Highly selective single-mode graphene bandpass filter based on Wilkinson power divider structure

Abstract

In this paper, we introduce a novel graphene nanoribbon bandpass filter designed using the Wilkinson power divider structure for single-mode operation. Through the three-dimensional finite-difference time-domain (3D-FDTD) technique, we analyze transmission spectra and electromagnetic field distributions. Our primary goals are to achieve high transmission efficiency, improved adjustability, and an excellent quality factor (Q-factor). The proposed single-mode graphene nanoribbon bandpass filter exhibits outstanding performance characteristics, including a 45 THz free spectral range (FSR), 95 % transmission efficiency, and a full width at half maximum (FWHM) of 0.14 THz at the resonant frequency of 15 THz. By changing the chemical potential (or bias voltage) to manipulate the conductivity and dielectric constant of the graphene surface, we successfully tune the center frequency of the filter within the 10–20 THz range. This flexibility, combined with exceptional transmission efficiency and Q-factor, positions our filter as a prime candidate for seamless integration into compact optical devices. Additionally, by adjusting the refractive index of the substrate, we achieve a sensitivity exceeding 7 THz/RIU or 7500 nm/RIU, making our filter a promising sensor for applications requiring precise detection and measurement capabilities.