title: Compact cryogenic self-aligning fiber-to-detector coupling with losses below one percent.
abstract: We present a compact packaging technique for coupling light from a single-mode telecommunication fiber to cryogenic single-photon sensitive devices. Our single-photon detectors are superconducting transition-edge sensors (TESs) with a collection area only a factor of a few larger than the area of the fiber core which presents significant challenges to low-loss fiber-to-detector coupling. The coupling method presented here has low loss, cryogenic compatibility, easy and reproducible assembly and low component cost. The system efficiency of the packaged single-photon counting detectors is verified by the "triplet method" of power-source calibration along with the "multiple attenuator" method that produces a calibrated single-photon flux. These calibration techniques, when used in combination with through-wafer imaging and fiber back-reflection measurements, give us confidence that we have achieved coupling losses below 1% for all devices packaged according to the self-alignment method presented in this paper.
authors.affiliation: Department of Physics, Albion College, Albion, Michigan, USA. ajmiller@albion.edu
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Miller
authors.forename: Adriana E
authors.initials: AE
authors.lastname: Lita
authors.forename: Brice
authors.initials: B
authors.lastname: Calkins
authors.forename: Igor
authors.initials: I
authors.lastname: Vayshenker
authors.forename: Steven M
authors.initials: SM
authors.lastname: Gruber
authors.forename: Sae Woo
authors.initials: SW
authors.lastname: Nam