{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/44449"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/44449","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Coupling light to superconductive photon counters","abstract":"Superconductive nanowire single-photon detectors (SNSPDs) are an emerging, ultrasensitive photon counting technology which may enable fiber-based, long-haul quantum key distribution. Our group has successfully developed a robust process to fabricate SNSPDs, and has demonstrated device-detection-efficiency above 50% at near infrared wavelengths. However, one remaining challenge must be taken - efficiently coupling light into the detector. This step is difficult because of the small active area of the SNSPD and its low temperature operation. In this thesis, I have designed two experimental setups to couple the light from fiber to the detector at a cryogenic temperature of 4 K: one is for immersion device-testing in a dewar; another is for packaging the detector inside a cryocooler. In addition, I have designed and fabricated SNSPDs suitable for the coupling with single-mode fiber, based on my theoretical calculation of the system detection-efficiency. Some important parameters to characterize the detectors such as system-detection-efficiency, dark-count rate, and counting rate vs. optical input power have been measured.","abstract_html":"Superconductive nanowire single-photon detectors (SNSPDs) are an emerging, ultrasensitive photon counting technology which may enable fiber-based, long-haul quantum key distribution. Our group has successfully developed a robust process to fabricate SNSPDs, and has demonstrated device-detection-efficiency above 50% at near infrared wavelengths. However, one remaining challenge must be taken - efficiently coupling light into the detector. This step is difficult because of the small active area of the SNSPD and its low temperature operation. In this thesis, I have designed two experimental setups to couple the light from fiber to the detector at a cryogenic temperature of 4 K: one is for immersion device-testing in a dewar; another is for packaging the detector inside a cryocooler. In addition, I have designed and fabricated SNSPDs suitable for the coupling with single-mode fiber, based on my theoretical calculation of the system detection-efficiency. Some important parameters to characterize the detectors such as system-detection-efficiency, dark-count rate, and counting rate vs. optical input power have been measured.","abstract_has_math":false,"creators":["Hu, Xiaolong"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.","school":null,"contributors":[],"advisors":["Karl K. Berggren."],"committee_chairs":[],"committee_members":[],"year":2008,"date_issued":"2008","date_published":"2008","updated_at":"2026-07-22T22:22:19Z","subjects":["Electrical Engineering and Computer Science."],"languages":["eng"],"rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. 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Our group has successfully developed a robust process to fabricate SNSPDs, and has demonstrated device-detection-efficiency above 50% at near infrared wavelengths. However, one remaining challenge must be taken - efficiently coupling light into the detector. This step is difficult because of the small active area of the SNSPD and its low temperature operation. In this thesis, I have designed two experimental setups to couple the light from fiber to the detector at a cryogenic temperature of 4 K: one is for immersion device-testing in a dewar; another is for packaging the detector inside a cryocooler. In addition, I have designed and fabricated SNSPDs suitable for the coupling with single-mode fiber, based on my theoretical calculation of the system detection-efficiency. Some important parameters to characterize the detectors such as system-detection-efficiency, dark-count rate, and counting rate vs. optical input power have been measured."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:title","label":"Title","values":["Coupling light to superconductive photon counters"]}]}],"canonical_facts":{"dc:contributor.advisor":["Karl K. Berggren."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science."],"dc:contributor.other":["Massachusetts Institute of Technology. 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In this thesis, I have designed two experimental setups to couple the light from fiber to the detector at a cryogenic temperature of 4 K: one is for immersion device-testing in a dewar; another is for packaging the detector inside a cryocooler. In addition, I have designed and fabricated SNSPDs suitable for the coupling with single-mode fiber, based on my theoretical calculation of the system detection-efficiency. Some important parameters to characterize the detectors such as system-detection-efficiency, dark-count rate, and counting rate vs. optical input power have been measured."],"dc:description.degree":["S.M."],"dc:identifier.uri":["http://hdl.handle.net/1721.1/44449"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Electrical Engineering and Computer Science."],"dc:title":["Coupling light to superconductive photon counters"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:22:19Z"}