DIGITAL INFRARED BOLOMETERS USING SUPERCONDUCTORS AND SPINTRONICS

<p dir="ltr">Bolometers are essential in infrared (IR) detection due to their sensitivity to changes in temperature caused by incident IR radiation. They possess a higher level of sensitivity than other IR detectors at the same operating temperature, making them indispensable in applications such as thermal imaging, remote sensing, free space communication, and spectroscopy. However, bolometers still need further improvement regarding sensing spectral range and read-out speed. Superconducting nanowire single-photon detectors (SNSPDs), as bolometers operating at low temperatures, are crucial enablers of quantum metrology applications. Although SNSPDs have already exceeded the performance of semiconductor-based photon detectors in the visible and near-infrared spectral range, their performance has been limited in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectrum applications due to insufficient energy to cause a breakdown of superconductivity. Predicting the behavior of SNSPDs is important for performance optimization as their device physics highly depends on material properties. We present a vortex crossing theory of photon detection to provide a unified definition of system detection efficiency, dark count rates, and the intrinsic timing jitter in terms of vortex dynamics. We propose a metamaterial design utilizing vortex engineering to enable the next generation of SNSPDs in the LWIR and MWIR range. We also develop the theory for a new class of type-1.5 SNSPDs based on two-bandgap superconductors with high transition temperatures such as MgB₂. For the room temperature operation, we will focus on a new type of bolometric IR detector based on a highly structured spintronic material with the potential of sub-GHz read-out speed. We will propose and demonstrate promising solutions for its sensitivity improvement using the study of atomic spin dynamics and transduction layer design. We will discuss the design of plasmonic nanostructure meta-surfaces, which have the capabilities of tunable narrow/broadband absorption in both MWIR and LWIR regimes.</p>