Ultrafast WDM logic

Ultrafast all-optical logic gates that accept optical inputs in which wavelength designates bit position within the overall byte are proposed and demonstrated. Four-wave mixing is shown to provide a conditional test function that can be used to construct any multi-input logic gate. Polarization provides the logic state for each bit. Implementations that use semiconductor optical amplifiers as the four-wave mixing medium can be monolithic and compact

Spectral logic gates for byte-wide WDM signal processing

We propose a new class of all-optical logic gates based on four-wave mixing, designed to operate on multiwavelength input signals. We demonstrate the XOR function with two 2.5-Gbit/s modulated input signals

A general resonance theory based on Mourre's inequality

We study the perturbation of bound states embedded in the continuous spectrum which are unstable by the Fermi Golden Rule. The approach to resonance theory based on spectral deformation is extended to a more general class of quantum systems characterized by Mourre's inequality and smoothness of the resolvent. Within the framework of perturbation theory it is still possible to give a definite meaning to the notion of complex resonance energies and of corresponding metastable states. The main result is a quasi-exponential decay estimate up to a controlled error of higher order in perturbation theory.Comment: 17 page

Four-wave mixing mediated by the capture of electrons and holes in semiconductor quantum-well laser amplifiers

An experimental technique based on frequency-resolved four-wave mixing is proposed for the investigation of phonon-assisted capture of electrons and holes in electrically pumped semiconductor quantum wells. We show how this technique can be used to directly measure the intrinsic capture lifetime, with no need for involved numerical fits. We also present experimental results from an application of the technique to a multiquantum-well semiconductor optical amplifier. The possible impact of phase matching on the results is discussed