There is growing interest in superconducting nanowire single-photon detectors (SNSPDs) for their high detection efficiency, low noise, and broad wavelength-sensitivity range. Typically, silica fibers are used to deliver light to the detectors inside the cryostat, which works well for wavelengths from visible through 1550 nm. To access longer-wavelength infrared photons, other types of fibers, such as chalcogenide and fluoride fibers, need to be used. Here, we examine the infrared-wavelength transmission of straight and coiled silica optical fibers as candidates to couple infrared light to SNSPDs. We find that the silica fibers offer good transmission up to 2.2 μm wavelength. Above this wavelength, the transmission rolls off; the fibers exhibit 3 dB/m loss at 2.5 μm. High bend-loss sensitivity of some fibers can be used to adjust the long-wavelength transmission cutoff of the fiber to limit noise photons due to blackbody radiation.
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机译：超导纳米线单光子检测器（SNSPD）的高检测效率，低噪声和宽波长敏感度范围引起了人们越来越多的兴趣。通常，石英纤维用于将光传递至低温恒温器内部的检测器，该波长对可见光至1550 nm的波长都适用。为了访问更长波长的红外光子，需要使用其他类型的纤维，例如硫属化物和氟化物纤维。在这里，我们检查了直的和盘绕的石英光纤的红外波长传输，作为将红外光耦合到SNSPD的候选对象。我们发现，石英纤维在高达2.2μm的波长下具有良好的透射率。在此波长以上，传输会衰减；光纤在2.5μm处的损耗为3 dB / m。某些光纤的高弯曲损耗敏感性可用于调节光纤的长波透射截止，以限制由于黑体辐射引起的噪声光子。
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