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

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 similar to 100% but insertion loss (IL) as low as similar to-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.

Automated summary

A graphene-based long-wavelength infrared modulator with high contrast is presented. The frequency detuning of magnetic and electric surface plasmons can be controlled by adjusting the graphene Fermi energy, leading to high modulation depth and low insertion loss.