Stereolithography forms terahertz PCs with 2 µm spatial resolution

The many uses of photonic crystals (PCs)-waveguiding, optical filtering, and others-are just as valuable in the terahertz as in the visible and IR regions.

The many uses of photonic crystals (PCs)-waveguiding, optical filtering, and others-are just as valuable in the terahertz as in the visible and IR regions. Researchers at Osaka University (Osaka, Japan) are creating terahertz PCs that have a spatial (structural) resolution of 2 µm; the PCs are fabricated from a mix of ceramic and resin that can either be used as is, or can be sintered to form a slightly smaller pure-ceramic PC.

A microstereolithography machine, which relies on a digital-micromirror device made by Texas Instruments (Dallas, TX) to create the patterns, is used to fabricate successive layers of the PC, taking 1.3 minutes to form each 40 x 40 mm layer. A diamond structure was chosen for the PC because it forms complete bandgaps. Upon sintering, the 500 µm lattice period shrinks to 380 µm. After sintering at 1600ºC for two hours, complete bandgaps were measured between 320 and 420 GHz in the Γ-X <100> direction, 330 and 400 GHz in the Γ-K <110> direction, and 260 and 355 GHz in the Γ-L <111> direction. Contact Yoshinari Miyamoto at miyamoto@jwri.osaka-u.ac.jp.

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