2026-10-27 東北大学
フレキシブル・ストレッチャブル単結晶シリコン基板
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2026/10/press20261027-02-Silicon.html
- https://opg.optica.org/optica/fulltext.cfm?uri=optica-13-11-2237
伸縮性シリコン有効媒質に基づくテラヘルツフォトニック材料の屈折率調整 Refractive index tuning of terahertz photonic materials based on a stretchable silicon effective medium
Hidemasa Yamane, Yoshiharu Yamada, Yusuke Kondo, Ken Miyajima, Masayuki Fujita, and Shuichi Murakami
Optica Published: October 20, 2026
DOI:https://doi.org/10.1364/OPTICA.596183
Abstract
High-resistivity single-crystal silicon (Si) is a low-loss and microfabrication-compatible platform for terahertz (THz) photonics, but its brittleness has largely limited Si THz components to mechanically rigid structures. Here, we demonstrate a structurally stretchable Si effective medium in which the optical properties of a Si/air dielectric composite are mechanically tuned by deforming the Si framework itself. A 200µm-thick high-resistivity Si slab was patterned by MEMS micromachining into a subwavelength spiral-spring through-hole lattice, converting bulk Si into a mechanically compliant, substrate-free photonic medium. In this architecture, the same monolithic Si microstructure provides both mechanical compliance and electromagnetic functionality: Uniaxial elongation changes the Si/air filling fraction and structural anisotropy, thereby tuning the effective permittivity and birefringence of the medium. THz time-domain spectroscopy verifies this concept by showing high transmission below 0.6 THz and a monotonic, polarization-dependent decrease in the retrieved effective refractive index; at 12.6% elongation, the effective index decreases by approximately 6%–8% without a detectable increase in extinction. These results establish structurally flexibilized bulk Si as a MEMS-compatible platform for mechanically tunable and structurally flexible all-dielectric THz effective media, providing a basis for future deformable THz photonic components after device-specific optical and mechanical optimization.
