Abstract: A spot-size converter includes a substrate, a first core provided over the substrate, and second and third cores provided over the substrate and over or under the first core with a cladding layer sandwiched therebetween and extending in parallel to the substrate and the first core.

Abstract: An optical waveguide includes a substrate, a first core provided over the substrate and having a first taper region that extends from one side toward the other side and has a sectional area that decreases toward the other side, and a plurality of second cores provided over the substrate and over or under the first core with a first cladding layer sandwiched therebetween and extending in parallel to the substrate and the first core.

Abstract: A semiconductor light source includes a substrate, an optical waveguide having a reflection structure provided on the substrate with an oxide film in between and a semiconductor light emitting element provided on the optical waveguide. The optical waveguide includes a constant width core layer portion located in a center portion, tapered core layer portions that are provided on either side of the constant width core layer and of which the core width gradually increases and a constant width core layer portion for an optical wire waveguide. The semiconductor light emitting element is placed so as to cover at least a portion of the tapered core layer portions on both sides.

Abstract: An optical functional device equivalent to a 2×2 Mach-Zehnder optical switch is produced by forming two 3 dB couplers and input/output waveguides on a substrate. Two optical phase modulation paths are formed on corresponding waveguides between 3 dB couplers. A channel region having an opposite electric polarity is formed between source and drain regions, having the predetermined electric polarity, formed on the substrate. The optical phase modulation path is insulated from the surrounding area and disposed above the channel region. Additionally, a control electrode (i.e. a gate region) subjected to high-density doping is formed above the optical phase modulation path. By applying an electric voltage having the predetermined polarity to the control electrode, the source region, and the drain region, it is possible to generate hot carriers, in proximity to the optical phase modulation path, so as to accumulate charges and change a refractive index, thus setting a desired light-wave input/output path.

Abstract: An integrated light source includes an optical circuit (3) including at least an interference optical switch and a light emitting unit (2) outputting optical signals having the same phase to multiple input ends, and an interference optical switch (21), for example, includes an optical coupler (33ab) coupling or splitting and outputting optical signals input through multiple optical waveguides to a first and a second output ports, a first optical waveguide (32a) having one end inputting an optical signal and the other end connected to the optical coupler (33ab), a second optical waveguide (32b) having one end inputting an optical signal, the other end connected to the optical coupler (33ab), and the same optical path length as the first optical waveguide (32a), and a phase shifter (31a) disposed on the first optical waveguide (32a) and switching phase differences of an optical signal transmitted through the first optical waveguide (32a) according to a control signal (S21).

Abstract: At least two light-emitting elements emit light to a branching device, and the branching device divides the light that entered into an input port into at least two and emits the light from M number of output ports. An optical modulator individually modulates the M number of light beams that were emitted. When a first light-emitting element driven normally fails, the first light-emitting element is stopped and a second light-emitting element that was stopped is driven, thereby maintaining the emission of the modulated M number of light beams.

Abstract: A semiconductor light source includes a substrate, an optical waveguide having a reflection structure provided on the substrate with an oxide film in between and a semiconductor light emitting element provided on the optical waveguide. The optical waveguide includes a constant width core layer portion located in a center portion, tapered core layer portions that are provided on either side of the constant width core layer and of which the core width gradually increases and a constant width core layer portion for an optical wire waveguide. The semiconductor light emitting element is placed so as to cover at least a portion of the tapered core layer portions on both sides.

Abstract: Light that returns through reflection from the optical connection portion between a semiconductor optical waveguide and an optically functional element is reduced through the use of a simplified structure in a semiconductor optical waveguide device. The device is provided with an anti-reflection diffraction grating having the period to prevent light that has been led through the semiconductor optical waveguide towards the portion connected to the optically functional element from being reflected in the direction from which the light has been led.

Abstract: An integrated light source includes an optical circuit (3) including at least an interference optical switch and a light emitting unit (2) outputting optical signals having the same phase to multiple input ends, and an interference optical switch (21), for example, includes an optical coupler (33ab) coupling or splitting and outputting optical signals input through multiple optical waveguides to a first and a second output ports, a first optical waveguide (32a) having one end inputting an optical signal and the other end connected to the optical coupler (33ab), a second optical waveguide (32b) having one end inputting an optical signal, the other end connected to the optical coupler (33ab), and the same optical path length as the first optical waveguide (32a), and a phase shifter (31a) disposed on the first optical waveguide (32a) and switching phase differences of an optical signal transmitted through the first optical waveguide (32a) according to a control signal (S21).

Abstract: An optical waveguide coupler includes a substrate and an optical waveguide of a multi-layer structure of a first clad layer/a first waveguide layer/a second clad layer, at least, on the end surface side of an optical input and output provided on the substrate, characterized in that the first waveguide layer has such a distribution of the refractive index that the refractive index is the highest at the center of the first waveguide layer in the multi-layer structure in the stacking direction, and the first waveguide layer has such a protrusion in a convex form that the center portion having the highest refractive index protrudes in a cross section that is perpendicular to the end surface of the optical input and output and perpendicular to the main surface of the substrate.

Abstract: An optical device includes: a first cladding layer; a core layer disposed on the first cladding layer and, with increase in its sectional area, extending from a first end which receives/outputs light along a direction from the first end toward a second end; a slab layer disposed on the first cladding layer and extending to the second end along the direction from the first end toward the second end; a rib layer disposed on the slab layer and, with decrease in its sectional area, extending to the second end along the direction from the first end toward the second end; and a second cladding layer disposed on the core layer and the rib layer. The core layer and both of the slab and rib layers are optically coupled in a part in which the sectional are of the core and rib layers is the maximum.

Abstract: An optical semiconductor device includes a silicon oxide layer configured to be formed on a substrate; an optical waveguide part configured to be formed on the silicon oxide layer; a cladding layer configured to be formed covering the optical waveguide part; and a semiconductor laser configured to be disposed on the substrate. Laser light emitted from the semiconductor laser enters the optical waveguide part. The optical waveguide part increases transmittance of light when the wavelength becomes greater within an oscillation wavelength range of the semiconductor laser.

Abstract: The spot size converter includes a first cladding layer, a first core layer and a second core layer arranged side by side on the first cladding layer so as to extend from a first end which receives/outputs light along a direction from the first end toward a second end, a third core layer which is disposed on the first cladding layer between the first and second core layers, is a member different from the first and second core layers, and extends to the second end along the direction from the first end toward the second end, and a second cladding layer disposed on the first, second, and third core layers.

Abstract: A light source circuit transmits light incident from a semiconductor laser source to a plurality of optical devices. At least one optical branch section is formed to branch one input-side optical waveguide at least into a first output-side optical waveguide terminal and a second output-side optical waveguide terminal. A light path length (L1) between the optical branch section and a next-stage optical branch section or the optical device is connected to the first output-side optical waveguide extending from the optical branch section and a light path length (L2) between the optical branch section and the next-stage optical branch section selected such that the absolute value of a difference between (L1) and (L2) is (¼+i/2) times (i is zero or a positive integer) the wavelength of the light transmitted through the light source circuit.

Abstract: In order to provide a spot size converter and a method for making the same which enable the optical connection with low loss and are able to reduce the excess loss for the position misalignment in mounting, a spot size converter according to an exemplary aspect of the present invention includes: a substrate on which an optical waveguide including a first core is laminated and which includes a notch; a core reducing part which is formed so that a cross-section area of the first core may gradually decrease toward an end part of the first core in the direction of light propagation; a second core which surrounds the core reducing part and is made of a material whose refractive index is smaller than that of the first core; a peripheral clad which surrounds the second core and is made of a material whose refractive index is smaller than that of the second core; and a lower clad which is formed in a lower part of the second core and includes the peripheral clad; wherein the lower clad is formed in the notch.

Abstract: An optical waveguide coupler includes a substrate and an optical waveguide of a multi-layer structure of a first clad layer/a first waveguide layer/a second clad layer, at least, on the end surface side of an optical input and output provided on the substrate, characterized in that the first waveguide layer has such a distribution of the refractive index that the refractive index is the highest at the center of the first waveguide layer in the multi-layer structure in the stacking direction, and the first waveguide layer has such a protrusion in a convex form that the center portion having the highest refractive index protrudes in a cross section that is perpendicular to the end surface of the optical input and output and perpendicular to the main surface of the substrate.

Abstract: Light that returns through reflection from the optical connection portion between a semiconductor optical waveguide and an optically functional element is reduced through the use of a simplified structure in a semiconductor optical waveguide device. The device is provided with an anti-reflection diffraction grating having the period to prevent light that has been led through the semiconductor optical waveguide towards the portion connected to the optically functional element from being reflected in the direction from which the light has been led.

Abstract: The invention relates to a spot-size converter, a manufacturing method thereof, and an integrated optical circuit device, and ensures easier coupling to the optical fiber and higher accuracy in manufacturing the spot-size converter. A first core that is extended from a first end configured to input/output light toward a second end, and a second core that is formed by a plurality of cores, and formed at a position to be evanescent-coupled to the first core, and moreover extended along a direction from the first end toward the second end are provided, and, on the second core, a third core that has a taper unit and is formed at a position to be evanescent-coupled to the second core in a lamination direction is provided.

Abstract: An optical semiconductor device includes: a substrate of semiconductor; an array having a plurality of active regions arranged on the substrate so as to emit light to the same direction, the plurality of active regions being arranged more densely at ends of the array than in the center of the array in a direction crossing the light emitting direction; and electrodes which inject current to the plurality of active regions.

Abstract: At least two light-emitting elements emit light to a branching device, and the branching device divides the light that entered into an input port into at least two and emits the light from M number of output ports. An optical modulator individually modulates the M number of light beams that were emitted. When a first light-emitting element driven normally fails, the first light-emitting element is stopped and a second light-emitting element that was stopped is driven, thereby maintaining the emission of the modulated M number of light beams.