Photonic band gap characteristics of one-dimensional graphene-dielectric periodic structures

In this paper, we study theoretically, the transmission properties of a one-dimensional graphene-dielectric periodic structure by using the transfer matrix method. Within the framework of this method, we confirm earlier finding that a periodic structure composed of a stack of monolayer graphene sheets separated by dielectric slabs, possesses photonic band-gap (PBG) properties and supports a series of bandpass and band-stop regions at low-terahertz frequencies. Our calculations showed that the suggested structure possesses in addition to the structural Bragg gaps, a new type of band gap that exhibits a rather versatile behavior with varying angle of incidence. We find this type of band gap is omnidirectional (omni-gap) for both transverse electric (TE) and transverse magnetic (TM) polarizations. Our results show that 1D graphene-dielectric periodic structures are very good candidates for band gap engineering. Specifically, we demonstrate the existence of a band gap region for both polarizations which survives for incident angles as high as 80°. Moreover, we show how our proposed structure can also function as a highly efficient polarization splitter. It is also found that the band gaps can be tuned by tuning the properties of the graphene via a gate voltage. In order to investigate difference between the omni-gap and Bragg PBG, we plot the electromagnetic field profiles for some critical frequencies. The proposed structure is promising and can work as a gate tunable perfect stop filter which completely blocks both polarizations, and may have many other potential applications.