A thermocouple based on wideband hybrid metamaterial absorber for mid-infrared photo-thermoelectric detector

Abstract

A mid-infrared (MIR) photo-thermoelectric (PTE) detector is proposed based on a hybrid thermocouple consisting of a wideband metamaterial absorber and Seebeck material. When a mid-infrared wave illuminates the detector, the incident energy of the MIR beam is efficiently detected in this process of converting the energy of the light wave into the absorbed heat firstly by the wideband metamaterial absorber, and then outputting a voltage change according to the variation in temperature by a semiconductor material with a high Seebeck coefficient. Because of the existence of the metamaterial absorber, the high absorptions are almost achieved at a wide wavelength range from 3.4μm to 4.8μm with the absorptivity over 80%, and the average absorptivity is 93.6%. Meanwhile, the perfect absorptions appear at the wavelengths of 3.6μm, 4μm and 4.4μm. Comparing with the other reported detectors based on black materials and multilayer resonant cavities, this metamaterial absorber has a high absorptivity as well as a wide bandwidth, facilitating the maximum responsivity of single thermocouple as high as 0.89V/W. This hybrid thermocouple is able to operate at room temperature and has the advantages of angle insensitivity, simple in structure and easy integration, which has good potential applications in mid-infrared detection, sensing and imaging.