Tunable THz supper absorber based on graphene nano ribbons for bio-sensing applications

Abstract

Leveraging periodic arrays of graphene ribbons and a flexible spacer, a highly adjustable THz wave absorber is discussed in the paper. The structure includes two stacked layers while a thick metallic plate covers the structure from beneath. The exploited periodic arrays of graphene ribbons with four different widths are placed on top of the Kapton spacer. The structure is modeled by passive circuit elements as an impedance while numerical full wave simulation is also performed to verify the validity and accuracy of the impedance matching concept. According to simulation results, an acceptable convergence is obtained between two separate simulations while the circuit model is developed by a MATLAB mfile, and full wave analysis is achieved via CST software. Both simulation paths verify multi-band absorption peaks in the THz spectrum with highly reliable and robust absorption peaks. According to the results, six absorption peaks with higher than 90 % adsorption are achieved. The response sensitivity is investigated versus design parameters that show appropriate robustness against geometrical parameters while the response is able to be fully controlled by changing the graphene patterns' chemical potentials. Such an adjustable wave absorber is in great demand for building larger optical systems including medical and security sensors.