Dynamical management of light propagation through hybrid graphene and dielectric layered systems

Abstract

Light management based on nanostructure-material engineering, is very important for optoelectronic applications. Here, through integrating single- layer graphene, we construct two different hybrid structures (layered graphene/dielectric/graphene and nano-patterned graphene/dielectric/graphene), and theoretically study their dynamic light transportation properties (reflection(R), transmission (T) and absorption (A)) in two different spectral regions (visible and THz) by changing the Fermi level (EF) of the graphene layers. In the wavelength region of 300−1200 nm, tuning EF has very weak influence on R, T and A for both systems. For the system without nano-patterning, R is high throughout the whole wavelength region (300−1200 nm); but a broad absorption window (530−700 nm) with A of ∼50 % is maintained for the nano-structures in the 0−3.0 eV tuning range of EF. In the wavelength region of 30−1000 μm, tuning EF plays a significant role in changing optical propagation characteristics for both systems, but with very different behaviors. For the nano-structured system, approximately 5% fluctuation of light absorption around 50 % is observed over the whole spectral range (30−1000 μm) under the EF tuning range (from 0 to 3.0 eV). However, for the layered structure, high absorption (∼60 %) is only achieved from 600 to 1000 μm under the EF tuning range of 0−0.5 eV. When changing EF of the two graphene layers independently, it is found that the top graphene layer plays an important role in light management. Increasing the size of the nanostructure to 400 nm improves the absorption of the nano-patterned system to 92 % at a single wavelength of 670 μm.