Phase and amplitude near-resonance self-action in periodically modulated laser beams

Derbov, Vladimir L.; Serov, Vladislav V.; Пластун, И. Л.; Larionov, D.A.

doi:10.1109/icton.2003.1263133

Cited by 2 publications

(4 citation statements)

References 11 publications

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“…When the period of modulation approaches the atomic relaxation times, it becomes necessary to solve simultaneously the full set of equations, describing the field propagation and the medium response as processes distributed in time and space. In our previous paper [1] we have considered the propagation of a beam, having initially the Gaussian transverse profile and the frequency, harmonically modulated in time, through a two-level near-resonance medium with saturation of absorption and refraction. Within the framework of the scalar paraxial approximation an algorithm for direct numerical solution of relevant Maxwell-Bloch equations was developed using the decomposition in terms of Gauss-Laguerre modes for the transverse field pattern and the second-order implicit scheme for propagation.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, in the present paper we use the model and algorithm described in [1] to simulate the measurement of the output on-axis intensity I versus the input instantaneous frequency co defined as the time derivative of the beam phase. It appears that the dependence I(w) is extremely sensitive both to the temporal effects of the delayed medium response and to the spatial effects of beam self-focusing and selfaperturing.…”

Section: Introductionmentioning

confidence: 99%

“…MATHEMATICAL MODEL Using the scalar paraxial approximation the propagation of a modulated axially symmetric laser beam through a two-level medium can be described by a set of normalized Maxwell-Bloch equations [1] 2i1a + I a +V2 E =gP(1 (az c at ) (1) aD =y[D-t+i(E* P-E P*)] 213 We.B1.4…”

Section: Introductionmentioning

confidence: 99%

“…(1) -(3) we use the second-order scheme for the evolution in z and t, while the transverse structure of the field is approximated by the decomposition in terms of Laguerre-Gauss modes [1]. The input laser frequency is considered to be harmonically modulated, c0(t) = coo + c sin Qt, where coo is the carrier laser frequency, c is the amplitude of the frequency modulation, Q is the frequency of modulation.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Transient Phenomena and Time-Dependent Resonance Self-Action in Phase-Modulated Laser Beams

Derbov

Serov

Пластун

et al. 2007

2007 9th International Conference on Transparent Optical Networks

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Transient behaviour of a phase-modulated laser beam in a two-level saturable absorber is studied basing of full spatio-temporal scalar numerical model. Joint effect of delayed self-focusing and transient response of the medium are shown to manifest themselves most clearly in the dependence of the output intensity of the beam upon its input instantaneous frequency, which is most relevant in spectroscopic measurements.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transient Phenomena and Time-Dependent Resonance Self-Action in Phase-Modulated Laser Beams

Derbov

Serov

Пластун

et al. 2007

2007 9th International Conference on Transparent Optical Networks

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Non-Stationary Saturated Absorption and Refraction Effects in Laser Beams with Periodical Modulation of Frequency

Derbov

Пластун

Serov

et al. 2006

2006 International Workshop on Laser and Fiber-Optical Networks Modeling

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Periodical modulation of frequency, typical for spectroscopic purposes, is numerically modelled in transversely limited, propagating through a saturable two-level absorber. At modulation periods comparable with the atomic relaxation times the time and frequency dependence of the output intensity exhibits the manifestations of delayed medium response, including time-dependent lens and aperture effects that may be of importance in spectroscopy.Laser beam due to saturated refraction and absorption in near-resonance media has been extensively studied since predicted theoretically [1] and observed experimentally [2], including the extremely high absorption and saturation conditions (see, e.g., [3]). In particular, near-resonance self-focusing has been shown to yield asymmetry in the transmission spectra [4]. To get a transmission spectrum one usually has to vary the laser frequency periodically in the vicinity of the atomic resonance. When the frequency variation is slow, the medium response follows it adiabatically and the steady-state susceptibility theory is valid. The situation is different when the modulation period approaches the atomic relaxation times. In this case the transient (in general, nonlinear) response of the medium can be correctly described only within the full spatio-temporal description based on Maxwell-Bloch equations. Numerical implementations of such approaches are well-known in short pulse (see, e.g., [5]) Experimental manifestations of non-stationary near-resonant self-focusing of frequencymodulated beams have been reported before in saturation spectroscopy [6].Previously (see [7] and references therein) we have presented the method and some results of the numerical modeling of transient near-resonance self-action of periodically modulated beams. Now we focus our attention on the dependence of the output intensity upon the input laser frequency, which is supposed to be harmonically modulated. It appears that this dependence is very sensitive to the non-stationary properties of the medium that start to manifest themselves at relatively low modulation frequencies of the order of 10% of the transition width. Specific oscillatory features due to transient response of the medium are observed at large modulation amplitudes.Passing through a resonant absorbing medium, the frequency-modulated beam gradually acquires intensity modulation, which is neither nonlinear, nor transient and caused merely by different absorption at different frequencies. In weak fields this effect is independent of refraction, since the latter is linear, and, thus, no induced lens appears. First, we calculate the output intensity versus the input laser frequency sweeping periodically the near-resonance region. We start from weak non-saturating fields to distinguish between the non-stationary and nonlinear effects. The latter are included by increasing the field amplitude

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Phase and amplitude near-resonance self-action in periodically modulated laser beams

Cited by 2 publications

References 11 publications

Transient Phenomena and Time-Dependent Resonance Self-Action in Phase-Modulated Laser Beams

Transient Phenomena and Time-Dependent Resonance Self-Action in Phase-Modulated Laser Beams

Non-Stationary Saturated Absorption and Refraction Effects in Laser Beams with Periodical Modulation of Frequency

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