High-Q terahertz bandstop filter via cuboid frame structure

A terahertz (THZ) bandstop filter can be used to filter interference signals in a filter passband. The quality factor (Q) is the most important index in evaluating the transmission performance of the filter. Usually, a higher Q value, a narrow bandwidth and a larger stopband slope ensures good filtering accuracy and transmission response. However, the Q value taken from metamaterial structures designed on the plane is only ever in single digits, resulting in a less than satisfactory filtering performance. Herein, a high-Q THZ bandstop filter based on metamaterials was proposed. To fabricate this 3D metamaterial structure, a microtopographic substrate-guided method with feasible and high accuracy capacities was proposed. As a result, it is ascertained that the device is in the filtering state in the range 1.038-1.102 THz while it is stopped in the range 1.062-1.066 THz. The similarity between the experimental and simulated transmissions is up to 86.32%, indicating that the fabricating method possesses high accuracy. Accordingly, the Q value was calculated to be as high as 532. In future, the bandstop filter with this record Q value can be widely used in THZ detection, imaging and sensing. Meanwhile, the proposed fabrication method is effectively applied to a 3D metamaterial and a THZ device as well.