Optical mixing of frequencies of a strong bichromatic field interacting with a three-level atom. II. Numerical results

1982 ◽  
Vol 60 (2) ◽  
pp. 245-251 ◽  
Author(s):  
Constantine Mavroyannis ◽  
K. J. Woloschuk ◽  
D. A. Hutchinson ◽  
Christine Downie
Keyword(s):  
Ground State ◽  
Laser Field ◽  
Excitation Spectra ◽  
Laser Fields ◽  
Level Atom ◽  
Reduced Frequency ◽  
Spontaneous Emission Probability ◽  
Bichromatic Field ◽  
Optical Mixing ◽  
Selection Of

We have numerically calculated the excitation spectra arising from the 3rd order mixing of the frequencies ωa and ωb of two laser fields interacting with a three-level atom, where each laser field resonantly couples the ground state with each excited state of the atom, respectively. In the limit of high photon densities, the excitation spectra near the reduced frequency X = (ω−ωa + 2ωb)/γ0 ≈ 0 are considered as a function of the reduced Rabi frequencies ηa and ηb of the two laser fields, respectively and γ0 is the spontaneous emission probability. For ηa < ηb the spectra consist of a doublet peaked at [Formula: see text] and its intensity is constant. When ηa = ηb, the spectra are composed of five pairs of bands peaked at [Formula: see text], and [Formula: see text]. When ηa < ηb the computed spectra consist of five pairs of bands, where the intensities of the peaks at [Formula: see text] and [Formula: see text] are positive indicating absorption, those at [Formula: see text] are negative implying amplification, and the two pairs of peaks at [Formula: see text] have positive and negative components describing the mixed process of absorption–amplification. The intensities of these bands are found to vary as (ηa/ηb)2 for (ηa/ηb) > 1 and, therefore, the intensities of the bands are immensely enhanced as the value of the ratio (ηa/ηb) increases. The computed spectra for a wide selection of Rabi frequencies are graphically presented and compared with those derived by analytical methods.

Resonance fluorescence spectra from a three level atom interacting with a strong bichromatic field: induced two photon transitions

1983 ◽  
Vol 61 (1) ◽  
pp. 15-29 ◽  
Author(s):  
Douglas A. Hutchinson ◽  
Christine Downie ◽  
Constantine Mavroyannis
Keyword(s):  
Ground State ◽  
Rabi Frequency ◽  
Resonance Fluorescence ◽  
Excitation Spectra ◽  
Laser Fields ◽  
Two Photon ◽  
Photon Transition ◽  
Level Atom ◽  
Photon Excitation ◽  
The One

This investigation describes the interaction of a three level atom with two laser fields. One of the transitions from the ground state is in resonance with twice the frequency of the first laser and the other transition from the ground state is in resonance with the second laser. The Green's function formalism is used to derive expressions from which the induced two photon and one photon excitation spectra are computed. Also, approximate expressions are derived for the excitation spectra in the appropriate frequency regions. These results agree well with the numerical computations based upon the precise expressions. The interference between the two transitions produce some splittings; these splittings depend upon the Rabi frequency of the one photon transition. The intensities of the weak peaks depend upon the ratio of the Rabi frequency of the two photon transition to the frequency of the first laser. Some features of the excitation spectra are interpreted in terms of previous knowledge about the behavior of two level atoms in strong laser fields.

A laser-excited three-level atom

1990 ◽  
Vol 68 (3) ◽  
pp. 321-333 ◽  
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.

Optical mixing of frequencies of a strong bichromatic field interacting with a three-level atom

1981 ◽  
Vol 59 (12) ◽  
pp. 1917-1929 ◽  
Author(s):  
Constantine Mavroyannis
Keyword(s):  
Spectral Function ◽  
Excitation Spectrum ◽  
Graphical Representation ◽  
Single Band ◽  
Laser Fields ◽  
Optical Amplification ◽  
Lorentzian Line ◽  
Level Atom ◽  
Bichromatic Field ◽  
Optical Mixing

We have studied the excitation spectrum arising from the optical mixing of the frequencies of a strong bichromatic field interacting with a three-level atom, where the two initially populated modes ωa and ωb are equal to the two atomic transition frequencies, respectively. In the limit of high photon densities, the excitation spectrum near the frequency ω = ωa – 2ωb has been calculated as a function of the parameter η = Ωa2/Ωb2, where Ωa and Ωb are the Rabi frequencies of the two laser fields, respectively. For [Formula: see text] and for weak fields for which [Formula: see text], the spectral function describes a Lorentzian line peaked at the frequency ω = ωa – 2ωb and has a width of the order of γ0, where γ0/2 is the natural width for a two-level atom. When Ωb2 > γ02 and [Formula: see text], the band at ω = ωa – 2ωb splits into two bands described by two Lorentzian lines peaked at ω = ωa – 2ωb ± Ωb/√2 and have spectral widths of the order of 3γ0/4. The ratio of the height of the band ω = ωa – 2ωb to the height ω = ωa – 2ωb ± Ωb/2 is 3:2. The probability amplitudes for both bands take large negative values indicating that optical amplification of the signal field may be expected to occur at these frequencies. When Ωa = Ωb = Ω, η = 1, and for Ω2 < γ02, the spectral function describes a single band at ω = ωa – 2ωb while for Ω2 > γ02, the single band splits into five pairs of bands which are separated from the frequency ω = ωa – 2ωb by frequency shifts which are equal to: ± Ω/√2, [Formula: see text], ± Ω, ± Ω√2, and ± Ω√3, respectively, and have spectral widths of the order of 3γ0/4. For [Formula: see text] and for laser fields for which Ωa2 > γ02 and Ωb2 > γ02, the spectral function consists of three pairs of bands. The probability amplitudes for these bands vary linearly with η and may take large values for [Formula: see text]. A complete discussion of the excitation spectrum as well as a graphical representation of the derived results has been given.

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

1992 ◽  
Vol 70 (6) ◽  
pp. 427-431 ◽  
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.

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

1990 ◽  
Vol 68 (4-5) ◽  
pp. 411-421 ◽  
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.

Non-linear optical mixing of frequencies of a strong bichromatic field interacting with a two-level atom at high photon densities

1983 ◽  
Vol 49 (3) ◽  
pp. 631-643 ◽  
Author(s):  
Constantine Mavroyannis ◽  
K.J. Woloschuk
Keyword(s):  
Level Atom ◽  
Bichromatic Field ◽  
Non Linear ◽  
Optical Mixing ◽  
Linear Optical

ENHANCEMENT AND EXTENSION OF HIGH-ORDER HARMONIC EMISSION AND AN ISOLATED SUB-100 AS PULSE GENERATION FROM TWO-COLOR LASER FIELDS

2010 ◽  
Vol 09 (04) ◽  
pp. 735-744 ◽  
Author(s):  
YA-HUI GUO ◽  
HAI-XIANG HE ◽  
JIAN-YONG LIU ◽  
GUO-ZHONG HE
Keyword(s):  
Laser Pulse ◽  
Delay Time ◽  
Laser Field ◽  
Extreme Ultraviolet ◽  
Pulse Generation ◽  
Laser Fields ◽  
High Order Harmonic ◽  
Fundamental Laser ◽  
Color Scheme ◽  
Selection Of

We theoretically propose a method to generate a coherent and ultrabroad extreme ultraviolet supercontinuum using Ar + ions. When the medium is exposed to a two-color laser field, which is synthesized by a few-cycle fundamental laser pulse and its second-harmonics pulse, the harmonics spectrum presents a two-plateau structure. For the selection of the short quantum path utilizing the two-color scheme, the supercontinuum in the second plateau is almost synchronously emitted and a single 58 attosecond (as) pulse can be directly obtained. By increasing the intensity of the controlling field or adjusting the delay time of the two laser fields, a more intense isolated as pulse will be generated.

Excitation spectra for the V configuration of a three-level atom in resonance with two laser fields

1985 ◽  
Vol 63 (2) ◽  
pp. 144-150
Author(s):  
D. A. Hutchinson
Keyword(s):  
Excited States ◽  
Excitation Spectrum ◽  
Ground State ◽  
Central Peak ◽  
Decay Rates ◽  
Closed Form Expression ◽  
Form Expression ◽  
Excitation Spectra ◽  
Level Atom ◽  
Special Cases

The excitation spectrum is calculated for a three-level atom interacting with two strong electromagnetic fields. The two fields are in resonance with the atomic transition frequencies from the ground state to the two excited states. The excitation spectrum consists of a central peak and two pairs of side bands for each of the two transitions. If the decay rates of the two excited states are equal a relatively simple closed form expression is derived for the excitation spectrum. For unequal decay rates numerical methods are used to determine the excitation spectrum for selected special cases.

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