Abstract: A method for launching a high-power signal into anomalous-dispersion fiber without suffering excess spectral broadening and waveform distortion. A high-power signal is launched as very short optical solitons, typically with a pulse width of approximately 1 to 10 ps. The pulse width of the solitons will broaden adiabatically (or nearly adiabatically) as they propagate down the anomalous-dispersion fiber as the average power of the soliton decreases. At the same time, the optical spectrum will narrow. After some distance of travel, when the width of the pulses have broadened to a suitable duration and the average power has decreased to a point where penalties from nonlinearities are insignificant, the pulses enter a significantly linear propagation regime with first order dispersion near zero. A dispersion-shifted fiber may be used or any additional dispersion can be compensated at the receiver. Consequently, no further significant broadening of the spectrum occurs when the signal is received at the receiver.

Abstract: Distributed feedback devices such as distributed feedback lasers are modified by introduction of a central coupling strength discontinuity or other deviation from uniform nature of the distributed perturbations, in order to promote the transmission of oscillation of a single mode in preference over the nearest redundant modes. The class of deviations from uniform coupling strength may be mathematically termed antisymmetric deviations, because they are deviations about the midpoint of the perturbation pattern which result in a distinction of effect of the two halves of the pattern, taking either half as a reference pattern by itself.

Abstract: Electrode for electrochemically machining electrically conducting workpieces, in particular machining them by removal of material, which electrode is locally coated with a screening layer consisting of a polycristalline semiconductor material, which layer preferably comprises two component layers of p and n-conductivity type respectively.