Integral fabrication of terahertz hollow-core metal rectangular waveguides with a combined process using wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution

The application requirements of terahertz hollow-core metal rectangular waveguides with a high-working frequency have become increasingly urgent with the rapid development of terahertz technology. Integral fabrication of terahertz hollow-core metal rectangular waveguides can improve considerably the transmission performance of terahertz signals. However, with current manufacturing techniques, the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides is difficult owing to their characteristically small end face size and the need for strict dimensional accuracy and high internal surface quality. In this paper, an innovative combined process of wire electrochemical micromachining, electrochemical deposition, and selective chemical dissolution is proposed firstly to overcome this puzzle. Taking the fabrication of an integral 1-THz hollow-core metal rectangular waveguide as an example, the manufacturing methods involved in each step are described particularly, together with the corresponding experimental investigations. With the end face size of 127 μm × 254 μm, edge radius less than 5 μm, and internal surface roughness less than 0.08 μm, the experimental results satisfy the design requirements for a 1-THz hollow-core metal rectangular waveguide. This study demonstrates that the proposed combined process is flexible, controllable, and suitable for the high-precision integral fabrication of high-working-frequency terahertz hollow-core metal rectangular waveguides.