Design of Terahertz Waveguide Filters For Hybrid Manufacturing Based On CNC Milling and Laser Micro-Machining

摘要

This paper presents the design of terahertz waveguide filters, operating in the WR-3 frequency range of 220-325 GHz, which are ideally suited to a hybrid manufacturing platform. The platform considered in this research combines the capabilities of CNC milling and laser micro-machining to produce components that incorporate meso and micro scale features. The functional filtering features of the waveguide devices are micro size and require a higher dimensional accuracy and good surface integrity. Therefore, these features were designed for laser micro-machining with a dimensional accuracy better than 10 μm. At the same time other features used to assemble the device were made sufficiently large, meso scale, and thus to produce them using CNC milling with much higher material removing rates. By designing THz waveguide filter that incorporate micro and meso scale features it was possible to combine the capabilities of these two technologies and reduce the production time significantly while a higher resolution and dimensional accuracy was achieved for the filter structure. The design for manufacturing analysis of a WR-3 4th-order filter was carried by using a 2nd-order filter to demonstrate and assess the advantages of applying a hybrid manufacturing approach for its production. In particular, to validate the design, the 2nd-order filter was fabricated from a copper workpiece and its microwave performance was assessed. The results showed a relatively good agreement with the simulation results. Several factors which may impact the filter's microwave performance were identified and discussed. The feasibility study demonstrated the suitability of the proposed filter structure for hybrid manufacturing of small to medium size batches of THz waveguide devices with high design flexibility.