Terahertz electromagnetic fences on a graphene surface plasmon polariton platform

Xidong Wu,Xiang Guo

doi:10.1038/s41598-017-03205-x

Abstract

Controlling the loss of graphene can be used in the field of transformation optics. We propose a new concept of electromagnetic fence on a monolayer graphene surface plasmon polariton platform. Using a Dot-Density-Renderer quasicrystal metasurface, we can simulate the absorption of gradient index optics structures. Numerical simulations show that the incident waves to our designed electromagnetic fence are trapped toward the central lines and quickly absorbed by the high-loss region. Two basic types of electromagnetic fence and its composite structures have been designed and analyzed, which exhibit excellent broadband absorbing performances at 8 THz–12 THz. Because of its advantages in controlling the soft-boundary effects and easy manufacturing characteristics, the proposed electromagnetic fence seems very promising for THz–frequency-transformation plasmonics applications.

Highlights

Because of the ability to overcome the diffraction limit of light in microchip-sized devices, surface plasmon polariton (SPP) are considered as one of the most promising candidates for nanophotonic components[1,2,3]
The large effective index of graphene can efficiently constrain SPP waves around graphene sheet, which presents a variety of possibilities in the design of optical transformation devices, such as modulators[15,16,17,18], filter[19], cloaks[20], and absorbers[21,22,23,24]
The uneven ground plane below the dielectric spacer support can be used to tune the chemical potential of graphene to achieve desired permittivity patterns. This scheme is limited by soft-boundary effects[27], which imply that the designed uneven ground plane pattern cannot be precisely mapped to the required permittivity pattern

Summary

Result

It can be clearly observed in both cases that the incident SPP waves are trapped towards the central line of the black strip and get well absorbed. It can be seen that the EM-1 and EM-2 are well isolated by the designed black ring, which validates the good performance of the EM fence This is more obvious when comparing the waves inside and outside of the black ring, which shows the amplitude distribution of the electric fields from COMSOL simulations.

Conclusion

The surface conductivity of graphene can be modeled using the

Additional Information