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InGaAlP/InGaP visible laser diodes emitting in the 600 nm range are considered to be promising optical sources for use in optical information systems such as high density optical disks, laser beam printers, and bar-code readers.1 One of the important problems to be solved for practical use is high threshold current of this system. Among many methods, high doping in the clad layer and compressive strain in the active layer2 are considered the most effective ones to reduce a threshold current. This study demonstrates that a very low threshold current can be obtained for simple one step epitaxial structure by applying these two effects.

Using stored energy considerations an operationally well defined general expression is derived for the capacitance of a p–n Junction. The separation of this capacitance into space charge and diffusion parts is carried out in a functional rather than a regional manner, based on the distinction between the time dependences of dielectric relaxation and carrier recombination. Par l'emploi des reflexions d'energie emmagasinee on tire une expression bien definie operationnelle pour la capacite d'une jonction p–n. Ensuite on partage cette capacite entre une partie de la charge d'espace et une partie de la diffusion dans une maniere fonctionelle plutǒt que regionale. La base de ce partage est le difference entre la dependance temporelle de la remise dielectrique et celle de la recombinaison des porteurs.

In this study, the propagation of electromagnetic waves in one-dimensional plasma photonic crystals (PPCs), namely, superlattice structures consisting alternately of a homogeneous unmagnetized plasma and dielectric material, is simulated numerically using the finite-difference time-domain (FDTD) algorithm. A perfectly matched layer (PML) absorbing technique is used in this simulation. The reflection and transmission coefficients of electromagnetic (EM) waves through PPCs are calculated. The characteristics of the photonic band gap (PBG) are discussed in terms of plasma density, dielectric constant ratios, number of periods, and introduced layer defect. These may provide some useful information for designing plasma photonic crystal devices.

In this paper, the second-order and fourth-order relativistic chromatic variational functions for all kinds of relativistic chromatic aberrations of a combined electrostatic-magnetostatic focusing-deflection system have been derived in detail. Here, the relativistic chromatic aberrations produced by the variations of accelerating voltage, currents of magnetostatic round lenses, voltages of electrostatic round lenses and excitations of deflector multipoles are considered.

The perturbation of the Ba atom by radiation from a color center laser in the range between 8400 and 8700 cm−1 is experimentally studied. The study was performed by the method of resonance ionization spectroscopy by simultaneously irradiating a beam of Ba atoms by a color center laser and a dye laser at 17735 cm−1. The dynamic polarizabilities of the 5d6p1F03 and 6p2 1D2 levels are measured.

The tectonics of the Grimaldi area are described and analyzed in detail from high-resolution Lunar Orbiter photographs.

This paper describes the state of the art in free space optical interconnects as applied to chip-to-chip communication. We will review various technologies that integrate micro lasers and optical detectors with silicon CMOS, provide optical link characteristics obtained with these devices, and discuss the capabilities of low cost and robust optoelectronic packaging techniques to seamlessly integrate optics and electronics at the board level.

The acquisition of systems to locate and interdict Special Nuclear Material (SNM) is significantly enhanced when trade space analysis of and CONOPS development for various proposed sensor systems is performed using realistic operational scenarios in a synthetic simulation environment. To this end, the U. S. Defense Threat Reduction Agency (DTRA) has developed a collaborative constructive simulation environment hosted at the DTRA Center at Ft. Belvoir, VA. The simulation environment includes a suite of modeling and simulation (M&S) tools, scenario vignette representations, geographic information databases, and authoritative sensor system representations. Currently focused on modeling the detection and interdiction of in-transit SNM, the M&S tools include the Monte Carlo N-Particle (MCNP) simulation for detailed nuclear transport calculations and the JHU/APL enhanced Joint Semi-Automated Forces (JSAF) synthetic simulation environment and several associated High-Level Architecture (HLA) federate simulations for engagement-level vignette executions. This presentation will focus on the JHU/APL enhancements to JSAF which have enabled the execution of SNM detection vignettes. These enhancements include the addition of a user-configurable Radioactive Material (RM) module for representation of SNM objects, a user-configurable RM Detection Module to represent operational and notional gamma and neutron detectors, a Radiation Attenuation Module to calculate net emissions at the detector face in the dynamic JSAF environment, and an RM Stimulation Module to represent notional proton and photon beam systems in active interrogation scenarios.

This paper presents the evolution with structural parameters of the linearity of the transconductance of multichannel HEMTs measured under low and microwave frequencies. Compared to theoretical calculations, the measured transconductance is in good agreement excepted at high doping levels. These discrepancies are attributed to parasitic effects. The discussion of the different possibilities brings us to conclude that the gate leakage current is most probably involved in the observed phenomena.