Double-etch geometry for millimeter-wave photonic band-gap crystals

Abstract

We have designed and developed a new double-etch technique for fabricating three-dimensional millimeter-wave photonic band-gap crystals. This technique doubles the band-gap frequency obtainable from silicon wafers. By introducing overetching, the double-etch geometry allows one-way tuning of the midgap frequency. We have experimentally demonstrated this property by fabricating and testing structures with different overetch ratios. Terahertz spectroscopy techniques were used to measure photonic band-gap crystals with midgap frequencies ranging from 340 to 375 GHz.