Black Phosphorous-Based Nanostructures for Refractive Index Sensing with High Figure of Merit in the Mid-infrared

Two-dimensional materials have emerged as new type of smart materials that may impact advanced photonic devices. Here, to increase the light absorption, a black phosphorus-based nanostructure is proposed. The presented nanostructure has a grating-shaped structure based on monolayer/multilayer black phosphorus and silica. To access reasonable absorption, the structure is numerically simulated by the finite difference time domain (FDTD) method. To benchmark this nanostructure, the black phosphorus permittivity in the wavelength range of 5 to 15 μm was calculated, to achieve the transfer spectrum based on the lateral length changes of black phosphorus (i.e., L = 100, 150, 170 nm) and the silica substrate which is extracted from Palick experimental results; the proposed nanostructure is simulated using the FDTD method. Also, changes in the refractive index of the surroundings have been used to compute significant parameters in the nanosensors, such as sensitivity, FWHM, and FOM. The proposed nanostructure can be used in tunable absorbers in the range of infrared wavelengths.