Fig. 1. Structure design of 850 GHz band-pass filter

Fig. 2. Femtosecond laser processing technology platform and blowing-dust removal module

Fig. 3. Machining path and machining effect along step profile scanning

Fig. 4. Machining path and machining effect along vertical scanning direction

Fig. 5. Morphology of core structure under different blowing pressures

Fig. 6. Depth and morphology of core structure under different laser powers

Fig. 7. Depth and morphology of core structure at different scanning rates

Fig. 8. Depth and morphology of core structure under different scanning layers

Fig. 9. Depth and morphology of core structure under different Z-axis increments

Fig. 10. Core structure of terahertz filter processed by femtosecond laser

Fig. 11. Comparison of measured results and simulated results of THz filter performance