Abstract: An optical fiber communication apparatus includes a main optical fiber having dispersive characteristics; a semiconductor laser diode for outputting an optical signal transmitted through the main optical fiber; a photodiode for receiving the optical signal output from the main optical fiber and a dispersion canceling short distance optical fiber having a total dispersion approximately the same as and in a reverse phase from the total dispersion of the main optical fiber at the wavelength of the optical signal, correcting the total dispersion produced by the main optical fiber and located at one of the input and output end of the main optical fiber. An optical signal traveling through the signal transmission line becomes a reformed rectangular waveform at the output end so that reading errors can be eliminated, resulting in highly reliable communication.

Abstract: A semiconductor laser includes a semiconductor substrate of a first conductivity type, a gain guiding structure comprising of a first conductivity type, a lower cladding layer disposed on the substrate, an active layer disposed on the lower cladding layer and having a light emitting region, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the active layer, and a multiquantum barrier layer interposed between the upper cladding layer and the active layer excluding the light emitting region. In this structure, the multiquantum barrier layer reduces leakage current flowing outside of the light emitting region of the active layer and increases effective current flowing into the light emitting region, whereby the light output of the laser is significantly increased.