Double plasmon-induced transparency 3 bit graphene encoder

Abstract

In this paper, a 3 bit encoder was proposed which was based on double plasmon-induced transparency (PIT) effect. This structure consists of the bright-bright mode and realizes a double PIT window in the 0.1–3 THz range. Electric field distributions reveal that the double PIT effect is originated from the strong destructive interference between three bright modes, the Lorentz oscillation coupling model is utilized to confirm the finite-integration time-domain (FITD) simulation regardless of the x-polarization direction or y-polarization direction. When the incident light is x-polarized, encoding frequencies were at 0.976 THz, 1.525 THz and 2.069 THz, respectively; while in y-polarization, encoding frequencies were at 1.579 THz, 1.935 THz and 2.589 THz, respectively. Results depict that the Modulation Depth (MD) could reach 98 % regardless of the x-polarization direction or the y-polarization direction. As an electro-optical switch, the maximum MD could reach ≥98 %, the minimum IL could reach 0.35 dB, the maximum ER could reach ≥14 dB. Besides the encoder, the proposed structure is of great importance for the design of optical switches, terahertz modulators and slow light devices.