Effect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-division-multiplexing fiber-optic links

Pinkert, T. J.; Böll, Oliver; Willmann, Lorenz; Jansen, G. S. Matthijs; Dijck, Elwin; Groeneveld, Bart G. H. M.; Smets, Rob; Bosveld, F. C.; Ubachs, Wim; Jungmann, Klaus-Peter; Eikema, K.S.E.; Koelemeij, J.C.J.

doi:10.1364/ao.54.000728

Cited by 22 publications

(14 citation statements)

References 24 publications

(35 reference statements)

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“…A fiber-based femtosecond frequency comb (Menlo Systems FC1500) is used to measure the frequency of the light at wavelengths λ 1 and λ 2 (see Fig 3). Its long term stability is provided by a GPS disciplined rubidium clock (FS 725) with an intrinsic frequency stability of 10 −11 in 1 s integration time and 10 −12 in 10 000 s. This clock also serves as long term reference for all rf frequencies in the experiment and its stability has been verified to ∆ν/ν ≈ 10 −11 via an optical fiber network [13].…”

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confidence: 99%

Determination of transition frequencies in a singleBa+138ion

et al. 2015

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Transition frequencies between low-lying energy levels in a single trapped 138 Ba + ion have been measured with laser spectroscopy referenced to an optical frequency comb. By extracting the frequencies of one-photon and two-photon components of the line shape using an eight-level optical Bloch model, we achieved 0.1 MHz accuracy for the 5d 2 D 3/2 -6p 2 P 1/2 and 6s 2 S 1/2 -5d 2 D 3/2 transition frequencies, and 0.2 MHz for the 6s 2 S 1/2 -6p 2 P 1/2 transition frequency.Trapped single ions can be exploited to investigate the interaction between light and matter, and to construct optical clocks [1]. For these applications based on high precision spectroscopy a good understanding of the optical line shapes involved is indispensable. We have employed an optical frequency comb [2] to measure transition frequencies in Ba + and a model based on optical Bloch equations to extract atomic parameters from fluorescence spectra. These are essential ingredients for high precision experiments, in particular for atomic parity violation measurements in single Ba + [3,4] and Ra + ions [5,6] in the search for new physics [7]. In this work the frequencies of transitions between three of the lowest fine structure levels in the 138 Ba + ion are addressed. These levels form a Λ-configuration as shown in Fig. 1. The level 6p 2 P 1/2 decays to the levels 6s 2 S 1/2 and 5d 2 D 3/2 with a branching ratio of about 3:1 [8]. We have measured the transition frequencies in a single 138 Ba + ion by driving the transitions 6s 2 S 1/2 -6p 2 P 1/2 and 5d 2 D 3/2 -6p 2 P 1/2 , employing an optical frequency comb as frequency reference. The dynamics of the population of the 2 P 1/2 level can be described by optical Bloch equations [9][10][11]. Coherent coupling between the 2 S 1/2 and 2 D 3/2 levels is observed when the two laser fields are detuned by the same amount from the respective atomic resonances. In this condition a two-photon process causes coherent population trapping, reducing the population of the 2 P 1/2 level [12]. For the measurements reported here a single Ba + ion is confined in a hyperbolic Paul trap (see Fig. 2). The trap is operated at frequency ω rf /2π = 5.44 MHz with a peak-to-peak rf voltage of typically V rf = 600 V. Additional electrodes provide a dc potential to compensate the effect of mechanical imperfections and stray fields, minimizing the micromotion of the ion in the trap. The trap is loaded by photoionization of 138 Ba atoms with laser light at wavelength 413.6 nm. The trap is mounted in a UHV chamber with residual gas pressure below 10 −10 mbar. Doppler cooling and detection of the Ba + ions is achieved with laser light at wavelengths λ 1 and λ 2 (see Fig 1). Laser light to drive the 6s 2 S 1/2 -6p 2 P 1/2 tran- * e.a.dijck@rug.nl † Present address: Department of Physics, Columbia University, New York, NY 10027 FIG. 1. Low-lying energy levels of the Ba+ ion. The wavelengths of the investigated transitions are given. FIG. 2. Schematic diagram of the hyperbolic Paul trap used for trapping Ba+ ions, consisting of ...

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Determination of transition frequencies in a singleBa+138ion

et al. 2015

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“…Distributed Temperature Sensing (DTS) technique for testing the inside of fibre cable cores and use of weather stations to test the outside temperatures in aerial cables have both revealed that either approach is reliable in analyzing the impact of temperature on PMD in fibre cables [1,2,7].…”

Section: Literature Reviewmentioning

confidence: 99%

“…For buried cables, algorithms have been applied on metrological weather data to determine temperature at the depth where the cable is buried [7]. This method has been used to analyze frequency-shifts and chromatic dispersion.…”

Section: Literature Reviewmentioning

confidence: 99%

Impact of Temperature and Relative Humidity on PMD in Directly Buried Optical Fibre Cables in Semi-Arid and Tropical Highlands in Kenya

Ndunda

Dehayem-Kamadjeu

Waswa

2018

International Journal of Optics

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The telecommunication industry has implemented fibre deployment guidelines that reliably safeguard cable health during installation in the field. While installed fibre cables remain buried in the field, temperature and moisture in the locality subject them to mechanical expansions and corrosion. Directly buried fibre cables experience accelerated degradation that results from exposure to harsh environments. This increases pulse spreading and overlaps, with a mean time duration, known as Differential Group Delay (DGD), on the signal, as it propagates along the cable. DGD is stochastic; thus, Mean DGD is determined and presented as Polarization Mode Dispersion (PMD). This work undertook a real life assessment of how fluctuations in temperature and relative humidity influence PMD in directly buried fibre optical links, in a case study that focused on the fibre cable network owned by Liquid Telecom Kenya. The network spans across two key climatic ecosystems, namely, rift valley highlands and northern lowlands. The analysis revealed that fibre cables experience higher PMD in semi-arid areas by a factor of 2.6, compared to highland areas.

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“…On links with phase-coherent amplification, 10 −20 fractional frequency uncertainty has been demonstrated, so fiber links do not limit the clock signal uncertainty. Efforts are underway to establish a network of fiber connection between European research institutes, including preliminary work on a 298 km link in the Netherlands between Amsterdam and Groningen [77].…”

Section: Optical Fiber Networkmentioning

confidence: 99%

“…4.3). Its long term stability is provided by a gps-disciplined rubidium clock (SRS fs ) with an intrinsic frequency stability of 10 −11 in 1 s integration time and 10 −12 in 10 000 s. This clock also serves as long term reference for all rf frequencies in the experiment and its stability has been verified to ∆ν/ν ≈ 10 −11 via an optical fiber network [77].…”

Section: Determination Of Optical Frequenciesmentioning

confidence: 99%

Spectroscopy of Trapped ¹³⁸Ba⁺ Ions for Atomic Parity Violation and Optical Clocks

Dijck

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Trapped Ba + and Ra + ions offer the possibility to test the Standard Model by performing an independent high-precision determination of the Weinberg angle (sin 2 θ W) at low momentum transfer. In such a measurement of atomic parity violation, table-top experiments complement studies of weak interaction effects at high energy in the search for new physics. The singly-charged heavy alkaline earth metal ions combine high intrinsic sensitivity with tractable atomic structure owing to their single valence electron. In addition, trapped Ba + or Ra + ions can serve as reference for an optical atomic clock that is sensitive to variation of the fine structure constant α. Determining sin 2 θ W requires localizing a single laser-cooled Ba + or Ra + ion in a standing-wave light field to a fraction of an optical wavelength. High-precision atomic theory calculations are crucial for interpreting the measurements and need experimental input. We have performed preparatory spectroscopy measurements with trapped Ba + ions and investigated experimental techniques for characterizing ion traps. We have determined the optical transition frequencies between low-lying levels of 138 Ba + with laser spectroscopy referenced to an optical frequency comb. Using a lineshape model based on eight-level optical Bloch equations, we determined the 6s 2 S 1/2-5d 2 D 3/2 transition frequency to be 146 114 384.0(0.1) MHz and the 5d 2 D 3/2-6p 2 P 1/2 transition frequency to be 461 311 878.5(0.1) MHz, obtaining for the first time sub-MHz precision on these transitions. Light shifts play an important role in the measurement of sin 2 θ W and offer a way to obtain information on (ratios of) atomic transition matrix elements. We have carried out an exploratory study of the light shift in 138 Ba + caused by an off-resonant laser tuned close to the 5d 2 D 3/2-6p 2 P 1/2 transition. The observed spectra are analyzed by combining the optical lineshapes with calculated light shifts of individual Zeeman components. Atomic state lifetimes provide a benchmark for calculations of transition amplitudes. We have measured the lifetime of the long-lived 5d 2 D 5/2 level in 138 Ba + using a technique based on quantum jumps with one to four trapped ions. We have investigated known systematic effects in detail to evaluate their influence. We measured the lifetime of the 5d 2 D 5/2 level to be 26.3(0.6) s, which is about 4σ shorter than previously published experimental results. This discrepancy needs to be clarified to ensure the reliability of atomic parity violation measurements ahead. This work contributes toward a precise determination of sin 2 θ W with trapped Ba + or Ra + ions in search of physics beyond the Standard Model.

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Effect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-division-multiplexing fiber-optic links

Cited by 22 publications

References 24 publications

Determination of transition frequencies in a singleBa+138ion

Determination of transition frequencies in a singleBa+138ion

Impact of Temperature and Relative Humidity on PMD in Directly Buried Optical Fibre Cables in Semi-Arid and Tropical Highlands in Kenya

Spectroscopy of Trapped ¹³⁸Ba⁺ Ions for Atomic Parity Violation and Optical Clocks

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