Femtosecond laser pulse train effect on Doppler profile of cesium resonance lines (original) (raw)
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High-resolution spectroscopy with a femtosecond laser frequency comb
Optics Letters, 2005
The output of a mode-locked femtosecond laser is used for precision single-photon spectroscopy of 133 Cs in an atomic beam. By changing the laser's repetition rate, the cesium D 1 ͑6s 2 S 1/2 → 6p 2 P 1/2 ͒ and D 2 ͑6s 2 S 1/2 → 6p 2 P 3/2 ͒ transitions are detected and the optical frequencies are measured with accuracy similar to that obtained with a cw laser. Control of the femtosecond laser repetition rate by use of the atomic fluorescence is also implemented, thus realizing a simple cesium optical clock.
Physical Review A, 2004
We investigate coherent accumulation processes in three-level atoms excited by a train of ultrashort pulses in the case where the atomic relaxation times are greater than the laser repetition period. In this situation the resonances of the laser field with the atomic system are determined by the laser frequency comb rather than by the spectrum of a single pulse. Using the density matrix formalism, we develop a perturbative theory that is valid for arbitrary pulse shapes. The excitation of a Doppler-broadened atomic vapor by hyperbolic-secant pulses and 0 pulses is analyzed. It is shown that pulse shape has a great influence on the accumulation process and can change the spectral periodicity of the pattern impressed on the Doppler profile of the medium due to the two-photon absorption process. The effect of interpulse phases is also investigated, and we show that the atomic populations can vary by more than one order of magnitude with small variations of the laser repetition rate, while being insensitive to variations of the laser offset. Finally, the theory is adapted for the temporal-coherent-control technique, and its results are compared with previously reported experimental data.
Physical Review A, 2004
Optical frequencies of the hyperfine components of the D 2 line in 133 Cs are determined using high-resolution spectroscopy and a femtosecond laser frequency comb. A narrow-linewidth probe laser excites the 6s 2 S 1/2 ͑F =3,4͒ → 6p 2 P 3/2 ͑F =2,3,4,5͒ transition in a highly collimated atomic beam. Fluorescence spectra are taken by scanning the laser frequency over the excited-state hyperfine structure. The laser optical frequency is referenced to a Cs fountain clock via a reference laser and a femtosecond laser frequency comb. A retroreflected laser beam is used to estimate and minimize the Doppler shift due to misalignment between the probe laser and the atomic beam. We achieve an angular resolution on the order of 5 ϫ 10 −6 rad. The final uncertainties ͑ϳ ± 5 kHz͒ in the frequencies of the optical transitions are a factor of 20 better than previous results [T. Udem et al., Phys. Rev. A 62, 031801 (2000).]. We find the centroid of the 6s 2 S 1/2 → 6p 2 P 3/2 transition to be f D2 = 351 725 718.4744͑51͒ MHz.
Spectroscopy with a mode-locked Femtosecond Laser Frequency Comb
2011
We summarise high-resolution, high-precision spectroscopy experiment where caesium-133 atoms in a vapour cell are excited directly with a femtosecond laser frequency comb. In this experiment the laser beam is sent counter-propagating by the beam-splitting cube, focussed to a reasonable waist in the interaction region in the vapour cell, thereby exciting a multitude of low lying transitions allowing the measurement of transition energies and hyperfine coupling coefficients for the 8S1/2, 9S1/2 and 7D3/2,5/2 states.
Precise Measurement of Hyperfine Structure of Cesium 7S1/2 Excited State
Applied Sciences, 2020
We present a precise measurement of the hyperfine structure of cesium 7 S 1 / 2 excited state by employing electromagnetically induced spectroscopy (EIS) with a cesium three-level cascade ( 6 S 1 / 2 − 6 P 3 / 2 − 7 S 1 / 2 ) atom in a room temperature vapor cell. A probe laser, λ p = 852 nm, was coupled to a transition | 6 S 1 / 2 ⟩ → | 6 P 3 / 2 ⟩ , related frequency locked to the resonance hyperfine transition of | 6 S 1 / 2 ⟩ → | 6 P 3 / 2 ⟩ with a Fabry–Perot (FP) cavity and an electro-optic modulator (EOM). A coupling laser, λ c = 1470 nm, drove the | 6 P 3 / 2 ⟩ → | 7 S 1 / 2 ⟩ transition with the frequency scanned over the | 6 P 3 / 2 ⟩ → | 7 S 1 / 2 ⟩ transition line. The hyperfine level interval was extracted to be 2183.61 ± 0.50 MHz by analyzing EIS spectroscopy. The optical–optical double-resonance (OODR) spectroscopy is also presented for comparison, with the corresponding value of the hyperfine level interval being 2183.48 MHz ± 0.04 MHz, and the measured hyperfine spl...
Coupling between cw lasers and a frequency comb in dense atomic samples
Journal of Physics B: Atomic, Molecular and Optical Physics, 2010
We report on a detailed investigation of the coupling between a femtosecond-laser frequency comb and a cw diode laser interacting with an atomic medium of variable density. The comb is printed on a Doppler-broadened atomic transition and the frequency-dependent transmission of the cw laser is monitored as it is scanned over the inhomogenously broadened absorption profile. The printing process and its probing are analysed, experimentally and theoretically, as a function of both laser intensities and the atomic density. The results reveal the importance of optical pumping and power broadening by both lasers, allowing us to determine various regimes of competition between them.
Physical Review A, 2011
33.20.Xx Spectra induced by strong-field or attosecond laser irradiation 32.80.Wr Other multiphoton processes 33.20.Kf Visible spectra (molecules) 82.20.Rp State to state energy transfer We report on the observation of extra sub-Doppler lines in a saturated absorption experiment when exploring the vicinity of the 6S 1/2-8P 3/2 transition of Cs ( = 388 nm). These extra lines are observed only under a relatively strong irradiation of both the pump and the probe beams. Extra narrow lines are also observed in co-propagating nonlinear spectroscopy, and around the lines of the V-type three-level system 8P 3/2-6S 1/2-8P 1/2 ( 1 = 388 nm, 2 = 389 nm). We attribute theses extra-lines to a probing of high-lying molecular caesium, produced as a result of the optical excitation of Cs atoms, as the low Cs atom density ( 10 12 cm-3) is unable to populate significantly the dimer states in the condition of thermal equilibrium.
Femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission
Physical Review A, 2010
We study the dynamics of wave packets in cesium dimers using a femtosecond-controlled pump-probe technique. We implement configurations with one pulse (pump) or two pulses (pump and control) to produce vibrational wave packets on the electronic excited state. The transmission of an additional, variable-delay probe pulse is measured to monitor the time evolution of the wave packets. In the case
Strong-field two-photon absorption in atomic cesium: an analytical control approach
Optics Express, 2009
We have considered an analytical control of two-photon absorption process of atoms in the strong-field interaction regime. The experiment was performed on gaseous cesium atoms strongly interacting with a shaped laser-pulse from a femtosecond laser amplifier and a programmable pulse-shaper. When this shaped laser-pulse transfers the atomic population from the 6s ground state to the 8s excited state, we have found that both positively-and negatively-chirped laser pulses, compared with a Gaussian pulse, enhance this excitation in the strong-field regime of laser-atom interaction. This unusual phenomena is explained because the temporal shape of the laser intensity compensates the effect of dynamic Stark shift for the two-photon resonant condition to be optimally maintained. We provide analytic calculations using the strong-field phase matching, which show good agreement with the experiment.