Ge on Si micro-disk, ring and racetrack cavities are fabricated and strained using silicon nitride stressor layers. Photoluminescence measurements demonstrate emission at wavelengths ≥ 2.3 μm, and the highest strained samples demonstrate in-plane, tensile strains of > 2 %, as measured by Raman spectroscopy. Strain analysis of the micro-disk structures demonstrate that shear strains are present ...

We report room-temperature lasing from an optically pumped subwavelength-scale cylindrical InGaAsP pillar surrounded by circular Bragg reflectors on a metal substrate with a dielectric spacer layer. By taking advantage of wide in-plane photonic bandgaps and proper vertical antiresonances, three dielectric Bragg pairs produce a sufficient optical feedback capable of low threshold lasing from the...

Numerical analysis of diffraction by a single aperture surrounded by a circular shallow channel in a metallic screen shows the possibility of a 50-fold increase of the electric field intensity inside the central aperture, when compared to the incident field. Detailed analysis of cavity modes and their coupling through surface plasmon wave determine the parameters leading to maximum field enhanc...

We demonstrate single-mode lasing at telecommunication wavelengths from a circular nanocavity employing a radial Bragg reflector. Ultrasmall modal volumes and submilliwatt pump thresholds level are observed for lasers with InGaAsP quantum well active membrane. The electromagnetic field is shown to be tightly confined within the 300 nm central pillar of the cavity. The quality factors of the res...

Two macrotricyclic ligands composed of two face-to-face octadentate metal chelates were synthesized. These cage-shaped disodium complexes had special recognition ability for various counter anions. Specific chiral dicarboxylates bound to the complexes within the cavity and exhibited chirality induction properties. For instance, N-Boc-Asp dianion strongly induced circular dichroism (CD) signals,...

Coplanar-strip horn antennas are switched photoconductively to generate picosecond bursts of freely propagating electromagnetic energy with bandwidth covering 15-75 GHz. The antennas are fabricated on GaAs grown by molecular beam epitaxy at low substrate temperatures. These antennas are used to perform transient scattering measurements from slit-coupled circular and coaxial cavities; Prony’s me...

1 Ringresonator modelling Optical microresonator circuits [1, 2, 3] are considered, consisting of a number of not necessarily identical circular cavities and straight waveguides, with evanescent wave interaction between these elements. A simple configuration with a single cavity and two straight bus waveguides serves as an example to explain the frequency-domain Hybrid analytical/numerical Coup...

Cavity reflex antenna (CRA) employing a circular patch type FSS (Frequency Selective Surface) superstrate is investigated. Analysis in terms of gain, bandwidth (impedance and gain) and radiation pattern has been presented. The aim of this work was to study low profile CRA having very thin superstrate sizes. In this CRA a circular patch antenna is used as a feeding source. The circular patch typ...

Just prior to the emergence of the tooth into the oral cavity, a small circular crater forms in the gingival epithelium immediately above the crown. The craters appear to expand in diameter during eruption to accommodate the emerging crown of the tooth. The observations support the concept that the crown of the tooth does not actively push through and rupture the gingival epithelium, but rather...

A new genus and species of Desmodoridae was found in deep-sea sediments of the Campos Basin. Although the cuticle annulation of the new species is similar to members of Desmodorinae, many morphological features are strong enough to classify it within the Spiriniinae. Spirodesma magdae nov. gen. nov. sp. is characterized mainly by the presence of a unique form of unispired amphids, with circular...