Near-absolute polarization insensitivity in graphene based ultra-narrowband perfect visible light absorber

Abstract

Strong light-graphene interaction is essential for the integration of graphene to nanophotonic and optoelectronic devices. The plasmonic response of graphene in terahertz and mid-infrared regions enhances this interaction, and other resonance mechanisms can be adopted in near-infrared and visible ranges to achieve perfect light absorption. However, obtaining near-absolute polarization insensitivity with ultra-narrow absorption bandwidth in the visible and near-infrared regimes remains a challenge. In this regard, we numerically propose a graphene perfect absorber, utilizing the excitation of guided-modes of a dielectric slab waveguide by a novel sub-wavelength dielectric grating structure. When the guided-mode resonance is critically coupled to the graphene, we obtain perfect absorption with an ultra-narrow bandwidth (full-width at half-maximum) of 0.8 nm. The proposed design not only preserves the spectral position of the resonance, but also maintains >98% absorption at all polarization angles. The spectral position of the resonance can be tuned as much as 400 nm in visible and near-infrared regimes by tailoring geometrical parameters. The proposed device has great potential in efficient, tunable, ultra-sensitive, compact and easy-to-fabricate advanced photodetectors and color filters.

Semiconductor Thin Film Based Metasurfaces and Metamaterials for Photovoltaic and Photoelectrochemical Water Splitting Applications

“…Infinite‐fold symmetric designs, such as nanoshperes, nanodiscs, and nanopillars, can be used to mitigate this deficiency . It is worth to note that proper arrangement of particles can also provide this polarization insensitivity, even for elongated asymmetric design units . Lank et al demonstrated a strong light absorption using Si nanopillars .…”

“…This is important for the practical application of this strategy considering the fact that the incident solar irradiation is also unpolarized. Besides these symmetric designs, the polarization insensitivity can be acquired by arrangement of gratings in a proper way . A recent study proposed a metamaterial based mirror based on periodic patterns of Ag nanoparticles on Ag film .…”

Graphene/PbS quantum dot hybrid structure for application in near-infrared photodetectors

“…Graphene is a representative metallic layered material consisting of carbon atoms arranged in a hexagonal lattice with strong inplane chemical bonds 12 – 14 . Although graphene has high electron concentration, weak light absorption and fast carrier recombination limit its application in optoelectronics 15 , 16 . PbS colloidal quantum dots (QDs) are promising semiconductors for application as active material in near-infrared optoelectronics because of their small and tunable direct band gap 17 , 18 .…”

Lithography‐Free Random Bismuth Nanostructures for Full Solar Spectrum Harvesting and Mid‐Infrared Sensing

“…In contrast to the broadband absorbers, some studies aim to design narrowband absorbers that have an absorbance peak at single resonance wavelength. Many different nanopattern configurations were employed for achieving narrowband absorbers that are highly sensitive to the changes in the dielectric properties of their surroundings . Liu et al designed an MIM nanodisk narrowband perfect absorber with a sensitivity of 400 nm RIU −1 (refractive index unit) .…”