Integrated Terahertz Band-Stop Filter Based on Effective Medium

We propose a terahertz band-stop filter based on substrateless effective-medium-clad dielectric waveguides. The Bragg grating filter is built into a single high-resistivity silicon wafer and operates at the WR-3 band (220-330 GHz) with the inplane polarization. Due to the controllable air-silicon effective-medium permittivity, an additional degree of freedom can be accessed in the design of Bragg grating structure, which allows to modulate the modal indices for broadband operation. Hybrid effective medium claddings are introduced to further reduce the insertion loss with a small footprint. The results are experimentally validated. The techniques to improve the filter characteristics by controlling the effective medium are adaptable to the microwave and optical regimes.