Design of High-Precision Terahertz Filter Based on Directional Optimization Correction Method

The directional optimization correction (DOC) method is proposed to reduce the performance error between desired and fabricated terahertz (THz) devices. Three 340 GHz terahertz filters with a bandwidth of 20 GHz are designed and fabricated. The traditional global optimization correction (GOC) method and the proposed DOC method are used to optimize and reduce the performance error, respectively. It is garnered that the center frequency error and bandwidth error of the fabricated terahertz filter optimized by the GOC method are reduced to 3.5 GHz (~1.03%) and 2.2 GHz (~11%), respectively. Meanwhile, the center frequency error and bandwidth error of the fabricated terahertz filter optimized by the DOC method are reduced to 0.2 GHz (~0.06%) and 0.4 GHz (~2.0%), respectively, which has fewer optimization parameters and higher accuracy than the GOC method. Furthermore, the in-band return loss (RL) of two optimized terahertz filters based on the DOC and GOC methods is less than 15 dB, and the in-band insertion loss (IL) is less than 2.3 dB.