Two Frequency-Division Demultiplexing Using Photonic Waveguides by the Presence of Two Geometric Defects

This paper presents a theoretical work of a new device concept for frequency division demultiplexing with excellent performance based on waveguides system containing segments and loops in the presence of two geometrics defects. This system permits the separation of two frequency, based on 1D photonic waveguides loops structures. The system under consideration possesses a Y‑shaped demultiplexer configuration, consisting of a single input and two output channels (transmission lines). Each output channel contains an alternating unit cell consisting of a segment and a loop. The creation of a geometrical defect at the segment level in the middle of each output line allows the creation of two defect modes inside the bandgaps. The numerical results show that this demultiplexer system is able to separate two signals (electromagnetic waves) of different frequencies and guide each signal through an output channel. We perform the analytical calculation of the transmission rates T₁, T₂, and reflection R using the interface response theory, which is based on Green’s function method for the proposed demultiplexer system. The proposed device offers high transmission efficiency, high quality factor and a large frequency difference between defect modes, hence, it is highly desirable for frequency division demultiplexing applications.