Abstract: An optical signal transmission system equipped with a magneto-optical modulator is provided. The magneto-optical modulator works to modulate an optical beam emitted from a light source and consists of a polarizer, a magneto-optical element, an analyzer, a dc field generator, a high-frequency field generator, and an impedance adjuster. The dc field generator works to apply a dc bias field to the magneto-optical element. The high-frequency generator is responsive to the high-frequency signal from said high-frequency signal generator to apply a high-frequency field to the magneto-optical element. The impedance adjuster works to adjust impedance of the high-frequency field generator for establishing effective transmission of the high-frequency signal to the high-frequency field generator, thereby increasing a modulation range up to frequencies higher than an upper limit of typical magneto-optical modulators.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: An optical signal transmission system equipped with a magneto-optical modulator is provided. The magneto-optical modulator works to modulate an optical beam emitted from a light source and consists of a polarizer, a magneto-optical element, an analyzer, a dc field generator, a high-frequency field generator, and an impedance adjuster. The dc field generator works to apply a dc bias field to the magneto-optical element. The high-frequency generator is responsive to the high-frequency signal from said high-frequency signal generator to apply a high-frequency field to the magneto-optical element. The impedance adjuster works to adjust impedance of the high-frequency field generator for establishing effective transmission of the high-frequency signal to the high-frequency field generator, thereby increasing a modulation range up to frequencies higher than an upper limit of typical magneto-optical modulators.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: A magneto-optical device using a rare earth iron garnet material, wherein the rare earth garnet material is expressed in the following formula: (BixGdyRzY3−x−y−z)(Fe5−wGaw)O12, wherein x is defined in a range of 0.84≦x≦1.10, y is defined in the range of 0.73≦y≦1.22, z is defined in the range of 0.02≦z≦0.03, and w is defined in the range of 0.27≦w≦0.32, and wherein R is at least one element selected from rare earth elements.

Abstract: A second-order nonlinear optical material comprises a glass body poled from a first direction and a second direction, which differ from each other, so that the glass body exhibits little birefringence relative to a beam being propagated in a third direction substantially vertical to said first direction and said second direction, respectively, wherein said glass body comprises a major proportion of SiO2 and a minor proportion of germanium. A method for making the material, and optical modulator devices comprising the material are also described.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: An optical sensor apparatus capable of accurate measurement without using a filter circuit, and therefore being further capable of pulse driving an LED and thus reducing power consumption, is provided. To achieve such an optical sensor apparatus, when an optical current sensor 10 is not sensing the current to be measured, an optical current sensor signal processing circuit 11 first supplies dc light of a specific intensity to the optical current sensor 10, and then adjusts the intensity of the light so that the intensity of light returned from the optical current sensor 10 to the signal processing circuit 11 is a specific predetermined value. When the optical current sensor 10 is sensing the current, the signal processing circuit 11 electrically processes the optical signal from the optical current sensor 10 to measure the current.

Abstract: An optical magnetic field sensor probe for detecting a magnetic field to be measured as an output light intensity, by disposing a polarizer, a magneto-optical device, and an analyzer mutually different in the transmission and polarization direction with respect to said polarizer, along the running direction of light, has an input optical fiber for feeding into to said polarizer through a first lens, and an output optical fiber for emitting an output light from said analyzer through a second lens, wherein said input optical fiber, said first lens, said magneto-optical device, said second lens and said output optical fiber are composed in a confocal optical system, and said first lens and said second lens are drum lenses.

Abstract: An optical fiber modulator comprises an optical fiber, a substrate having a groove pattern in which the optical fiber is fixed, and a modulation unit including a polarizer, an electrooptic element, and an analyzer aligned in a light path of the optical fiber in this order, wherein the electrooptic element is made of a poled portion of the optical fiber, and when the electrooptic element is in an electric field-free condition, an absolute value, .delta., of a phase difference of a beam passed through the electrooptic element is within the following range(m/2-1/6).pi..ltoreq..delta..ltoreq.(m/2+1/6).pi.wherein m is an odd number. When the portion of the optical fiber is poled from two different directions, the modulation unit should further include a wave plate, and an absolute value, .delta.1, of a phase difference of a beam passed through the wave plate and the electrooptic element is within the following range of (n/2-1/6).pi..ltoreq..delta..ltoreq.(n/2+1/6).pi. wherein n is an odd number.

Abstract: A magneto-optical element comprises a film of a Bi-substituted rare earth iron garnet selected from garnets of the following chemical formulas(Bi.sub.x Gd.sub.y R.sub.z Y.sub.3-x-y-z)(Fe.sub.5-w Ga.sub.w)O.sub.12wherein R represents at least one element selected from the group consisting of rare earth elements other than Gd, and x, y, z and w are such that 1.00.ltoreq.x.ltoreq.1.30, 0.42.ltoreq.y.ltoreq.0.60, 0.01.ltoreq.z.ltoreq.0.05 and 0.40.ltoreq.w.ltoreq.0.62, and(Bi.sub.x' Gd.sub.y' R.sub.z' Y.sub.3-x'-y'-z')Fe.sub.5 O.sub.12wherein R is as defined above, and x', y' and z' are such that 1.10.ltoreq.x'.ltoreq.1.30, 1.00.ltoreq.y'.ltoreq.1.80, 0.ltoreq.z'.ltoreq.0.06. An optical magnetic field sensor capable of detecting zeroth to higher order beams of diffracted light is also described.

Abstract: An optical fiber sensor which is adapted for use in combination with a horseshoe-type iron core comprises a substrate having a groove pattern established by a pair of elongated spaced, parallel grooves, and a third groove which intersects the paired grooves at right angles. An optical fiber having a U-shaped portion is inserted into and fixed in the groove pattern, and an optical modulation unit, which is fixedly provided in a light path of the optical fiber, is placed in the third groove. The substrate is a composite which comprises a non-magnetic portion and soft magnetic portions fixed to either side of the non-magnetic portion. The paired elongated grooves are formed in the soft magnetic portions, while the optical modulation unit is fixed to the non-magnetic portion. A method for making such a composite substrate is also described.

Abstract: An optical fiber sensor which comprises a substrate having a groove pattern, an optical fiber which includes a shaped, bare optical fiber portion of an inverted U form and capable of being received or accommodated in the groove pattern of the substrate, and jacketed optical fiber portions extending from the shaped optical fiber rod portion at opposite ends thereof, and an optical modulation unit which is fixedly provided in a light path of the bare optical fiber portion and placed in at least one groove formed in the substrate. A method for fabricating the sensor is also described. The sensors include magnetic filed/current, electric field/voltage and temperature sensors.

Abstract: A magneto-optical element comprises a film of a Bi-substituted rare earth iron garnet selected from garnets of the following chemical formulas(Bi.sub.x Gd.sub.y R.sub.z Y.sub.3-x-y-z)(Fe.sub.5-w Ga.sub.w)O.sub.12wherein R represents at least one element selected from the group consisting of rare earth elements other than Gd, and x, y, z and w are such that 1.00.ltoreq.x.ltoreq.1.30, 0.42.ltoreq.y.ltoreq.0.60, 0.01.ltoreq.z.ltoreq.0.05 and 0.40.ltoreq.w.ltoreq.0.62, and(Bi.sub.x 'Gd.sub.y 'R.sub.z 'Y.sub.3-x'-y'-z')Fe.sub.5 O.sub.12wherein R is as defined above, and x', y' and z' are such that 1.10.ltoreq.x'.ltoreq.1.30, 1.00.ltoreq.y'.ltoreq.1.80, 0.ltoreq.z'.ltoreq.0.06. An optical magnetic field sensor capable of detecting zeroth to higher order beams of diffracted light is also described.

Abstract: A magnetic field measurement apparatus with high sensitivity and high accuracy in which a Bi-substituted rare-earth iron garnet crystal with a high and no temperature dependent sensitivity constant grown by liquid phase epitaxy is used for a magneto-optic element.

Abstract: A current and voltage detector for a distribution system is provided with a lower section, an upper section and a fastener for combining the lower and upper sections into one body. The lower section comprises: a first groove for receiving an electric wire of the distribution system; an optical type current sensor; an optical type voltage sensor; and a potential divider for supplying a voltage to the voltage sensor. The upper section comprises: a second groove for receiving the electric wire; and a U-shaped magnetic core for applying a magnetic field to the current sensor.