Abstract: A manufacturing method for an optical connector includes inserting and fixing a multi-core fiber into a ferrule, wherein at least one of a plurality of cores of the multi-core fiber is a spiral core, inserting the ferrule into a housing and aligning the cores with the housing around a central axis of the multi-core fiber, and obliquely polishing the ferrule until a width of an end surface of the ferrule perpendicular to a direction of the central axis reaches a predefined width.

Abstract: Provided is a method of manufacturing an optical device that includes a multicore fiber including a plurality of cores and a fan-in/fan-out device including single-core fibers that are respectively connected to the cores based on a plurality of connection combinations when the multicore fiber is rotated. The method includes: a first step of determining an optical loss for each of the cores while changing the connection combinations between the single-core fibers and the cores; and a second step of selecting one of the connection combinations according to a result of the first step and connecting an end portion of the multicore fiber and an end portion of the fan-in/fan-out device to connect the single-core fibers with the cores based on the one of the connection combinations.

Abstract: Provided is a method of manufacturing an optical device that includes a multicore fiber including a plurality of cores and a fan-in/fan-out device including single-core fibers that are respectively connected to the cores based on a plurality of connection combinations when the multicore fiber is rotated. The method includes: a first step of determining an optical loss for each of the cores while changing the connection combinations between the single-core fibers and the cores; and a second step of selecting one of the connection combinations according to a result of the first step and connecting an end portion of the multicore fiber and an end portion of the fan-in/fan-out device to connect the single-core fibers with the cores based on the one of the connection combinations.

Abstract: Provided is a micro optical circuit including a first micro optical waveguide and a second micro optical waveguide with a boundary face therebetween, in which the height of the first and second micro optical waveguides is different from each other, and the side faces of the first micro optical waveguide are connected to the side faces of the second micro optical waveguide at first and second connection points in a plan view. An intersection between the boundary face and the center line equidistant from the two side faces of the second micro optical waveguide is present in a region between a first straight line and a second straight line in a plan view, the first straight line passing through the first and second connection points, the second straight line crossing the second micro optical waveguide so as not to cross the first micro optical waveguide.

Abstract: Provided is a semiconductor optical integrated circuit which consumes less electric power than a conventional semiconductor optical integrated circuit. A semiconductor optical integrated circuit (1) includes a semiconductor layer (13) in which (i) an optical waveguide (LG) including heated section I1 through I3 and (ii) heater parts H1 and H2 are provided. The optical waveguide (LG) meanders such that the heated sections I1 through I3 are juxtaposed to one another. Each heater part Hi is arranged between a heated section Ii and a heated section Ii+1 which are adjacent to each other.

Abstract: In order to reduce a high frequency loss of a substrate-type optical waveguide without facilitating, in a low frequency domain, a reflection by an entrance end of a traveling-wave electrode, the substrate-type optical waveguide includes a coplanar line, provided on an upper surface of an upper cladding, which includes (i) a traveling-wave electrode connected to a P-type semiconductor region and (ii) an earth conductor connected to an N-type semiconductor region. The traveling-wave electrode and the earth conductor are provided so that a distance D therebetween decreases as a distance from an entrance end of the traveling-wave electrode increases.

Abstract: Provided is an optical modulation element which includes an optical waveguide. The optical waveguide includes: a rib part; a first slab part extending from the first side face of the rib part; aid a second slab part extending from the second side face of the rib part. The optical waveguide includes a first semiconductor region and a second semiconductor region which have an opposite conductive type from each other. The first semiconductor region includes an upper section, a lateral section, and a lower section. The second semiconductor region is sandwiched between the upper section and the lower section so as to be substantially in direct contact with the upper section, the lateral section, and the lower section. At least one of an end face of the upper section and an end face of the lower section flushes with the first side face of the rib part.

Abstract: Provided is a semiconductor optical integrated circuit which consumes less electric power than a conventional semiconductor optical integrated circuit. A semiconductor optical integrated circuit (1) includes a semiconductor layer (13) in which (i) an optical waveguide (LG) including heated section I1 through I3 and (ii) heater parts H1 and H2 are provided. The optical waveguide (LG) meanders such that the heated sections I1 through I3 are juxtaposed to one another. Each heater part Hi is arranged between a heated section Ii and a heated section Ii+1 which are adjacent to each other.

Abstract: The substrate-type optical waveguide includes a rib-slab type core. A depletion layer exists in a rib part and, in any cross section of the core, a width of a first slab part is set to be greater than a width of a second slab part.

Abstract: In order to reduce a high frequency loss of a substrate-type optical waveguide without facilitating, in a low frequency domain, a reflection by an entrance end of a traveling-wave electrode, the substrate-type optical waveguide includes a coplanar line, provided on an upper surface of an upper cladding, which includes (i) a traveling-wave electrode connected to a P-type semiconductor region and (ii) an earth conductor connected to an N-type semiconductor region. The traveling-wave electrode and the earth conductor are provided so that a distance D therebetween decreases as a distance from an entrance end of the traveling-wave electrode increases.

Abstract: Provided is a light combining/dividing element which allows generation of reflected light to be suppressed, as compared with a conventional light combining/dividing element. A core of the light combining/dividing element includes an MMI part which is connected to a first core and to each of a second core and a third core. A width of a rib of a rib waveguide of the MMI part becomes narrower from a width equal to that of a channel waveguide to a width equal to that of the first core.

Abstract: Provided is an optical modulation element which includes an optical waveguide. The optical waveguide includes: a rib part; a first slab part extending from the first side face of the rib part; aid a second slab part extending from the second side face of the rib part. The optical waveguide includes a first semiconductor region and a second semiconductor region which have an opposite conductive type from each other. The first semiconductor region includes an upper section, a lateral section, and a lower section. The second semiconductor region is sandwiched between the upper section and the lower section so as to be substantially in direct contact with the upper section, the lateral section, and the lower section. At least one of an end face of the upper section and an end face of the lower section flushes with the first side face of the rib part.

Abstract: Provided is a substrate-type optical waveguide, having a phase modulation function, (i) in which a reflection of a signal to be inputted via a coplanar line is restrained and (ii) which consumes less power. In a case where the substrate-type optical waveguide is partitioned into a plurality of sections by cross sections orthogonal to a direction in which light propagates through a core, a local capacitance in each of the plurality of sections gradually increases as a distance from an entrance end surface increases.

Abstract: Provided is a micro optical circuit including a first micro optical waveguide and a second micro optical waveguide with a boundary face therebetween, in which the height of the first and second micro optical waveguides is different from each other, and the side faces of the first micro optical waveguide are connected to the side faces of the second micro optical waveguide at first and second connection points in a plan view. An intersection between the boundary face and the center line equidistant from the two side faces of the second micro optical waveguide is present in a region between a first straight line and a second straight line in a plan view, the first straight line passing through the first and second connection points, the second straight line crossing the second micro optical waveguide so as not to cross the first micro optical waveguide.

Abstract: The substrate-type optical waveguide includes a rib-slab type core. A depletion layer exists in a rib part and, in any cross section of the core, a width of a first slab part is set to be greater than a width of a second slab part.

Abstract: Provided is a light combining/dividing element which allows generation of reflected light to be suppressed, as compared with a conventional light combining/dividing element. A core of the light combining/dividing element includes an MMI part which is connected to a first core and to each of a second core and a third core. A width of a rib of a rib waveguide of the MMI part becomes narrower from a width equal to that of a channel waveguide to a width equal to that of the first core.

Abstract: A boundary surface (12S) which divides a rib (12) of a rib-slab type core (11) into a p-type semiconductor region (12a) and an n-type semiconductor region (12b) is constituted by a first flat surface (S1) serving as a junction surface of a first lateral p-n junction (J1), a second flat surface (S2) serving as a junction surface of a vertical p-n junction (J2), and a third flat surface (S3) serving as a junction surface of a second lateral p-n junction (J3).