Abstract: A semiconductor laser particularly adapted for operation in the self-pulsation mode and method for production thereof. A central mesa is formed in the upper cladding layer and normally requires relatively thick sections at either side of the mesa in order to form a wageguide of sufficient thickness to cause self-pulsation operation. In order to control the thickness of the upper cladding layer bounding the mesa, the mesa is first formed by etching the regions bounding the mesa to relatively thin sections capable of ready gauging by optical interferometry. A composite upper clading layer is then formed by utilizing MOCVD crystal growth techniques to form a buffer layer on the upper cladding layer bounding the mesa, the buffer layer having an aluminum content about the same as the aluminum content of the AlGaAs upper cladding layer.

Abstract: A multi-point light emission type semiconductor laser device including a plurality of light emission points which are produced on a p type or n type semiconductor layer monolithically and are capable of being driven independently includes electrically insulating or semi-insulating semiconductor regions provided at intermediate portions of light emission points in the p type or n type semiconductor layer. A separation groove is further produced up to reaching the insulating or semi-insulating regions from the side opposite to the semiconductor layer. Thus, respective light emission points are perfectly electrically separated each other by this separation groove and the region.

Abstract: A semiconductor laser includes a first cladding layer having a forward mesa with at least one end at least partially spaced from the adjacent facet of the laser. A current blocking layer buries the mesa at its sides and at least partially at the ends of the mesa so that the ends are at least partially spaced from the facets. The current blocking layer reduces current injection and surface recombination at the facets at least partially spaced from the mesa ends, thereby increasing the catastrophic optical damage level of the laser. The mesa is formed without etching or exposing the active layer so that formation of interfaces that refract light or shorten laser lifetime are avoided. An increase in COD level of about 20 percent is achieved in the invention.

Abstract: A photodetector device includes a stack of a light-absorbing layer, a window layer on a substrate, and a region in the window layer formed by reversing the conductivity type of the window layer extending to the light-absorbing layer. A surface protecting film is disposed on the window layer, with a light receiving area being left uncovered. An electrode makes ohmic contact with the reversed conductivity region and surrounds the light receiving area. A metallic light-blocking film is disposed on the protecting film with an insulating gap therebetween. The inner edge of the light-absorbing film is located in alignment with or inward of the p-n junction between the reversed conductivity type region and the window layer.

Abstract: A monolithic multiple beam semiconductor laser having a low power and a high power beam. A number of factors in the laser are coordinated in order to assure that both the low and high power beams operate at precisely the same frequency. The front and rear facet reflectances of the respective low and high power cavities are coordinated to each other and to the rated operating power levels of the respective lasers to achieve the same operating frequency from both beams. In a particular example, the low power cavity has front and rear facet reflectivities of 30% and a rated output power of 3 mw. The high power cavity has a rated operating power of 20 mw, a front facet reflectivity of 2%, and a rear facet reflectivity of 60%.

Abstract: A semiconductor laser particularly adapted for operation in the self-pulsation mode and method for production thereof. A central mesa is formed in the upper cladding layer and normally requires relatively thick sections at either side of the mesa in order to form a waveguide of sufficient thickness to cause self-pulsation operation. In order to control the thickness of the upper cladding layer bounding the mesa, the mesa is first formed by etching the regions bounding the mesa to relatively thin sections capable of ready gauging by optical interferometry. A composite upper cladding layer is then formed by utilizing MOCVD crystal growth techniques to form a buffer layer on the upper cladding layer bounding the mesa, the buffer layer having an aluminum content about the same as the aluminum content of the AlGaAs upper cladding layer.

Abstract: A semiconductor laser includes a first cladding layer having a forward mesa with at least one end at least partially spaced from the adjacent facet of the laser. A current blocking layer buries the mesa at its sides and at least partially at the ends of the mesa so that the ends are at least partially spaced from the facets. The current blocking layer reduces current injection and surface recombination at the facets at least partially spaced from the mesa ends, thereby increasing the catastrophic optical damage level of the laser. The mesa is formed without etching or exposing the active layer so that formation of interfaces that refract light or shorten laser life-time are avoided. An increase in COD level of about 20 percent is achieved in the invention.

Abstract: A semiconductor laser device having a double heterojunction structure disposed on a current blocking layer which is disposed on a convex ridge includes a buffer layer having a conductivity-type opposite that of the current blocking layer disposed between the current blocking layer and the double heterojunction structure. A current injection groove in the ridge penetrates the current blocking and buffer layers so that the lower cladding layer of the double heterojunction structure contacts the ridge. Therefore, a thin active layer may be produced using the liquid phase epitaxy ridge effect. The pn junction between the current blocking layer and the lower cladding layer is stabilized by the intervening buffer layer.

Abstract: A multi-point light emission type semiconductor laser device including a plurality of light emission points which are produced on a p type or n type semiconductor layer monolithically and are capable of being driven independently includes electrically insulating or semi-insulating semiconductor regions provided at intermediate portions of light emission points in the p type or n type semiconductor layer. A separation groove is further produced up to reaching the insulating or semi-insulating regions from the side opposite to the semiconductor layer. Thus, respective light emission points are perfectly electrically separated each other by this separation groove and the region.

Abstract: A semiconductor laser includes a facet protection film consisting of an Al.sub.2 O.sub.3 film of optical length .lambda./4 and a SiO.sub.2 film of optical length .lambda./4 produced on the Al.sub.2 O.sub.3 film, and the facet reflectivity takes a value with in 21.+-.3%.