Electrostatic Field Analysis of Electrooptic Devices

We describe a Finite Difference Method for the determination of the electrostatic field in a multilayered electrooptic device. The Laplace equation is solved, assuming a suitable closed area, by taking into account the different permittivities of the various layers. The effect of a higher permittivity in the guiding layer has been explicitly considered. As a practical example, we calculate the phase shift of a guided optical wave within an electrooptic modulator. A review of the various methods in use for the field analysis is given. Some criteria for the selection of the appropriate method are also mentioned.

Kaon B parameter with Wilson fermions

We calculate the kaon B parameter in quenched lattice QCD at beta=6.0 using Wilson fermions at kappa=0.154 and 0.155. We use two kinds of nonlocal (''smeared'') sources for quark propagators to calculate the matrix elements between states of definite momentum. The use of smeared sources yields results with much smaller errors than obtained in previous calculations with Wilson fermions. By combining results for p=(0,0,0) and p=(0,0,1), we show that one can carry out the noperturbative subtraction necessary to remove the dominant lattice artifacts induced by the chiral-symmetry-breaking term in the Wilson action. Our final results are in good agreement with those obtained using staggered fermions. We also present results for B parameters of the DELTAI = 3/2 part of the electromagnetic penguin operators, and preliminary results for B(K) in the presence of two flavors of dynamical quarks.

Polarization Changes of Radiation through Stimulated Raman Scattering

We study change in the polarization of electromagnetic waves due to the stimulated Raman scattering in a plasma. In this process an electromagnetic wave undergoes coherent scattering off an electron plasma wave. It is found that some of the observed polarization properties such as the rapid temporal variations, sense reversal, rotation of the plane of polarization, and change of nature of polarization in the case of pulsars and quasars could be accounted for through stimulated Raman scattering.

A simple equivalent circuit analysis of rectangular folded-waveguide slow-wave structure

A simple yet accurate equivalent circuit model was developed for the analysis of slow-wave properties (dispersion and interaction impedance characteristics) of a rectangular folded-waveguide slow-wave structure. Present formulation includes the effects of the presence of beam-hole in the circuit, which were ignored in existing approaches. The analysis was benchmarked against measurement as well as with 3D electromagnetic modeling using MAFIA for two typical slow-wave structures operating in Ka- and Q-bands, and close agreements were observed. The analysis was extended for demonstrating the effect of the variation of beam-hole radius on the RF interaction efficiency of the device. (C) 2009 Elsevier GmbH. All rights reserved.