Compact Broadband Terahertz Filter Based on Effective Medium

Broadband filters are critical for wide communication capacity but have footprint and fabrication limitations. We present a broadband filter based on cascaded effective-medium-cladded all-silicon Bragg gratings, which has a compact size of 17 mm x 3.9 mm x 0.25 mm. The proposed design leads to a stopband covering the whole IEEE terahertz wireless communications band from 252-325 GHz with an average rejection level of 20 dB, and a passband from 220-252 GHz with the insertion loss less than -3 dB. Attributed to the introduction of a longitudinal effective-medium slot in the middle of the host waveguide, the filtering bandwidth and rejection level is significantly increased, leading to a decrease in the filter footprint and an additional degree of design flexibility compared to conventional Bragg grating filters. Such a broadband filter can be used in terahertz communication systems, terahertz sensors and other emerging terahertz technologies.

Automated summary

We propose a broadband filter based on cascaded effective-medium-cladded all-silicon Bragg gratings, which has a compact size of 17 mm x 3.9 mm x 0.25 mm. The filter covers the whole IEEE terahertz wireless communications band from 252-325 GHz with an average rejection level of 20 dB, and has a passband from 220-252 GHz with the insertion loss less than -3 dB. The introduction of a longitudinal effective-medium slot in the middle of the host waveguide significantly increases the filtering bandwidth and rejection level, reducing the filter footprint and providing additional design flexibility compared to conventional Bragg grating filters. Such a broadband filter can be used in terahertz communication systems, terahertz sensors, and other emerging terahertz technologies.