Publications (21)17.82 Total impact
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Article: Phase-coherent frequency comparison of optical clocks using a telecommunication fiber link.
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ABSTRACT: We have explored the performance of 2 "dark fibers" of a commercial telecommunication fiber link for a remote comparison of optical clocks. These fibers establish a network in Germany that will eventually link optical frequency standards at PTB with those at the Institute of Quantum Optics (IQ) at the Leibniz University of Hanover, and the Max Planck Institutes in Erlangen (MPL) and Garching (MPQ). We demonstrate for the first time that within several minutes a phase coherent comparison of clock lasers at the few 10(-15) level can also be accomplished when the lasers are more than 100 km apart. Based on the performance of the fiber link to the IQ, we estimate the expected stability for the link from PTB to MPQ via MPL that bridges a distance of approximately 900 km.IEEE transactions on ultrasonics, ferroelectrics, and frequency control 01/2010; 57(1):175-81. · 1.80 Impact Factor -
Article: Long-distance remote comparison of ultrastable optical frequencies with 1e-15 instability in fractions of a second
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ABSTRACT: We demonstrate a fully optical, long-distance remote comparison of independent ultrastable optical frequencies reaching a short term stability that is superior to any reported remote comparison of optical frequencies. We use two ultrastable lasers, which are separated by a geographical distance of more than 50 km, and compare them via a 73 km long phase-stabilized fiber in a commercial telecommunication network. The remote characterization spans more than one optical octave and reaches a fractional frequency instability between the independent ultrastable laser systems of 3e-15 in 0.1 s. The achieved performance at 100 ms represents an improvement by one order of magnitude to any previously reported remote comparison of optical frequencies and enables future remote dissemination of the stability of 100 mHz linewidth lasers within seconds. Comment: 7 pages, 4 figures08/2009; -
Article: Phase- coherent comparison of two optical frequency standards over 146 km using a telecommunication fiber link
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ABSTRACT: We have explored the performance of two "dark fibers" of a commercial telecommunication fiber link for a remote comparison of optical clocks. The two fibers, linking the Leibniz University of Hanover (LUH) with the Physi-kalisch-Technische Bundesanstalt (PTB) in Braunschweig, are connected in Hanover to form a total fiber length of 146 km. At PTB the performance of an optical frequency standard operating at 456 THz was imprinted to a cw trans-fer laser at 194 THz, and its frequency was transmitted over the fiber. In order to detect and compensate phase noise related to the optical fiber link we have built a low-noise optical fiber interferometer and investigated noise sources that affect the overall performance of the optical link. The frequency stability at the remote end has been measured using the clock laser of PTB's Yb+ frequency standard operating at 344 THz. We show that the frequency of a frequency-stabilized fiber laser can be transmitted over a total fiber length of 146 km with a relative frequency uncertainty below 1E-19, and short term frequency instability given by the fractional Allan deviation of sy(t)=3.3E-15/(t/s).06/2009; -
Article: Interrogation Laser for a Strontium Lattice Clock.
IEEE T. Instrumentation and Measurement. 01/2009; 58:1252-1257. -
Article: The Stability of an Optical Clock Laser Transferred to the Interrogation Oscillator for a Cs Fountain.
IEEE T. Instrumentation and Measurement. 01/2009; 58:1258-1262. -
Article: Optical frequency synthesis and measurement using fibre-based femtosecond lasers
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ABSTRACT: We report the synthesis and measurement of an ultra-precise and extremely stable optical frequency in the telecommunications window around 1543 nm. Using a fibre-based femtosecond frequency comb we have phase-stabilised a fibre laser at 194 THz to an optical frequency standard at 344 THz, thus transferring the properties of the optical frequency standard to another spectral region. Relative to the optical frequency standard, the synthesised frequency at 194 THz is determined to within 1 mHz and its fractional frequency instability is measured to be less than 2*10^{-15} at 1 s, reaching 5*10^{-18} after 8000 s. We also measured the synthesised frequency against a caesium fountain clock: here the frequency comparison itself contributes less than 4 mHz (2*10^{-17}) to the uncertainty. Our results confirm the suitability of fibre based frequency comb technology for precision measurements and frequency synthesis, and enable long-distance comparison of optical clocks by using optical fibres to transmit the frequency information.09/2008; -
Article: Absolute frequency measurement of the magnesium intercombination transition $^1S_0 \to ^3P_1$
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ABSTRACT: We report on a frequency measurement of the $(3s^2)^1S_0\to(3s3p)^3P_1$ clock transition of $^{24}$Mg on a thermal atomic beam. The intercombination transition has been referenced to a portable primary Cs frequency standard with the help of a femtosecond fiber laser frequency comb. The achieved uncertainty is $2.5\times10^{-12}$ which corresponds to an increase in accuracy of six orders of magnitude compared to previous results. The measured frequency value permits the calculation of several other optical transitions from $^1S_0$ to the $^3P_J$-level system for $^{24}$Mg, $^{25}$Mg and $^{26}$Mg. We describe in detail the components of our optical frequency standard like the stabilized spectroscopy laser, the atomic beam apparatus used for Ramsey-Bord\'e interferometry and the frequency comb generator and discuss the uncertainty contributions to our measurement including the first and second order Doppler effect. An upper limit of $3\times10^{-13}$ in one second for the short term instability of our optical frequency standard was determined by comparison with a GPS disciplined quartz oscillator.12/2007; -
Article: Absolute frequency measurement of the magnesium intercombination transition^{1} S_ {0}→^{3} P_ {1}
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ABSTRACT: We report on a frequency measurement of the (3s 2) 1 S0 → (3s3p) 3 P1 clock transition of 24 Mg on a thermal atomic beam. The intercombination transition has been referenced to a portable primary Cs frequency standard with the help of a femtosecond fiber laser frequency comb. The achieved uncertainty is 2.5 × 10 −12 which corresponds to an increase in accuracy of six orders of magnitude compared to previous results. The measured frequency value permits the calculation of several other optical transitions from 1 S0 to the 3 PJ -level system for 24 Mg, 25 Mg and 26 Mg. We describe in detail the components of our optical frequency standard like the stabilized spectroscopy laser, the atomic beam apparatus used for Ramsey-Bordé interferometry and the frequency comb generator and discuss the uncertainty contributions to our measurement including the first and second order Doppler effect. An upper limit of 3 × 10 −13 in one second for the short term instability of our optical frequency standard was determined by comparison with a GPS disciplined quartz oscillator.12/2007; -
Article: An Optical Lattice Clock with Spin-polarized 87Sr Atoms
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ABSTRACT: We present a new evaluation of an 87Sr optical lattice clock using spin polarized atoms. The frequency of the 1S0-3P0 clock transition is found to be 429 228 004 229 873.6 Hz with a fractional accuracy of 2.6 10^{-15}, a value that is comparable to the frequency difference between the various primary standards throughout the world. This measurement is in excellent agreement with a previous one of similar accuracy.The European Physical Journal D 09/2007; · 1.48 Impact Factor -
Article: net.researchgate.refind.jaxb.schema.dblp.Sup@34c8537b
IEEE T. Instrumentation and Measurement. 01/2007; 56:601-604. -
Article: Long term comparison of two fiber based frequency comb systems.
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ABSTRACT: Mode-locked erbium-doped fiber lasers are ideal comb generators for optical frequency metrology. We compare two fiber frequency combs by measuring an optical frequency independently with both combs and comparing their results. The two frequency measurements agree within 6x10-16. This is to our knowledge the first direct comparison between two fiber based frequency combs.Optics Express 03/2005; 13(3):904-9. · 3.59 Impact Factor -
Article: Optical frequency measurements using fs-comb generators.
IEEE T. Instrumentation and Measurement. 01/2005; 54:750-753. -
Article: Phase-locked two-branch erbium-doped fiber laser system for long-term precision measurements of optical frequencies.
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ABSTRACT: We present a highly versatile approach to the application of femtosecond Er:fiber lasers in optical frequency metrology. Our concept relies on the implementation of two parallel amplifiers, seeded by a single master oscillator. With the comb spacing locked to a frequency of 100 MHz, we apply the output from the first amplifier to generate a feedback signal to achieve a simultaneous phase-lock for the comb offset frequency. The output of the independently configurable second amplifier enables precision frequency measurements in the visible and near-infrared. As a first application, we continuously measure the absolute frequency of a resonator-stabilized diode laser over a period of 88 hours.Optics Express 12/2004; 12(24):5872-80. · 3.59 Impact Factor -
Chapter: An Optical Frequency Standardwith Cold and Ultra-cold Calcium Atoms
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ABSTRACT: An optical frequency standard ( = 657nm) based on cold and ultra-cold neutral Ca atoms is operated at PTB and its frequency has been measured with respect to the Cs hyperfine transition over eight years. Since measurements of this kind can be used to detect possible variations of fundamental constants, we present the status of the Ca optical frequency standard with emphasis to the systematic contributions to the frequency that might mimick variations of the ratio of the Ca and Cs frequency. We show that the uncertainty resulting from the residual velocity of the cold atoms at 3 mK limits the fractional uncertainty to 2 10–14. Applying a novel method for producing ultra-cold atoms (T 10 K) a first frequency measurement has been performed where the contributions from the residual velocity now become insignificant at that level of uncertainty. A residual fractional uncertainty below 10–15 is expected for the near future.08/2004: pages 229-244; -
Article: Optical frequency standard based on cold Ca atoms.
IEEE T. Instrumentation and Measurement. 01/2003; 52:250-254. -
Article: Ultraprecise measurement of optical frequency ratios.
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ABSTRACT: We developed a novel technique for frequency measurement and synthesis, based on the operation of a femtosecond comb generator as transfer oscillator. The technique can be used to measure frequency ratios of any optical signals throughout the visible and near-infrared part of the spectrum. Relative uncertainties of 10(-18) for averaging times of 100 s are possible. Using a Nd:YAG laser in combination with a nonlinear crystal we measured the frequency ratio of the second harmonic nu(SH) at 532 nm to the fundamental nu(0) at 1064 nm, nu(SH)/nu(0) = 2.000 000 000 000 000 001x (1 +/- 7x10(-19)).Physical Review Letters 03/2002; 88(7):073601. · 7.37 Impact Factor -
Article: Ultra-precise measurement of optical frequency ratios
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ABSTRACT: We developed a novel technique for frequency measurement and synthesis, based on the operation of a femtosecond comb generator as transfer oscillator. The technique can be used to measure frequency ratios of any optical signals throughout the visible and near-infrared part of the spectrum. Relative uncertainties of $10^{-18}$ for averaging times of 100 s are possible. Using a Nd:YAG laser in combination with a nonlinear crystal we measured the frequency ratio of the second harmonic $\nu_{SH}$ at 532 nm to the fundamental $\nu_0$ at 1064 nm, $\nu_{SH}/\nu_0 = 2.000 000 000 000 000 001 \times (1 \pm 7 \times 10^{-19})$. Comment: 4 pages, 4 figures08/2001; -
Article: Frequency measurement of visible light
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ABSTRACT: Frequency measurements of the Ca optical frequency standard based on an ensemble of cold atoms are described. They represent the first phase-coherent frequency measurement of visible radiation directly related to the primary standard of time and frequency. The optical frequency was provided by the Ca intercombination line (1S0−3P1). Sub-kHz resolution close to the natural linewidth of the optical clock transition was observed by time-separated pulsed excitation. The measured frequency is νCa = 455 986 240 494.13 kHz with a total relative uncertainty of 2.5⋅10−13. © 1999 American Institute of Physics.AIP Conference Proceedings. 01/1999; 457(1):348-356. -
Article: Fiber-based Femtosecond Lasers for Optical Clocks
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ABSTRACT: The use of femtosecond laser combs based on modelocked fiber lasers is discussed for their applications as optical clockworks in optical clocks with unprecedented accuracy and stability, to compare optical clocks with very different optical frequencies without limitation by the comparison process, to generate highly stable microwave signals from frequency stabilized lasers, or to transmit optical frequencies over telecommunication fiber networks. -
Article: Phase-locked two-branch erbium-doped fiber laser system for long-term precision measurements of optical frequencies
Opt. Express. 12(24):5872-5880.
Top co-authors
Top Journals
Institutions
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1999–2010
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Physikalisch-Technische Bundesanstalt
Braunschweig, Lower Saxony, Germany
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2007
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Université Paul Sabatier - Toulouse 3
Toulouse, Midi-Pyrenees, France
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