Nonideal Optical Cavity Structure of Superconducting Nanowire Single-Photon Detector
Nonideal Optical Cavity Structure of Superconducting Nanowire Single-Photon Detector
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DOI：
10.1109/jstqe.2014.2331955
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发表时间：
2014-11-01
影响因子：
4.9
通讯作者：
Xie, Xiaoming
中科院分区：
文献类型：
--
作者：
Li, Hao;Zhang, Weijun;Xie, Xiaoming
光学腔结构是超导纳米线单光子探测器获得高探测效率的关键因素。实际上，复杂的制造工艺可能导致非理想的光学腔结构。在这项研究中制造的SNSPD的横截面透射电子显微镜图像显示出意想不到的弧形光学腔，这可能是由于定义NbN纳米线时SiO2层的过度蚀刻而产生的。通过时域有限差分法进行光学模拟，分析了弧形光腔结构对不同偏振态光吸收效率的波长依赖性等影响。器件的中心波长由于弧形腔结构而发生蓝移。这种效果相当于高度降低的平腔。研究结果可为SNSPD的设计和制作提供参考。
Optical cavity structure has been proven to be a crucial factor for obtaining high detection efficiency in superconducting nanowire single-photon detector (SNSPD). Practically, complicated fabrication processes may result in a nonideal optical cavity structure. The cross-sectional transmission electron microscope image of SNSPD fabricated in this study shows unexpected arc-shaped optical cavities, which could have originated due to the over-etching of SiO2 layer while defining NbN nanowire. The effects of the arc-shaped optical cavity structure, such as the wavelength dependence of the optical absorption efficiency for different polarization, were analyzed by performing optical simulations using finite-difference time-domain method. The central wavelength of the device is found to exhibit a blue shift owing to the arced cavity structure. This effect is equivalent to the flat cavity with a reduced height. The results may give interesting reference for SNSPD design and fabrication.