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The performance of a rhodamine B-doped polymer optical fiber amplifier is evaluated through experimental and numerical analyses. The amplifier is subjected to pump and signal pulses of several nanosecond duration and subsequently analyzed by means of a mathematical model. Cross section measurements are also carried out using the computed data. Results show that the fiber amplifier is capable of performing high-power and high-gain amplification.

A polymer optical fiber amplifier (POFA) of the graded-index (GI) type, with gain in the visible region, was successfully prepared for the first time, to our knowledge, with the interfacial-gel polymerization technique. An input signal of 0.85 W at 591 nm was amplified to 420 W (27-dB gain) by injection of 690 W of pump power at 532 nm into a GI POFA with a 0.5-m length. The efficiency of conversion of pump energy to signal amplification was more than 60%. Key words: Graded index, polymer optical fiber amplifier, amplification, organic dye, Rhodamine B.

Several realistic structures for Aharonov-Bohm type electron interferometers were presented. The design featured a double-quantum-wire array with Schottky gates fabricated from modulation-doped asymmetric double quantum well structures. It was shown that an exact 1:1 beam splitter could be produced by a properly designed barrier between the two quantum wires.

The absorption and refractive index change in semiconductor quantum-well structures (QWS) are studied through a numerical technique. The technique, based on the finite-element method, uses the Lorentzian function and Kramers-Kronig relations for the analysis of the absorption spectrum and refractive index variations caused by external electric field in the QSWs. Results obtained from the application of this technique show very good agreement with the measured data.

Reports on realistic structures for electron interferometers constituted by the control of the wavefunctions in double quantum wire structures. Calculation of electron wave functions and propagation by scattering matrix formalism; Features of semiconductor devices based on quantum interference phenomena; Schematic structure of the electron interferometer.

Abstract: We have discussed the Na+ concentration dependence of the intermolecular distance of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) dimers in aqueous solution of NaOH. We have particularly focused on the transition of the PTCDA dimers which is sensitive to the intermolecular distance and we have found that the state is split for the higher lying sublevel and the lower lying sublevel with the increase of the Na+ concentrations. From the energy shift of the lower lying sublevel, we have estimated the intermolecular distance of the PTCDA dimer, that changes from 7.5 to 4.9Å by the Na+ concentration. [Copyright &y& Elsevier]