a near-infrared perfect absorber assisted by tungsten-covered ridges

A periodic tungsten-covered dielectric ridge on substrate assembly is proposed in this article to investigate the perfect absorption in the near-infrared regime. the localized dipolar resonance and the propagating surface plasmon mode significantly restrict the reflectance thus forming two discrete absorption peaks. in the process of discovering perfect absorption, the geometrical parameters such as the tungsten layer thickness, ridge depth and width, substrate spacer thickness and the lateral period are correspondingly numerically explored and a rather high absorption rate of 99.9% can be achieved. furthermore, the absorption peak is sensitive to the ground substrate index which makes it a potential candidate for compactly integrated on chip sensing applications. the polarization direction of the incident light modulates the absorption to a wider bandwidth and the oblique incidence splits the propagating mode along with a rather weak fano-type absorption peak. the research pave way for transition metal integrated on chip absorption system.