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Fabrication process of semiconductor lasers
New Patents
4782493
4783425
GAS DISCHARGE TUBE WITH HOLLOW CATHODE FOR METAL VAPOR LASER
FABRICATION PROCESS OF SEMICONDUCTOR LASERS
Nikola V Sabotinov, Margarita G Grozeva, Ivan R Angelov, Sofia, Bulgaria assigned to Institute PO Phisica Na Tvardoto Tyalo
Tadashi Fukuzawa, Yuichi Ono, Shinich Nakatsuka, Takashi Kajimura, Tokyo, Japan assigned to Hitachi Ltd
4783373
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. Quality of the crystal decreases, too, due to the heating. This invention therefore provides a fabrication process of semiconductor lasers in which the cover layer disappears due to interdiffusion of constituent elements that stem from the diffusion of impurities such as zinc ions in the undoped GaAs layer.
ARTICLE WITH THIN FILM COATING HAVING AN ENHANCED EMISSIVITY AND REDUCED ABSORPTION OF RADIANT ENERGY
4787824
This invention relates to a gas discharge hollow cathode tube for laser using metal vapors having a vacuum compact housing where an anode and a hollow spiral cathode are mounted connected to a source of excitation, the hollow cathode contains an active metal medium, having evenly distributed apertures on the pipe’s upper inner part, and resistance wire fitted inside the hollow cathode supplied from an electric source. This apparatus avoids the disadvantages of a similar gas discharge tube having metal in the cylindrical cathode where the metal vapors enter the discharge zone uncontrollably, causing metal accumulation in some zones which thus partially covers the laser tube aperture, and because the high-level ionic metal laser levels are not efficiently excited as it operates under low voltages, it cannot be used for generation using easily fusable metals as the spiral cathode cannot be made of such metals. The invention also has improved stability and efficacy of the generation.
Philip W Baumeister, Matthew Krisl assigned Optical Coating Laboratory Inc
to
A coating useful for a solar cell is formed by concurrent deposition of two materials, such as silicon dioxide and magnesium fluoride, on a substrate within a single vacuum chamber. The deposition is monitored to enable control of the ratio of the materials and the thickness of the coating. An alternative embodiment of a coating employs alternating layers of different materials which form pairs or periods, each having a very small optical thickness. By virtue of the coatings, emissivity is enhanced by suppression of the reststrahlen reflectance and solar absorption is reduced by external reflection of the ultraviolet portion of the solar spectrum.
ROTATING LIQUID RING VACUUM PUMP Michae Cole, Ipswich, United signed to Genevac Limited
Kingdom
as-
A method of and apparatus for pumping fluids wherein a rotating ring of liquid traverses a hollow probe which has a surface aperture out of which the fluid to be pumped is sucked into the rotating liquid ring, wherein the fluid migrates to a collection region inside the rotating liquid ring, from where the fluid can pass to a fluid outlet, and wherein a gas which does not condense under the prevailing operating conditions is also fed to the collection region in order to assist throughput of the fluid being pumped.
4782493
4783425
GAS DISCHARGE TUBE WITH HOLLOW CATHODE FOR METAL VAPOR LASER
FABRICATION PROCESS OF SEMICONDUCTOR LASERS
Nikola V Sabotinov, Margarita G Grozeva, Ivan R Angelov, Sofia, Bulgaria assigned to Institute PO Phisica Na Tvardoto Tyalo
Tadashi Fukuzawa, Yuichi Ono, Shinich Nakatsuka, Takashi Kajimura, Tokyo, Japan assigned to Hitachi Ltd
4783373
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. Quality of the crystal decreases, too, due to the heating. This invention therefore provides a fabrication process of semiconductor lasers in which the cover layer disappears due to interdiffusion of constituent elements that stem from the diffusion of impurities such as zinc ions in the undoped GaAs layer.
ARTICLE WITH THIN FILM COATING HAVING AN ENHANCED EMISSIVITY AND REDUCED ABSORPTION OF RADIANT ENERGY
4787824
This invention relates to a gas discharge hollow cathode tube for laser using metal vapors having a vacuum compact housing where an anode and a hollow spiral cathode are mounted connected to a source of excitation, the hollow cathode contains an active metal medium, having evenly distributed apertures on the pipe’s upper inner part, and resistance wire fitted inside the hollow cathode supplied from an electric source. This apparatus avoids the disadvantages of a similar gas discharge tube having metal in the cylindrical cathode where the metal vapors enter the discharge zone uncontrollably, causing metal accumulation in some zones which thus partially covers the laser tube aperture, and because the high-level ionic metal laser levels are not efficiently excited as it operates under low voltages, it cannot be used for generation using easily fusable metals as the spiral cathode cannot be made of such metals. The invention also has improved stability and efficacy of the generation.
Philip W Baumeister, Matthew Krisl assigned Optical Coating Laboratory Inc
to
A coating useful for a solar cell is formed by concurrent deposition of two materials, such as silicon dioxide and magnesium fluoride, on a substrate within a single vacuum chamber. The deposition is monitored to enable control of the ratio of the materials and the thickness of the coating. An alternative embodiment of a coating employs alternating layers of different materials which form pairs or periods, each having a very small optical thickness. By virtue of the coatings, emissivity is enhanced by suppression of the reststrahlen reflectance and solar absorption is reduced by external reflection of the ultraviolet portion of the solar spectrum.
ROTATING LIQUID RING VACUUM PUMP Michae Cole, Ipswich, United signed to Genevac Limited
Kingdom
as-
A method of and apparatus for pumping fluids wherein a rotating ring of liquid traverses a hollow probe which has a surface aperture out of which the fluid to be pumped is sucked into the rotating liquid ring, wherein the fluid migrates to a collection region inside the rotating liquid ring, from where the fluid can pass to a fluid outlet, and wherein a gas which does not condense under the prevailing operating conditions is also fed to the collection region in order to assist throughput of the fluid being pumped.