106 research outputs found
A Large Area Fiber Optic Gyroscope on multiplexed fiber network
We describe a fiber optical gyroscope based on the Sagnac effect realized on a multiplexed telecom fiber network. Our loop encloses an area of 20 km2 and coexists with Internet data traffic. This Sagnac interferometer achieves a sensitivity of about (10-8 rad/s)/sqrt(Hz), thus approaching ring laser gyroscopes without using narrow linewidth laser nor sophisticated optics. The proposed gyroscope is sensitive enough for seismic applications, opening new possibilities for this kind of optical fiber sensors
Beyond the fundamental noise limit in coherent optical fiber links
It is well known that temperature variations and acoustic noise affect
ultrastable frequency dissemination along optical fiber. Active stabilization
techniques are in general adopted to compensate for the fiber-induced phase
noise. However, despite this compensation, the ultimate link performances
remain limited by the so called delay-unsuppressed fiber noise that is related
to the propagation delay of the light in the fiber. In this paper, we
demonstrate a data post-processing approach which enables us to overcome this
limit. We implement a subtraction algorithm between the optical signal
delivered at the remote link end and the round-trip signal. In this way, a 6 dB
improvement beyond the fundamental limit imposed by delay-unsuppressed noise is
obtained. This result enhances the resolution of possible comparisons between
remote optical clocks by a factor of 2. We confirm the theoretical prediction
with experimental data obtained on a 47 km metropolitan fiber link, and propose
how to extend this method for frequency dissemination purposes as well
Synthetic dimensions and spin-orbit coupling with an optical clock transition
We demonstrate a novel way of synthesizing spin-orbit interactions in
ultracold quantum gases, based on a single-photon optical clock transition
coupling two long-lived electronic states of two-electron Yb atoms. By
mapping the electronic states onto effective sites along a synthetic
"electronic" dimension, we have engineered synthetic fermionic ladders with
tunable magnetic fluxes. We have detected the spin-orbit coupling with
fiber-link-enhanced clock spectroscopy and directly measured the emergence of
chiral edge currents, probing them as a function of the magnetic field flux.
These results open new directions for the investigation of topological states
of matter with ultracold atomic gases.Comment: Minor changes with respect to v1 (we have corrected some typos, fixed
the use of some mathematical symbols, added one reference
Linearity of a silicon carbide photodiode in the deep-UV spectral region: implications on Doppler broadening thermometry
Analysis of survival in lung transplantation: Simple diagnostic tests in a new "SELeCT" Score used as prognostic tool. Results from a single center cohort study
Robust optical frequency dissemination with a dual-polarization coherent receiver
Frequency dissemination over optical fiber links relies on measuring the phase of fiber-delivered lasers. Phase is extracted from optical beatnotes and the detection fails in case of beatnotes fading due to polarization changes, which strongly limit the reliability and robustness of the dissemination chain. We propose a new method that overcomes this issue, based on a dual-polarization coherent receiver and a dedicated signal processing that we developed on a field programmable gated array. Our method allowed analysis of polarization-induced phase noise from a theoretical and experimental point of view and endless tracking of the optical phase. This removes a major obstacle in the use of optical links for those physics experiments where long measurement times and high reliability are required
Optical frequency fiber dissemination at 10^−19 uncertainty level in Italy
We describe the realization of a coherent optical fiber link for the metrological frequency dissemination on the national scale. This infrastructure will improve the frequency references used in radio-astronomy and in atomic physics and will benefit several laboratories in Italy involved in high resolution spectroscopy, matter physics and radioastronomy. The present infrastructure will be part of a forthcoming European network of optical links. This paper describes the haul implementation, the characterization and the future applications of this backbone. © 2014 AEIT
LinkO: unâinfrastruttura in fibra ottica per confronti remoti di tempo e frequenza ad alta accuratezza
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