Mechanism investigation of a narrow-band super absorber using an asymmetric Fabry-Perot cavity

摘要

We propose a metal-insulator-metal super absorber based on an asymmetric Fabry-Perot cavity, by which a perfect narrow-band absorption can be achieved. In this structure, two silver layers form a cavity spaced by a lossless silicon oxide layer. The absorption of the absorber can reach about 98% and its absorption peak can be tuned by altering the thickness of the middle SiO_2 layer. We further present a deep comprehension on the physics mechanism of such high absorption. This super absorber can be easily fabricated by mature thin film technology, which make it an appropriate candidate for photodetectors, sensing, and spectroscopy.