Abstract: Disclosed is an optical semiconductor device that provides an optical gain or optical loss depending on application of electric current. The optical semiconductor device comprises: a lower clad layer; an active layer disposed on the lower clad layer, the active layer generating optical gain or optical loss depending on injection of carriers; an upper clad layer disposed on the active layer, the upper clad layer serving to trap light in the active layer in cooperation with the lower clad layer; and a temperature control part for controlling the temperature distribution of the active layer along the light propagation axis in such a manner that temperature of the active layer varies depending on positions in the active layer.

Abstract: A semiconductor laser diode and a method of fabricating the same are provided. The semiconductor laser diode includes: a substrate; a predetermined compound semiconductor layer formed on the substrate; a lower cladding layer formed on the compound semiconductor layer; an active layer formed on the lower cladding layer; an upper cladding layer formed on the active layer and having a ridge formed in the middle thereof; trenches formed to a predetermined depth on at least one side of the ridge to penetrate the active layer from the upper cladding layer; a current blocking layer formed on surfaces of the upper cladding layer, except a top surface of the ridge, and inner walls of the trenches; a contact layer formed on the top surface of the ridge; and a first electrode formed on top surfaces of the contact layer and the current blocking layer.

Abstract: A distributed feedback semiconductor laser and a method of manufacture includes first and second clad layers having predetermined refractive indexes that are formed on a semiconductor substrate. A guide layer propagates light between the first and second clad layers. An oscillating clad layer oscillates light at a predetermined wavelength and an amplifying clad layer amplifies the light with a predetermined gain between the first clad layer and the guide layer. The distributed feedback semiconductor laser is divided into a laser oscillation section including the oscillating clad layer and a laser amplification section including the amplifying active layer. First and second gratings are formed on the lower surface of the guide layer in the laser oscillation section and in the laser amplification section, respectively.

Abstract: A distributed feedback semiconductor laser and a method of manufacture includes first and second clad layers having predetermined refractive indexes that are formed on a semiconductor substrate. A guide layer propagates light between the first and second clad layers. An oscillating clad layer oscillates light at a predetermined wavelength and an amplifying clad layer amplifies the light with a predetermined gain between the first clad layer and the guide layer. The distributed feedback semiconductor laser is divided into a laser oscillation section including the oscillating clad layer and a laser amplification section including the amplifying active layer. First and second gratings are formed on the lower surface of the guide layer in the laser oscillation section and in the laser amplification section, respectively.

Abstract: Disclosed are nickel-based amorphous alloy compositions, and particularly quaternary nickel-based amorphous alloy compositions containing nickel, zirconium and titanium as main constituent elements and additive Si or P, the quaternary nickel-zirconium-titanium-silicon alloy compositions comprising nickel in the range of 45 to 63 atomic %, zirconium plus titanium in the range of 32 to 48 atomic % and silicon in the range of 1 to 11 atomic %, and being represented by the general formula: Nia(Zr1−xTix)bSic. Also, at least one kind of element selected from the group consisting of V, Cr, Mn, Cu, Co, W, Sn, Mo, Y, C, B, P, Al can be added to the alloy compositions in the range of content of 2 to 15 atomic %. The quaternary nickel-zirconium-titanium-phosphorus alloy compositions comprising nickel in the range of 50 to 62 atomic %, zirconium plus titanium in the range of 33 to 46 atomic % and phosphorus in the range of 3 to 8 atomic %, and being represented by the general formula: Nid(Zr1−yTiy)ePf.

Abstract: Disclosed is a polarization insensitive semiconductor optical amplifier (SOA) in an optical amplifying element having a substrate and a multi-layer structure, crystal growth layer including an active layer formed on the substrate. In the inventive optical amplifier, the active layer is divided into first and second areas having different polarization modes. An electrode means independently applies currents to the first and second areas. Therefore, the polarization insensitive semiconductor optical amplifier is capable of separately controlling TE and TM polarization gains so as to approximately equalize the TE polarization gain to the TM polarization gain.

Abstract: Disclosed is the use of 2-oxoasiatic acid in the treatment of dementia or cognitive disorders.

Abstract: Asiatic acid derivatives having a modified A-ring, as represented by formula 1 are disclosed. ##STR1## Pharmaceutical compositions and methods of treating cancer and hepatotoxicity utilizing compounds of formula 1 are also disclosed.

Abstract: A distributed feedback semiconductor laser device having a semiconductor substrate, a bottom electrode formed on a bottom surface of the substrate, a corrugation-shaped grating formed on a top surface of the substrate, an active waveguide layer whose energy band gap profile and whose light propagation constant are varied along cavity length direction of the laser device, the active waveguide layer being formed over the corrugation-shaped grating, a clad layer formed to cover the active waveguide layer, and a top electrode formed on a top of the clad layer. The active waveguide layer is grown by a selective metal organic vapor phase epitaxy with use of slender insulation masks having a variation in width, the slender insulation masks being arranged at both sides of an area on which the active waveguide layer is grown.

Abstract: A distributed feedback semiconductor laser device having a semiconductor substrate, a bottom electrode formed on a bottom surface of the substrate, a corrugation-shaped grating formed on a top surface of the substrate, an active waveguide layer whose energy band gap profile and whose light propagation constant are varied along a cavity length direction of the laser device, the active waveguide layer being formed over the corrugation-shaped grating, a clad layer formed to cover the active waveguide layer, and a top electrode formed on a top of the clad layer. The active waveguide layer is grown by a selective metal organic vapor phase epitaxy with use of slender insulation masks having a variation in width, the slender insulation masks being arranged at both sides of an area on which the active waveguide layer is grown.