title: Coupling of ultrathin tapered fibers with high-Q microsphere resonators at cryogenic temperatures and observation of phase-shift transition from undercoupling to overcoupling.
abstract: We cooled ultrathin tapered fibers to cryogenic temperatures and controllably coupled them with high-Q microsphere resonators at a wavelength close to the optical transition of diamond nitrogen vacancy centers. The 310-nm-diameter tapered fibers were stably nanopositioned close to the microspheres with a positioning stability of approximately 10 nm over a temperature range of 7-28 K. A cavity-induced phase shift was observed in this temperature range, demonstrating a discrete transition from undercoupling to overcoupling.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, Japan.
authors.forename: Masazumi
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Noda
authors.forename: Akira
authors.initials: A
authors.lastname: Tanaka
authors.forename: Kiyota
authors.initials: K
authors.lastname: Toubaru
authors.forename: Hong-Quan
authors.initials: HQ
authors.lastname: Zhao
authors.forename: Shigeki
authors.initials: S
authors.lastname: Takeuchi
mesh_terms: D003080:Cold Temperature; D005336:Fiber Optic Technology / Q000295:instrumentation*; D008863:Microspheres; D014159:Transducers