observed. It was noted that the splitting peaks shifted in opposite directions for the same PMs when coupling points with the tapered fibers were varied. This phenomenon can be applied to select similarly sized microparticles and to recognize PMs in optical devices.