Low loss silicon window material for submillimeter waves using micromachined artificial dielectrics for anti-reflection coating

A high-resistivity silicon wafer was used to design a broad-band low loss window material for 600 GHz by micromachining an artificial dielectric as a quarter wave transformer on the front and rear side of the wafer. The artificial dielectric is made from a 2-dimensional periodic structure to ensure the same transmission characteristics for horizontally and vertically polarized waves.