Siemens Aktiengesellschaft

Walter Proebster

Erich Gottwald

Hans-Ludwig Althaus

Christoph Glingener

Werner Paetsch

Dieter-Josef Will

Wolfgang Goepfert

The stimulated Brillouin backscatter is reduced by non-linear effects, such as self-phase modulation or cross-phase modulation. Due to the cross-phase modulation, a bandwidth spread and, as result thereof, a reduction of the stimulated Brillouin backscatter is also achieved by supplying at least one amplitude-modulated pump signal.

Method for reducing stimulated brillouin backscatter

In known modulation current regulators, a low-frequency pilot signal is often superimposed on the digital useful signal and the two superposition products resulting in a light signal are evaluated. Due to the cut-in delay of a laser diode, the preconduction current of the laser diode in laser diode transmitters having transmission rates of at least a few 100 Mbit/s must be set so high that a superposition product only results in the light output signal and, therefore, a regulation of the modulation current is no longer possible in the known manner. For regulating the modulation current given high transmission rates, at least one pulse sequence is periodically inserted into the digital transmission signal or a pulse sequence already contained in the digital transmission signal is evaluated, the pulse sequence being composed of at least one part having a majority of logical one pulses and a part having a majority of logical zero pulses.

Method and apparatus for modulation current regulation for laser diodes

A coupling arrangement for coupling light of a semiconductor laser diode into a multimode glass fiber. The laser diode emits light along a first optical axis, and the glass fiber receives this light through a light entry surface and transmits it along a second optical axis. The received light forms a maximum intersection angle with the second optical axis which angle is greater than it would be in case both axes coincided. In a preferred embodiment, the laser light is emitted in form of a wedge having a plane of symmetry which bisects the angle of aperture of this wedge and contains the first optical axis. Best results are obtained in this embodiment, if the angle of aperture is about 10.degree. and the maximum intersection angle is up to 8.degree..

Coupling arrangement for coupling light of a semiconductor laser diode

A method and apparatus for variable attenuation of a flexible optical waveguide empart a variable curvature to the waveguide such that selected, conditioned radition losses result. In one embodiment the curvature is emparted by winding a portion of the waveguide around a grooved roller, in other embodiments the curvature is emparted by slides which are laterally moveable within curved recesses of a supporting frame, the slides engaging the waveguide and causing the waveguide to conform to varying portions of the curved recesses.

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Munich, Germany

Walter Proebster