We theoretically and experimentally investigate relevant noise processes arising in optical fiber links, which fundamentally limit their relative stability. derive the unsuppressed delay for three configurations of links: two-way method, Sagnac interferometry, actively compensated link, respectively designed frequency comparison, rotation sensing, transfer. also consider an alternative setup allowing real-time comparison demonstrate its effectiveness on a proof-of-principle experiment with...

Advanced satellite-based frequency transfers by two-way carrier-phase (TWCP) and integer precise point positioning have been performed between the National Institute of Information Communications Technology Korea Research Standards Science. We confirm that disagreement them is less than at an averaging time several days. In addition, overseas ratio measurement Sr Yb optical lattice clocks was directly TWCP. achieved uncertainty mid-10-16 level after a total 12 h. The consistent with recently...

We measured the absolute frequency of 1S0–3P0 transition 171Yb atom confined in a one-dimensional optical lattice relative to SI second. The determined was 518 295 836 590 863.38(57) Hz. uncertainty reduced by factor 14 compared with our previously reported value 2013 due significant improvements decreasing systematic uncertainties. This result is expected contribute determination new recommended for secondary representations

We report a measurement of the absolute frequency 1S0-3P0 transition in 171Yb optical lattice clock at KRISS (KRISS-Yb1) for 14 months, which was referenced to SI second by primary and secondary standards worldwide via TAI (International Atomic Time). The determined is 518 295 836 590 863.75(14) Hz with relative uncertainty 2.6x10^-16, agrees well other reports. This result expected contribute future update CIPM recommendation standards.

A telecommunication optical fiber can stabilize the comb-line frequencies of ultrashort pulse lasers to quadrillionth level.

578-nm yellow light with an output power of more than 10 mW was obtained using a waveguide periodically-poled-lithium-niobate crystal as nonlinear medium for second harmonic generation, which is the highest at this wavelength generation solid state laser source without enhancement ring cavity, to our knowledge. To achieve result we made high 1156-nm external-cavity diode maximum 250 mW. This system expected be excellent alternative sum-frequency advantage simplicity and cost-effectiveness,...

We present a hybrid fiber link combining effective optical frequency transfer and evaluation of performances with self-synchronized two-way comparison. It enables us to detect the round-trip noise each forward backward one-way noises simultaneously. The various signals acquired this setup allow study quantitatively several properties links. check reciprocity accumulated forth back over bi-directional level 3.1(±3.9) × 10-20 based on 160000s continuous data. also analyze correlation between...

The weighted mean is widely used in combining data sets of experimental measurements with a weight proportional to the value number divided by sample variance conventional method. However, this standard procedure not appropriate for obtaining frequency phase-stabilized signal white phase noise, since are autocorrelated. autocorrelation obtained case noise and new weighting method proposed. Using this, uncertainty associated given. effect counter dead-time also discussed.

We have measured the absolute frequency of excited state transition 5P(3/2)-4D(5/2) in a (87)Rb atom with femtosecond comb, utilizing recently developed spectroscopic technique double resonance optical pumping method. The energy level 4D(5/2) is determined by measuring 5S(1/2)-5P(3/2) simultaneously. hyperfine structure constants are obtained using frequency. magnetic dipole constant, A, to be (-16.747+/-0.010) MHz an uncertainty reduced 60-fold compared previous result. electric quadrupole...

The frequency of a laser diode is stabilized onto the line centers double-resonance optical pumping spectra, and absolute frequencies hyperfine-structure components $5{P}_{3/2}\text{\ensuremath{-}}4{D}_{3/2}$ excited-state transition for two isotopes $^{87}\text{R}\text{b}$ $^{85}\text{R}\text{b}$ atoms are measured using fiber femtosecond comb system. $4{D}_{3/2}$ state constants Rb determined by utilizing ratio from accurately values other states rubidium. magnetic-dipole $A$ to be...

We report the absolute frequency values of all (ten) hyperfine transitions $5{P}_{3/2}\ensuremath{-}4{D}_{5/2}$ and $5{P}_{3/2}\ensuremath{-}4{D}_{3/2}$ for $^{87}\mathrm{Rb}$ $^{85}\mathrm{Rb}$ atoms via use an optical comb by measuring a laser diode stabilized onto line centers double-resonance pumping spectra. Here we on frequencies two...

A stable single-frequency fiber ring laser is proposed that operates in a single mode for more than an hour by incorporating unpumped erbium-doped (EDF) as saturable absorber filter and optimizing the length of EDF used gain medium. This can be continuously tuned to 25-GHz spacing precisely matches ITU-T grids temperature control etalon filter. had signal-to-source spontaneous emission ratio higher 70 dB, lasing frequencies 361 channels was matched with excellent flatness. Frequency offset...

Radiative decay from the excited ${}^{1}\phantom{\rule{-0.16em}{0ex}}{P}_{1}$ state to metastable ${}^{3}\phantom{\rule{-0.16em}{0ex}}{P}_{2}$ and ${}^{3}\phantom{\rule{-0.16em}{0ex}}{P}_{0}$ states is expected limit attainable trapped atomic population in a magneto-optic trap of ytterbium (Yb) atoms. In experiments we have carried out with optical repumping ${}^{3}\phantom{\rule{-0.16em}{0ex}}{P}_{0,2}$ ${}^{3}\phantom{\rule{-0.16em}{0ex}}{P}_{1}$, observe an enhanced yield atoms state. The...

The linewidth of a distributed-feedback (DFB) diode laser at 1156 nm, which free-running was 3 MHz, reduced to 15 kHz using an all-fiber interferometer with 5-m-long path imbalance. Optical power loss and bandwidth limitation were negligible this short optical fiber patch cord. This result achieved without acoustic vibration isolations, the frequency lock could be maintained over weeks. In addition its simplicity, compactness, robustness, cost-effectiveness, technique can applied any...

We analyze both the s- and p-wave collision induced frequency shifts propose an over-π pulse scheme to cancel in optical lattice clocks interrogated by a Rabi pulse. The collisional are analytically solved as function of area inhomogeneity frequencies. Experimentally measured Yb clock good agreement with analytical calculations. Based on our analysis, combined small below 0.1 allows fractional uncertainty level 10−18 Sr canceling shift.

We study threshold features of a Brillouin-shifted Stokes comb generated in distributed fiber Raman amplifier. When the input power Brillouin pump is linearly increased high gain, first wave grows exponentially at much lower and then experiences an appreciable decrease vicinity comb's threshold. This reduction Stokes, which we did not see mentioned previous reports, was caused by transfer to higher-order lines initiated generation. Moreover, effects pumping direction on are investigated.

This study demonstrates 578 nm yellow light generation with a narrow linewidth using waveguide periodically poled lithium niboate (PPLN) and an optical injection-locked diode laser. The frequency of external cavity laser used as master operating at 1156 in injection-locking mode was locked into high-finesse the Pound-Drever-Hall technique, which results reduction estimated to be approximately 1.6 kHz. In effort amplify power, distributed feed-back phase-locked by technique. A PPLN for second...

Abstract Relativistic redshift correction should be accurately considered in frequency comparisons between standards. In this study, we evaluated the relativistic at Korea Research Institute of Standards and Science (KRISS) using three different methods, depending on whether approach was traditional or modern geopotential model global local. The results methods agreed well with one another, height an Yb optical lattice clock (KRISS-Yb1) determined to 75.15 m uncertainty 0.04 respect...

We obtain a heterodyne beat signal between an iodine-stabilized He-Ne laser at 633 nm and low power comb mode of optical frequency synthesizer with enhanced signal-to-noise ratio (SNR) up to approximately 35 dB. This is accomplished by the adoption fiber coupler reduction shot noise induced adjacent modes. SNR improved more than 15 dB compared that conventional methods. measure absolute mentioned above directly utilizing SNR. A quantitative analysis some information on experimental criteria...

The long-term carrier-envelope phase (CEP) coherence of a femtosecond laser with same pulse-to-pulse CEP value, obtained using the direct locking method, is demonstrated by employing quasi-common-path interferometer (QPI). For evaluation stability, noise properties stabilized QPI are compared those Mach-Zehnder f-2f interferometer, for which power spectral density and Allan deviation were calculated from beat signals interferometers. With improved coherent signal an accumulated well below 1...

Abstract An ensemble time, which is indicated by TA ( temps atomique , in French), was generated every minute combining four active hydrogen masers with the reduced Kalman filter (Kred) algorithm. The frequency averaged over 12 h and then mean steered to primary secondary standards developed KRISS a micro-phase stepper (MPS). physically realized called time (KET). We investigated frequency-state estimate outputted from Kred algorithm control signal applied MPS, according abnormal temperature...

In this paper, we report on the implementation and stability analysis of a drift-compensated frequency synthesizer from cryogenic sapphire oscillator (CSO) designed for Cs/Rb atomic fountain clock. The has two microwave outputs 7 9 GHz Rb Cs atom interrogation, respectively. short-term these signals, measured using an optical comb locked to ultrastable laser, is better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math...