Active Control For Nonreciprocal Optical Transmission Direction Based On Optical Tamm States

The optical isolator is an important device in optical system.With the development of integrated optics,the traditional optical isolator has been unable to meet the needs of social development.Because of this kind of demand,many scholars did a lot of work in this domain in recent years.The general tendency of the research is miniaturized,integrated and adjustable.The nonreciprocal property of surface states is the main research direction recently.Surface electromagnetic waves exist on the interface between different dielectrics.It has many important applications in integrated optics and biosensors.The most famous surface wave is the surface plasmon polaritons which exist on the interface between metal and dielectric.The optical Tamm state is another surface wave wcich exists on the interface of photonic crystals.The hybrid states of optical Tamm states and surface plasmon polaritons will be formed in some structures,called Tamm plasmon polaritons.To obtain active control of nonreciprocal optical transmission,it realizes the nonreciprocal magnetic Tamm plasmon polaritons which are based on Tamm plasmon polaritons and magneto-optical effect.The structure is composed of graphene photonic crystal and magneto-optical semiconductor.Tamm plasmon polaritons are realized on their interface.The time-reversal symmetry is broken by applying external magnetic field,which gives rise to nonreciprocal magnetic Tamm plasmon polaritons.The frequency of magnetic Tamm plasmon polaritons can be obtained based on admittance-matching theory.Through transfer matrix method,it obtains the formula of the system transmittance.The transmission spectrums of system are investigated based on the formula.The influence of structural parameters which include the thickness of In Sb,the truncation of the dielectric layer close to InSb and the number of graphene photonic crystal periods on magnetic Tamm plasmon polaritons is investigated by analyzing transmission spectrums under different conditions.The adjustion of external parameters which include the incident angle of light wave,graphene chemical potential and external magnetic field on nonreciprocal resonant transmission is also investigated.The results show that active control of unidirectionallight is achieved based on magnetic Tamm plasmon polaritons by modulating external magnetic field and graphene chemical potential.Furthermore,flexible switch between one-way forward and one-way backward transmission is realized.This design may find promising applications in optical diode,nonreciprocal filter and unidirectional absorber.