National Repository of Grey Literature 4 records found  Search took 0.00 seconds. 
Stable optical frequency transfer between ISI and CESNET workplaces
Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Jelínek, Michal ; Hrabina, Jan ; Řeřucha, Šimon ; Mikel, Břetislav ; Lazar, Josef ; Číp, Ondřej ; Smotlacha, V. ; Havliš, O. ; Vojtěch, J.
The contribution reports on the current state of a 306km long experimental line for transfering stable optical frequency from a telecommunication band laser standard between ISI CAS (Brno) and CESNET (Prague). The bidirectional link uses a telecommunication fiber with a dedicated DWDM window of 1540-1546 nm.1540-1546 nm. In the Czech rep. this technology can be utilized currently in two fields: remote comparisons of optical frequency standards and remote callibration of instruments (optical spectral analyzers) in industrial applications that do not allow transporting the device to a specialized laboratory. The stability of the optical frequency transfer was evaluated. A long-term measurement of transport delay was conducted. \n
Distribution of the accurate optical frequency and time via photonic networks in the Czech Republic
Číp, Ondřej ; Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Řeřucha, Šimon ; Hrabina, Jan ; Lešundák, Adam ; Mikel, Břetislav ; Lazar, Josef ; Vojtěch, J. ; Smotlacha, V.
To verify the stability of the frequency of optical clock an intensive research in the transmission of stable frequency via optical fibers is in progress for many years. Interconnection of large cities and metropolitan networks with optical fiber running DWDM allowing to transfer many optical signals in parallel over one fiber at the same time contributes significantly to troubleshoot the problem. Between nodes of ISI Brno and the main center of CESNET there are several dedicated bi-directional channels through the DWDM technology. The first tests are ongoing with the transfer of accurate time, which are using the possibility of bi-directional communication over a single fiber, thus the phase delay including Doppler shift are reflected on the two signals as well. From periodic measurements can subsequently be evaluated daily, weekly and seasonal fluctuations of the delay and after deduction of such data from the measured data a mutual stability of used time normal can be determined. The second technique is a full compensation of phase of the laser wave through active control of phase changes of the wave during its transmission from the ISI to the node of CESNET. At present, a characterization of the behavior of individual system elements, including their commissioning is in progress.
Time and frequency transfer in all-optical network
Smotlacha, V. ; Kuna, Alexander
This paper describes usage of all-optical network for time metrology application - Time and frequency transfer between two geographically distant sites. Although several approaches exist, there is no production implementation yet. Our method is based on newly developed adapters utilizing channels in a DWDM (Dense Wavelength-Division Multiplexing) network. We present results of tests performed in real production all-optical network including the time transfer between atomic clocks in Prague and Vienna over more than 500 km long optical path
Optical infrastructure for time and frequency transfer
Smotlacha, V. ; Vojtěch, J. ; Kuna, Alexander
The paper describes optical infrastructure for time and frequency transfer in the Czech republic. The infrastructure is heterogeneous and utilises resources of the Czech academic optical network. It allows to interconnect Cesium standards in distant sites with the national time and frequency laboratory and to distribute accurate time and stable frequency. We also present results and compare them with other methods of time transfer

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2 Smotlacha, V.
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