17 research outputs found
Polaritonic modes in a dense cloud of atoms
We analyze resonant light scattering by an atomic cloud in a regime where
near-field interactions between scatterers cannot be neglected. We first use a
microscopic approach and calculate numerically the eigenmodes of the cloud for
many different realizations. It is found that there always exists a small
number of polaritonic modes that are spatially coherent and superradiant. We
show that scattering is always dominated by these modes. We then use a
macroscopic approach by introducing an effective permittivity so that the
atomic cloud is equivalent to a dielectric particle. We show that there is a
one-to-one correspondence between the microscopic polaritonic modes and the
modes of a homogeneous particle with an effective permittivity
On-Chip Backward Stimulated Brillouin Scattering in Lithium Niobate Waveguides
We report on the first experimental demonstration of backward stimulated
Brillouin scattering (SBS) in Lithium Niobate on Insulator (LNOI) waveguides.
Performing polarization-dependent pump-probe experiments, we successfully
quantified both intramodal and intermodal scattering among fundamental modes,
showcasing substantial gains up to 10mW. Such large gains
on simple waveguides open a pathway for unlocking novel opto-electro-mechanical
phenomena within the LNOI platform
Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors
Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe
Guidelines for postoperative care in gynecologic/oncology surgery: Enhanced Recovery After Surgery (ERAS®) Society recommendations - Part II.
This article is freely available via Open Access. Click on the 'Additional Link' above to access the full-text via the publisher's site.Published (Open Access
Revisiting the Role of Metallic Antennas to Control Light Emission by Lead Salt Nanocrystal Assemblies
International audienceThin films of lead salt nanocrystals (NCs) offer attractive opportunities as active media for near-infrared optoelectronics but suffer from limiting trade-offs between optical and electrical properties. While NCs separated by nanometer-long ligands are good light emitters, NCs capped with shorter molecules provide a high carrier mobility but degrade the photo- and electroluminescence and broaden the narrow emission spectrum. Here we show that this severe quenching and spectral broadening can be averted with an unconventional use of metallic antennas. The resulting NC-antenna hybridization not only provides a strong boost in luminescence, but also makes it possible to remodel the emission spectrum in radical ways, even at wavelengths where the NC assembly does not emit light. These results cannot be explained with the standard theory of single-emitter luminescence assisted by optical antennas. We propose an alternative model based on a statistical description of light emission by an ensemble of emitters and discuss important consequences of our findings for nano-optics and solution-processed optoelectronics
Topological photonic crystals in the visible: design and angle-resolved characterization of the bulk and edge states
We fabricated and characterized photonic crystals with non-trivial topological bulk states and pseudo-time-reversal-symmetry protected helical edge states in the visible regime. With a 30-keV electron beam, we excite coherent cathodoluminescence in the nanostructured material and derive photonic band structures
Electrons Generate Self-Complementary Broadband Vortex Light Beams Using Chiral Photon Sieves
Restoration of s-polarized evanescent waves and subwavelength imaging by a single dielectric slab
It was predicted a few years ago that a medium with negative index of refraction would allow for perfect imaging. Although no material has been found so far that behaves as a perfect lens, some experiments confirmed the theoretical predictions in the near-field, or quasi-static, regime where the behaviour of a negative index medium can be mimicked by a thin layer of noble metal, such as silver. These results are normally attributed to the excitation of surface plasmons in the metal, which only leads to the restoration of p-polarized evanescent waves. In this work, we show that the restoration of s-polarized evanescent waves and, correspondingly, sub-wavelength imaging by a single dielectric slab are possible. Specifically, we show that at ? = 632 nm a thin layer of GaAs behaves as a superlens for s-polarized waves. Replacing the single-metal slab by a dielectric is not only convenient from a technical point of view, it being much easier to deposit and control the thickness and flatness of dielectric films than metal ones, but also invites us to re-think the connection between surface plasmon excitation and the theory of negative refraction.Imaging Science and TechnologyApplied Science