Electromagnetically Induced Transparency and Absorption in Directly Coupled Whispering-Gallery Mode Microcavities

Optical interference and the related effects are key elements which could exhibit the properties of both classical and quantum optical systems. Usually, the interference between different optical paths may produce intriguing effects, such as the electromagnetically induced transparent (EIT) and so on. In this work, we study the interference effects in directly coupled whispering-gallery mode (WGM) micro-resonators, in which the emergence of EIT and electromagnetically induced absorption (EIA) could be observed. We find by tuning the coupling strength between the resonators, the modulation phase may control the appearance and disappearance of EIT (EIA). Furthermore, we prove the existence of fast and slow light, and propose a scheme for effective switching between them. This work provides a new strategy for obtaining slow light and quantum storage in the WGM micro-resonators.