Design and Simulation of Terahertz Apodized Bragg Grating Using Coplanar Stripline Transmission Line a 1 µm-thin Membrane

Abstract

Abstract A guided-wave THz System-on-Chip THz System-on-Chip (TSoC) is emerging as an attractive alternative to the routine free-space THz systems to reduce physical bulk, propagation loss, pulse dispersion and cost of free-space THz systems. Recently, our research group succeeded in demonstrating a novel waveguided TSoC based on the coplanar stripline Coplanar Stripline (CPS) transmission lines on a 1 µm-thin Silicon Nitride membrane. The novelty of this membrane-based platform was bonding the transmitter and receiver directly on the transmission line to eliminate the radiation loss by the routine THz optics. Besides, the delicate thin-membrane dramatically reduces the dielectric loss of the platform which results in low-loss and low-dispersion THz-bandwidth pulses. In this paper, we introduce the design, theoretical model and the simulation results of a novel THz Apodized Bragg Grating (TABG) based on a periodic reflection of consecutive different impedance sections of CPS transmission lines on the membrane platform. This structure was introduced based on theoretical modelling and the simulation results. The CPS-TABG consists of 20 λ/2-length cascaded sections. The central frequency of the bandstop filter was selected around 0.8 THz to avoid signal distortion of the received terahertz pulse.