Abstract: An optical switch in which the adverse effect of heating can be restrained is realized.

Abstract: A matrix optical switch that can switch the transmission path of an optical signal without requiring a driving unit for each optical switch is realized. A matrix optical switch for switching a transmission path of an optical signal by connecting plural input sides and plural output sides, respectively, comprises: a semiconductor optical waveguide substrate; a photo mask choosing system for selecting and arranging one photo mask from plural photo masks each of which has printed thereon a pattern connecting plural input sides to plural output sides; and a light source for casting output light having larger energy than a band gap of the semiconductor optical waveguide substrate onto a photon injection area between the plural input sides and the plural output sides on the semiconductor optical waveguide substrate via the selected photo mask.

Abstract: An active diffraction grating that has a high degree of freedom in control, small size and high reliability is realized.

Abstract: An optical signal processing apparatus capable of performing high-speed operation is to be realized. According to this invention, at least one photodiode for converting an optical signal to an electrical signal, and a resonant tunneling diode for having the electrical signal of this photodiode inputted thereto and performing switch operation are provided to acquire a digital signal.

Abstract: According to this invention, electrodes are formed on both sides of a part of an optical waveguide formed on a substrate and a voltage is applied between the electrodes to change the refractive index at the part of the optical waveguide where the electrode is formed. Therefore, the traveling direction of light can be changed. Moreover, an optical waveguide formed on a substrate, plural electrodes formed on both sides of the optical waveguide, plural incidence units formed at one end of the substrate, and plural emission units formed at the other end are provided. A voltage applied to an arbitrary electrode of the plural electrodes is controlled to change the refractive index at the part of the optical waveguide where the voltage is applied. Light emitted from an arbitrary incidence unit and incident on a core of the substrate thus becomes incident on an arbitrary emission unit.

Abstract: In an optical switch, a carrier-accumulating layer in which injected carriers are accumulated is provided on a semiconductor substrate having a waveguide formed thereon so that injected effective carriers tend to be accumulated in an effective part, and the burden on a driving circuit is thus reduced to realize high-speed operation. At the same time, when a clad on the carrier injection side, of clad layers formed on both sides of the waveguide, is a second clad layer, and a clad on the substrate side is a first clad layer, a third clad layer is formed on the first clad layer to reduce propagation loss in the waveguide.

Abstract: An optical router capable of efficiently allocating optimum optical paths to optical signals at optimum timings is provided in accordance with the present invention.

Abstract: The present invention has been made to realize an optical router capable of preventing optical signals from conflicting with each other and of efficiently allocating an optimum optical path.

Abstract: The present invention provides a method for joining of high-temperature oxide superconductors per se or a high-temperature oxide superconductor and other conductive material through a very simple process. According to this method, the joining is carried out by using an alloy comprising 0.1%-90% by weight of at least one divalent metallic element and the balance as a brazing material and heating and melting the brazing material. The resulting joined body has a joint low in resistance. The divalent metallic element of the alloy is preferably an element of Group IIA or IIB of the Periodic Table or a transition metal.