Metal-clad-suspended self-biasing graphene modulator with tunable figure of merit

In this letter, a research on the metal-clad-suspended self-biasing graphene modulator is conducted theoretically. The results reveal a higher light–graphene interaction for the more compact modulator. In addition, when the light–graphene interaction is enhanced, the light–metal interaction is also higher, which causes larger insertion loss and makes the figure of merit (FOM) lower. The length of π-phase shift is reduced to 6.35 µm for the Mach–Zehnder modulator, which is the smallest size achieved up to date. The modulator’s FOM can be tuned by changing the air gap (d) between the moveable metal plates and the suspended structure. In the case when this air gap increases, the configuration represents closer fundamental limits design. Moreover, the cut-off mode is discussed, and it has potential to be used in the tunable filter application. This tunable configuration of modulator is believed to have potential that can pave the way to design tunable light–matter interaction device and has evaluated for the near fundamental limits design.