![]() ![]() Traditional forward design method is generally based on the specific analytical theory. RDM can provide solutions for many THz devices which are difficult to be designed by traditional methods and theories. Low insertion losses and crosstalk can be achieved. Finite-Difference Time-Domain (FDTD) simulation results show that the demultiplexers can output THz waves of different frequencies from different Ports, and their transmittances can reach more than 0.75 in a wide frequency range after bandwidth optimization. In this work, silicon-based two-port and three-port on-chip THz demultiplexers are architected by RDM. At present, several methods have been proposed to fabricate demultiplexers, including using ring resonators, coupled cavity waveguides, directional coupling, a graphene plasmonic cross-shaped resonator, metamaterials and metasurfaces. A wavelength demultiplexer can effectively expand the wave transmission capacity and improve the integration of the optical system. However, RDM has not been widely applied to the design of the THz devices. In recent years, RDM has been widely utilized in the design of nanophotonic devices, such as a polarization beam splitter designed by a direct binary search algorithm, a nanophotonic wavelength router designed by a genetic algorithm, an on-chip multi-channel focusing wavelength demultiplexer designed by an objective-first algorithm, etc. The novel approach, different from traditional methods, accomplish designs by exploring all possible structures in the whole design area, and the final device has more complex functions, a higher performance and a smaller volume. The reverse design method (RDM) as a unique tactic, by treating target performance as assessment standards, utilizing intelligent algorithms to optimize an initial structure and, eventually, finding out a satisfying device. Miniaturized, integrated and high-performance on-chip THz functional devices are highly desired. Limited by the theoretical value calculated by the self-imaging analytical theory, it is difficult to make the size of the devices smaller. Traditional design methods excessively rely on the designer’s experience and optical theories, by continually adjusting the structural parameters of the devices to achieve particular performance, such as THz demultiplexers, filters, polarizers and power splitters. Compared with modern integrated optical systems, they are bulky and expensive, which is not conducive to facilitate THz applications. However, the existing THz systems are composed of many discrete optical components. Terahertz (THz) technology has broad application prospects in many fields, such as sensing, non-destructive testing, spectroscopy, medical imaging, biology, communication and so on. ![]()
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