Non-reciprocal diplexer and power combiner/divider from topological cavities with both splitting and combining functions

Multiplexers and power combiners/dividers are crucial in many applications of electromagnetic waves including microwave terahertz communication. Full-duplex communication requires the separation transmitted received signals; thus, non-reciprocal multiplexers very essential. In this work, we present numerically study a design concept for such circuits from topological cavities. First, quad-port circulator is made cavity two trivial waveguides, which effectively operates as band-pass filter. Then, by parallelly connecting multiple circulators together, diplexers formed. These due to nature photonic insulators, yet unlike previously proposed or combiners/dividers, they can both split combine frequencies flows. The also makes them robust any fabrication error suitable practical full-duplex applications.