Long-distance frequency transfer over an urban fiber link using optical phase stabilization

Journal of the Optical Society of America B (Impact Factor: 1.81). 07/2008; DOI: 10.1364/JOSAB.25.002029
Source: arXiv

ABSTRACT We transferred the frequency of an ultra-stable laser over 86 km of urban fiber. The link is composed of two cascaded 43-km fibers connecting two laboratories, LNE-SYRTE and LPL in Paris area. In an effort to realistically demonstrate a link of 172 km without using spooled fiber extensions, we implemented a recirculation loop to double the length of the urban fiber link. The link is fed with a 1542-nm cavity stabilized fiber laser having a sub-Hz linewidth. The fiber-induced phase noise is measured and cancelled with an all fiber-based interferometer using commercial off the shelf pigtailed telecommunication components. The compensated link shows an Allan deviation of a few 10-16 at one second and a few 10-19 at 10,000 seconds.

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    ABSTRACT: We report the design and performance of a transportable laser system at 1543 nm, together with its application as the source for a demonstration of optical carrier frequency transmission over 118 km of an installed dark fiber network. The laser system is based around an optical reference cavity featuring an elastic mounting that bonds the cavity to its support, enabling the cavity to be transported without additional clamping. The cavity exhibits passive fractional frequency insensitivity to vibration along the optical axis of 2.0×10−11 m−1 s2. With active fiber noise cancellation, the optical carrier frequency transmission achieves a fractional frequency instability, measured at the user end, of 2.6×10−16 at 1 s, averaging down to below 3×10−18 after 20,000 s. The fractional frequency accuracy of the transfer is better than 3×10−18. This level of performance is sufficient for comparison of state-of-the-art optical frequency standards and is achieved in an urban fiber environment.
    Applied Optics 12/2014; 53(35). DOI:10.1364/AO.53.008157 · 1.69 Impact Factor
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    ABSTRACT: We theoretically and experimentally investigate relevant noise processes arising in optical fiber links, which fundamentally limit their relative stability. We derive the unsuppressed delay noise for three configurations of optical links: two-way method, Sagnac interferometry, and actively compensated link, respectively designed for frequency comparison, rotation sensing, and frequency transfer. We also consider an alternative two-way setup allowing real-time frequency comparison and demonstrate its effectiveness on a proof-of-principle experiment with a 25-km fiber spool. For these three configurations, we analyze the noise arising from uncommon fiber paths in the interferometric ensemble and design optimized interferometers. We demonstrate interferometers with very low temperature sensitivity of respectively -2.2, -0.03 and 1 fs/K. We use one of these optimized interferometers on a long haul compensated fiber link of 540km. We obtain a relative frequency stability of 3E-20 after 10,000 s of integration time.
    Journal of the Optical Society of America B 12/2014; 32(5). DOI:10.1364/JOSAB.32.000787 · 1.81 Impact Factor
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    ABSTRACT: Along with the rapid development of the optical clocks, optical frequency transfer via communication fibers has shown much higher precision than the conventional methods. In this paper, we report the progress on the optical frequency transfer via communication fibers at NTSC. Over a 71-km spooled fiber, the optical frequency transfer with a residual instability (Allan deviation) of 5.4E-15 at 1s and 5.6E-18 at 104s is demonstrated. Furthermore, for a measurement bandwidth of 100 Hz, the instability is 1.2E-15 at one second and 1.4E-18 at 104 s. This transfer instability is fundamentally limited by the fiber length. The Allan deviation curves fall as τ-1 for short times, which is consistent with the fact that the transferred signal is dominated by white phase noise. This experimental achievement provides the foundation for the upcoming optical transfer experiment over a 300-km urban communication fiber link.
    2014 IEEE International Frequency Control Symposium (FCS); 05/2014

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