Mid-infrared broadband absorber of full semiconductor epi-layers

We demonstrate mid-infrared dual channel near-perfect absorbers based on full semiconductor epi-layers theoretically. Strong absorption (>99.9%) is observed at 25.04 THz. Through introducing composite grating and controlling the thickness of the dielectric layer, we can get a broadband absorption with absorptivity above 80% at the range from 8 μm to 12 μm with a good incidence angle tolerance. The structure investigated in this paper shows a broadband, all-semiconductor, plasmonic architecture, which is of great importance for many applications such as bolometers, cloaking, imaging devices and also can be used in enhancing interaction of mid-infrared radiation with integrated semiconductor optoelectronic elements.