RESUMO
We use low-resolution optical lithography joined with solid state dewetting of crystalline, ultra-thin silicon on insulator (c-UT-SOI) to form monocrystalline, atomically smooth, silicon-based Mie resonators in well-controlled large periodic arrays. The dewetted islands have a typical size in the 100 nm range, about one order of magnitude smaller than the etching resolution. Exploiting a 2 µm thick SiO2 layer separating the islands and the underlying bulk silicon wafer, we combine the resonant modes of the antennas with the etalon effect. This approach sets the resonance spectral position and improves the structural colorization and the contrast between scattering maxima and minima of individual resonant antennas. Our results demonstrate that templated dewetting enables the formation of defect-free, faceted islands that are much smaller than the nominal etching resolution and that an appropriate engineering of the substrate improves their scattering properties. These results are relevant to applications in spectral filtering, structural color and beam steering with all-dielectric photonic devices.
RESUMO
We present experimental evidence for the different mechanisms driving the fluctuations of the local density of states (LDOS) in disordered photonic systems. We establish a clear link between the microscopic structure of the material and the frequency correlation function of LDOS accessed by a near-field hyperspectral imaging technique. We show, in particular, that short- and long-range frequency correlations of LDOS are controlled by different physical processes (multiple or single scattering processes, respectively) that can be-to some extent-manipulated independently. We also demonstrate that the single scattering contribution to LDOS fluctuations is sensitive to subwavelength features of the material and, in particular, to the correlation length of its dielectric function. Our work paves a way towards complete control of statistical properties of disordered photonic systems, allowing for designing materials with predefined correlations of LDOS.
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We report on the observation of Anderson localization of near-visible light in two-dimensional systems. Our structures consist of planar waveguides in which disorder is introduced by randomly placing pores with controlled diameter and density. We show how to design structures in which localization can be observed and describe both the realization of the materials and the actual observation of Anderson localized modes by near-field scanning microscopy.
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A revisited realization of the Young's double slit experiment is introduced to directly probe the photonic mode symmetry by photoluminescence experiments. We experimentally measure the far field angular emission pattern of quantum dots embedded in photonic molecules. The experimental data well agree with predictions from Young's interference and numerical simulations. Moreover, the vectorial nature of photonic eigenmodes results in a rather complicated parity property for different polarizations, a feature which has no counterpart in quantum mechanics.
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Successful management of a patient with an intracardiac tumor thrombus of renal carcinoma is described. This case and a few others in the literature have led us to consider the clinical signs of cavo-atrial obstruction, frequently silent and unspecific; the diagnostic methodology, especially based upon CAT scan and cavography, and the type of surgery and surgical technique called for, especially as regards the approach and the possible use of extracorporeal circulation (ECC).
Assuntos
Adenocarcinoma/cirurgia , Átrios do Coração , Neoplasias Renais/patologia , Células Neoplásicas Circulantes , Veia Cava Inferior , Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/patologia , Feminino , Átrios do Coração/diagnóstico por imagem , Humanos , Neoplasias Renais/diagnóstico por imagem , Neoplasias Renais/cirurgia , Métodos , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X , Veia Cava Inferior/diagnóstico por imagemRESUMO
A patient with superior vena cava thrombosis from cancer of the right lung is described. The particular interest of this case resides in: The numerical scantiness of cases reported in the literature: 12 cases reviewed; The exceptional nature of the etiopathogenic mechanism: paraneoplastic thrombosis; and the more precise problems relating to the indication, technique and tactics with respect to surgery.
Assuntos
Cardiopatias/cirurgia , Neoplasias Pulmonares/cirurgia , Síndromes Paraneoplásicas/etiologia , Pneumonectomia/métodos , Trombose/cirurgia , Veia Cava Superior/cirurgia , Adenocarcinoma/complicações , Adenocarcinoma/cirurgia , Adenocarcinoma Bronquioloalveolar/complicações , Adenocarcinoma Bronquioloalveolar/cirurgia , Idoso , Circulação Extracorpórea , Átrios do Coração/cirurgia , Humanos , Veias Jugulares/diagnóstico por imagem , Neoplasias Pulmonares/complicações , Masculino , Radiografia , Trombose/diagnóstico por imagem , Trombose/etiologiaRESUMO
As materials functionality becomes more dependent on local physical and electronic properties, the importance of optically probing matter with true nanoscale spatial resolution has increased. In this work, we mapped the influence of local trap states within individual nanowires on carrier recombination with deeply subwavelength resolution. This is achieved using multidimensional nanospectroscopic imaging based on a nano-optical device. Placed at the end of a scan probe, the device delivers optimal near-field properties, including highly efficient far-field to near-field coupling, ultralarge field enhancement, nearly background-free imaging, independence from sample requirements, and broadband operation. We performed ~40-nanometer-resolution hyperspectral imaging of indium phosphide nanowires via excitation and collection through the probes, revealing optoelectronic structure along individual nanowires that is not accessible with other methods.