Abstract: The invention relates to a method of transferring electronically stored funds via a communications network with a first mobile user terminal which administers a first account, particularly a prepaid account, for telephone services,

Abstract: An interferometric semiconductor laser (YL) as well as optoelectronic arrangements with such a laser are disclosed. The laser has a special coupling segment (Z) which allows high optical output to be obtained without affecting the filtering function or significantly restricting the tuning range of the laser. Such a laser can be coupled with low loss to a subsequent optoelectronic component (e.g., a wavelength converter (WK)) which is monolithically integrated with the laser.

Abstract: The device comprises a treatment laser and at least two diagnosis lasers of differing wavelengths, wherein a receiving means is allocated to each diagnosis laser. The signal of the receiving means is led to an electronic evaluation and control means. In the distal end section of the endosopic part of the device the light beams of all lasers are guided together.

Abstract: For use in digital optical telecommunication systems, optical semiconductor components are shown having a transition region for the expansion of the mode field of a light wave in order to reduce losses when coupling to an optical fiber or an optical waveguide of a supporting plate. An optical semiconductor component contains a deep ridged waveguide (RIDGE) with a cover layer (DS) disposed on a substrate (SUB.) The ridged waveguide (RIDGE) has a first (MQW) and second (BULK) waveguide cores, these being separated by a separating layer (SEP). The thickness of this separating layer increases in a transition region (UB1) along a longitudinal direction (L) of the ridged waveguide (RIDGE), thus increasing the vertical distance between the two waveguide centers (MQW, BULK).

Abstract: A semiconductor device is operated as an optical filter. The semiconductor device has a substrate and a monolithically integrated branched waveguide structure disposed above the substrate, portions of the waveguide structure being divided into a plurality of regions by troughs, one of the regions being a branching region. Light is radiated into the waveguide structure at an end face of one of the regions and currents that are smaller than respective laser threshold currents of the regions flow through the regions, including the branching region, perpendicular to a propagation direction of light through the waveguide.

Abstract: An interferometric semiconductor laser includes a cavity in the form of a Y and at east three individually actuatable active segments. A central segment couples together the individually actuatable active segments. The central segment is an active or passive segment that acts as a beam divider. The arrangement of the segments forms two resonator paths which contain at least one common active segment. At least one resonator path includes an active segment that does not belong to the other resonator path. In the absence of, or with the same actuation of the active segments, the optical path length of one resonator path differs from the optical path length of the other resonator path.

Abstract: A semiconductor laser that is monolithically integrated on a substrate and whose cavity has a branched structure that is simply contiguous in a topological sense, and which includes a plurality of regions that enclose the cavity, is operated as a mode-locked semiconductor laser, with an alternating current flowing through at least one region in addition to a direct current. The frequency of the alternating current is related to the reciprocal of the round-trip time or an integral multiple of this reciprocal of light pulses generated by the alternating current in the semiconductor laser.

Abstract: A semiconductor laser in which the photons injected from its waveguide region into the laser active region are those whose energies differ from the energy sum of the chemical potential of the electron-hole pairs and the energy of the longitudinal acoustic phonons by less than one-half the thermal energy is described. A current directed into the photon emission region in the area of the Bragg grating causes photons of this energy to be injected into the laser active region which is constituted of a layer of indium gallium arsenide phosphide.