Structure-selected graphene/metallic surface plasmon coupling regime and infrared modulation application

Abstract

Here we present a graphene-based long-wavelength infrared modulator characteristic of extra-high contrast, where the frequency detuning degree of magnetic and electric surface plasmons (SPs) is controllable by the gated graphene Fermi energy. If the device is designed to work in a strong SP-coupling regime by selecting an appropriate low-lossy gate dielectric thickness, a modulation depth (MD) up to ∼100% but insertion loss (IL) as low as ∼−0.37 dB is achievable. Moreover, a compromised MD > 90% with IL < −1.0 dB is still retainable in two broadband ranges. The disclosed underlying mechanism to the device working state in the strong, electromagnetic-induced transparency (EIT), or weak SP-coupling regime, indicates the coupling regime shows a strong dependence on the dielectric thickness, which is related to the magnetic-SP mode volume, while the working wavelength can be selected in a broader spectral range by scaling the device geometry. These findings are helpful to construct those optoelectronics for infrared absorption enhancement, EIT, and strong coupling spectral characteristic itself.

Predictable infrared dual-band narrow-band absorber for infrared detection

“…where b is the spacing between adjacent structures, s¢¢ is the imaginary part of the conductivity of grapheme; s¢ is the real part of the conductivity of graphene. Due to the addition of the L G term to the circuit, the impedance of the entire circuit then changes as [49]: The change in the Fermi level of graphene will lead to the corresponding change in conductivity, which has an impact on the inductance L G of graphene. According to equation (15), when the metal dimensions in the structure are fixed, the only change in the equation is L .…”

Dynamically tunable multiple plasmon-induced transparency effect based on monolayer graphene structure system with rectangular defect cavities

“…Nevertheless, just the single-band PIT effect can be achieved from many graphene-based systems. Thus, the attainment of dynamically tunable multiple-PIT effect via the use of a monolayer graphene structure within the THz band remains a challenge [35][36][37].…”