Abstract: A semiconductor laser device is provided which is designed to prevent end surface optical damage, thereby permitting an increase in the output of the semiconductor laser. To achieve this, an active layer at the light emitting end surface portion of the semiconductor laser device is recessed inwardly by a distance between 50 nm and 300 nm (depending on the amount of etching) from the end surfaces of the crystal layers lying on both sides of the active layer. The recess serves to improve the heat dissipation of the active layer portion. This results in improving the amount of light output of the semiconductor laser which is possible without causing optical damage. A method for making the device is also provided. This method permits achieving the above-noted advantages simply by adding an etching step to the conventional semiconductor laser fabrication process, without requiring special equipment or technique.

Abstract: A method may be used to dry etch a sample including a plurality of regions different from each other in the photo-absorption of a light having a specified wavelength using an etching gas plasma. The method is capable of selectively etching the desired material from a plurality of materials having different types of band gap energies or from a plurality of materials having different band gap energies. The method includes a step of irradiating a light having the specified wavelength on the sample for reducing an etching rate of a region having a large photo-absorption coefficient to the light, thereby selectively etching a region having a small photo-absorption coefficient to the light.

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: In a semiconductor laser device having an active layer and clad layers, lens-like portions which magnify radiation are formed in the active layer and/or a clad layer where the radiation leaks, thereby making it possible to enlarge a stripe width and to produce a fundamental mode oscillation of high output. Futher, a lens-like portion which condenses the radiation is formed at an end face of an emission port for a laser beam, thereby making it possible to narrow a radiant angle of the laser beam.

Abstract: A stripe groove is formed on a semiconductor substrate and buried by lamination of multiple semiconductor layers, and a channel being lower than the substrate surface is formed outside the groove near at least one mirror edge, such that a laser diode with decreased astigmatism can be produced.

Abstract: A p-GaAlAs cladding layer is exposed to the air if a groove of the form of a stripe is formed by chemical etching in an n-GaAs layer that serves as a current confinement layer on the p-GaAlAs cladding layer, the groove being so formed as to reach the cladding layer. The GaAlAs is oxidized so easily that an unstable degradation layer is formed on the surface thereof. To solve this problem according to the prior art, an undoped GaAs layer that serves as a cover layer is formed on the p-GaAlAs cladding layer, the n-GaAs layer is formed, and the etching is effected so that the undoped GaAs layer is simply exposed. The undoped GaAs layer is then heated in the MBE apparatus while being irradiated with the As molecular beam and is thermally etched. Therefore, the cladding layer is exposed in vacuum and the p-GaAlAs layer is formed thereon. However, this method is not suited for mass-production since the thermal etching is unstable and it needs the MBE apparatus of a very high degree of vacuum.

Abstract: A semiconductor laser which has a super lattice layer between a substrate and a light confinement layer, and in which a portion of the super lattice layer other than a portion corresponding to the radiation region of an active layer is disordered to block the electric current. The disordering is effected in a self-aligned manner to simplify the manufacturing process. Therefore, and element which oscillates and maintains a fundamental transverse mode is obtained with a good yield.

Abstract: A compound of the formula ##STR1## wherein R.sub.1 is lower alkyl, aryloxy(lower)alkyl or ar(lower)alkyl,R.sub.2 is lower alkyl,Coor.sub.3 is esterified carboxy selected from lower alkoxycarbonyl and ar(lower)alkoxycarbonyl,X is halogen selected from bromine and chlorine, andX' is hydrogen or halogen selected from bromine and chlorine,Said aryl and said ar each constituting phenyl, tolyl or xylyl, and a method of making it are disclosed.