Phase Coherent Vacuum-Ultraviolet to Radio Frequency Comparison with a Mode-Locked Laser

Reichert, J.; Niering, M.; Holzwarth, Ronald; Weitz, Martin; Udem, Th.; Hänsch, Theodor W.

doi:10.1103/physrevlett.84.3232

Cited by 214 publications

(91 citation statements)

References 21 publications

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“…In doing so, they have created a clockwork able to count optical field oscillations of more than 10 15 cycles per second. Their method dramatically simplified and improved the instrumentation for high-precision optical spectroscopy and opened the door for the development of next-generation clocks based on optical quantum transitions [4][5][6][7][8][9][10][11][12][13][14][15].…”

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confidence: 99%

From quantum transitions to electronic motions

Krausz

2016

Appl. Phys. B

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The frequency of microwave to optical radiation absorbed or emitted upon electronic transitions between quantum states of atoms has been the most accurately measured physical quantity to date, allowing to put the laws of quantum physics to a test, determine fundamental constants (and their possible drifts), and define the standards for time and length [1]. Precision spectroscopy underlying these applications relies on excited quantum states the energy of which (with respect to the ground state) is precisely defined. Heisenberg's uncertainty principle dictates that such states decay on very long timescales (by atomic standards). Accurate measurement of this energy requires highly stationary sinusoidal waves consisting of trillions to quadrillions of identical cycles.By sharp contrast, wavepackets formed by the superposition of stationary quantum states evolve on ultrafast timescales. Nuclear wavepacket motions, in terms of which quantum mechanics describes molecular dynamics of any kind, occur on a timescale of several to several hundred femtoseconds (1 fs = 10 −15 s), see Ref.[2], whereas electronic wavepacket dynamics underlying any dynamic change of electronic structure unfolds over tens to thousands of attoseconds (1 as = 10 −18 s), see Ref.[3]. Observing and controlling dynamic changes of molecular and electronic structure in real time therefore call for femtosecond-and attosecond-duration pulses and femtosecond-and attosecond-varying forces, respectively.From these considerations, it appears plausible that measuring quantum transitions and capturing dynamics require very different forms of radiation, with seemingly little room for any synergies. Hence, not very surprisingly, the fields of precision laser spectroscopy and ultrafast laser science evolved independently over decades with little interaction or even communication between the respective scientific communities. This state of affairs changed Abstract Laser spectroscopy and chromoscopy permit precision measurement of quantum transitions and captures atomic-scale dynamics, respectively. Frequency-and time-domain metrology ranks among the supreme laser disciplines in fundamental science. For decades, these fields evolved independently, without interaction and synergy between them. This has changed profoundly with controlling the position of the equidistant frequency spikes of a mode-locked laser oscillator. By the self-referencing technique invented by Theodor Hänsch, the comb can be coherently linked to microwaves and used for precision measurements of energy differences between quantum states. The resultant optical frequency synthesis has revolutionized precision spectroscopy. Locking the comb lines to the resonator round-trip frequency by the same approach has given rise to laser pulses with controlled field oscillations. This article reviews, from a personal perspective, how the bridge between frequency-and time-resolved metrology emerged on the turn of the millennium and how synthesized severalcycle laser fields have been instrumental in establish...

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confidence: 99%

From quantum transitions to electronic motions

Krausz

2016

Appl. Phys. B

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“…The principle of frequency measurements using a femtosecond laser comb has been widely described [5,6,12], and the specific technique used in this experiment was initially employed in the measurement of an OsO 4 frequency, as recently published in detail [13]. A mode-locked Ti:Sa laser produces a train of fs pulses.…”

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confidence: 99%

“…This gives a long-term stability and frequency reproducibility limited by the performance of the current electronics, various optical links and, possibly, the reference maser. The fs technology is necessarily operated in a new area of precision, comparable with the best currently in use [5,6]. Figure 1 gives a block outline of the entire experiment.…”

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Two-photon Ramsey fringes at 30 THz referenced to an H maser/Cs fountain via an optical-frequency comb at the 1-Hz level

Shelkovnikov

Grain

Butcher

et al. 2004

IEEE J. Quantum Electron.

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Index Terms--Carbon dioxide lasers, Frequency stability, SF 6 , Optical frequency standard. I. INTRODUCTIONThe carbon dioxide laser has given to the 30 THz spectral region particular significance in frequency metrology. The current standard at 30THz is provided by the CO 2 laser locked onto a saturated absorption resonance of OsO 4 in a cell, the reference signal having full width half maximum (FWHM) of 20 kHz [1,2]. The same area is particularly rich in molecular spectra and many problems in this area, together with questions of fundamental physics, have been investigated using the related saturation spectroscopy [3,4]. Typical linewidths are 1-100 kHz. This paper presents continuing work on a two-photon Ramsey fringe experiment on a supersonic beam of SF 6 with the objectives, now essentially realized, of resolving the entire complex hyperfine structure over some 50 kHz and establishing absolute frequencies at the 1Hz level. Both aspects represent huge advances over cell saturation techniques. Two experimental developments have led to the recent advances. First, the distance between the absorption zones has been increased to 1m, so that the fringe periodicity is now 200 Hz for pure SF 6 . Data is routinely recorded with a signal-to-noise ratio (SNR) of 20 in a bandwidth of 1 Hz. The implied limit on the resolution of two components within the hyperfine structure of the SF 6 spectrum is only 10Hz. This is indeed found when fringe patterns are fitted. Second the entire system can now be directly related to the frequency comb of a femtosecond laser, itself referenced to a Hydrogen maser. The maser is compared to a Caesium fountain and to the GPS system. This gives a long-term stability and frequency reproducibility limited by the performance of the current electronics, various optical links and, possibly, the reference maser. The fs technology is necessarily operated in a new area of precision, comparable with the best currently in use [5,6]. Figure 1 gives a block outline of the entire experiment.Two related series of experiments are presented. First the central Ramsey fringe is employed as the reference point for a molecular clock; the clock frequency is measured, and its performance established, relative to the H maser. Second, and separately, Ramsey fringes are measured on an absolute frequency scale provided by the H maser. This gives a second measurement of the central fringe and the entire spectrum of Ramsey fringes over 50 kHz is put onto an absolute frequency scale.This work is partly directed at a new frequency standard. Since a two-photon transition is used the absolute frequency depends on the optical power. Given the absolute scale, this small effect can be investigated and results are reported.

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“…Comb offset detection and control techniques [16,17,18] as well as techniques for sub-femtosecond pulse stabilization [19] have been developed and reported extensively in recent years.…”

Section: Laser Frequency Stabilization Methodsmentioning

confidence: 99%

Optical Phase Locking of Modelocked Lasers for Particle Accelerators

Plettner

Sinha²,

Wisdom³

et al.

Proceedings of the 2005 Particle Accelerator Conference

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Particle accelerators require precise phase control of the electric field through the entire accelerator structure. Thus a future laser driven particle accelerator will require optical synchronism between the high-peak power laser sources that power the accelerator. The precise laser architecture for a laser driven particle accelerator is not determined yet, however it is clear that the ability to phase-lock independent modelocked oscillators will be of crucial importance. We report the present status on our work to demonstrate long term phaselocking between two modelocked lasers to within one dregee of optical phase and describe the optical synchronization techniques that we employ.

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Phase Coherent Vacuum-Ultraviolet to Radio Frequency Comparison with a Mode-Locked Laser

Cited by 214 publications

References 21 publications

From quantum transitions to electronic motions

From quantum transitions to electronic motions

Two-photon Ramsey fringes at 30 THz referenced to an H maser/Cs fountain via an optical-frequency comb at the 1-Hz level

Optical Phase Locking of Modelocked Lasers for Particle Accelerators

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