Electrically tunable grating metamaterials polarization-independent filter based on graphene-lithium niobate

In this paper, we propose an electrically tunable coupling filter that utilizes orthogonal gratings together with graphene. The position of the transmission valley can be altered by varying the gate voltage's strength, and the electrotunable properties of lithium niobate are described. Under resonance conditions, monolayer graphene is comparable to a conductive electrode that completes all of this device's absorption. By optimizing the substrate thickness and grating duty cycle, this device can achieve perfect filtering with an absorption rate of 99% at 801 nm. Coupled mode theory is also used to explain the spectrum response. Additionally, we discover that this serial filter exhibits polarization insensitive properties between 0 to 30 degree, such a filter with superior performance will play an significant role in fields such as plasmonic nanowaveguides.