Abstract: Laser diodes containing aluminum at high concentration in an active layer have been usually suffered from remarkable facet deterioration along with laser driving operation and it has been difficult for the laser diodes to attain high reliability. An aluminum oxide film lacking in oxygen is formed adjacent to the semiconductor on an optical resonator facet, by which facet deterioration can be minimized and, accordingly, the laser diode can be operated with no facet deterioration at high temperature for long time and a laser diode of high reliability can be manufactured at a reduced cost.

Abstract: The present invention provides a highly reliable ridge-waveguide semiconductor laser diode and an optical module. The p-side electrode of the ridge-waveguide laser diode has a first conductor layer region and a second conductor layer region formed on the first conductor layer region. At least one of facets of the second conductor layer region is recessed inward from a reflection facet. Thus, the ridge-waveguide semiconductor laser diode has a structure in which strain which is caused by the electrode stress to be applied on the diode facet is reduced and the saturable absorption does not occur. The ridge-waveguide semiconductor laser diode thus obtained is highly reliable, and the optical module using the same is remarkably high in reliability.

Abstract: A semiconductor laser having high speed modulation function over a wide temperature range can be attained by making an active layer region of a semiconductor laser as a multiple quantum well structure of InGaAlAs or InGaAs material system, and defining the bandgap wavelength of the barrier layer to less than 950 nm, or alternatively, by making the bandgap wavelength of a barrier to less than 1000 nm and the bandgap wavelength optical guide layer substantially equal with or shorter than that of the barrier layer in a structure having a multiple quantum well of the same material system having an active layer and an optical guide layer in adjacent therewith.