Absorption spectra for strong pump and probe in atomic beam of cesium atoms (2009) (original) (raw)
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Absorption spectra for strong pump and probe in atomic beam of cesium atoms
Physical Review A, 2009
We calculate the pump and probe absorption spectra for the cycling F g =4→ F e = 5 transition D 2 line of 133 Cs in an atomic beam, interacting with a strong resonant +-polarized pump and a probe of comparable intensity and either − or polarization. The aim is to reproduce and analyze the experiments of Dahl et al. ͓Opt. Lett. 33, 983 ͑2008͔͒ who showed for a +-polarized pump and −-polarized probe that the pump absorption spectrum switches from an "absorption within transparency" ͑AWT͒ structure, when the probe is weaker than the pump, to a "transparency within transparency" ͑TWT͒ structure, when the probe is stronger than the pump. For all other polarization combinations, the pump spectrum displays AWT behavior at all probe intensities. We analyze our results by considering the contributions that derive from the individual m g → m e transitions. When the +-polarized pump is stronger than the −-polarized probe, the population is swept toward the m g → m e = m g + 1 transitions with the highest values of m g , and the pump absorption spectrum has an AWT structure and resembles that of an N system. However, when the probe is stronger than the pump, the population is swept toward the m g =−F g → m e = m g − 1 transition when the probe is near resonance, and to the m g = F g → m e = m g + 1 transition when the probe is detuned from resonance. The pump and probe spectra are mirror images of each other and resemble those of a V system where the probe has a peak at line center and the pump spectrum has a TWT structure. For a strong + pump and an even stronger probe, the population concentrates in the intermediate transitions, and the AWT to TWT changeover does not occur. We also show that the narrow features in the spectra at line center derive from transfer of coherence from the excited to the ground hyperfine levels.
Pump-probe absorption in Cesium atomic beam.
We calculate the pump and probe absorption spectra for the cycling F g =4→ F e = 5 transition D 2 line of 133 Cs in an atomic beam, interacting with a strong resonant + -polarized pump and a probe of comparable intensity and either − or polarization. The aim is to reproduce and analyze the experiments of Dahl et al. ͓Opt. Lett. 33, 983 ͑2008͔͒ who showed for a + -polarized pump and − -polarized probe that the pump absorption spectrum switches from an "absorption within transparency" ͑AWT͒ structure, when the probe is weaker than the pump, to a "transparency within transparency" ͑TWT͒ structure, when the probe is stronger than the pump. For all other polarization combinations, the pump spectrum displays AWT behavior at all probe intensities. We analyze our results by considering the contributions that derive from the individual m g → m e transitions. When the + -polarized pump is stronger than the − -polarized probe, the population is swept toward the m g → m e = m g + 1 transitions with the highest values of m g , and the pump absorption spectrum has an AWT structure and resembles that of an N system. However, when the probe is stronger than the pump, the population is swept toward the m g =−F g → m e = m g − 1 transition when the probe is near resonance, and to the m g = F g → m e = m g + 1 transition when the probe is detuned from resonance. The pump and probe spectra are mirror images of each other and resemble those of a V system where the probe has a peak at line center and the pump spectrum has a TWT structure. For a strong + pump and an even stronger probe, the population concentrates in the intermediate transitions, and the AWT to TWT changeover does not occur. We also show that the narrow features in the spectra at line center derive from transfer of coherence from the excited to the ground hyperfine levels.
Pump-probe spectroscopy of degenerate 2-level systems with arbitrarily strong fields (2008)
2008
We study the pump and probe absorption spectra, as a function of the probe detuning, in a degenerate two-level atomic system, for the case where the probe intensity is high enough to affect the pump absorption. The theory is valid for any F g → F e alkali-metal transition interacting with an arbitrarily intense pump and probe ͑with general Rabi frequencies ⍀ 1,2 ͒ which are perpendicularly polarized with either Ϯ or polarization. We have constructed a computer program that can calculate the spectra without requiring one to write out the Bloch equations explicitly. We show that, when the pump is Ϯ polarized and the probe polarized, or vice versa, the pump and probe absorptions depend on the Zeeman coherences between the nearest-neighboring ground or excited Zeeman sublevels, whereas when the pump is + polarized and the probe − polarized, or vice versa, the Zeeman coherences that directly determine the absorption are between next-nearest neighbors. We report calculations of the pump and probe absorption spectra for the cycling F g =2→ F e = 3 transition in the D 2 line of 87 Rb, interacting with a resonant + -polarized pump and either aor a − -polarized probe. The probe and pump absorption spectra are analyzed by considering the contributions that derive from the individual m g → m e transitions. We then show how these contributions depend on the ground-and excited-state populations and Zeeman coherences, and investigate the role played by transfer of coherence from the excited to the ground hyperfine state. We show that the pump and probe absorption spectra are mirror images of each other when ⍀ 1 Ն⍀ 2 Ͼ⌫, and have the same behavior at line center and complementary behavior in the wings, when ⍀ 1 Ն⍀ 2 Ͻ⌫ ͑⌫ is the rate of spontaneous decay from F e to F g ͒.
Pump-probe spectroscopy in degenerate two-level atoms with arbitrarily strong fields
Physical Review A, 2008
We review our previous work on pump-probe spectroscopy in realistic degenerate two-level systems and model systems. In particular, we discuss the role of transfer of coherence (TOC) between the ground and excited hyperfine states in producing electromagnetically-induced transparency (EIA) peaks in the probe spectrum, when an F g → F e = F g + 1 transition in an alkali-metal atom interacts with a strong pump and weak probe that have perpendicular polarizations. When the pump is σ + polarized and the probe π polarized, this system can be modelled by an N system. We also discuss the role of transfer of population (TOP) between the Zeeman levels of the ground hyperfine state in producing EIA peaks when the pump and probe have the same polarization. This system can be modelled using a double two-level system. The role of Doppler broadening and phase-changing collisions in modifying the EIA-TOC and EIA-TOP absorption and refraction spectra is also discussed. All these spectra were calculated using MATLAB programs that both construct and solve the relevant Bloch equations. In our recent work, we consider the effect of a strong probe on the pump absorption and refraction spectra when the pump and probe polarizations are linear and perpendicular. It is difficult to solve this problem numerically due to the large number frequencies involved. In order to simplify the problem, we considered two cases: (i) σ + polarized pump and π polarized probe, and (ii) σ + polarized pump and σ − polarized probe, and investigated a series of transitions in both Rb and Cs, using modified versions of the MATLAB programs devised for the weakprobe case. A number of interesting differences from the weak-probe case were found. For example, when the probe is sufficiently strong, we found the pump and probe spectra to show complementary behavior. In addition, as the number of Zeeman levels increase, the EIA peaks become progressively sharper, and are accompanied by steeper dispersion.
2011
In this work the quantum interference effect on the weak probe absorption in a closed three-level V atomic system driven by a coherent driving field is shown to result from the twoquantum processes, constructive for the amplification channels and destructive for the absorption channel. A fourth state in the atom is coupled incoherently to the V system and acts as both an incoherent pumping reservoir and as a stationary, final state in perturbation theory. The application refers to Be-like carbon ions where non-linear pump process of the 1s 2 2s5s(1 S e)-1s 2 2p5s(1 P 0) transition is combined with the absorption or emission of a single probe photon corresponding to 1s 2 2s5s(1 S e)-1s 2 2p7s(1 P 0) transition. The system is analyzed within the Rmatrix Floquet theory and codes results.
Physical Review A, 1999
A numerical method is introduced that solves the optical Bloch equations describing a two-level atom interacting with a strong polychromatic pump field with an equidistant spectrum and an arbitrarily intense monochromatic probe field. The method involves a transformation of the optical Bloch equations into a system of equations with time-independent coefficients at steady state via double harmonic expansion of the densitymatrix elements, which is then solved by the method of matrix inversion. The solutions so obtained lead immediately to the determination of the polarization of the atomic medium and of the absorption and dispersion spectra. The method is applied to the case when the pump field is bichromatic and trichromatic, and the physical interpretation of the numerically computed spectra is given. ͓S1050-2947͑99͒10409-8͔
International Journal of Advance Engineering and Research Development, 2016
A density matrix based analytical model is developed to study the coherent probe field propagation through a four-level 'V' type system in presence of a coherent control field. The model allows coupling of the probe field from the upper ground level to both of the excited levels keeping the control field locked to a particular transition. The addition of an extra ground level to a conventional three-level 'V' type system creates extra decay paths to the ground levels for the upper level population. A set of sixteen density matrix based equations are formed and then solved analytically under rotating wave approximation to study the probe response under steady state condition. The simulated probe absorption spectra shows absorption dip at the centre of a transparency window only under Doppler broadened condition although the conventional EIT window appears under Doppler free condition. The dependence of the field induced absorption signal on the Rabi frequency of the control field, population transfer rate among the ground levels and temperature of the vapour medium has been studied in details.
Nonlinear ground-state pump-probe spectroscopy
Physical Review A, 2000
A theory of pump-probe spectroscopy is developed in which optical fields drive two-quantum, Raman-like transitions between ground state sublevels. Three fields are incident on an ensemble of atoms. Two of the fields act as the pump field for the two-quantum transitions. The absorption or gain of an additional probe field is monitored as a function of its detuning from one of the fields which constitutes the pump field. Although the probe absorption spectrum displays features common to those found in pump-probe spectroscopy of single-quantum transitions, new interference effects are found to modify the spectrum. Many of these features can be explained within the context of a dressed atom picture.
Hyperfine spectroscopy using co-propagating pump-probe beams
Arxiv preprint arXiv: …, 2010
We have shown earlier that hyperfine spectroscopy in a vapor cell using co-propagating pumpprobe beams has many advantages over the usual technique of saturated-absorption spectroscopy using counter-propagating beams. The main advantages are the absence of crossover resonances, the appearance of the signal on a flat (Doppler-free) background, and the higher signal-to-noise ratio of the primary peaks. Interaction with non-zero-velocity atoms causes additional peaks, but only one of them appears within the primary spectrum. We first illustrate the advantages of this technique for high-resolution spectroscopy by studying the D2 line of Rb. We then use an acoustooptic modulator (AOM) for frequency calibration to make precise hyperfine-interval measurements in the first excited P 3/2 state of 85,87 Rb and 133 Cs.
Optics Letters, 2007
The probe absorption spectra in single and multiple tripod systems formed when a weak polarized pump and a tunable polarized probe interact with a Zeeman split F g → F e = F g −1 atomic transition are characterized by two interfering stimulated Raman features separated by an electromagnetically induced absorption (EIA) peak at the line center. These Raman features can appear as either sharp stimulated emission peaks or electromagnetically induced transparency windows. In the multitripod systems, the EIA and stimulated emission peaks derive from the combined effects of interference between the stimulated Raman features and transfer of coherence from the excited to ground states.