Unsteady mixed convection flows in a lid-driven square cavity filled with a fluid-saturated porous medium is investigated numerically. The two vertical walls of the enclosure are insulated while the bottom wall is cooled. The top wall is heated sinusoidally and moving at a constant speed. The governing equations are solved numerically by using finite volume method with SIMPLE algorithm. The res...

We have designed photonic crystal suspended membranes with optimized optical and mechanical properties for cavity optomechanics. Such resonators sustain vibration modes in the megahertz range with quality factors of a few thousand. Thanks to a two-dimensional square lattice of holes, their reflectivity at normal incidence at 1064 nm reaches values as high as 95%. These two features, combined wi...

In lasers with nonorthogonal eigenmodes the excess-noise factor K can be large, especially in unstable-cavity lasers with hard-edged intracavity apertures. To the best of our knowledge, we report the first detailed study of the dependence of K on aperture shape. Calculations and measurements of K for unstable-cavity lasers with variable-size apertures of triangular, square, pentagonal, hexagona...

The stability of flow in a lid-driven cavity is investigated using an accurate numerical technique based on a hybrid scheme with spectral collocation and high-order finite differences. A global stability analysis is carried out and critical parameters are identified for various aspect ratios. It is found that while there is reasonable agreement with the literature for the critical parameters le...

A calculational scheme is presented to model the interaction of light with active dielectric media, represented by four-level atomic materials, surrounded by photonic crystals. Optically pumped lasing is studied in three model systems: a Fabry-Perot cavity, a line of defects in a two-dimensional square lattice of rods, and a cylindrical photonic crystal. Field profiles and conversion efficienci...

Environmentally stable high-power erbium fiber soliton lasers are constructed by Kerr or carrier-type mode locking. We obtain high-energy pulses by using relatively short fiber lengths and providing large amounts of negative dispersion with chirped fiber Bragg gratings. The pulse energies and widths generated with both types of soliton laser are found to scale with the square root of the cavity...

We explore the physics of optomechanical systems in which an optical cavity mode is coupled parametrically to the square of the position of a mechanical oscillator. We derive an effective master equation describing two-phonon cooling of the mechanical oscillator. We show that for high temperatures and weak coupling, the steady-state phonon number distribution is nonthermal (Gaussian) and that e...

inhalation of fungal spores is shown to participate in the development of allergic rhinitis symptoms. in this study, relation between presence of alternaria in the human nasal cavity and allergic rhinitis is assessed. in a case-control study, 58 allergic rhinitis patients were compared with a well-matched control group of fifty healthy volunteers for sensitization to alternaria (by skin prick t...

The buoyancy-driven fluid flow and heat transfer in a square cavity with partially active side walls filled with Cu-water nanofluid is investigated numerically. The active parts of the left and the right side-walls of the cavity are maintained at temperatures Th and Tc, respectively, with Th>Tc. The enclosure’s top and bottom walls, as well as, the inactive parts of its side walls are kept insu...

This paper presents results of a numerical study of mixed convection and entropy generation of Cu–water nanofluid in a square ventilating cavity at different inclination angles. Except a piece of bottom wall with a uniform heat flux, all of the cavity walls are insulated. The inlet port is placed at the bottom of the left wall and the outlet port is positioned at the top of the right wall....