Photonic crystal terahertz-wave absorbers

点击翻译按钮获取中文摘要

Terahertz (THz) waves, which are located in the region between radio and light waves (0.1 THz - 10 THz), have attracted a great deal of interest in various fields. The highly-efficient THz perfect absorbers have attracted much attention recently due not only to scientific interest but also to various possible applications. However, thin, planar THz-wave absorbers with near perfect absorptivity and sufficiently broad bandwidth have not yet been demonstrated. Here we utilize the in-plane resonance of a thin, planar photonic-crystal slab with negligible absorption loss to successfully demonstrate and visualize THz-wave trapping. We artificially introduce free carriers, which interact with the trapped waves and capture them in the slab by absorption. Our system exhibits an experimental absorptivity (interaction efficiency) of > 99 % and a broad bandwidth (absorptivity >= 90 %) that covers 17 % of the centre frequency.