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Uncertainty of a frequency comparison with distributed dead time and measurement interval offset
Yu, Dai-Hyuk,Weiss, Marc,Parker, Thomas E BUREAU INTERNATIONAL DES POIDS ET MESURES 2007 METROLOGIA -BERLIN- Vol.44 No.1
<P>A theory is presented for estimating the uncertainty of a frequency comparison in the presence of distributed dead time or measurement interval offset using an extension of the method of Douglas and Boulanger (1997 <I>Proc. 11th European Frequency and Time Forum</I> pp 345–9). The uncertainties due to the distributed dead time and lumped dead time with mixed power law noise type are calculated and compared. It is shown that the use of distributed measurements of frequencies can greatly reduce the uncertainty as compared with that of lumped measurements. When a measurement interval offset is present, two different methods are possible for the frequency estimation and uncertainty evaluation. We compare and discuss the different results for the different methods.</P>
Park, Chang Yong,Yu, Dai-Hyuk,Lee, Won-Kyu,Park, Sang Eon,Kim, Eok Bong,Lee, Sun Kyung,Cho, Jun Woo,Yoon, Tai Hyun,Mun, Jongchul,Park, Sung Jong,Kwon, Taeg Yong,Lee, Sang-Bum Springer-Verlag 2013 METROLOGIA -BERLIN- Vol.50 No.2
<P>We measured the absolute frequency of the optical clock transition <SUP>1</SUP>S<SUB>0</SUB>(<I>F</I> = 1/2)–<SUP>3</SUP>P<SUB>0</SUB>(<I>F</I> = 1/2) of <SUP>171</SUP>Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 863.5(8.1) Hz. The frequency was measured against Terrestrial Time (TT; the SI second on the geoid) using an optical frequency comb of which the frequency was phase-locked to an H-maser as a flywheel oscillator traceable to TT. The magic wavelength was also measured as 394 798.48(79) GHz. The results are in good agreement with two previous measurements of other institutes within the specified uncertainty of this work.</P>
Lee, Won-Kyu,Park, Chang Yong,Yu, Dai-Hyuk,Park, Sang Eon,Lee, Sang-Bum,Kwon, Taeg Yong Optical Society of America 2011 Optics express Vol.19 No.18
<P>578-nm yellow light with an output power of more than 10 mW was obtained using a waveguide periodically-poled-lithium-niobate crystal as a nonlinear medium for second harmonic generation, which is the highest output power at this wavelength using second harmonic generation of a solid state laser source without an enhancement ring cavity, to our knowledge. To achieve this result we made a high power 1156-nm external-cavity diode laser with the maximum output power of more than 250 mW. This system is expected to be an excellent alternative to the system using the sum-frequency generation with the advantage of simplicity and cost-effectiveness, and will be used as a clock laser of the ytterbium optical lattice clock with robust and reliable operation.</P>
Kim, Eok B.,Lee, Jae-hwan,Trung, Luu Tran,Lee, Wong-Kyu,Yu, Dai-Hyuk,Ryu, Han Young,Nam, Chang Hee,Park, Chang Yong The Optical Society 2009 Optics express Vol.17 No.23
<P>We developed an optical frequency synthesizer (OFS) with the carrier-envelope-offset frequency locked to 0 Hz achieved using the 'direct locking method.' This method differs from a conventional phaselock method in that the interference signal from a self-referencing f-2f interferometer is directly fed back to the carrier-envelope-phase control of a femtosecond laser in the time domain. A comparison of the optical frequency of the new OFS to that of a conventional OFS stabilized by a phase-lock method showed that the frequency comb of the new OFS was not different to that of the conventional OFS within an uncertainty of 5.68x10(-16). As a practical application of this OFS, we measured the absolute frequency of an acetylene-stabilized diode laser serving as an optical frequency standard in optical communications.</P>