Abstract: A bar code reader comprises a semiconductor laser diode. A first end face of the laser diode is optically coupled to an end of an optical fiber. A second end face of the laser diode is optically coupled to a detector. The bar code is scanned at the free end of the optical fiber. This information is read by the semiconductor laser diode by way of optical feedback.

Abstract: In a semiconductor laser with iso-electronic doping or with a quantum-well structure, efficiency is considerably increased by lateral injection. For this purpose, the active region is composed of active layers and barrier layers which are laterally bounded by semiconductor zones preferably degenerate, which inject charge carriers in the longitudinal direction of the active layers. The population inversion in the active layers is further increased in that superinjection occurs at the transition with the degenerate zones.

Abstract: A semiconductor laser device has a semiconductor body in which two or more lasers are provided which can generate substantially parallel radiation beams of preferably different frequencies which are situated close together. According to the invention, the semiconductor body has at least one semiconductor laser of the double hetero-junction type (DH-type) comprising a plurality of semiconductor layers with a radiating p-n junction parallel to the semiconductor layers and at least one semiconductor laser of the TJS ("Transverse Junction Stripe") type, the p-n junction surface of which is transverse to that of the DH-laser. The device comprises a layer structure having at least two active layers, each between two passive layers. One laser is formed in a mesa-shaped part of the body which comprises both active layers, the other in an adjacent part in which the uppermost active layer is absent. The TJS-laser is preferably provided in the last-mentioned part. More than two lasers may also be provided.

Abstract: In optical communication systems as well as in video disc playback equipment, it is necessary to position a light source such as a semiconductor laser at an exact distance from a lens of the optical system. In accordance with the invention this is done by mounting the laser in a tubular cover which is in a telescopic, press fit engagement with a holder provided with the lens. The desired exact distance between the laser and the lens is adjusted by relative compression between the cover and the holder. Because the engaging walls of the cover and holder are covered with a layer of indium, the walls will slide smoothly over each other during adjustment of the desired distance.