RESUMEN
We fabricated a rigid bandpass filter with a broad far-infrared wavelength range of high transmission using a silicon subwavelength structure with a Babinet complementary metamaterial half-mirror pair, despite its apparent light-blocking structure. The rigid one-piece filter was produced by a simple process involving photolithography, dry etching, and deposition, each performed only once. The transmission principle relies on the Fabry-Perot resonance with a metamaterial half-mirror pair that exhibits extraordinary optical transmission due to spoof surface plasmon polaritons. The transmission center wavelength was successfully predicted by the basic equation of Fabry-Perot resonance with an effective medium approximation. In contrast, a narrower bandwidth and a lower minimum transmittance than those predicted from the basic equation were provided by the subwavelength Si structure between the metamaterial mirrors, resulting in enhanced bandpass filter characteristics.
RESUMEN
We developed broadband antireflection structures for millimeter-wave and submillimeter-wave applications, particularly cryogenic applications. The structures were fabricated on silicon using deep reactive ion etching. Three-layer subwavelength structures were fabricated on both sides of a silicon plate with an area of 20mm2. The transmittances of the structures were measured at 28 K. The average transmittance was 97.6% in the frequency range of 200-450 GHz.