Improved Bend Loss Formula Verified for Optical Fiber by Simulation and Experiment

This paper presents an improved curvature loss formula for optical waveguides, which is shown to accurately predict the bend loss of both single-mode and multimode fibers. The formula expands upon a previous formula derived by Marcuse, greatly improving its accuracy for the case of multimode fiber. Also presented are the results of bent fiber simulations using the beam propagation method (BPM), and experimental measurements of bend loss. Agreement among simulation, formula and measurement support the validity of both theoretical methods. BPM simulations showed that the lowest order modes of the bent fiber were reduced to their linearly polarized constituents prior to the onset of significant bend loss. This implies that certain LP mode orientations should propagate with much lower loss than previously expected, and should impact the mode stripping ability of bent large mode area fibers, as employed in fiber lasers and amplifiers.     

NSCL溅射金属离子产生研究进展(摘要)

Production of metallic ion beams in support of the experimental program at the Coupled Cyclotron Facility at the NSCL required the development of ion sputtering feed of metallic molybdenum,nickel,uranium, and zirconium for use with the ARTEMIS ion source.The production of high intensity lower to medium charge state ions required high material consumption,posing some significant difficulties in reliable long term beam stability.Resultant and ongoing hardware and technique developments to resolve these difficulties will be presented in this poster along with interesting effects of the ion source solenoid field polarity on the sputtering process.     

INSPAD: a system for automatic bond pad inspection

A method of detecting probe mark defects in semiconductor bond pads is presented that uses digitized images of color Polaroid photographs from an optical microscope. INSPAD inspects the bond pads in a magnified IC circuit image taken after the electrical testing stage. These are: probe marks must not extend beyond pad boundaries such that they damage glassivation; scratches on the bond pads must not exceed 50% of the bond pad width; and the probe marks must not exceed 25% of the bond pad area. Three types of commonly used bond pad geometries have been addressed. Morphological filtering is performed on the bond pad, to isolate and identify the major probe mark regions. Inspection of each pad takes approximately 2 to 3 s on an Apollo DN-4000 workstation which makes it suitable for real-time applications     

Surface High-Energy Laser

We describe a design strategy for high-power solid-state laser oscillators using local correction of thermally induced optical distortion. This offers a potential for scaling lowest order Gaussian mode solid-state laser oscillators directly to high average power, e.g. >100 kW, while using a relatively simple near confocal ring resonator. The waste heat is necessarily produced in the gain region; however, the design strategy facilitates scaling by allowing the laser oscillator to function as though the waste heat was produced in a surface region external to the gain medium.     

Synthesis and axial chirality of an enantiopure aminodibenzazepinone

A route for the synthesis of (S,S)-7-amino-5-methyl-5H-dibenzo[b,d]azepin-6(7H)-one hydrochloride is disclosed. The synthesis includes a Friedel–Crafts alkylation to form the seven-membered ring and a highly efficient classical resolution. Additional studies on the enantiopure material showed the amine to be highly resistant to racemization, which led us to investigate the unexpected stability. We propose that the inherent axial chirality contained in the dibenzazepinone works to produce an interesting chirality transfer mechanism, which accounts for the observed robustness of the stereocenter. This previously unrecognized stereochemical element exists within this specific class of molecules, and they should be drawn in a manner which displays the axial chirality.     

Neuere Methoden zum Nachweis, zur Isolierung und quantitativen Bestimmung des Eiwei?es sowie seiner h?heren und tieferen Abbauprodukte

Ohne Zusammenfassung     

MEMS-tunable vertical-cavity SOAs

We present the signal gain, wavelength tuning characteristics, saturation properties, and noise figure (NF) of MEMS-based widely tunable vertical-cavity semiconductor optical amplifiers (VCSOAs) for various optical cavity designs, and we compare the theoretical results to data generated from a number of experimental devices. Using general Fabry-Pe/spl acute/rot relationships, it is possible to model both the wavelength tuning characteristics and the peak signal gain of tunable vertical-cavity amplifiers, while a rate-equation analysis is used to describe the saturation output power and NF as a function of the VCSOA resonant wavelength. Additionally, the basic design principles for an integrated electrostatic actuator are outlined. It is found that MEMS-tunable VCSOAs follow many of the same design trends as fixed-wavelength devices. However, with tunable devices, the effects of varying mirror reflectance and varying single-pass gain associated with the MEMS-based tuning mechanism lead to changing amplifier properties over the wavelength span of the device.     

Classical electrodynamic systems interacting with classical electromagnetic random radiation

In the past, a few researchers have presented arguments indicating that a statistical equilibrium state of classical charged particles necessarily demands the existence of a temperature-independent, incident classical electromagnetic random radiation. Indeed, when classical electromagnetic zero-point radiation is included in the analysis of problems with macroscopic boundaries, or in the analysis of charged particles in linear force fields, then good agreement with nature is obtained. In general, however, this agreement has not been found to hold for charged particles bound in nonlinear force fields. The point is raised here that this disagreement arising for nonlinear force fields may be a premature conclusion on this classical theory for describing atomic systems, because past calculations have not directed strict attention to electromagnetic interactions between charges. This point is illustrated here by examining the classical hydrogen atom and showing that this problem has still not been adequately solved.