Combined fabrication of terahertz hollow-core metal rectangular waveguide cavity using electrochemical deposition and selective chemical dissolution

The terahertz hollow-core metal rectangular waveguide cavity is a typical terahertz rectangular cavity structure that has several advantages and is widely used. However, the fabrication of the terahertz hollow-core metal rectangular waveguide cavity with high working frequency has not made recent breakthroughs, especially when the working frequency is 1-THz and above. In this paper, a combined process of electrochemical deposition and selective chemical dissolution is proposed first to manufacture the terahertz hollow-core metal rectangular waveguide cavity with high working frequency. Taking the fabrication of a 1.7-THz hollow-core metal rectangular waveguide as an example, the manufacturing methods and experiments of each step are described systematically. A terahertz hollow-core metal rectangular waveguide cavity with an end face size of 81.9 × 162.7 µm2, the edge radius less than 10 µm, the internal bottom surface roughness less than 0.08 µm, and the internal side surface roughness less than 0.3 µm is obtained. These experimental results are matched with the processing requirements of a 1.7-THz hollow-core metal rectangular waveguide. This flexible and controllable combined process makes it possible to manufacture more types of terahertz hollow-core metal rectangular cavity structures with high working frequency.