Abstract: A reflection-type variable optical attenuator comprises: a main attenuator unit including a first birefringent crystal plate, a Faraday rotational angle varying unit, and a second birefringent crystal plate arranged in this order; an input port and an output port that are arranged on a side of one end of the main attenuator unit; and a two-point reflection-type optical path varying reflector that is arranged on a side of the other end of the main attenuator unit. Light that comes in from the input port makes a round trip in the main attenuator unit and goes out through the output port.

Abstract: The present invention is provided for considerably shortening the construction time of a building that is applied to nuclear power plants. When constructing the building, megablocks having a height that extends to a plurality of floors are produced, and together with combining those megablocks, concrete is poured inside them to form a wall member composed of a megawall structure of steel plate reinforced concrete construction. Alternatively, in addition to the wall megablocks, floor megablocks for forming the floor member of the building are used, and together with combining those megablocks, concrete is poured inside or above them to form a structural member (wall member and floor member) composed of a megawall structure of steel plate reinforced concrete construction.

Abstract: Various optical devices are provided including a Faraday rotation devices improved in wavelength and temperature characteristics and an optical attenuator reduced in wavelength dependence and temperature-dependent loss. The present invention is a Faraday rotation device 22 having permanent magnets 24, 30 magnetized in an axial direction of through-holes and Faraday elements 28, 32 having a same Faraday rotation direction with respect to a same magnetization direction, the permanent magnets being arranged directed in the same magnetization direction along an optical path, part of the Faraday elements being accommodated in the through-hole of the permanent magnet, the remaining Faraday elements being arranged between the plurality of permanent magnets, whereby the Faraday elements are to be applied by magnetic fields in opposite directions. In the case of a device variable in Faraday rotation angle, an electromagnet (variable magnetic field applying means) 36 is provided.

Abstract: A variable optical attenuator is disclosed which comprises a plane-parallel birefringent element for separation/synthesis which separates light beams having orthogonal polarization directions on the same optical path, the birefringent element synthesizing light beams on different optical paths; a light converging lens disposed adjacent to the birefringent element for separation/synthesis; a reflecting mirror disposed at a focal point of the lens opposite to the birefringent element for separation/synthesis with respect to the lens; a variable polarization rotating device; and an input port and an output port which are disposed at the end of the birefringent element for separation/synthesis; the variable polarization rotating device being disposed at any position between the birefringent element for separation/synthesis and the reflecting mirror, the variable polarization rotating device controlling the rotational angle of the polarization direction of incident light beams from the input port, to thereby contr

Abstract: The present invention is provided for considerably shortening the construction time of a building that is applied to nuclear power plants. When constructing the building, megablocks having a height that extends to a plurality of floors are produced, and together with combining those megablocks, concrete is poured inside them to form a wall member composed of a megawall structure of steel plate reinforced concrete construction. Alternatively, in addition to the wall megablocks, floor megablocks for forming the floor member of the building are used, and together with combining those megablocks, concrete is poured inside or above them to form a structural member (wall member and floor member) composed of a megawall structure of steel plate reinforced concrete construction.

Abstract: This invention concerns a so-called double-moat uni-surface type semiconductor device in which two concentric moats are provided in one main surface of the substrate and the edges of the two pn-junctions for blocking main circuit voltages applied to the device are exposed in the surfaces of the moats. Semiconductor layers having high impurity concentrations and serving as channel stoppers are formed on the semiconductor layers exposed in the one main surface of the substrate, contiguous to the moats and spaced apart from the pn-junctions, each high impurity concentration layer having the same conductivity type as the semiconductor layer on which it is formed. The moats are filled with surface passivating material.

Abstract: A semiconductor controlled rectifier comprises a semiconductor substrate having four layers of alternate n- and p-type conductivities and includes two main surfaces one of which is formed of the exposed surface of first and second layers and the other of which is formed of the exposed surface of a fourth layer. A gate electrode of a rectangular shape is disposed on the second layer on the one main surface and a cathode electrode is disposed on the first layer so as to extend along at least two sides of the rectangular gate electrode. The cathode electrode portion extending along the short side of the rectangular gate extends slightly beyond a p-n junction defined between the first and second layers, so as to be in ohmic contact with the second layer.