Terahertz polarization-insensitive and all-optical tunable filter using Kerr effect in graphene disks arrays

In this paper, we propose and investigate a novel terahertz all-optical tunable filter comprised of arrays of graphene microdisks deposited on a dielectric substrate. The proposed filter exhibits a wide-angle response and also due to the symmetric structure is polarization-insensitive. The transmission line theory (TLT) using the circuit model of graphene disks arrays consists of parallel series R-L-C is exploited to investigate the structure for various lattice fill-factor and chemical potential. The results obtained via this approach show excellent agreement with the results of a second different method using the Full-wave numerical modeling. The novel proposed TLT method using an easy to implement MATLAB code takes advantage of extremely short computational time (less than a few seconds) along with a significant reduction in the required memory in comparison to the Full-wave simulations. In addition, the Kerr nonlinearity is studied through the harmonic balance method in steady-state regime. Our investigation reveals that a linear Red-shift occurs in the transmission spectra as the intensity of incident light increases. The proposed filter has potential applications in spectral imaging, communication systems and all-optical switching in the terahertz band.