Abstract: An optical waveguide element includes: a cladding portion made of silica-based glass; and a plurality of optical waveguides positioned in the cladding portion and made of silica-based glass in which ZrO2 crystal particles are dispersed. The optical waveguide element is a planar lightwave circuit. The plurality of optical waveguides configure an arrayed waveguide grating element.

Abstract: A cross optical waveguide structure includes a first optical waveguide, a second optical waveguide, and an intersection portion positioned in the same plane. The first optical waveguide includes a first fixed-width portion, a second fixed-width portion, a first tapering portion, and a second tapering portion. The second optical waveguide includes a third fixed-width portion, a fourth fixed-width portion, a third tapering portion, and a fourth tapering portion. The intersection portion is linked to the first to the fourth tapering portions having such a tapering shape that a mode field radius of the light input to the first fixed-width portion, the second fixed-width portion, or the third fixed-width portion, and the fourth fixed-width portion is reduced by the first tapering portion, the second tapering portion, the third tapering portion, the fourth tapering portion, respectively, and the light is collected in the intersection portion.

Abstract: An optical module includes a single-mode optical fiber; a high relative refractive-index difference optical fiber having a larger core-to-cladding relative refractive-index difference than that of the single-mode optical fiber fusion-spliced to a first end of the high relative refractive-index difference optical fiber; a planar lightwave circuit that includes an optical waveguide having a core of quartz-based glass doped with a refractive-index raising dopant and a cladding of quartz-based glass, and is connected at a first end thereof to a second end, opposite to the first end, of the high relative refractive-index difference optical fiber; and a silicon thin-wire waveguide element that includes a silicon thin-wire waveguide having a silicon core and a cladding whose refractive index lower than that of the silicon core, and is connected to a second end, opposite to the first end, of the optical waveguide of the planar lightwave circuit.

Abstract: An optical waveguide circuit device includes: an optical waveguide circuit including a cladding layer formed on a substrate and made from silica-based glass, and an optical waveguide formed within the cladding layer and made from silica-based glass; heaters formed over the cladding layer and the optical waveguide and configured to heat the optical waveguide; wiring line electrode layers formed over the cladding layer, each of the wiring line electrode layers being coupled to a corresponding heater of the heaters and configured to allow electrical power to be supplied to the coupled heater; and an insulating layer covering the cladding layer, the heaters, and the wiring line electrode layers. The wiring line electrode layers adjacent to each other in a plan view are formed in different wiring layers. The wiring line electrode layers adjacent to each other in the same wiring layer are spaced by at least a predetermined distance.

Abstract: A cross optical waveguide structure includes a first optical waveguide, a second optical waveguide, and an intersection portion positioned in the same plane. The first optical waveguide includes a first fixed-width portion, a second fixed-width portion, a first tapering portion, and a second tapering portion. The second optical waveguide includes a third fixed-width portion, a fourth fixed-width portion, a third tapering portion, and a fourth tapering portion. The intersection portion is linked to the first to the fourth tapering portions having such a tapering shape that a mode field radius of the light input to the first fixed-width portion, the second fixed-width portion, or the third fixed-width portion, and the fourth fixed-width portion is reduced by the first tapering portion, the second tapering portion, the third tapering portion, the fourth tapering portion, respectively, and the light is collected in the intersection portion.

Abstract: An optical waveguide element includes: a cladding portion made of silica-based glass; and a plurality of optical waveguides positioned in the cladding portion and made of silica-based glass in which ZrO2 crystal particles are dispersed. The optical waveguide element is a planar lightwave circuit. The plurality of optical waveguides configure an arrayed waveguide grating element.

Abstract: An optical waveguide structure includes: a cladding; a first core in the cladding having a first end surface; a second core in the cladding having a second end surface; slit formed horizontally with respect to a waveguide direction of the light to be waveguided by the first and second cores; and a first part and a second part composed of a material identical to a material of the cladding, wherein a pair of the first and second end surfaces disposed opposing each other with the slit interposed between the pair of the first and second end surfaces, the first part is interposed between the first end surface and the slit, and the second part is interposed between the second end surface and the slit.

Abstract: An optical waveguide element includes: a cladding portion made of silica-based glass; and a plurality of optical waveguides positioned in the cladding portion and made of silica-based glass in which ZrO2 crystal particles are dispersed. The optical waveguide element is a planar lightwave circuit. The plurality of optical waveguides configure an arrayed waveguide grating element.

Abstract: An optical waveguide circuit device includes: an optical waveguide circuit including a cladding layer formed on a substrate and made from silica-based glass, and an optical waveguide formed within the cladding layer and made from silica-based glass; heaters formed over the cladding layer and the optical waveguide and configured to heat the optical waveguide; wiring line electrode layers formed over the cladding layer, each of the wiring line electrode layers being coupled to a corresponding heater of the heaters and configured to allow electrical power to be supplied to the coupled heater; and an insulating layer covering the cladding layer, the heaters, and the wiring line electrode layers. The wiring line electrode layers adjacent to each other in a plan view are formed in different wiring layers. The wiring line electrode layers adjacent to each other in the same wiring layer are spaced by at least a predetermined distance.

Abstract: An optical waveguide structure includes: a cladding; a first core in the cladding having a first end surface; a second core in the cladding having a second end surface; slit formed horizontally with respect to a waveguide direction of the light to be waveguided by the first and second cores; and a first part and a second part composed of a material identical to a material of the cladding, wherein a pair of the first and second end surfaces disposed opposing each other with the slit interposed between the pair of the first and second end surfaces, the first part is interposed between the first end surface and the slit, and the second part is interposed between the second end surface and the slit.

Abstract: An optical module includes a single-mode optical fiber; a high relative refractive-index difference optical fiber having a larger core-to-cladding relative refractive-index difference than that of the single-mode optical fiber fusion-spliced to a first end of the high relative refractive-index difference optical fiber; a planar lightwave circuit that includes an optical waveguide having a core of quartz-based glass doped with a refractive-index raising dopant and a cladding of quartz-based glass, and is connected at a first end thereof to a second end, opposite to the first end, of the high relative refractive-index difference optical fiber; and a silicon thin-wire waveguide element that includes a silicon thin-wire waveguide having a silicon core and a cladding whose refractive index lower than that of the silicon core, and is connected to a second end, opposite to the first end, of the optical waveguide of the planar lightwave circuit.

Abstract: An optical waveguide element includes: a cladding portion made of silica-based glass; and a plurality of optical waveguides positioned in the cladding portion and made of silica-based glass in which ZrO2 crystal particles are dispersed. The optical waveguide element is a planar lightwave circuit. The plurality of optical waveguides configure an arrayed waveguide grating element.

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 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 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: 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 arrayed waveguide grating includes: at least one first waveguide; a first slab waveguide connected to the at least one first waveguide; a plurality of second waveguides; a second slab waveguide connected to the plurality of second waveguides; and an arrayed waveguide. The arrayed waveguide includes: M channel waveguides connected between the first slab waveguide and the second slab waveguide, wherein M is a natural number; and a phase correcting portion configured to provide a predetermined phase to at least a part of the M channel waveguides by one or both of a width and a length of the at least the part of the M channel waveguides being changed.

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.