Ultrafast double-pulse parametric amplification for precision Ramsey metrology

Kandula, D. Z.; Renault, A.; Gohle, Christoph; Wolf, A.; Witte, Stefan; Hogervorst, W.; Ubachs, Wim; Eikema, K.S.E.

doi:10.1364/oe.16.007071

Cited by 18 publications

(21 citation statements)

References 18 publications

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“…A Mach-Zehnder-like configuration is used to interfere the original comb pulses with those amplified by the NOPCPA, as described in [56] and Sec. III C.…”

Section: Overview and Principle Of Xuv Comb Generation And Excitamentioning

confidence: 99%

“…Here we present a concise description of the system, while further details can be found in [56,59]. The amplifier operates at a repetition rate of 28 Hz, and amplifies two subsequent FC pulses to a level of typically 5 mJ each.…”

Section: B Noncollinear Optical Parametric Amplifiermentioning

confidence: 99%

“…The phase-measurement setup is an advanced version of the one reported earlier [56]. In order to deal with the demand for higher spectral resolution of the phase-measurement setup and the spatial dependence of the phase shift between the pulses, several improvements were made.…”

Section: Phase-shift Measurements In the Infraredmentioning

confidence: 99%

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XUV frequency-comb metrology on the ground state of helium

et al. 2011

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The operation of a frequency comb at extreme ultraviolet (xuv) wavelengths based on pairwise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency-comb laser in the near-infrared range is reported. It is experimentally demonstrated that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p 1 P 1 states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited-state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure, thereby using the helium atom as a precision phase ruler, yields an estimated timing jitter between the two upconverted-comb laser pulses of 50 attoseconds, which is equivalent to a phase jitter of 0.38 (6) cycles in the xuv at 51 nm. This sets a quantitative figure of merit for the operation of the xuv comb and indicates that extension to even shorter wavelengths should be feasible. The helium metrology investigation results in transition frequencies of 5 740 806 993 (10) and 5 814 248 672 (6) MHz for excitation of the 1s4p and 1s5p 1 P 1 states, respectively. This constitutes an important frequency measurement in the xuv, attaining high accuracy in this windowless part of the electromagnetic spectrum. From the measured transition frequencies an eight-fold-improved 4 He ionization energy of 5 945 204 212 (6) MHz is derived. Also, a new value for the 4 He ground-state Lamb shift is found of 41 247 (6) MHz. This experimental value is in agreement with recent theoretical calculations up to order mα 6 and m 2 /Mα 5 , but with a six-times-higher precision, therewith providing a stringent test of quantum electrodynamics in bound two-electron systems.

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“…A Mach-Zehnder-like configuration is used to interfere the original comb pulses with those amplified by the NOPCPA, as described in [56] and Sec. III C.…”

Section: Overview and Principle Of Xuv Comb Generation And Excitamentioning

confidence: 99%

Section: B Noncollinear Optical Parametric Amplifiermentioning

confidence: 99%

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XUV frequency-comb metrology on the ground state of helium

et al. 2011

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“…A bandwidth of 6 nm (rectangular spectrum, leading to % 300 fs pulses after compression) is selected from the FC laser so that after up-conversion to the XUV only one state in helium is excited at a time. A noncollinear parametric double-pulse amplifier [22] is used to amplify two subsequent FC pulses (5.5-10 ns apart) at a repetition rate of 28 Hz. Parametric amplification intrinsically has small transient effects [24] so that differential pulse distortions are kept to a minimum.…”

mentioning

confidence: 99%

“…Parametric amplification intrinsically has small transient effects [24] so that differential pulse distortions are kept to a minimum. They are monitored using spectral interferometry with the unaltered FC pulses as a reference [22]. Wave front deformations in the amplified beam are reduced by spatial filtering.…”

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confidence: 99%

Extreme Ultraviolet Frequency Comb Metrology

et al. 2010

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The remarkable precision of frequency-comb (FC) lasers is transferred to the extreme ultraviolet (XUV, wavelengths shorter than 100 nm), a frequency region previously not accessible to these devices. A frequency comb at XUV wavelengths near 51 nm is generated by amplification and coherent upconversion of a pair of pulses originating from a near-infrared femtosecond FC laser. The phase coherence of the source in the XUV is demonstrated using helium atoms as a ruler and phase detector. Signals in the form of stable Ramsey-like fringes with high contrast are observed when the FC laser is scanned over P states of helium, from which the absolute transition frequency in the XUV can be extracted. This procedure yields a 4 He ionization energy at h Â 5 945 204 212ð6Þ MHz, improved by nearly an order of magnitude in accuracy, thus challenging QED calculations of this two-electron system. Mode-locked frequency-comb (FC) lasers [1,2] have revolutionized the field of precision laser spectroscopy. Optical atomic clocks using frequency combs are about to redefine the fundamental standard of frequency and time [3]. FC lasers have also vastly contributed to attosecond science by providing a way to synthesize electric fields at optical frequencies [4], made long distance absolute length measurements possible [5], and have recently been employed to produce ultracold molecules [6]. FC based precision spectroscopy on simple atomic systems has provided one of the most stringent tests of bound state quantum electrodynamics (QED) as well as upper bounds on the drift of fundamental constants [7]. Extending these methods into the extreme ultraviolet (XUV, wavelengths below 100 nm) spectral region is highly desirable since this would, for example, allow novel precision QED tests [8].Currently the wavelength range below 120 nm is essentially inaccessible to precision frequency metrology applications due to a lack of power of single frequency lasers and media for frequency up-conversion. Spectroscopic studies on neutral helium using amplified nanosecond laser pulses [9,10] are notoriously plagued by frequency chirping during amplification and harmonic conversion which limits the accuracy. These kind of transient effects can be avoided if a continuous train of high power laser pulses (produced by a FC) can be coherently up-converted. This would transfer the FC modes, at frequencies f n ¼ f CEO þ nf rep , where f CEO is the carrier-envelope offset frequency, f rep is the repetition frequency of the pulses, and n an integer mode number, to the XUV. Similar to what was shown in the visible [11,12], the up-converted pulse train could be used to directly excite a transition, with each of the up-converted modes acting like a single frequency laser.By amplification of a few pulses from the train, and producing low harmonics in crystals and gasses, sufficient coherence has been demonstrated down to 125 nm to perform spectroscopic experiments [13,14]. To reach wavelengths below 120 nm in the extreme ultraviolet or even x rays, high harmonic generati...

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Precision Laser Spectroscopy in the Extreme Ultraviolet

Eikema

Ubachs

2011

Handbook of High‐resolution Spectroscopy

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Techniques for the production of short wavelengths in the extreme ultraviolet wavelength range are described, spanning low‐order harmonic generation in the perturbative regime for narrow bandwidth XUV production to the plateau‐regime with the three‐step collisional model for the generation of high harmonics with broadband ultrafast pulses. In addition, the intermediate regime is discussed for pulses of 300 ps duration, as well as the regime of harmonic conversion based on continuous wave lasers aiming at the production of coherent Lyman‐α radiation. Applications of XUV sources in the frequency domain typically rely on the production of XUV‐light from narrowband Fourier‐transform‐limited pulses for recording high‐resolution spectra. Alternatively, harmonically upconverted pulses of ultrashort duration (with inter‐pulse coherence) can be used for spectroscopic studies in the time and frequency domain (such as direct frequency comb spectroscopy techniques). Examples of both approaches for atomic and molecular spectroscopy are discussed at some length. For precision metrology on atomic systems, a focus is put on the Lamb shift determination in the He ground state. In the realm of molecular spectroscopy, predissociation phenomena in the nitrogen molecule are highlighted, with relevance for dissociation processes occurring in the upper layers of the Earth atmosphere. Similar predissociation phenomena in carbon monoxide are also treated in some detail, in this case with relevance for the chemistry in interstellar clouds. Precision XUV spectroscopy of molecular hydrogen is discussed as well, as it relates to the possibility of detecting a variation of the proton–electron mass ratio on a cosmological time scale. In the last section, applications of direct frequency comb spectroscopic techniques at short wavelengths are explained and prospects are given for using these techniques at extreme ultraviolet wavelengths.

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Ultrafast double-pulse parametric amplification for precision Ramsey metrology

Cited by 18 publications

References 18 publications

XUV frequency-comb metrology on the ground state of helium

XUV frequency-comb metrology on the ground state of helium

Extreme Ultraviolet Frequency Comb Metrology

Precision Laser Spectroscopy in the Extreme Ultraviolet

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