The statistical distribution of the experimentally obtained higher-order moments of optical scintillation probability density is studied. It is shown that this distribution is strongly dependent on the size of the data sample. At reasonable sample sizes the correct estimation of the theoretical value is improbable. At practically available sample sizes the region of the most probable values of the estimated higher-order moment is almost independent of the scintillation probability density function (PDF). The distinction between the candidate PDFs is almost impossible at reasonable sample sizes.
We demonstrate an elliptically symmetric plasmonic lens that is illuminated by a radially-like polarization field. This illumination function is TM polarized with regard to the plasmonic lens, ensuring optimum coupling of the incident light into surface plasmons polaritons. The structure is analyzed theoretically by using the Green function approach, and a finite difference time domain simulation. Both approaches provide similar results. Specifically we calculate and experimentally measure the field distribution on the surface and a few microns above it. The results show strong dependency of the electric field distribution on the eccentricity of the elliptic structure and the illumination wavelength. The interference of surface plasmons generates a structured pattern consisting of distinct peaks distributed inside the ellipse with locations that are wavelength dependent. This pattern can be used in several applications including structured illumination microscopy, particles beam trapping and sensing.
A methodology is described for phase restoration of an object function from differential interference contrast (DIC) images. The methodology involves collecting a set of DIC images in the same plane with different bias retardation between the two illuminating light components produced by a Wollaston prism. These images, together with one conventional bright-field image, allows for reduction of the phase deconvolution restoration problem from a highly complex nonlinear mathematical formulation to a set of linear equations that can be applied to resolve the phase for images with a relatively large number of pixels. Additionally, under certain conditions, an on-line atomic force imaging system that does not interfere with the standard DIC illumination modes resolves uncertainties in large topographical variations that generally lead to a basic problem in DIC imaging, i.e., phase unwrapping. Furthermore, the availability of confocal detection allows for a three-dimensional reconstruction with high accuracy of the refractive-index measurement of the object that is to be imaged. This has been applied to reconstruction of the refractive index of an arrayed waveguide in a region in which a defect in the sample is present. The results of this paper highlight the synergism of far-field microscopies integrated with scanned probe microscopies and restoration algorithms for phase reconstruction.
Silicon-on-insulator (SOI) and bulk metal–oxide–semiconductor (MOS) transistors were fabricated simultaneously and tested electrically and optically at room temperature. The electroluminescence (EL) spectrum has been measured in both types of devices. A visible emitted radiation was observed when both devices were operated in the avalanche breakdown mode. In the case of SOI device, five different peaks at a photon energy of 2.31, 2.06, 1.81, 1.63, and 1.50 eV were observed. The regular spacing between the measured peaks indicates cavity effects due to the various layers of the SOI MOS transistor structure. The thin silicon layer thickness of 400 Å seems to be responsible for the factor of about 16 in the EL intensity of the SOI device as compared to the bulk device.
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