In passive fathometer processing, the presence of wavelets in the estimate of the medium's Green's function corresponds to the location of reflectors in the seabed; amplitudes are related to seabed properties. Bayesian methods have been successful in identifying reflectors that define layer interfaces. Further work, however, revealed that phase shifts are occasionally present in the wavelets an...

Radio-frequency experimental measurements of magnetically coupled chains of L-C resonators supporting magneto-inductive (MI) waves are presented. MI waveguides are constructed using printed circuit board (PCB) inductors and external capacitors. Methods for increasing the nearest-neighbour coupling and reducing the non-nearest neighbour coupling using double-sided PCBs are demonstrated. Conditio...

A monolithic, three-section, and widely tunable mid-infrared (mid-IR) quantum cascade laser (QCL) is demonstrated. This electrically tuned laser consists of a gain section placed between two super structure grating (SSG) distributed Bragg reflectors (DBRs). By varying the injection currents to the two grating sections of this device, its emission wavelength can be tuned from 4.58 μm to 4.77 μm ...

This Letter reports on an optical pumping scheme, termed resonant pumping, for an erbium-doped distributed feedback (DFB) waveguide laser. The scheme uses two mirrors on either side of the DFB laser, forming a pump cavity that recirculates the unabsorbed pump light. Symmetric distributed Bragg reflectors are used as the mirrors and are designed by matching the external and internal quality fact...

A key limitation for future Small Satellite communications and radar missions will be available antenna reflector aperture. Two types of reflectors are dominant for satellite RF systems today, rigid, single-piece reflectors and deployable mesh reflectors. Single-piece reflectors are limited to the aperture that fits inside a launch vehicle without packaging the reflective surface. Mesh reflecto...

Various spectral control techniques can be applied to improve the performance of a thermophotovoltaic (TPV) device. For example, back surface reflector (BSR) is common structure TPV devices. A conventional metal BSR enhances photogeneration rate by increasing absorption probability photons via reflections, affording second chance for absorption. However, effects passivation and external lumines...

Gas mixing in a T-shape micro mixer has been simulated using the Direct Simulation Monte Carlo (DSMC) method. It is considered that the adequate mixing occurs when the mass composition of the species, CO or N2, deviates below 1 % from their equilibrium composition. The mixing coefficient is defined as the ratio of the mixing length to the main channel’s height. As the inlet Kn increases, while ...

Highly reflective coatings with strong light scattering effect have many applications in optical components and optoelectronic devices. This work reports titanium dioxide (TiO(2)) pigment-based reflectors that have 2.5 times higher broadband diffuse reflection than commercially produced aluminum or silver based reflectors and result in efficiency enhancements of a single-junction amorphous Si s...

This article discusses possible solutions to limitations in light extraction efficiency of light-emitting diodes (LEDs) using new types of triple-layer omni-directional reflectors (ODRs). The ODRs have lower mirror losses than metal reflectors and distributed Bragg reflectors (DBRs). High-reflectivity ODRs have been incorporated into AlGaInP LEDs and GaInN LEDs. It is shown that the ODR signifi...

Electrically switchable broadband infrared reflectors that are relatively transparent in the visible region have been fabricated using polymer stabilised cholesteric liquid crystals. The IR reflectors can change their reflection/transmission properties by applying a voltage in response to changes in environmental conditions. Simulations predict that a significant amount of energy can be saved o...