Terahertz Imager Based on a THz-to-IR Converter

Abstract

A new terahertz (THz) imager based on THz-to-IR conversion has been proposed and studied. The THz-to-IR converter consists of an ultra-thin resonant THz absorber (meta-absorber) whose backside is coated with an emission layer with an emission factor close to unity. The absorption of THz radiation leads to converter heating, which is recorded by an IR camera from the emission layer side. The small thickness of the converter (more than 50 times smaller than the working wavelength of THz radiation) determines its low heat capacity, resulting in an increase in the sensitivity and operating speed of the imager. Optimization of the optics of the THz imager, making cuts in the converter structure to reduce the blooming and increase the response, and the IR image processing method increasing the signal-to-noise ratio, provided the sensitivity of the THz imager similar to the sensitivity of thermal detectors in the 8–12 μm IR range.