Abstract: A semiconductor optical amplifier integrated laser includes a semiconductor laser oscillator portion that oscillates laser light having a wavelength included in a gain band and a semiconductor optical amplifier portion that amplifies laser light output from the semiconductor laser oscillator portion. The semiconductor laser oscillator portion and the semiconductor optical amplifier portion have one common p-i-n structure, the common p-i-n structure includes an active layer, a cladding layer provided apart from the active layer, and a common functional layer formed in the cladding layer, and the common functional layer includes a first portion that reflects light having a wavelength within the gain band in the semiconductor laser oscillator portion and a second portion that transmits light having a wavelength within the gain band in the semiconductor optical amplifier portion.

Abstract: A semiconductor optical amplifier integrated laser includes a semiconductor laser oscillator portion that oscillates laser light having a wavelength included in a gain band and a semiconductor optical amplifier portion that amplifies laser light output from the semiconductor laser oscillator portion. The semiconductor laser oscillator portion and the semiconductor optical amplifier portion have one common p-i-n structure, the common p-i-n structure includes an active layer, a cladding layer provided apart from the active layer, and a common functional layer formed in the cladding layer, and the common functional layer includes a first portion that reflects light having a wavelength within the gain band in the semiconductor laser oscillator portion and a second portion that transmits light having a wavelength within the gain band in the semiconductor optical amplifier portion.

Abstract: To provide an optical semiconductor device having excellent long-term reliability, the optical semiconductor device includes: a substrate; a mesa structure provided on the substrate; a semiconductor burial layer provided in contact with two sides of the mesa structure; and an electrode containing Au, which is provided above the semiconductor burial layer. The mesa structure includes a first conductivity type semiconductor layer, a multiple-quantum well layer, and a second conductivity type semiconductor layer, which are stacked in the stated order from a substrate side. The semiconductor burial layer includes a first semi-insulating InP layer provided in contact with side portions of the mesa structure, a first anti-diffusion layer provided in contact with the first semi-insulating InP layer, and a second semi-insulating InP layer provided on the first anti-diffusion layer. The first anti-diffusion layer has an Au diffusion constant that is smaller than that of the first semi-insulating InP layer.

Abstract: A semiconductor optical amplifier integrated laser includes a semiconductor laser oscillator portion that oscillates laser light having a wavelength included in a gain band and a semiconductor optical amplifier portion that amplifies laser light output from the semiconductor laser oscillator portion. The semiconductor laser oscillator portion and the semiconductor optical amplifier portion have one common p-i-n structure, the common p-i-n structure includes an active layer, a cladding layer provided apart from the active layer, and a common functional layer formed in the cladding layer, and the common functional layer includes a first portion that reflects light having a wavelength within the gain band in the semiconductor laser oscillator portion and a second portion that transmits light having a wavelength within the gain band in the semiconductor optical amplifier portion.

Abstract: In one embodiment, a seed layer, an underlayer, and a magnetic domain control layer are laminated on both sides of a magnetoresistive sheet unit. A lower electrode film is thinly formed on an upper portion of the magnetic domain control film. A portion of the lower electrode film near the magnetoresistive sheet unit does not protrude substantially from an upper surface of the magnetoresistive sheet unit. Should the portion protrude, a step from the upper surface of the magnetoresistive sheet unit is about 14 nm or less. This portion and the upper surface of the magnetoresistive sheet unit are formed into a flat surface. An upper electrode film is formed thickly on an upper portion of the lower electrode film on an outside thereof so as to circumvent the flat surface. A protective layer, an upper gap film, and an upper magnetic shield film are also formed.

Abstract: Making thinner the magnetic domain control layer deteriorates the magnetic properties. Also, disturbances tend to increase the magnetization dispersion of the magnetic domain control layer, thereby lowering the magnetic domain control bias magnetic field. In one embodiment of the invention, a first magnetic domain control layer is provided in the proximity of the free layer of the GMR sensor in such a way that the track width is Twr1. Outside the first magnetic domain control layer is provided a second magnetic domain control layer. The second magnetic domain control layer placed outside the first magnetic domain control layer gives the first magnetic domain control layer an external bias field. The amount of magnetization of the tip of the first magnetic domain control layer is polarized and increased by the bias magnetic field from the second magnetic domain control layer.

Abstract: A magnetoresistive head comprises a free magnetic layer that has first and second free magnetic films sandwiching a non-magnetic intermediate film therebetween, the respective magnetizing directions of the first and the second free magnetic films are antiparallel. The length of the free magnetic layer in the direction of the track width is 200 nm or less, and a difference between a product of saturation magnetic flux density and a film thickness of the first free magnetic film, and that of the second free magnetic film is within a range from 1 to 3 nmT. By this structure, the variation of output and the variation of asymmetry is greatly decreased at a track width of 200 nm or less.

Abstract: A magnetoresistive head comprises a free magnetic layer that has first and second free magnetic films sandwiching a non-magnetic intermediate film therebetween, the respective magnetizing directions of the first and the second free magnetic films are antiparallel. The length of the free magnetic layer in the direction of the track width is 200 nm or less, and a difference between a product of saturation magnetic flux density and a film thickness of the first free magnetic film, and that of the second free magnetic film is within a range from 1 to 3 nmT. By this structure, the variation of output and the variation of asymmetry is greatly decreased at a track width of 200 nm or less.

Abstract: Multiple thin films of spin-valve GMR sensor are formed in a trapezoidal cross-sectional shape by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer and a nonmagnetic protective layer on a lower insulated gap layer. The amount of etching of the lower insulated gap layer produced in the process of patterning the spin-valve giant magnetoresistive layers into the multiple thin films of spin-valve GMR sensor is 10 nm or less. Further, the angle ? which the tangent line of each side face of the multiple thin films to the middle line of the free magnetic layer in its thickness direction forms with respect to the middle line of the free magnetic layer becomes 45 degrees or more. This structure makes it possible to provide such a spin-valve giant magnetoresistive head that it meets the requirements for securing constant breakdown voltage and preventing instability of MR output voltage waveform.

Abstract: Multiple thin films of spin-valve GMR sensor are formed in a trapezoidal cross-sectional shape by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer and a nonmagnetic protective layer on a lower insulated gap layer. The amount of etching of the lower insulated gap layer produced in the process of patterning the spin-valve giant magnetoresistive layers into the multiple thin films of spin-valve GMR sensor is 10 nm or less. Further, the angle ? which the tangent line of each side face of the multiple thin films to the middle line of the free magnetic layer in its thickness direction forms with respect to the middle line of the free magnetic layer becomes 45 degrees or more. This structure makes it possible to provide such a spin-valve giant magnetoresistive head that it meets the requirements for securing constant breakdown voltage and preventing instability of MR output voltage waveform.

Abstract: Making thinner the magnetic domain control layer deteriorates the magnetic properties. Also, disturbances tend to increase the magnetization dispersion of the magnetic domain control layer, thereby lowering the magnetic domain control bias magnetic field. In one embodiment of the invention, a first magnetic domain control layer is provided in the proximity of the free layer of the GMR sensor in such a way that the track width is Twr1. Outside the first magnetic domain control layer is provided a second magnetic domain control layer. The second magnetic domain control layer placed outside the first magnetic domain control layer gives the first magnetic domain control layer an external bias field. The amount of magnetization of the tip of the first magnetic domain control layer is polarized and increased by the bias magnetic field from the second magnetic domain control layer.

Abstract: A magnetoresistive head comprises a free magnetic layer that has first and second free magnetic films sandwiching a non-magnetic intermediate film therebetween, the respective magnetizing directions of the first and the second free magnetic films are antiparallel. The length of the free magnetic layer in the direction of the track width is 200 nm or less, and a difference between a product of saturation magnetic flux density and a film thickness of the first free magnetic film, and that of the second free magnetic film is within a range from 1 to 3 nmT. By this structure, the variation of output and the variation of asymmetry is greatly decreased at a track width of 200 nm or less.

Abstract: A magnetoresistive head comprises a free magnetic layer that has first and second free magnetic films sandwiching a non-magnetic intermediate film therebetween, the respective magnetizing directions of the first and the second free magnetic films are antiparallel. The length of the free magnetic layer in the direction of the track width is 200 nm or less, and a difference between a product of saturation magnetic flux density and a film thickness of the first free magnetic film, and that of the second free magnetic film is within a range from 1 to 3 nmT. By this structure, the variation of output and the variation of asymmetry is greatly decreased at a track width of 200 nm or less.

Abstract: Making a geometric track width small does not decrease a read track width, resulting only in an output being reduced. In one embodiment, a seed layer, an underlayer, and a magnetic domain control layer are laminated on both sides of a magnetoresistive sheet unit. A lower electrode film is thinly formed on an upper portion of the magnetic domain control film. A portion of the lower electrode film near the magnetoresistive sheet unit does not protrude substantially from an upper surface of the magnetoresistive sheet unit. Should the portion protrude, a step from the upper surface of the magnetoresistive sheet unit is about 14 nm or less. This portion and the upper surface of the magnetoresistive sheet unit are formed into a flat surface. An upper electrode film is formed thickly on an upper portion of the lower electrode film on an outside thereof so as to circumvent the flat surface. A protective layer, an upper gap film, and an upper magnetic shield film are also formed.

Abstract: Multiple thin films of spin-valve GMR sensor are formed in a trapezoidal cross-sectional shape by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer and a nonmagnetic protective layer on a lower insulated gap layer. The amount of etching of the lower insulated gap layer produced in the process of patterning the spin-valve giant magnetoresistive layers into the multiple thin films of spin-valve GMR sensor is 10 nm or less. Further, the angle &thgr; which the tangent line of each side face of the multiple thin films to the middle line of the free magnetic layer in its thickness direction forms with respect to the middle line of the free magnetic layer becomes 45 degrees or more. This structure makes it possible to provide such a spin-valve giant magnetoresistive head that it meets the requirements for securing constant breakdown voltage and preventing instability of MR output voltage waveform.

Abstract: Multiple thin films of spin-valve GMR sensor are formed in a trapezoidal cross-sectional shape by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer and a nonmagnetic protective layer on a lower insulated gap layer. The amount of etching of the lower insulated gap layer produced in the process of patterning the spin-valve giant magnetoresistive layers into the multiple thin films of spin-valve GMR sensor is 10 nm or less. Further, the angle &thgr; which the tangent line of each side face of the multiple thin films to the middle line of the free magnetic layer in its thickness direction forms with respect to the middle line of the free magnetic layer becomes 45 degrees or more. This structure makes it possible to provide such a spin-valve giant magnetoresistive head that it meets the requirements for securing constant breakdown voltage and preventing instability of MR output voltage waveform.

Abstract: A magnetoresistive head comprises a free magnetic layer that has first and second free magnetic films sandwiching a non-magnetic intermediate film therebetween, the respective magnetizing directions of the first and the second free magnetic films are antiparallel. The length of the free magnetic layer in the direction of the track width is 200 nm or less, and a difference between a product of saturation magnetic flux density and a film thickness of the first free magnetic film, and that of the second free magnetic film is within a range from 1 to 3 nmT. By this structure, the variation of output and the variation of asymmetry is greatly decreased at a track width of 200 nm or less.

Abstract: A magnetoresistive reproducing head is manufactured by forming a magnetoresistive film and a lead layer continuously, then etching only the lead layer by using a first layer photo-resist pattern, forming a second layer photo-resistive pattern while leaving the first layer photo-resist pattern, etching the magnetoresistive film and then forming a domain control film and an outer lead layer, thereby enabling to avoid the effect at all on the positional relation between the lead layer and domain control film, whereby a head in which the riding amount of the lead layer on the magnetoresistive film is in right-to-left symmetry and the sensitivity profile is in right-to-left symmetry can be manufactured at a good yield.

Abstract: Multiple thin films of spin-valve GMR sensor are formed in a trapezoidal cross-sectional shape by laminating an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, a free magnetic layer and a nonmagnetic protective layer on a lower insulated gap layer. The amount of etching of the lower insulated gap layer produced in the process of patterning the spin-valve giant magnetoresistive layers into the multiple thin films of spin-valve GMR sensor is 10 nm or less. Further, the angle &thgr; which the tangent line of each side face of the multiple thin films to the middle line of the free magnetic layer in its thickness direction forms with respect to the middle line of the free magnetic layer becomes 45 degrees or more. This structure makes it possible to provide such a spin-valve giant magnetoresistive head that it meets the requirements for securing constant breakdown voltage and preventing instability of MR output voltage waveform.