2026-05-07 東北大学
図1. 単層シリコン基板上に作製したテラヘルツ光スイッチの外観写真 (a)全体写真、(b)拡大写真
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/05/press20260507-03-terahertz.html
- https://ieeexplore.ieee.org/document/11482691
高抵抗単結晶シリコン基板上に一体成形された可動式シリコン導波路を備えたテラヘルツ光スイッチ Terahertz Optical Switches with Movable Silicon Waveguides Monolithically Fabricated on High-Resistivity Single-Crystal Silicon Substrates
Kohei Chiba; Yoshiaki Kanamori
IEEE Transactions on Terahertz Science and Technology Published:16 April 2026
DOI:https://doi.org/10.1109/TTHZ.2026.3683533
Abstract
Photonic integrated circuits (PICs) based on dielectric waveguides are being developed for Beyond 5G/6G communication systems. Variable passive elements, essential for PICs, present challenges for downsizing and low power consumption in the terahertz range. Variable passive elements based on micro-electromechanical systems (MEMS) are promising solutions; however, the previous terahertz variable passive elements based on MEMS have complex structures processed on all layers of silicon-on-insulator (SOI) substrates. They can be fabricated on a single layer of silicon substrate, which is cheaper than an SOI substrate. However, to the best of our knowledge, there have been no demonstrations. We proposed a terahertz optical switch, which is one of the variable passive elements, based on comb-drive actuators fabricated on a single layer of silicon substrate. A comb-drive actuator was designed for 200 μm displacement at 104.5 V. An optical switch was designed for an extinction ratio of 18.9 dB at 300 GHz. The device was fabricated on a single layer of high-resistivity single-crystal silicon substrate, achieving a displacement of 185.4 μm at 93 V and an extinction ratio of 13.69 dB at 300 GHz. The optical switch part measured 5.65 mm long and power consumption was only 3.6 mW, outperforming previous works. While conventional comb-drive actuators are fabricated on SOI substrates, our design was fabricated on a single layer of silicon substrate. The proposed single-layer comb-drive actuator can be applied to variable phase shifters, directional couplers, and add/drop filters. This work addresses key challenges in terahertz variable passive elements and contributes to the advancement of terahertz PICs for Beyond 5G/6G communications.
