THz Measurements and Calibration Based on a Blackbody Source

This paper presents a low-cost measurement setup for THz applications, based on a blackbody source, which is a commercial off-the-shelf (COTS) component. This measurement approach resembles the natural operating conditions of passive imaging systems and hence is more adequate in the characterization of the operation of THz sensors and filters for passive systems than narrowband THz sources. The calibration methodology of mesh filters that may block the unwanted IR radiation as well as that of THz thermal sensors is discussed. The components for uncooled passive thermal imaging: the innovative CMOS-SOI-NEMS thermal sensor (the TeraMOS) as well as mesh filters are characterized in the measurement setup presented here. The TeraMOS sensor reported here is a small array of 4 ×4 pixels, each 100 ×100 (μm)², with CMOS transistors with W/L=2/40, which are electrically connected but are thermally isolated. The NEP is of the order of NEP/√Hz|1 Hz=10 pW/√Hz, when viewing blackbodies at T=1300 K. The values of D* and NETD, obtained from this NEP, are 0.2·10¹⁰ cm√Hz/W and ~ 0.2 K. The corresponding NETD of a single pixel is ~ 0.8 K, indicating that this uncooled THz sensor in standard CMOS-SOI technology may enable monolithic uncooled passive THz imagers.