The reverse design method (RDM) is a frontier direction in the optical research field. In this work, RDM is applied to the design of terahertz demultiplexers, including two-port and three-port terahertz demultiplexers, with areas of 3 mm × 3 mm and 5 mm × 5 mm, respectively. The Finite-Difference Time-Domain (FDTD) simulation results show that the terahertz waves at frequencies of 0.5 THz and 0.417 THz can be well separated by the two-port demultiplexer, and the transmittances of the two outputs reach as high as 0.75 after bandwidth optimization. Meanwhile, the three-port terahertz demultiplexer can have terahertz waves separated from three Ports, and the crosstalk between adjacent channels is less than -18 dB.
Keywords: FDTD; demultiplexer; reverse design; terahertz.