Interference spectra in a two-level atom

We have considered the interference spectra arising from the competition between a spontaneous process and one induced by a laser field in a two-level atom. Expressions for the spectral functions have been derived describing the spectra of the excited and ground states of the atom in the low- and high-intensity limit of the laser field. For the excited-state spectra in the low-intensity limit, the frequency profiles of the two peaks, which arise from the spontaneous and the induced processes, cancel each other out completely near the center of the line, while for the ground state the induced process dominates. For finite values of the detuning, the spectra of the excited state consist of two peaks, which have positive and negative frequency profiles, respectively. The computed spectra have been graphically presented and discussed. In the high-intensity limit, the dynamic Stark effect dominates the spectra of the excited and ground states of the atom. Expressions for the correlation functions have been derived that describe the emission or the absorption of a laser photon at two different times. The derived expressions for the corresponding delay functions in the low- and high-intensity limits have been found to be identical to those recently proposed in the literature. The laser field has been treated as a classical as well as a quantized entity.

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Induced absorption and stimulated emission in a driven two-level atom

Canadian Journal of Physics ◽

10.1139/p92-072 ◽

1992 ◽

Vol 70 (6) ◽

pp. 427-431 ◽

Cited By ~ 2

Author(s):

Constantine Mavroyannis

Keyword(s):

Excited State ◽

Ground State ◽

Laser Field ◽

Low Frequency ◽

Ultrashort Pulses ◽

Stimulated Emission ◽

Spectral Lines ◽

Laser Photon ◽

Induced Absorption ◽

Level Atom

We have considered the induced processes that occur in a driven two-level atom, where a laser photon is absorbed and emitted by the ground and by the excited states of the atom, respectively. In the low-intensity limit of the laser field, the induced spectra arising when a laser photon is absorbed by the ground state of the atom consist of two peaks describing induced-absorption and stimulated-emission processes, respectively, where the former prevails over the latter. Asymmetry of the spectral lines occurs at off-resonance and its extent depends on the detuning of the laser field. The physical, process where a laser photon is emitted by the excited state is the reverse of that arising from the absorption of a laser photon by the ground state of the atom. The former differs from the latter in that the emission of a laser photon by the excited state occurs in the low-frequency regime and that the stimulated-emission process prevails over that of the induced absorption. In this case, amplification of ultrashort pulses is likely to occur without the need of population inversion between the optical transitions. The computed spectra are graphically presented and discussed.

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A laser-excited three-level atom. II numerical results

Canadian Journal of Physics ◽

10.1139/p90-065 ◽

1990 ◽

Vol 68 (4-5) ◽

pp. 411-421 ◽

Cited By ~ 4

Author(s):

Constantine Mavroyannis

Keyword(s):

Excited State ◽

Laser Field ◽

Spectral Width ◽

Spectral Functions ◽

Laser Fields ◽

Atomic Transitions ◽

Level Atom ◽

Short Lifetime ◽

Strong Transition ◽

Long Lifetime

Numerical calculations are presented for the interference spectra of a laser-excited three-level atom, where the strong and the weak atomic transitions are driven by resonant and nonresonant laser fields, respectively. The spectral functions describing the interference spectra for the electric dipole allowed excited state have been considered in the low- and high-intensity limit of the laser field operating in the strong transition. The interference spectra arise from the competition between short-lifetime spontaneous processes and short- and long-lifetime excitations induced by the strong and the weak laser fields, respectively. Both laser fields have been treated as quantized and as classical entities. The computed spectra have been presented graphically for different values of the Rabi frequencies and detunings of the weak laser field. It is shown that the decrease in the intensity of the short-lifetime excitation may provide a measure of the spectral width of the long-lifetime excitation.

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Two-photon interference spectra induced by a bichromatic field in the excited state of a single three-level ion

Canadian Journal of Physics ◽

10.1139/p92-001 ◽

1992 ◽

Vol 70 (1) ◽

pp. 1-23 ◽

Cited By ~ 4

Author(s):

Constantine Mavroyannis

Keyword(s):

Excited State ◽

Ground State ◽

Correlation Functions ◽

Stark Effect ◽

Stimulated Emission ◽

Laser Fields ◽

Two Photon ◽

Dynamic Stark Effect ◽

Two Peaks ◽

Photon Resonance

We consider the interference spectra arising from the competition between a spontaneous process and two processes induced by two laser fields, which are coupled with a three-level atom in the "Λ" configuration. In the low-intensity limit of both laser fields and on two-photon resonance, the frequency profiles of the two peaks, which arise from the spontaneous and induced processes, cancel each other out completely at the center of the line for zero detuning and at the finite values of the detuning as well. At high intensities of the laser fields and on two-photon resonance, the dynamic Stark effect dominates the spectra of the excited state of the atom. Expressions for the interference spectra and correlation functions are derived, which describe the physical process of the absorption of a laser photon at two different times by the ground state of the atom. Interference spectra and correlation functions are calculated for the two-photon off-resonance and for the proces of the absorption of a photon by the ground state of the atom. In this case, the intensities of the frequency dips take negative values indicating that stimulated emission prevails for certain values of the detunings. Using values for the parameters involved close to those for Ba+, the computed two-photon resonance and off-resonance spectra are graphically presented and discussed.

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A laser-excited three-level atom

Canadian Journal of Physics ◽

10.1139/p90-051 ◽

1990 ◽

Vol 68 (3) ◽

pp. 321-333 ◽

Cited By ~ 5

Author(s):

Constantine Mavroyannis

Keyword(s):

Excited States ◽

Laser Field ◽

Excitation Spectra ◽

Spectral Functions ◽

Laser Fields ◽

At Resonance ◽

Level Atom ◽

Short Lifetime ◽

Strong Transition ◽

Long Lifetime

We considered the excitation spectra for the excited states of a three-level atom, where the strong and the weak atomic transitions are driven by resonant and nonresonant laser fields, respectively. The spectral functions describing the excitation spectra for the electric dipole allowed excited state and for the metastable state of the atom have been derived when both laser fields are quantized as well as when they are treated as classical entities. In the low-intensity limit of the laser field operating in the strong transition, there are two short-lifetime excitations, the spontaneous one and the induced one, which appear at the same frequency, and a long-lifetime excitation induced by the weak laser field. These excitations compete with each other at resonance as well as at finite detunings of the weak laser field. In the high-intensity limit of the laser field operating in the strong transition, the competition is between the short- and the long-lifetime side bands, which are induced by the strong and the weak laser fields, respectively. The ratio of the maximum intensities of the peaks describing the long- and the short-lifetime excitations exhibits a resonance variation with the detuning of the weak laser field. Comparison between the results obtained when the laser fields are treated as quantized and as classical entities is made.

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