Free-space Coupled Superconducting Nanostrip Single Photon Detector System based on GM Cryocooler
【Objective】This study aims to design and implement a free-space-coupled Superconducting Nanostrip Single Photon Detector (SNSPD) system based on a Gifford-McMahon (GM) cryocooler, addressing the limitations of traditional fiber-coupled systems in near/mid-infrared bands and polarization-sensitive ap...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
《光通信研究》编辑部
2025-06-01
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| Series: | Guangtongxin yanjiu |
| Subjects: | |
| Online Access: | http://www.gtxyj.com.cn/thesisDetails#10.13756/j.gtxyj.2025.250083 |
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| Summary: | 【Objective】This study aims to design and implement a free-space-coupled Superconducting Nanostrip Single Photon Detector (SNSPD) system based on a Gifford-McMahon (GM) cryocooler, addressing the limitations of traditional fiber-coupled systems in near/mid-infrared bands and polarization-sensitive applications, and thereby expanding the application scenarios of SNSPDs.【Methods】The paper focuses on addressing several key technical issues, including the design of low-vibration constant-temperature cavities, the preparation of SNSPD devices in high-temperature zones, and the design of filtering optical paths across temperature zones. Specifically, the low-vibration cryostat, combined with gas exchange chambers and bellows flexible connection technology, effectively suppresses the vibration transmission from the refrigerator. The SNSPD chip achieves high detection efficiency in the 4.2 K temperature zone by adjusting and optimizing the growth parameters of the disordered Niobium Titanium Nitride (NbTiN) thin film. The cross-temperature-zone filtering optical path successfully suppresses environmental stray light and blackbody radiation by using a combination of various commercial filter plates and oxidation-blackening treatment of the packaging box.【Results】The low-vibration refrigerator can reach a lowest temperature of 3.45 K, and can be stabilized at 3.75 K for a long time. The peak-to-peak value of the vibration amplitude is less than 4 μm. The optical alignment efficiency is close to 90%, and the System Detection Efficiency (SDE) can reach 50% at the lowest temperature. At this time, the Dark Count Rate (DCR) of the system is 70 cps.【Conclusion】This study successfully developed a GM cryocooler-based free-space-coupled SNSPD system, overcoming the technical limitations of traditional fiber-coupled systems in specific applications. The system exhibits excellent wavelength versatility, flexible signal-light coupling tunability, and superior polarization-maintaining performance. Future optimization of operating temperature, device fabrication processes, and customized filter design is expected to achieve higher SDE and lower DCR. |
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| ISSN: | 1005-8788 |