A visible-infrared double band photodetector absorber

•Visible band (400–800 nm) and infrared band (8–12 μm) double band detection.•Visible-infrared double band coaxial absorption with single pixel integration is realizes.•The micro-bolometer type structure is used in the structure proposed.•The COMSOL simulation software and Multilayer film absorption theory are used to analyze the structure. In this paper, a double-band visible-infrared photodetector absorber is proposed, which consists of a modified microbolometer and a metallic reflective layer which has a deep well. The simulated results show that the absorber proposed has high absorption peaks both at visible band (400–800 nm) and infrared band (8–12 μm), and the absorptivity at infrared band is more than 85% while the absorption rate at visible band exceeds 70%. By analyzing the simulation results, the absorption mechanism is discussed. The designed absorber not only has high absorption rate, but also realizes visible-infrared double band coaxial absorption with single pixel integration, hence it is favorable for various applications, such as night and day vision coaxial detecting, double band fusion detecting, and optical filter and bio-chemical sensor.