Abstract: A semiconductor laser has a semiconductor body with first and second main areas, preferably each provided with a contact area, and also first and second mirror areas. An active layer and a current-carrying layer are formed between the main areas. The current-carrying layer has at least one strip-type resistance region, which runs transversely with respect to the resonator axis and whose sheet resistivity is increased at least in partial regions compared with the regions of the current-carrying layer that adjoin the resistance region.

Abstract: A compactly constructed configuration for coupling radiation into an optical fiber in a highly effective manner has a semiconductor laser with a radiation exit window, and an optical fiber having a radiation entry end. The radiation exit window of the semiconductor laser faces the radiation entry end of the optical fiber. A resonator is provided and has an end mirror and an output mirror, between which the semiconductor laser is disposed. The output mirror of the resonator is formed by the optical fiber. An optical device is disposed between the semiconductor laser and the optical fiber and serves for imaging only the fundamental mode of the radiation of the semiconductor laser onto the radiation entry end of the optical fiber.