Transportable He-Ne/CH/sub 4/ optical frequency standard and absolute measurements of its frequency

Gubin, M. A.; Tyurikov, D A; Shelkovnikov, A.; Kovalchuk, Evgeny; Kramer, G.; Lipphardt, B.

doi:10.1109/3.477744

Cited by 39 publications

(8 citation statements)

References 14 publications

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“…1). 6 For example, an infrared methane optical frequency standard 12,13 can be used as a highly stable reference for an OPO and a visible frequency comb. Alternatively, an OPO phase locked to a visible frequency comb, which itself is referenced to a high performance microwave or optical clock, can provide stable emission with known absolute frequency in both the mid-IR and telecom spectral ranges.…”

Section: 2mentioning

confidence: 99%

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Combination of a continuous-wave optical parametric oscillator and a femtosecond frequency comb for optical frequency metrology

2005

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We combine a tunable continuous-wave optical parametric oscillator and a femtosecond Ti:Sapphire laser frequency comb to provide a phase-coherent bridge between the visible and mid-infrared spectral ranges. As a first demonstration of this new technique we perform a direct frequency comparison between an iodine stabilized Nd:YAG laser at 1064 nm and an infrared methane optical frequency standard at 3.39 µm. Accepted for publication in Optics Letters c 2005 Optical Society of AmericaContinuous-wave optical parametric oscillators (cwOPOs) are one of the most promising infrared (IR) laser sources for high-resolution molecular spectroscopy.

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Section: 2mentioning

confidence: 99%

“…The latter is integrated in a transportable He-Ne/CH 4 optical frequency standard and serves us as a highly stable (over hundreds of seconds) IR reference laser 12 . The methane standard and reference laser were both previously characterized during several absolute frequency comparisons.…”

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confidence: 99%

Combination of a continuous-wave optical parametric oscillator and a femtosecond frequency comb for optical frequency metrology

2005

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“…We used a phase heterodyne method to measure the refractive index. The idea of this approach is based on the well-known method of FM spectroscopy and the two-mode technique [13]. Our method is similar to that used for dispersion measurements [7] and for Doppler-free spectroscopy [14].…”

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confidence: 99%

Steep Anomalous Dispersion in Coherently Prepared Rb Vapor

Akulshin

Barreiro²,

Lezama³

1999

Phys. Rev. Lett.

163

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Steep dispersion of opposite signs in driven degenerate two-level atomic transitions have been predicted and observed on the D2 line of 87 Rb in an optically thin vapor cell. The intensity dependence of the anomalous dispersion has been studied. The maximum observed value of anomalous dispersion (dn/dν ≃ −6× 10 −11 Hz −1 ) corresponds to a negative group velocity Vg ≃ −c/23000. 42.50. Gy, 32.80.Qk, 42.62.Fi, Investigations of coherent effects in resonant media, namely coherent population trapping (CPT) and electromagnetically induced transparency (EIT) [1,2], which can dramatically modify the absorptive and dispersive properties of an atomic vapor, have caused a rebirth of interest in the problem of light propagation through a dispersive medium. In the last decade, the study of the dispersive properties of coherently prepared media was always under attention due to fundamental and practical interest.An ultra-large index of refraction in coherently prepared resonant gas was predicted [3] and a refractive index variation as large as ∆n ≈ 1 × 10 −4 was demonstrated in a dense Rb vapor [4]. It was also shown that a coherently driven medium exhibits large dispersion [5]. A high normal dispersion (up to dn/dν ≃ 1 × 10 −11 Hz −1 ) was measured on the Cs D 2 line in a vapor cell [6] and in an atomic beam [7]. Recently, extremely slow light group velocity (17 m/s) associated with normal dispersion was demonstrated in an ultracold atomic sample [8]. However, the same order of magnitude of group velocity (90 m/s) was observed in a hot dense vapor cell [9].All these investigations were carried on alkaline atoms where the absorption is strongly suppressed and dispersion is steep and normal (D ≡ dn/dν > 0) due to CPT between the two ground state hyperfine levels (Λ scheme). However, atomic coherence among Zeeman sublevels belonging to the same ground-state hyperfine level can led not only to usual EIT, but also to an absorption enhancement named as electromagnetically induced absorption (EIA) [10,11]. Since EIT/EIA effects in degenerate two-level systems can produce a significant variation in the absorption with subnatural width, one can predict a large absolute value of dispersion in this case. Notice that at resonance dispersion would be normal (D > 0) for EIT and anomalous (D < 0) for EIA. In both cases the absolute value of the dispersion can be several orders of magnitude greater than for a linear medium. In this letter we present the first observation of steep anomalous and normal dispersion in coherently prepared degenerate two-level atomic system.Refractive index and dispersion were analyzed with the model recently used to study subnatural EIA resonances [12]. In this model, two monochromatic optical fields, a drive field and a weak probe field with amplitudes E d , E p and frequencies ω d , ω p respectively are incident on motionless two-level atoms with resonance frequency ω 0 and electric dipole moment µ. The atomic levels are degenerate. The configuration is closed. The spontaneous decay rate is Γ. Finite interact...

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“…This technology recently revolutionized optical frequency metrology [5]. We describe as an example an optical clock based on Ti:sapphire technology and a methanestabilized HeNe laser [6,7,8].…”

Section: Introductionmentioning

confidence: 99%