Surface plasmon polaritons and their role in the enhanced transmission of light through periodic arrays of subwavelength holes in a metal film

We present results of the transmitted, reflected, and absorbed power associated with the enhanced transmittance of light through a silver film pierced by a periodic array of subwavelength holes. Comparing experimentally acquired dispersion curves under different polarization conditions shows that the transmission features of the array are consistent with p-polarized resonant modes of the structure. By exploring the regime in which no propagating diffracted orders are allowed, we further show that the transmittance maxima are associated with both reflectance minima and absorption maxima. These new results provide strong experimental evidence for transmission based on diffraction, assisted by the enhanced fields associated with surface plasmon polaritons.     

Electronic and vibrational properties of fluorenone in the channels of zeolite L

Fluorenone (C13H8O) was inserted into the channels of zeolite L by using gas-phase adsorption. The size, structure, and stability of fluorenone are well suited for studying host-guest interactions. The Fourier transform IR, Raman, luminescence, and excitation spectra, in addition to thermal analysis data, of fluorenone in solution and fluorenone/zeolite L are reported. Normal coordinate analysis of fluorenone was performed, based on which IR and Raman bands were assigned, and an experimental force field was determined. The vibrational spectra can be used for nondestructive quantitative analysis by comparing a characteristic dye band with a zeolite band that has been chosen as the internal standard. Molecular orbital calculations were performed to gain a better understanding of the electronic structure of the system and to support the interpretation of the electronic absorption and luminescence spectra. Fluorenone shows unusual luminescence behavior in that it emits from two states. The relative intensity of these two bands depends strongly on the environment and changes unexpectedly in response to temperature. In fluorenone/zeolite L, the intensity of the 300 nm band (lifetime 9 micros) increases with decreasing temperature, while the opposite is true for the 400 nm band (lifetime 115 micros). A model of the host-guest interaction is derived from the experimental results and calculations: the dye molecule sits close to the channel walls with the carbonyl group pointing to an Al3+ site of the zeolite framework. A secondary interaction was observed between the fluorenone's aromatic ring and the zeolite's charge-compensating cations.     

Fiber optic applications of multiple quantum well electroabsorption modulators

Electroabsorption modulators (eam) have proved to be very attractive both as optical sources (monolithically integrated NRZ transmitters andrz pulse generators) as well as for very fast signal processing (demultiplexing, regeneration, wavelength conversion,...). Their design criteria, technology and implementation in future networks are reviewed, and the main issues are discussed.     

Extinction ratio of cross-gain modulated multistage wavelength converters: model and experiments

Extinction ratio conservation, wide dynamic range, and large operating wavelength window are important features for all-optical wavelength converters. Practical converters may probably be multistage devices and have to be precisely modeled. We present an experimental analysis and phenomenological modeling of single- and multistage wavelength converters using cross-gain modulation in polarization insensitive multiquantum-well optical amplifiers. One of the studied double-stage converters is able to produce a large extinction ratio improvement with a regeneration factor higher than 1.5 for any conversion in the 1.53-1.56-/spl mu/m window. The phenomenological model yields a very good agreement with the experimental results.     

J/psi production in Indium-Indium collisions at 158 GeV/nucleon

The NA60 experiment studies muon pair production at the CERN Super Proton Synchrotron. In this Letter we report on a precision measurement of J/psi in In-In collisions. We have studied the J/psi centrality distribution, and we have compared it with the one expected if absorption in cold nuclear matter were the only active suppression mechanism. For collisions involving more than approximately 80 participant nucleons, we find that an extra suppression is present. This result is in qualitative agreement with previous Pb-Pb measurements by the NA50 experiment, but no theoretical explanation is presently able to coherently describe both results.     

Mathematical modelling of transformation plasticity in steels I: Case of ideal-plastic phases

Transformation plasticity in steels (i.e., the anomalous plastic flow observed during the progress of a phase transformation) is usually attributed to two distinct physical mechanisms, which have been proposed by Greenwood and Johnson and Magee. This paper proposes a theoretical approach to the problem, in the case where the Magee mechanism is negligible and the phases are ideal-plastic. An explicit expression for the transformation plastic strain rate is obtained for a steel undergoing a transformation under a small applied stress; this expression is consistent with experiments conducted on various materials. A finite element simulation provides a confirmation of the theoretical formula and allows for a detailed examination of the validity of some physical hypotheses made in the treatment. It also allows for a study of transformation plasticity under high applied stresses. Based on these results, a general (i.e., applicable for all kinds of stresses applied) model is proposed in the case of ideal-plastic phases.     

Demonstration of sliding-filter-controlled soliton transmission at20 Gbit/s over 14 Mm

Soliton transmission of a 20 Gbit/s time/polarisation multiplexed signal over 14 Mm path in a recirculating loop with 46.3 km amplification span has been demonstrated using the sliding-filter soliton control technique. Demultiplexing was achieved by using a polarisation-insensitive electroabsorption modulator     

Full polarization insensitivity of a 20 Gb/s strained-MQWelectroabsorption modulator

We report on a MQW electroabsorption modulator with tensile-strained wells. The device transmission is shown to be fully polarization insensitive, i.e. both in amplitude and phase. The modulation efficiency is over 20 GHz/V (bandwidth higher than 20 GHz and 1 V drive voltage) which is the highest figure of merit reported for any kind of polarization insensitive modulator. Full polarization independence is further demonstrated by 2.5 Gb/s transmission at 1.55 μm over 475 km of standard fiber without penalty at 10^-9 BER whatever the polarization