Random lasing in an inhomogeneous and disordered system of cold atoms

Gerasimov, L. V.; Kuprianov, D. V.; Havey, M. D.

doi:10.1134/s0030400x1509009x

Cited by 4 publications

(5 citation statements)

References 32 publications

(47 reference statements)

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“…In recent years they have attracted a great deal of attention, mainly due to the versatility stemming from cavity-less geometries and the ease of realization [1][2][3][4][5][6][7][8][9]. In liquid crystals, suitable dopants can provide the gain action through optical pumping, while optical birefringence in conjunction with intense fluctuations of the dielectric tensor yield the required recurrent multiple scattering for random resonances to occur [10][11][12][13][14][15][16][17].…”

mentioning

confidence: 99%

Soliton-assisted random lasing in optically-pumped liquid crystals

Perumbilavil

Piccardi

Buchnev

et al. 2016

Applied Physics Letters

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We demonstrate a novel random laser configuration by exploiting the coexistence of optical gain and light self-localization in a reorientational nonlinear medium. A spatial soliton launched by a near-infrared beam in dye-doped nematic liquid crystals enhances and confines stimulated emission of visible light in the optically-pumped gain-medium, yielding random lasing with enhanced features.In random lasers, a disordered distribution of scattering centers provides the required feedback for oscillations in optically amplifying media. In recent years they have attracted a great deal of attention, mainly due to the versatility stemming from cavity-less geometries and the ease of realization [1][2][3][4][5][6][7][8][9]. In liquid crystals, suitable dopants can provide the gain action through optical pumping, while optical birefringence in conjunction with intense fluctuations of the dielectric tensor yield the required recurrent multiple scattering for random resonances to occur [10][11][12][13][14][15][16][17]. In the nematic phase, moreover, liquid crystals are positive uniaxial materials subject to optic axis reorientation under the action of electric fields, either at low or optical frequencies [18]. The latter response provides a low-power mechanism for nonlinear optics [19] and light localization into self-confined lightbeams, the so-called "nematicons" [20]. Nematicons are bright spatial solitons (solitary waves) which are stable in two transverse dimensions due to the nonlocal response associated with the elastic intermolecular links in the liquid state [21,22]; they support graded-index waveguides able to confine additional (incoherent) signals/beams of different wavelengths as well as powers and profiles [23][24][25][26][27][28][29][30], are robust against refractive index perturbations [31-35] and collisional interactions [36][37][38]. Aided by nematicons, reorientational and electronic nonlinear responses, characterized by distinct time-and power-scales, can synergystically be combined [39,40]. Owing to their large numerical aperture [41], nematicon waveguides solitons have also been employed in experiments involving incoherent light generation by fluorescence [42] or amplified spontaneous emission [43], offering a means to better collect and couple the emitted light into optical fibers.In this Letter we demonstrate a novel example of synergy between diverse nonlinear responses: the combination of spatial solitons and random lasing into a "nematicon random laser", whereby a low-power self-confined beam provides a guided-wave landscape for the stimu- * assanto@uniroma3.it lated emission induced by collinear optical pumping of dye-doped nematic liquid crystals (NLC).Several benefits can be expected from adopting such light-induced guided-wave configuration for random lasing. At variance with standard thin film geometries, the thick NLC cell provides an extended volume where optical pumping can produce fluorescence and, in turn, stimulated emission and lasing action via random scattering and feedback. The la...

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confidence: 99%

Soliton-assisted random lasing in optically-pumped liquid crystals

Perumbilavil

Piccardi

Buchnev

et al. 2016

Applied Physics Letters

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“…Such an approach evidently ignores any cross interference in the process of multiple scattering, which seems a rather realistic assumption for a dilute and disordered atomic gas. The applicability of the Bethe-Salpeter approach has been successfully demonstrated for the theory of random lasing, see [46,47] In this section we show that even in taking a sim-pler approximation by transforming the Bethe-Salpeter equation to the light transport equation, and taking into account only the attenuation of the probe beam in the atomic sample, following the Beer-Lambert law, is enough to explain the data with a rather good agreement. This shows that the main physical ingredient of the experiment is the so-called "shadow effect": atoms at the back of the sample are less illuminated by the incident laser, which induces an effective reduction of the total scattering cross-section compared to a collection of independent atoms illuminated by the same laser intensity.…”

Section: B Rescaling According To the Beer-lambert Lawmentioning

confidence: 74%

Optical-depth scaling of light scattering from a dense and cold atomic Rb87 gas

et al. 2020

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We report investigation of near-resonance light scattering from a cold and dense atomic gas of 87 Rb atoms. Measurements are made for probe frequencies tuned near the F = 2 → F ′ = 3 nearly closed hyperfine transition, with particular attention paid to the dependence of the scattered light intensity on detuning from resonance, the number of atoms in the sample, and atomic sample size. We find that, over a wide range of experimental variables, the optical depth of the atomic sample serves as an effective single scaling parameter which describes well all the experimental data.

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“…If this active area was surrounded by the atoms trapping the emitted light, that would induce a certain soft cavity feedback and can create instability in the system. Such option has been recently demonstrated by a round of Monte-Carlo simulations in [71] In Fig. 4.4 we show the proposed experimental architecture, which implies preparation of a spatially inhomogeneous energy structure and population distribution of the hyperfine sublevels in the atomic ensemble.…”

Section: Random Lasing In a Inhomogeneous And Disordered System Of Comentioning

confidence: 80%

“…A second constraint would be that the soft cavity should be transversely small, on the order of a few microns or less, in order to limit the number of transverse optical quasimodes within the approximately cylindrical channel geometry. Further discussion of experimental feasibility of the scheme is performed in [71].…”

Section: Random Lasing In a Inhomogeneous And Disordered System Of Co...mentioning

confidence: 99%

Mesoscopic coherence in light scattering from cold, optically dense and disordered atomic systems

2017

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Coherent effects manifested in light scattering from cold, optically dense and disordered atomic systems are reviewed from a primarily theoretical point of view. Development of the basic theoretical tools is then elaborated through several physical atomic physics based processes which have been at least partly explored experimentally. These include illustrations drawn from the coherent backscattering effect, random lasing in atomic gases, quantum memories and light-atoms interface assisted by the light trapping mechanism. Current understanding and challenges associated with the transition to high atomic densities and cooperativity in the scattering process is also discussed in some detail.

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Random lasing in an inhomogeneous and disordered system of cold atoms

Cited by 4 publications

References 32 publications

Soliton-assisted random lasing in optically-pumped liquid crystals

Soliton-assisted random lasing in optically-pumped liquid crystals

Optical-depth scaling of light scattering from a dense and cold atomic Rb87 gas

Mesoscopic coherence in light scattering from cold, optically dense and disordered atomic systems

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