Dynamical switching of lasing emission by exceptional point modulation in coupled microcavities

In a non-Hermitian optical system with loss and gain, an exceptional point (EP) will arise under specific parameters where the eigenvalues and eigenstates exhibit simultaneous coalescence. Here we report a dynamical switching of lasing behavior in a non-Hermitian system composed of coupled microcavities by modulating the EPs. Utilizing the effect of gain, loss and coupling on the eigenstates of coupled microcavities, the evolution path of the eigenvalues related to the laser emission characteristics can be modulated. As a result, the lasing emission property of the coupled cavities exhibits an dynamical switching behavior, which can also be effectively controlled by tuning the gain and loss of the cavities. Moreover, the evolution behavior in a more complicated system composed of three coupled microcavities is investigated, which shows a better tunability compared with the two-microcavity system. Our results have correlated the EPs in non-Hermitian system with lasing emission in complex microcavity systems, which shows great potential for realizing dynamical, ultrafast and multifunctional optoelectronic devices for on-chip integrations.