High-order optical nonlinearity at low light levels

Greenberg, Joel A.; Gauthier, Daniel J.

doi:10.1209/0295-5075/98/24001

Cited by 33 publications

(24 citation statements)

References 39 publications

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“…We observe that decreasing |∆| and increasing OD result in smaller values of I thresh , since these changes enhance the lightmatter coupling strength [19,21]. The measured values of I thresh agree well with the model developed in Refs.…”

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confidence: 89%

“…The measured values of I thresh agree well with the model developed in Refs. [19] and [21] to describe the light-matter interaction in our system, where we take I thresh as the value of I p for which the gain becomes infinite. The lowest threshold we measure is I thresh = 1.1 ± 0.25 mW/cm 2 , which occurs for ∆/Γ = −3 and OD = 20 ± 1 and is comparable to the threshold intensity observed for a Bose-Einstein condensate [8].…”

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confidence: 99%

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Steady-state, cavityless, multimode superradiance in a cold vapor

Greenberg

Gauthier

2012

Phys. Rev. A

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We demonstrate steady-state, mirrorless superradiance in a cold vapor pumped by weak optical fields. Beyond a critical pump intensity of 1 mW/cm 2 , the vapor spontaneously transforms into a spatially self-organized state: a density grating forms. Scattering of the pump beams off this grating generates a pair of new, intense optical fields that act back on the vapor to enhance the atomic organization. We map out experimentally the superradiant phase transition boundary and show that it is well-described by our theoretical model. The resulting superradiant emission is nearly coherent, persists for several seconds, displays strong temporal correlations between the various modes, and has a coherence time of several hundred µs. This system therefore has applications in fundamental studies of many-body physics with long-range interactions as well as all-optical and quantum information processing. The study of collective light-matter interactions, where the dynamics of an individual scatterer depend on the state of the entire multi-scatterer system, has recently received much attention in the areas of fundamental research and photonic technologies [1,2]. One prominent example of collective behavior is superradiance [3], where light-induced couplings between initially incoherentlyprepared emitters cause the full ensemble to synchronize and radiate coherently [4]. While early studies of superradiance focused on collective scattering via the emitters' internal degrees of freedom, recent work demonstrates that formally identical behavior arises through the manipulation of the center-of-mass positions and momenta of cold atoms [5][6][7].In these studies, an initially uniformly-distributed gas of atoms pumped by external optical fields spontaneously undergoes a transition to a spatially-ordered state under certain circumstances [5][6][7][8]. This ordering arises from the momentum imparted to the atoms via optical scattering and can be understood as a form of atomic synchronization: instead of the atoms scattering light individually, the self-assembled density grating enables the entire ensemble to coherently scatter light as a single entity. The pump beams scatter off this grating and produce new optical fields that act back on the vapor to enhance the grating contrast. This emergent, dynamical organization can lead to reduced optical instability thresholds [9] and new phenomena [10] that are inaccessible using static, externally-imposed optical lattices [11].In order for superradiance to occur, the system must posses sufficient gain and feedback so that synchronization occurs more rapidly than dephasing. The main dephasing mechanisms are grating washout due to thermal atomic motion and the loss of photons from the interaction volume [5]. One can overcome the effects of thermal motion in free space by working at ultracold temperatures (T < 3 µK) and using optical fields detuned far from the atomic resonance in order to avoid recoilinduced heating [8,12]. Multi-mode superradiance has been observed in such systems [8], althou...

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Steady-state, cavityless, multimode superradiance in a cold vapor

Greenberg

Gauthier

2012

Phys. Rev. A

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“…In recent years, self-organizing instabilities due to the opto-mechanical coupling of light and cold [9][10][11][12][13][14] and ultracold [15,16] atoms have attracted remarkable interest. In many of these schemes a pump beam is scattered by the gas into an externally imposed mode (often selected by a cavity).…”

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Kinetic Theory for Transverse Optomechanical Instabilities

et al. 2014

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This version is available at https://strathprints.strath.ac.uk/47887/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.

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“…When coupling the dynamics of light and the centre-of-mass degrees of freedom of laser-cooled atoms, the dynamics becomes nonlinear and, above a critical value for the energy injected into the system, a transition is observed from a spatially homogeneous state to a state displaying some form of long-range order. This can be obtained in various configurations: transversally pumped cavities [1] where collective dynamics and self-organization in cold [2,3] and ultracold [4] gases have been investigated; collective atomic recoil lasing (CARL) where the spontaneous generation of a back-scattered beam within a monodirectional cavity is self-sustained by atomic bunching in the resulting optical potential [5][6][7]; in a counter-propagating geometry super-radiance and highorder nonlinearities stemming from atomic bunching have been studied [8][9][10] a continuous translational symmetry in the presence of a strong viscous damping was investigated for both cavity [11,12] and counter-propagating [10,13,14] geometries, whereas a single-mirror geometry in the absence of damping was the focus of recent theoretical [15] and experimental [16] research. The distinguishing feature of these studies is that the spatial scale of the emerging spatial structure is self-selected, so that the spontaneous breaking of two continuous symmetries is observed (rotations and translations in the plane).…”

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Self-organization in cold atomic gases: a synchronization perspective

Tesio

Robb

Oppo

et al. 2014

Phil. Trans. R. Soc. A.

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We study non-equilibrium spatial self-organization in cold atomic gases, where long-range spatial order spontaneously emerges from fluctuations in the plane transverse to the propagation axis of a single optical beam. The self-organization process can be interpreted as a synchronization transition in a fully connected network of fictitious oscillators, and described in terms of the Kuramoto model.

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High-order optical nonlinearity at low light levels

Cited by 33 publications

References 39 publications

Steady-state, cavityless, multimode superradiance in a cold vapor

Steady-state, cavityless, multimode superradiance in a cold vapor

Kinetic Theory for Transverse Optomechanical Instabilities

Self-organization in cold atomic gases: a synchronization perspective

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