Abstract: An optical logic device performs a logic operation on a plurality of input light signals. The optical logic device has a photoelectric conversion portion, in which photoreceivers for receiving input light signals are provided in parallel, that outputs an electric signal obtained by adding up outputs of the photoreceivers, and a comparator that compares a voltage level of the electric signal outputted from the photoelectric conversion portion with a predetermined voltage level.

Abstract: An optical switch has an optical waveguide whose output path of an optical signal branches into two, a carrier injection section which is provided to a branch portion of the optical waveguide and to which carriers are injected, and a refractive index change section which is provided to a optical waveguide layer of the optical waveguide and in which a refractive index changes in a case that carrier are injected to the carrier injection section, wherein the refractive index change section includes a quantum well layer.

Abstract: An optical logic device performs a logic operation on a plurality of input light signals. The optical logic device has a photoelectric conversion portion, in which photoreceivers for receiving input light signals are provided in parallel, that outputs an electric signal obtained by adding up outputs of the photoreceivers, and a comparator that compares a voltage level of the electric signal outputted from the photoelectric conversion portion with a predetermined voltage level.

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: 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.