Abstract: An optical waveguide element includes a cladding portion made of a silica-based glass, and an optical waveguide positioned in the cladding portion and made of a silica-based glass in which a ZrO2 particle is dispersed.

Abstract: A spot-size-converting optical waveguide includes a core portion. A first core portion of the core portion has a first straight portion and a first tapered portion. The first straight portion extends in a direction, having width and height that are approximately constant in the direction, and the first tapered portion is continuous with the first straight portion and decreases in width and height toward a termination portion. A second core portion of the core portion has a straight-portion-coating portion, a tapered-portion-coating portion, and a second tapered portion, the straight-portion-coating portion covers the first straight portion, the tapered-portion-coating portion covers the first tapered portion continuously with the straight-portion-coating portion and decreases in width and height along the first tapered portion's shape, and the second tapered portion increases in width and height toward the direction. A refractive index of the second core portion is lower than that of the first core portion.

Abstract: An object of the present invention is to provide a switch unit for optical signals which is capable of reducing an area required for arrangement and reducing manufacturing costs, and a switch apparatus including the switch unit. A switch unit 30 according to one embodiment of the present invention includes two optical switch arrays 34a, 34b arranged to face in opposite directions and in parallel on a substrate. The two optical switch arrays extend along a surface of a chip, and each have four optical switches 31 arranged in parallel. Such a configuration makes it possible to reduce the size of the switch unit because in an excess region of one of the optical switch array, the other optical switch array is disposed.

Abstract: An object of the invention is to provide a switch device, which achieves high expandability, high layout freedom, and low losses. A switch device of an embodiment includes a splitter unit, a first switch unit, a second switch unit, a fiber array which connects the splitter unit to the two switch units, and a control board. The fiber array includes multiple optical fibers bundled in an arrayed fashion. At an end of the fiber array on the splitter unit side, all the optical fibers are bundled into one and connected to the splitter unit. At an end of the fiber array on the switch unit side, the multiple optical fibers are divided into two groups and formed into two sub-fiber arrays, which are connected to the first switch unit and the second switch unit, respectively.

Abstract: An optical amplifier device comprising an input/output section that inputs incident light and outputs emission light; a polarized light splitting section that causes a polarized light component of the incident light input from the input/output section to branch, and outputs first polarization mode light having a first polarization and second polarization mode light having a second polarization different from the first polarization; a polarization converting section that receives the first polarization mode light, converts the first polarization to the second polarization, and outputs first polarization converted light; and an optical amplifying section that amplifies the first polarization converted light input to one end of a waveguide, outputs the resulting amplified first polarization converted light from another end of the waveguide, amplifies the second polarization mode light input to the other end of the waveguide, and outputs the resulting amplified second polarization mode light from the one end of t

Abstract: The invention of the present application provides an SOA-PLC hybrid integrated polarization diversity circuit including a PLC-PBS chip and an SOA-COS whose respective waveguides are coupled to each other. The PLC-PBS chip includes: first and second optical waveguides; a Mach-Zehnder interferometer circuit; and a half-wave plate placed in the first optical waveguide which TM mode light is split into. The SOA-COS includes: a third optical waveguide connected to the first optical waveguide; a fourth optical waveguide connected to the second optical waveguide; and an SOA formed in at least one of the third and fourth optical waveguides. One end of the third optical waveguide and one end of the fourth optical waveguide are connected to a U-turn optical waveguide, the one ends being not connected to the first optical waveguide and the second optical waveguide, respectively.

Abstract: An optical waveguide element includes a cladding portion made of a silica-based glass, and an optical waveguide positioned in the cladding portion and made of a silica-based glass in which a ZrO2 particle is dispersed.

Abstract: An optical branching element includes: an input waveguide; a tapered waveguide connected to the input waveguide; two branched waveguides that are connected to the tapered waveguide and arranged so as to form a Y-shape with the input waveguide and the tapered waveguide; and a plurality of strip-like waveguides that are provided so as to connect between the two branched waveguides and not to protrude outside the two branched waveguides, and formed so as to decrease in width as becoming distant from the tapered waveguide.

Abstract: An optical amplifier device comprising an input/output section that inputs incident light and outputs emission light; a polarized light splitting section that causes a polarized light component of the incident light input from the input/output section to branch, and outputs first polarization mode light having a first polarization and second polarization mode light having a second polarization different from the first polarization; a polarization converting section that receives the first polarization mode light, converts the first polarization to the second polarization, and outputs first polarization converted light; and an optical amplifying section that amplifies the first polarization converted light input to one end of a waveguide, outputs the resulting amplified first polarization converted light from another end of the waveguide, amplifies the second polarization mode light input to the other end of the waveguide, and outputs the resulting amplified second polarization mode light from the one end of t

Abstract: An optical branching element includes: an input waveguide; a tapered waveguide connected to the input waveguide; two branched waveguides that are connected to the tapered waveguide and arranged so as to form a Y-shape with the input waveguide and the tapered waveguide; and a plurality of strip-like waveguides that are provided so as to connect between the two branched waveguides and not to protrude outside the two branched waveguides, and formed so as to decrease in width as becoming distant from the tapered waveguide.

Abstract: The present invention aims to provide a low-wavelength-dependent optical coupler capable of concurrently achieving high process stability and low polarization dependence. An optical coupler 100 according to an embodiment includes a cladding layer 105 being formed on a substrate 104 and having two waveguides 101a, 101b inside. Three directional couplers 102a, 102b, 102c are each formed by bringing portions of the two waveguides close to each other in parallel, and the two delay paths 103a, 103b are each formed to give an optical path difference between the two waveguides. The delay path 103a is provided between the directional couplers 102a and 102b, and the delay path 103b is provided between the directional couplers 102b and 102c. The three directional couplers have the same coupling characteristic, and the two delay paths have different optical path differences from each other.

Abstract: There is provided a SSC chip whose yield may be improved and whose processing steps may be simplified as compare to those of a prior art PLC chip having a light waveguide circuit to which a spot-size converter (SSC) is added, a fiber array attached with the SSC chip, a PLC module attached with the SSC chip and a method for manufacturing the SSC chip. The SSC chip has four spot-size converters and is fabricated separately from a PLC chip. Each SSC has a straight waveguide having the same core width and height with an end of an input/output waveguide of the PLC chip, a horizontally tapered waveguide in which the core width is enlarged in a tapered shape in the horizontal direction from the core width of the straight waveguide, a vertically tapered waveguide in which the core height is enlarged in a tapered shape in the vertical direction from the core height of the horizontally tapered waveguide and a spot-size enlarged portion whose core width and core height are both enlarged.

Abstract: An optical waveguide circuit includes a polarization beam splitter connecting to a first input optical waveguide; an optical interference element receiving one of orthogonally polarization-split lights of a first light from the polarization beam splitter, and one of orthogonally-polarized lights from a second light input to a second input optical waveguide, the optical interference element causing interference therebetween; a first connection optical waveguide connecting the polarization beam splitter and the optical interference element; and a second connection optical waveguide connecting the second input optical waveguide and the optical interference element. The first and the second input optical waveguides have a straight-line shape or an S-shape including a first bending portion and a second bending portion to cancel the polarization-rotation of light taking place in the first bending portion.

Abstract: The invention provides a PLC-type DP-QPSK demodulator that reduces connection loss between a polarization beam splitter and a 90-degree hybrid circuit and aims at reducing the manufacturing cost and an optical transmission system using the same. In an embodiment of the invention, a PLC-type DP-QPSK demodulator that receives a DP-QPSK signal includes one PLC chip having a planar lightwave circuit. Input ports and output ports of signal light are provided at an input end and at an output end of the PLC chip, respectively. Within the planar lightwave circuit, there are integrated a polarization beam splitter that splits the DP-QPSK signal into an X-polarization QPSK signal and a Y-polarization QPSK signal, and two 90-degree hybrid circuits that mix the X-polarization QPSK signal and local oscillation light and the Y-polarization QPSK signal and local oscillation light, respectively, split each QPSK signal into orthogonal components I, Q and output them.

Abstract: The present invention provides a hybrid integrated optical module having a high coupling efficiency by suppressing a connection loss between waveguides. A hybrid integrated optical module according to an embodiment of the present invention is an optical module which integrates a semiconductor chip and a PLC chip. The semiconductor chip has a semiconductor waveguide and is mounted on a Si bench. The PLC chip includes a PLC substrate and an optical waveguide formed on the PLC substrate. An end face of the semiconductor chip protrudes from an end face of the Si bench toward the PLC chip side by a protrusion amount X. Gap adjustment (adjustment of a distance D) between the semiconductor waveguide and the optical waveguide becomes possible by setting a position where the end face of the semiconductor chip is brought into contact with an end face of the PLC chip to be a reference position (zero point).

Abstract: Disclosed are a PLC-type delay demodulation circuit and a PLC-type optical interferometer capable of reducing the size of a PLC chip with respect to the arrangement of various kinds of light output waveguides. In a PLC-type delay demodulation circuit, arm waveguides of a first MZI and arm waveguides of a second MZI are formed so as to overlap each other in the same region of a planar lightwave circuit. The optical paths of the MZIs are arranged such that the propagation directions of two DQPSK signals branched by a Y-branch waveguide are opposite to each other.

Abstract: A multiplexer/demultiplexer includes: a waveguide chip including a first chip and a second chip that are divided by a plane and obtained by cutting, together with a substrate, in a direction crossing an optical axis, a first slab waveguide of an AWG including the first slab waveguide and a second slab waveguide that are formed on the substrate; a first base to which the first chip is fixed; a second base separated from the first base and to which the second chip is fixed; and a member that has one end fixed to the first base or chip and another end fixed to the second base or chip, in a state in which cut surfaces of the first and second chips face each other, and that is configured to move the first base and the second base relatively to each other along the plane by expanding/contracting when temperature changes.

Abstract: The PLC-type delay demodulation circuit includes a planar lightwave circuit that is provided on one PLC chip and demodulates a DQPSK signal. The planar lightwave circuit includes a Y-branch waveguide that branches a DQPSK-modulated optical signal into two optical signals and first and second MZIs that delay the branched optical signals by one bit. A wave plate is provided in central portions of first and second arm waveguides of the first MZI and first and second arm waveguides of the second MZI in such a manner that the wave plate intersects all of the four arm waveguides, the four arm waveguides being close to one another in a portion where the wave plate is provided.

Abstract: An arrayed waveguide grating includes input waveguides, an input slab waveguide, n output waveguides, an output slab waveguide, and an arrayed waveguide. Gaps are formed in the output waveguides other than the output waveguides of both sides of an array of the output waveguides, respectively, such that loss increases toward the central side of the array. Sizes of the gaps in the output waveguides increase toward the central side of the array.

Abstract: A PLC-type delay demodulation circuit includes a planar lightwave circuit that is provided on one PLC chip and demodulates a DQPSK signal. The planar lightwave circuit includes a Y-branch waveguide that branches a DQPSK-modulated optical signal into two optical signals and first and second MZIs that delay the branched optical signals by one bit. The length of a short arm waveguide of the first MZI is different from the length of a short arm waveguide of the second MZI, and the length of an optical path from the Y-branch waveguide to output ports of the first MZI through the short arm waveguide of the first MZI is equal to that of an optical path from the Y-branch waveguide to output ports of the second MZI through the short arm waveguide of the second MZI.