Perfect light absorption in graphene by two unpatterned dielectric layers and potential applications

Abstract

In the spectral range from ultraviolet to near infrared, graphene lacks the capability to support plasmon polaritons, and has low optical absorptivity for applications due to its extremely small thickness. Many photonic structures based on sophisticated nanofabrication or metal plasmonics have been adopted to conquer this limitation, but they suffer from high expenses or metal parasitic losses. Here, a single-channel coherent perfect absorber simply based on two unpatterned dielectric layers is proposed to reach ∼100% light absorption in monolayer and few-layer graphene. The schemes for narrowband and broadband perfect absorption in graphene are systematically demonstrated, and their potential applications on fibre-integrated narrowband perfect absorbers, high-performance optical sensors, electric-optic modulators and broadband perfect absorbers are also investigated. Our research provides a simple and cost-effective method to completely trap the light from ultraviolet to near infrared in a sub-nanometre scale for a lot of high-performance photonic and optoelectronic devices based on graphene and potentially other 2D materials.