Optical characterization of 90 GHz band TESs in a dual-polarization dual-band pixel developed for AliCPT-1
摘要
The Ali CMB Polarization Telescope (AliCPT-1) is a ground-based telescope aiming to measure the cosmic microwave background (CMB) polarization anisotropies using transition-edge sensor (TES) bolometers. In recent years, we have been developing polarization-sensitive, dichroic TES bolometers to populate the focal plane of AliCPT-1, which is designed to accommodate 19 detector modules. This paper focuses on the optical performance of a single pixel, laying the groundwork for the future kilopixel detector array. The optical characterization includes passband, optical efficiency, and polarization response. The measured passband is 87-122 GHz, shifted upward from the target range of 77–109 GHz. This shift may be a result of an overestimation of the interlayer’s dielectric permittivity. The optical efficiency is measured to be 57%, and the cross-polarization levels are 2.3% and 6.2% for the two orthogonal 90 GHz TES bolometers. These results demonstrate the potential for scaling our single-pixel design to large-format TES arrays.