Quantum Theory of the Propagation of Nonclassical Light in a Near-Resonant Medium and its Application to Cone Emission

A time-dependent theory for conical emission during near-resonant propagation of laser light in an atomic vapor, which includes full propagation for the laser and frequency sidebands in a nonlinear two-level medium is presented. The density-matrix equations for the dipole moment and population are solved in the dressed atomic frame. The polarization source terms are accurate to order \ensuremath{\gamma}/R, where \ensuremath{\gamma} is a damping constant and R is the generalized Rabi frequency. Analytical plane-wave solutions and numerical, cylindrically symmetric propagation simulations including diffraction are presented. It is shown that the calculations with cylindrically symmetric fields and atomic excitation profiles are incapable of accounting for the high levels of optical gain that are responsible for the intense conical emission observed in experiments. This result is at first surprising, since the model accounts rigorously for all of the physical phenomena that have been previously proposed as being responsible for generating large gains, and the calculation matches the symmetry of the observations. The lack of large calculated gain seems to imply the existence of higher-order $(m>0)$ radial modes in the field for the experimental conditions that give rise to cone emission. In the simulations, however, the cylindrically symmetric fields do produce weak red-detuned cones with angular-frequency distributions similar to those seen in experiments.A time-dependent theory for conical emission during near-resonant propagation of laser light in an atomic vapor, which includes full propagation for the laser and frequency sidebands in a nonlinear two-level medium is presented. The density-matrix equations for the dipole moment and population are solved in the dressed atomic frame. The polarization source terms are accurate to order \ensuremath{\gamma}/R, where \ensuremath{\gamma} is a damping constant and R is the generalized Rabi frequency. Analytical plane-wave solutions and numerical, cylindrically symmetric propagation simulations including diffraction are presented. It is shown that the calculations with cylindrically symmetric fields and atomic excitation profiles are incapable of accounting for the high levels of optical gain that are responsible for the intense conical emission observed in experiments. This result is at first surprising, since the model accounts rigorously for all of the physical phenomena that have been previously proposed as being responsible for generating large gains, and the calculation matches the symmetry of the observations. The lack of large calculated gain seems to imply the existence of higher-order $(m>0)$ radial modes in the field for the experimental conditions that give rise to cone emission. In the simulations, however, the cylindrically symmetric fields do produce weak red-detuned cones with angular-frequency distributions similar to those seen in experiments.

Physical Review ADec 31, 20028 citations

Quantum optics and nonclassical light generation

Rahul Trivedi, Daniil M. Lukin, Jelena Vuckovic A

Jan 1, 20201 citation

Quantum Aspects of Light Propagation

Antonín Luk¿, Vlasta Peřinová

Springer eBooksJan 1, 200924 citations

Cone emission from laser-pumped two-level atoms. I. Quantum theory of resonant light propagation

Li You, Jan Mostowski, J. Cooper

This is the first of a series of papers on the theory of cone emission from a laser-pumped two-level atomic medium. Starting from microscopic quantum theory for both the active medium and the field, equations for the slowly varying macroscopic quantities are derived. In the steady-state limit, which experimentally corresponds to cw excitation, we find that the sources for the paraxial fields of interest have a long coherence length despite the random nature of spontaneous emission. These radiation sources enter into the equations for the fields in the same form as the source generated by four-wave mixing and therefore may be considered as a ``spontaneous four-wave mixing,'' since the photons emitted in the Rabi sidebands are correlated. This has far-reaching consequences on the physics of cone emission and also sheds some new light on the fluoresence from strongly driven atomic systems.This is the first of a series of papers on the theory of cone emission from a laser-pumped two-level atomic medium. Starting from microscopic quantum theory for both the active medium and the field, equations for the slowly varying macroscopic quantities are derived. In the steady-state limit, which experimentally corresponds to cw excitation, we find that the sources for the paraxial fields of interest have a long coherence length despite the random nature of spontaneous emission. These radiation sources enter into the equations for the fields in the same form as the source generated by four-wave mixing and therefore may be considered as a ``spontaneous four-wave mixing,'' since the photons emitted in the Rabi sidebands are correlated. This has far-reaching consequences on the physics of cone emission and also sheds some new light on the fluoresence from strongly driven atomic systems.

Physical Review ASep 1, 199220 citations

Semiclassical study of spectral evolution under propagation in an active medium

Li You, J. Cooper

We study the propagation of a near-resonant strong laser light with a broad background continuum spectrum in a dense gaseous two-level medium. Due to the nonlinear saturation caused by the driving of the coherent component of the field, spectral regions close to the Rabi sidebands with significant gain exist close to the resonance. The subsequent evolution of the spectrum of the propagating field displays interesting features, and in the stationary limit a broadening of the spectral line always eventually happens in the end which contradicts the coherent narrowing phenomenon for pulsed propagation. This may shed some new light on the mechanisms of cone emission.We study the propagation of a near-resonant strong laser light with a broad background continuum spectrum in a dense gaseous two-level medium. Due to the nonlinear saturation caused by the driving of the coherent component of the field, spectral regions close to the Rabi sidebands with significant gain exist close to the resonance. The subsequent evolution of the spectrum of the propagating field displays interesting features, and in the stationary limit a broadening of the spectral line always eventually happens in the end which contradicts the coherent narrowing phenomenon for pulsed propagation. This may shed some new light on the mechanisms of cone emission.

Physical Review AMay 1, 19951 citation

Quantum theory and light propagation

Series in optics and optoelectronicsNov 30, 20040 citations

(m>0)

radial modes in the field for the experimental conditions that give rise to cone emission. In the simulations, however, the cylindrically symmetric fields do produce weak red-detuned cones with angular-frequency distributions similar to those seen in experiments.