Abstract: A current measurement device (1 and 2) is for measuring a current (I) flowing through measurement target conductors (MC1 and MC2), and the current measurement device includes: a plurality of triaxial magnetic sensors (11, 12, and 13) disposed so that a magnetic sensing direction and a relative position have a prescribed relationship; a noise remover (25a) configured to remove noise components included in detection results of the plurality of triaxial magnetic sensors; a sign adder (25b) configured to add a sign to the detection results from which the noise components have been removed, based on sign information of each of the detection results of the plurality of triaxial magnetic sensors obtained at a specific point in time; and a current calculator (25c and 25d) configured to calculate a current flowing through the measurement target conductors by using the detection results to which the sign has been added by the sign adder.

Abstract: An input impedance matching circuit unit is employed, which is connected between a laser diode chip and a modulation signal input terminal in a module package of a semiconductor laser module that directly modulates micro-wave frequency signals. This input impedance matching circuit unit integrates structural elements such as a micro-strip line, a reactance element, and a bonding wire on a single dielectric surface.

Abstract: A light-emitting or light-receiving assembly is disclosed wherein the optical axis of input or output light to or from an optical fiber may not be shifted or dislocated under various environmental conditions. An optical isolator 3 is fixed on a lens mount 7 carrying a lens 2 and a ferrule 5 holding the optical fiber 12 therein is fixed to a ferrule holder 6 and the lens mount 7. Then, the distance between the lens 2 and an end surface 4 of the optical fiber is predetermined with a mechanical machining accuracy. This is followed by center-to-center adjustment through the use of a unit holder 8 placed around the lens mount 7. Thereafter, the lens mount 7 is fixedly secured to the unit holder 8 which in turn is fixedly secured to the laser mount 9, through the use of the YAG welding technique. An assembly unit 100 containing a semiconductor laser 1, the lens 2, the optical isolator 3 and the ferrule 4 is mounted on a temperature controlling Peltier effect element 10 by solder welding.

Abstract: An n-InP buffer layer 102, an InGaAsP active layer 103, a p-InP cladding layer 104 and a p-InGaAsP surface protective layer 105 are successively epitaxially grown on an n-InP substrate 101 having a (100) plane as a main plane. An etching mask 106, an insulating film, is formed in a stripe in the <011> direction by photolithography and dry etching. Using a solution comprising a mixture of hydrochloric acid, oxygenated water and acetic acid, the n-InP buffer layer 102 is etched to a depth lower than the p-InP cladding layer 103, to form a mesa stripe 107. Next, the insulating film 106 is removed and the p-InGaAsP surface protective layer 105 is removed using a solution comprising a mixture of sulfuric acid and oxygenated water. Thereafter, InP current blocking layers 108 and 109 are selectively formed at the regions other than the mesa stripe 107 by the liquid-phase epitaxial growth. Thus, a buried heterostructure semiconductor laser is fabricated, having good laser characteristics and a high reliability.

Abstract: A semiconductor laser comprising in the direction parallel to a junction on both sides of a stripe-shaped active layer of double-hetero structure a semi-insulating current blocking layer which has a refractive index smaller than that of the active layer and of which the resistance is increased by doping of an impurity.