Chiral Transmission In Whispering Gallery Mode Optical Microcavities

Whispering gallery mode(WGM)optical microcavities are popular devices for studying light-matter interactions due to their extremely high quality factor and small mode volume.It has a wide range of applications in the fields of ultra-low threshold lasers,nonlinear optics,and highsensitivity sensing.Chirality is a state that ensures propagation in a specific direction through a specific mechanism.It has been widely used in the fields of quantum Hall effect and topological semiconductors.However,there are relatively few studies on chirality in the field of optical microcavities.Due to the particularity of the chiral state,we can choose to control whether the light is unidirectionally emitted or bidirectionally emitted,which has a very important role in optical information processing.Moreover,the induced transparency and induced absorption phenomena in this state can be analyzed,which provides a new direction for the generation of fast and slow light and optical buffering technology that need to be solved in the field of optical communication.We investigated the chiral transmission in the system by tuning the WGM microcavity system to chiral state,the main contents are as follows:First,we investigate how the system can be induced to a chiral state by introducing asymmetric scattering from the nanotip in an achiral WGM microcavity.The apparent induced transparency and induced absorption phenomena at the chiral state of the indirectly coupled WGM microcavity system are analyzed,and the intensity of the induced absorption in the system does not change with the change of the phase shift.Second,a directly coupled WGM microcavity system is proposed,in which the coupling strength of the two microcavities determines whether the transmission spectrum induces transparency or absorption.At the phase shift θ=0.517π and 1.519π,when the coupling strength κ=13.4 MHz,there is an induced transparency phenomenon with the transmission spectrum close to 1,and when the coupling strength κ=174.1 MHz,there is an induced absorption phenomenon with the transmission spectrum close to 0.Based on this,the transition between induced transparency and induced absorption can be achieved by changing the coupling strength,and at this time,whether induced transparency or induced absorption occurs in the system can be determined by adjusting the phase shift.Finally,we study the fast light of-26.6μs and the slow light of 27.5μs that can be achieved in the system,which can have a good application in optical storage,and a strategy to achieve fast and slow light switching by changing the phase shift or coupling strength is given,which proves its application potential in quantum communication.