0.1 THz imaging with a monolithic High-T_c superconducting transition-edge detector

Terahertz detection has attracted significant interest for noninvasive bio-imaging and security systems. Superconducting bolometers are one of the promising technologies for ultra-sensitive terahertz detection. Here, we introduce a low-cost superconducting transition-edge detector used for THz imaging. The sensing element of the detector is a meander line patterned YBa2Cu3O7-x (YBCO) thin film that realizes a monolithic superconducting bolometer. The pattern consists of 15 lines that each one of them is 1.5 mm long and 50 µm wide. This pattern is designed to have a significant response to the 0.1 THz equivalents to 3 mm wavelength radiation without any coupled antenna or separate absorber that may reduce the detection speed. 400 nm YBCO film is fabricated by the metal-organic deposition (MOD) method, an economic and scalable chemical, vacuum-free technique. The dielectric substrate of the detector is chosen to be Yttrium-stabilized Zirconia (YSZ) that has the lowest thermal conductivity between YBCO substrates resulting in a higher bolometric response. YSZ substrate needs a buffer layer to have high-quality YBCO thin film on top, so a 20 nm Ce_0.9La_0.1O₂ (CLO) buffer layer is deposited by the same MOD method. Amplitude and phase of the response of the fabricated detector to the 0.1 THz wave source, versus modulation frequency are measured and the detector is used for imaging concealed objects including cigarettes and metallic items.