Line shape theory for a Doppler‐broadened signal in presence of an infrared pump
15 Oct 1985-Journal of Chemical Physics (American Institute of Physics)-Vol. 83, Iss: 8, pp 4015-4023
TL;DR: In this article, a theory of line shape for a Doppler broadened probe in the presence of a strong infrared pump is presented; the T1, T2 relaxations are introduced phenomenologically in these equations.
Abstract: A theory of line shape for a Doppler broadened probe in the presence of a strong infrared pump is presented. The optical analog of Bloch equations has been developed; the T1, T2 relaxations are introduced phenomenologically in these equations. Doppler broadening of both the pump and signal transitions are taken into account to obtain the absorption coefficient for the signal. This leads to a Doppler broadened Gaussian function weighted by a pump induced Lorentzian function whose position and linewidth are controlled by the detuning and power respectively of the pump radiation. The absorption coefficient is further modulated by a Lorentzian function containing the fourth power of the radiation. The off‐resonance pumping leads to two symmetrically located ‘‘Lamb dips’’ or ‘‘peaks’’ around the Gaussian pedestal for co‐ and counter propagating laser radiations. A calculation of the line shape of the central sub‐Doppler feature for the on‐resonance pumping is in good agreement with the observed variation of li...
TL;DR: In this paper, the lineshape of a pair of Doppler-free closely spaced transitions sharing a common level in the presence of a uniform radiation field is studied numerically.
TL;DR: In this paper, strong double-resonance signals are observed in silane pumped with a TEA-CO 2 laser and probed with a tunable diode laser, and the lineshapes of these signals have been modeled with an extension of three level density matrix theory to the case of a large bandwidth pump laser.
TL;DR: In this article, the interaction of two electromagnetic radiations with a four-level atom with two closely spaced common levels is studied for the cascade system, where the spacing between the close levels is assumed to be small so that the radiation frequency can act simultaneously on the two closely-spaced resonances.
TL;DR: The lineshapes of Fermi diads of thioacetamide and methyl thiourea have been measured at different temperatures in the 120-300 K range as mentioned in this paper.
Abstract: The lineshapes of Fermi diads of thioacetamide and methyl thiourea have been measured at different temperatures in the 120–300 K range. For computation of the lineshape, the dynamic part of the Fermi resonance interaction has been considered as a random perturbation by Redfield's theory. The optical Bloch equations are set up including the Redfield relaxation terms. The steady state solution of these equations lead to the absorption spectrum. The computed lineshape of a Fermi diad is shown to be a superposition of two Lorentzians and an interaction term. The linewidth of the Lorentzians are controlled by the Redfield and 1/ T 2 relaxation terms. The comparison of the computed curves with the observed spectra demonstrates the importance of the dynamic part of the interaction on the lineshape.
TL;DR: In this paper, a set of coupled optical Bloch equations has been solved to obtain the absorption lineshape for both copropagating and counter-propagating three-level double resonances in the presence of a strong infrared laser source.
01 Jan 1964
01 Apr 1977
TL;DR: In this paper, the theory of Resonant Interaction of a Laser Field and Gas was introduced and Narrow Saturation Resonances on Doppler-Broadened Transition was discussed.
Abstract: 1. Introduction.- 2. Elements of the Theory of Resonant Interaction of a Laser Field and Gas.- 3. Narrow Saturation Resonances on Doppler-Broadened Transition.- 4. Narrow Resonances of Two-Photon Transitions Without Doppler Broadening.- 5. Nonlinear Resonances on Coupled Doppler-Broadened Transitions.- 6. Narrow Nonlinear Resonances in Spectroscopy.- 7. Nonlinear Atomic Laser Spectroscopy.- 8. Nonlinear Molecular Laser Spectroscopy.- 9. Nonlinear Narrow Resonances in Quantum Electronics.- 10. Narrow Nonlinear Resonances in Experimental Physics.- 11. Conclusion.- Author Index.
01 Jan 1975
TL;DR: In this paper, a laser amplifier consisting of an ensemble of atoms, three energy levels of which form two coupled transitions of arbitrary frequencies, is treated, and the gain profile (or spontaneous emission) on the transition corresponding to the weak probe wave, modified by the perturbing field on the other transition, is calculated via a susceptibility.
Abstract: A laser amplifier to be treated in this work consists of an ensemble of atoms three energy levels of which form two coupled transitions of arbitrary frequencies. Two classical monochromatic travelling light waves are to be close to resonance with the transitions. The gain profile (or spontaneous emission) on the transition corresponding to the weak “probe” wave, modified by the perturbing field on the other transition, is calculated via a susceptibility. Within this framework, the atoms are described by an ensemble-averaged density matrix with full account of level degeneracies, light polarizations, and inelastic and dephasing collisions; an extension to elastic collisions and disorientation is straightforward. An integration over the thermal velocity distribution gives results applicable to gas discharges: directionally anisotropic narrow structures superimposed on the Doppler-broadened probe-gain profile due to non-linear interference effects in addition to saturation. At alower probe frequency, a peculiar non-Lorentzian signal appears even with transparency on the perturbing transition. At low intensities a distinction is reasonable of frequency correlations due to generalized two-quantum processes, and of a dynamic Stark splitting. These effects permit an information on the linewidth of the third forbidden transition. The connection with numerous related approaches is pointed out.
TL;DR: Laser induced line narrowing in coupled Doppler broadened transitions, noting mode crossing and spontaneous emission as mentioned in this paper, was shown to be useful in the detection of spontaneous emission in the presence of laser.
Abstract: Laser induced line narrowing in coupled Doppler broadened transitions, noting mode crossing and spontaneous emission