Abstract: An optielectronic device comprising a substrate crystal whose crystal plane is a (n11) plane tilted from the (100) plane toward the [110] direction, or [110] direction where (n>1). When the substrate is applied to an AlGaInP semiconductor laser, the optical device can be cleaved into a rectangular shape, as in the case of a (100) substrate crystal, resulting in easy handling of the chips and also is effective for making the lasting wavelength shorter, lowering the threshold current density for lasing, improving the continuous lasing temperature, etc. Furthermore, semiconductor lasers of different lasing wavelengths can be prepared under good control. Furthermore, a doping efficiency having no dependence on a tilt angle can be obtained by proper selection of a dopant. For example, Si is suitable as an n-type dopant entering sites of group III atom on an (n11) A plane (n.gtoreq.2).

Abstract: A semiconductor laser having a stripe-like lasing region, wherein the structure of the lasing region such as the mechanism of optical guiding of the lateral mode control structure is made different between the central portion in the lasing region and portions close to facets, in order to reduce optical feedback induced noise and astigmatism, and to facilitate the manufacture thereof.

Abstract: A high-power low-noise semiconductor laser device required for light sources for an erasable optical disc is a self-sustained pulsating semiconductor laser device in which an MQW structure is used for an active layer, and thus a kink output power and a light output power by which the self-pulsation is enabled are increased to 10 mW or more and noise is reduced. Another semiconductor laser device of a self-pulsation type has impurities that are doped in the active layer to reduce the self-pulsating frequency to obtain a low-noise characteristic even if higher optical feedback occurs.

Abstract: Disclosed is a semiconductor laser wherein an interface layer is provided on an upper cladding layer formed on an active layer, the interface layer having a smaller Al mole ratio than that of the upper cladding layer, thereby preventing oxidation of the semiconductor surface which is exposed to the atmosphere, and thus improving the crystallizability of a semiconductor layer which is to be formed subsequently. By setting the refractive index of this semiconductor layer so as to be smaller than that of the upper cladding layer, light can be confined in the active layer at increased efficiency.

Abstract: A semiconductor laser device having a stripe-shaped active region defined between a pair of end surfaces, at least one of the end surfaces having a curved cross-section in a plane parallel to the active region with a radius of curvature from 10 to 300 .mu.m, the stripe of the active region having such a width that a single transverse mode and a multi-longitudinal mode are allowed. The laser beam emitted from this laser can have little astigmatism and small spot size.

Abstract: A semiconductor laser device is provided with an optical confinement region constituted by first, second, third and fourth semiconductor layers provided on the upper part of a predetermined semiconductor substrate in contact with each other successively. The first and fourth semiconductor layers are smaller in refractive index than the second and third semiconductor layers, and the third semiconductor layer is larger in refractive index than the second semiconductor layer. On the other hand, the second and fourth semiconductor layers are larger in forbidden bandwidth than the third semiconductor layer. At least the first and fourth semiconductor layers are opposite in conductivity type to each other. In addition to this, the optical confinement region is formed into a mesa-stripe, and both side walls of this mesa-stripe which are substantially parallel to the traveling direction of a laser beam are embedded with a fifth semiconductor layer.

Abstract: A semiconductor injection laser device has a heterostructure wherein either of a p-layer and an n-layer which hold a lasing active layer therebetween is a semiconductor layer which has an energy band gap greater than that of the active layer, and the semiconductor injection laser device includes one of the semiconductor layers that adjoins the active layer being constructed of a semiconductor layer which has a stripe mesa portion and whose base part is 0.8.mu. to 1.5.mu. thick. The semiconductor injection laser device of this construction has a current injection region width limited by the width of the stripe mesa portion. As a result, not only a current flowing into the device can be made small, but also the device can be lased in a single mode of the lowest order with transverse modes of higher orders reduced.