Polarization converters based on ring-resonator phase-shifters

In this letter, novel devices based on ring-resonator phase-shifters are proposed for the realization of efficient polarization converters with periodical spectral response. The main spectral properties of several architectures, including parallel-coupled and directly coupled ring-resonators, are analytically investigated and conditions for complete polarization rotation are derived. The exploitation as polarization interleavers and polarization splitters/combiners is also briefly discussed.     

Cobol: perception and reality

The authors list the perceptions they have uncovered and counter them with the reality of Cobol. Some of the perceptions are: Cobol is a mainframe language-it has been available on PCs since their inception; Cobol stopped evolving in the 1970s, stopped growing in popularity in the 1980s, and stopped being used to develop client-server and Web-based applications in the 1990s; and Cobol is not an object-oriented language, when, in fact, it has objects galore     

Private practice: a choice, but what challenges!

Recent changes in the Canadian health care system are having an impact on the way health care services are delivered. As a result, opportunities are opening up for a whole new generation of autonomous and independent nurses who choose to work directly with clients in a private practice setting. In part one of this two-part article, the author describes the main responsibilities of the nurse entrepreneur. Stressed are the areas of competency and the entrepreneurial spirit required. Administrative, professional, legal and fiscal aspects of independent practice are also outlined. Part two of the article focuses on the ethical responsibilities of the nurse entrepreneur and the regulations concerning fees, publicity, insurance, and office and file management. The author recommends keeping current on new developments and establishing a process whereby clients can evaluate the quality of care they receive.     

A high-stability fiber amplifier source for the fiber opticgyroscope

We demonstrate an erbium-doped fiber amplifier (EDFA) source for the fiber gyroscope with an overall mean wavelength stability of four parts per million. This source, which amplifies the gyroscope signal before detection, is shown to be more stable than a similar single-pass source in a standard configuration. The effects of varying the fiber temperature, pump power, pump wavelength, gyroscope feedback power and signal polarization state on the output mean wavelength are individually explored. Experimental results are in excellent agreement with simulations     

A packet delay analysis for cellular digital packet data

We formulate and analyze a model of voice and data burst traffic for cellular digital packet data (CDPD). To develop a tractible model, we make some reasonable simplifying assumptions to model the voice traffic and one of the logical CDPD channels as an M/M/1 queue in a random environment. Rather than explicitly solve the resulting matrix quadratic equation, we develop an asymptotic analysis that gives us simple approximate formulas (with error bounds) for many performance measures of interest. In particular, one metric that we highlight comes from using our approximate mean data burst delay formula to characterize the performance of a set of interacting logical CDPD channels. We do so by describing it in terms of an equivalent number of independent, dedicated CDPD channels, We can use this metric to suggest what the optimal number of logical CDPD channels for a given system should be     

Optical fiber vibration sensor using (Pancharatnam) phase stepinterferometry

A fiber-optic vibration sensor based on polarization and phase-step interferometry is reported. Left- and right-circularly polarized light coming back from the reference and signal arms of a modified Michelson fiber interferometer is processed with an array of five linear analyzers separated angular steps of π/4 (rad) from each other. Thus, five interference patterns are acquired simultaneously and the dynamical phase retrieval problem is reduced to five-step interferometry in the time-domain. A vibration sensor as described above was built by the authors and its performance was investigated     

Experimental determination of electron and hole mobilities in MOSaccumulation layers

This letter presents for the first time, the experimentally determined majority carrier mobilities in the accumulation layer of a MOSFET for both p-type and n-type channel doping for a wide range of doping concentrations. The measured carrier mobility is observed to follow a universal behavior at high transverse fields, similar to that observed for minority carriers in MOS inversion layers. At the higher doping levels, the effective mobility for majority carriers at low to moderate transverse fields is found to be very close to the bulk mobility. This is believed to be due to carrier screening of the ionized impurity scattering which dominates at the higher doping concentrations     

Arsenic deactivation enhanced diffusion and the reverseshort-channel effect

The effect of enhanced diffusion caused by the electrical deactivation of arsenic on the reverse short-channel effect (RSCE) in NMOS devices is investigated. A simple four-mask process was utilized to fabricate deep sub-micron NMOS devices. Source/drain (S/D) implant and anneal conditions were varied in order to determine their implications on the RSCE. Results indicate that when high concentrations of arsenic deactivate, enhanced diffusion occurs, leading to significantly more RSCE. This implies that the dose of the arsenic implant and the subsequent anneals should be carefully considered in source/drain engineering     

Characterization of artificially patinated layers on artistic bronze exposed to laboratory SO2 contamination

Artificially patinated artistic bronze was exposed to the action of 0.10 and 12.68 ppm SO2 contamination in the laboratory at 100% relative humidity. The surface layers were characterized using electrochemical, atomic absorption, X-ray powder diffraction techniques and Fourier transform–infrared spectrometry. Thermal and calorimetric studies were also performed. Some of the compounds identified were cuprite (Cu2O), digenite (Cu1.8S), yarrowite (Cu9S8), chalcocite (Cu2S), brochantite (Cu4(OH)6SO4), bonattite (CuSO4·3H2O) and Sn2S3.