Far-infrared kinetic-inductance detectors
Far-infrared kinetic-inductance detectors
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远红外动感电感探测器
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
J. Sauvageau
中科院分区：
文献类型：
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作者：
E. Grossman;D. G. McDonald;J. Sauvageau
基于厚度小于超导穿透深度的微米级薄膜的、适合于直接探测和外差应用的极灵敏远红外探测器是可能的。这种薄膜的穿透深度以及其电感随温度和准粒子数（由有效温度T* 描述）而变化，从而产生热感应和非平衡光感应响应。入射辐射通过光刻天线耦合到小面积动态电感器中，并且由此产生的电感变化通过集成微带DC SQUID放大并转换为电压信号。该器件是敏感的，因为与具有大电容电抗的基于结的器件不同，动态电感器在远红外频率处自然地与天线阻抗（nu >2 Delta /h）以及在微波或视频频率处与超导（SQUID）阻抗（nu <<2 Delta /h）良好匹配。最好的动力学电感材料是那些具有低电子平均自由程、大穿透深度和高临界电流密度的材料。因此，常见的磁体合金如NbTi是液态氦温度操作的自然选择。详细的分析预测，在0.1 K下工作的铱动力学感应器测辐射热计的（声子限制的）NEP为4*10/sup-17/ W/平方根Hz。对于工作在4K的Nb-Ti混频器，预测在3 THz，200 MHz带宽下的外差噪声温度为2250 K（单边带）。
Extremely sensitive far-infrared detectors suitable for both direct detection and heterodyne applications, based on mu m-sized thin films with thickness less than a superconducting penetration depth are possible. The penetration depth of such a film, and therefore its inductance, varies with temperature and with quasiparticle population (described by an effective temperature T*), resulting in both bolometric and nonequilibrium photoinductive responses. Incident radiation is coupled into the small-area kinetic inductor by a lithographic antenna, and the resulting inductance changes are amplified and converted to a voltage signal by an integrated microstrip DC SQUID. The device is sensitive because, unlike junction-based devices with large capacitive reactances, the kinetic inductor is naturally well matched to the antenna impedance at the far-IR frequency ( nu >2 Delta /h) and to the preamplifier (SQUID) impedance at microwave or video frequencies ( nu <<2 Delta /h). The best kinetic inductor materials are those with low electronic mean free path, large penetration depth, and high critical current density. Thus, common magnet alloys such as NbTi are the natural choice for liquid-He temperature operation. A detailed analysis predicts a (phonon-limited) NEP of 4*10/sup -17/ W/ square root Hz for a bolometer with an iridium kinetic inductor operated at 0.1 K. A heterodyne noise temperature of 2250 K (single-sideband) at 3 THz, with a 200-MHz bandwidth, is predicted for a Nb-Ti mixer operated at 4 K.