Generation of an ultrastable 578 nm laser for Yb lattice clock

In this paper we described the development and the characterization of a 578 nm laser source to be the clock laser for an Ytterbium Lattice Optical clock. Two independent laser sources have been realized and the characterization of the stability with a beat note technique is presente

Absolute frequency measurement of the 1S0 - 3P0 transition of 171Yb

We report the absolute frequency measurement of the unperturbed transition 1S0 - 3P0 at 578 nm in 171Yb realized in an optical lattice frequency standard. The absolute frequency is measured 518 295 836 590 863.55(28) Hz relative to a cryogenic caesium fountain with a fractional uncertainty of 5.4x10-16 . This value is in agreement with the ytterbium frequency recommended as a secondary representation of the second in the International System of Units.Comment: This is an author-created, un-copyedited version of an article accepted for publication/published in Metrologia. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/1681-7575/aa4e62. It is published under a CC BY licenc

Frequency transfer via a two-way optical phase comparison on a multiplexed fiber network

We performed a two-way remote optical phase comparison on optical fiber. Two optical frequency signals were launched in opposite directions in an optical fiber and their phases were simultaneously measured at the other end. In this technique, the fiber noise was passively cancelled, and we compared two optical frequencies at the ultimate 1E-21 stability level. The experiment was performed on a 47 km fiber that is part of the metropolitan network for Internet traffic. The technique relies on the synchronous measurement of the optical phases at the two ends of the link, that is made possible by the use of digital electronics. This scheme offers several advantages with respect to active noise cancellation, and can be upgraded to perform more complex tasks

Realization of an Ultrastable 578-nm Laser for an Yb Lattice Clock

In this paper, we describe the development of an ultrastable laser source at 578 nm, realized using frequency sum generation. This source will be used to excite the clock transition 1S0-3P0 in an ytterbium optical lattice clock experiment. Two independent ultrastable lasers have been realized, and the laser frequency noise and stability have been characterize

Frequency noise characterization of diode lasers for vapor-cell clock applications

The knowledge of the frequency noise spectrum of a diode laser is of interest in several high-resolution experiments. Specifically, in laser-pumped vapor-cell clocks, it is well-established that the laser frequency noise plays a role in affecting clock performances. It is then relevant to characterize the frequency noise of a diode laser since such measurements are rarely found in the literature and hardly ever provided by vendors. In this article, we describe a technique based on a frequency-to-voltage (f/V) converter that transforms the laser frequency fluctuations into voltage fluctuations. In this way, it is possible to characterize the laser frequency noise power spectral density (PSD) in a wide range of Fourier frequencies, as required in cell clock applications

Planar-Waveguide External Cavity Laser Stabilization for an Optical Link with 1E-19 Frequency Stability

We stabilized the frequency of a compact planar-waveguide external cavity laser (ECL) on a Fabry-P\'erot cavity (FPC) through a Pound-Drever-Hall scheme. The residual frequency stability of the ECL is 1E-14, comparable to the stability achievable with a fiber laser (FL) locked to a FPC through the same scheme. We set up an optical link of 100 km, based on fiber spools, that reaches 1E-19 relative stability, and we show that its performances using the ECL or FL are comparable. Thus ECLs could serve as an excellent replacement for FLs in optical links where cost-effectiveness and robustness are important considerations

Absolute frequency measurement of a Yb optical clock at the limit of the Cs fountain

We present the new absolute frequency measurement of ytterbium (171Yb) obtained at INRiM with the optical lattice clock IT-Yb1 against the cryogenic caesium (133Cs) fountain IT-CsF2, evaluated through a measurement campaign that lasted 14 months. Measurements are performed by either using a hydrogen maser as a transfer oscillator or by synthesizing a low-noise microwave for Cs interrogation using an optical frequency comb. The frequency of the 171Yb unperturbed clock transition ${^1}$S$_0\rightarrow {^3}$P0 results to be 518 295 836 590 863.44(14) Hz, with a total fractional uncertainty of $2.7 \times 10^{-16}$ that is limited by the uncertainty of IT-CsF2. Our measurement is in agreement with the Yb frequency recommended by the Consultative Committee for Time and Frequency. This result confirms the reliability of Yb as a secondary representation of the second and is relevant to the process of redefining the second in the International System of Units on an optical transition