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Multiband fiber polygon for accurate time and coherent frequency transmission
Havliš, O. ; Vojtěch, J. ; Šlapák, M. ; Číp, Ondřej ; Čížek, Martin ; Hrabina, Jan ; Pravdová, Lenka ; Slodička, L.
The CESNET association, in cooperation with the Institute of Scientific Instruments of the Academy of Sciences of the Czech Republic (Institute of Scientific Instruments of the CAS, abbreviated ISI CAS), ČD Telematika and University Palacký in Olomouc (UPOL) Department of Optics built a multiband polygon on real optical routes . The multiband polygon is designed for two-way transmission of ultra-stable quantities, i.e. transmission of acurrate time and coherent frequency (T/F).
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SMV-2022-31: He-Ne-I2 cells
Hrabina, Jan ; Holá, Miroslava ; Lazar, Josef ; Šarlejová, Tatiana ; Šlechtický, Stanislav
The contractual research was oriented towards the development of optical frequency references intended for the frequency stabilisation of ultra-compact laser sources. These optical references were based on absorption cells filled with ultra-pure absorption gases and they allow precise locking of the lasers with the methods of laser spectroscopy. The cells will serve as the references of optical frequencies in systems of primary length standards (633 nm wavelength).
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Characterization of heating rate of laser-cooled Calcium ion in Paul trap
Čoupek, Filip ; Hrabina, Jan (referee) ; Číp, Ondřej (advisor)
This master thesis deals with the measurement of the heating rate of a single calcium ion trapped in a Paul linear trap. First, the trap in which the ion is trapped is described, followed by some of the most important effects acting on the ion. Subsequently, the various cooling techniques used to provide the best possible conditions to achieve the most accurate measurements are described. The work also includes a survey of thermometric methods and their statistical deviations to determine the heating rate of the ion, and subsequent comparisons under steady-state laboratory conditions for a particular position of the ion in the Paul trap. Experimental measurements of the heating rate of the ion are then made for its various positions in the axial direction of the trap, and the optimal position where the heating rate is lowest is found. Measurements of the ion heating rate for different frequencies of secular motion of the ion in the axial direction of the Paul trap are also included.
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Fragmentation-free ultrastable transfers through shared optical fibers
Vojtěch, J. ; Smotlacha, V. ; Havliš, O. ; Šlapák, M. ; Altmannová, L. ; Kundrát, J. ; Vohnout, R. ; Velc, R. ; Čížek, Martin ; Hrabina, Jan ; Řeřucha, Šimon ; Pravdová, Lenka ; Lazar, Josef ; Číp, Ondřej ; Kuna, Alexander ; Roztočil, J.
Fibre optics transfers of precise time and ultra-stable optical frequency are gradually becoming part of portfolio of network services of research and educational networks. These national infrastructures very often share fibres with regular data transmission, because of significant share of fibre cost rental on the Total Cost of Ownership (TCO). Situation is very similar in the Czech Republic, where there was more than 3000 km of ultra-stable transmissions within Czech e-Infrastructure, which itself runs over about 5800 km of dark fibre lines.
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Highly-coherent laser for precise optical frequencies dissemination
Pravdová, Lenka ; Čížek, Martin ; Hrabina, Jan ; Jelínek, Michal ; Řeřucha, Šimon ; Mikel, Břetislav ; Lazar, Josef ; Havliš, O. ; Altmannová, L. ; Smotlacha, V. ; Vojtěch, J. ; Velc, R. ; Číp, Ondřej
The paper presents a multipurpose laser with a very narrow spectral line, operating at a wavelength of 1540 nm and designed for cooled ions spectroscopy and the dissemination of precise optical frequencies over optical fibre links. The optical frequency of a commercial single-mode laser (NKT Photonics Koheras Basik) is spectrally narrowed to the level of several Hz using a high-quality optical resonator as an optical reference and an acousto-optic modulator as an active control element. The optical resonator is made of a low length thermal expansion coefficient material and is placed in a multi-shell vacuum chamber providing a stable operating environment. Optical frequency stabilisation uses PDH (Pound-Drewer-Hall) modulation and detection technique.
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