Abstract: An optical connector includes a ferrule, a ferrule holder, a housing, and an anti-rotation structure. The ferrule includes a through hole that extends in a first direction and holds an optical fiber inside the through hole. The ferrule holder is disposed on the outer periphery of the ferrule and is fixed to the ferrule. The anti-rotation structure is provided inside the housing and outside the ferrule, and prevents rotation of the ferrule about an axis with the ferrule holder. The ferrule holder includes a tubular holder main body that accommodates the ferrule therein, and a flange part that protrudes outward from the outer periphery of the holder main body. The flange part includes a configuration to fit with the anti-rotation structure. A center of the flange part in the first direction is located in a central region of the ferrule in the first direction.

Abstract: An optical connector-equipped fiber connection structure according to an embodiment includes at least three groups including two or more optical fibers adjacent to each other. In the groups, two or more of the optical fibers extend from a first multi-core connector to a second multi-core connector without intersecting with each other. Optical fibers of two groups in the at least three groups intersect with each other in a midway point going from the first multi-core connector to the second multi-core connector. Optical fibers of groups other than the two groups extend from the first multi-core connector to the second multi-core connector without intersecting with the other optical fibers extending from the first multi-core connector.

Abstract: An optical fiber includes a silica-based glass. The optical fiber includes a core, an optical cladding surrounding the core, and a physical cladding surrounding the optical cladding. The optical cladding includes a first region in contact with the core and surrounding the core. A photosensitive material is added to the core and the first region. A concentration of the photosensitive material in the first region is 30% or more of a concentration of the photosensitive material in the core. A value obtained by integrating a light intensity of an LP01 mode at a wavelength of 1310 nm in a region added with the photosensitive material is 87% or more of a value obtained by integrating the light intensity in an entire region of the optical fiber.

Abstract: An optical connector-equipped fiber connection structure according to an embodiment includes at least three groups including two or more optical fibers adjacent to each other. In the groups, two or more of the optical fibers extend from a first multi-core connector to a second multi-core connector without intersecting with each other. Optical fibers of two groups in the at least three groups intersect with each other in a midway point going from the first multi-core connector to the second multi-core connector. Optical fibers of groups other than the two groups extend from the first multi-core connector to the second multi-core connector without intersecting with the other optical fibers extending from the first multi-core connector.

Abstract: An optical fiber according to an embodiment includes a core having a single-peaked and graded refractive index profile, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding. The inner and outer claddings have refractive indices lower than the maximum refractive index of the core. A photosensitive region constituted by the core and the inner cladding contains a photosensitive material. The inner cladding has an outer diameter one time or more and two times or less the MFD of an LP01 mode in a 1310-nm wavelength band.

Abstract: An optical fiber according to an embodiment includes a core having a single-peaked and graded refractive index profile, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding. The inner and outer claddings have refractive indices lower than the maximum refractive index of the core. A photosensitive region constituted by the core and the inner cladding contains a photosensitive material. The inner cladding has an outer diameter one time or more and two times or less the MFD of an LP01 mode in a 1310-nm wavelength band.

Abstract: The stranded optical cable 10 includes a plurality of stranded multicore optical cables 12 and a cable sheath 16 covering the multicore optical cables 12, each multicore optical cable 12 including at least two of optical units 13 as a pair and a unit sheath 14 covering the optical units 13, each optical unit 13 being formed by bundling a plurality of optical fibers. And, parts of the cable sheath corresponding to both ends of the stranded optical cable 10 are removed to expose the multicore optical cables 12 certain lengths so that the optical connectors 21 are connected to the multicore optical cables 12, respectively.

Abstract: The present invention provides an optical module and an optical system that can form a two-way optical transmitting and receiving line with the same optical wiring configuration without using any special parts. The optical module includes a plurality of single-fiber optical adapters, a multi-fiber optical adapter, a plurality of single-fiber optical connectors mating with the respective single-fiber optical adapters, a multi-fiber optical connector mating with the multi-fiber optical adapter, and a plurality of optical fibers connecting the respective single-fiber optical connectors and the multi-fiber optical connector. Wiring of the optical fibers is configured to connect two single-fiber optical connectors inserted into adjacent single-fiber optical adapters and fiber holes in the upper tier and the lower tier in the same row of the multi-fiber optical connector.

Abstract: The present invention provides an optical module and an optical system that can form a two-way optical transmitting and receiving line with the same optical wiring configuration without using any special parts. The optical module includes a plurality of single-fiber optical adapters, a multi-fiber optical adapter, a plurality of single-fiber optical connectors mating with the respective single-fiber optical adapters, a multi-fiber optical connector mating with the multi-fiber optical adapter, and a plurality of optical fibers connecting the respective single-fiber optical connectors and the multi-fiber optical connector. Wiring of the optical fibers is configured to connect two single-fiber optical connectors inserted into adjacent single-fiber optical adapters and fiber holes in the upper tier and the lower tier in the same row of the multi-fiber optical connector.

Abstract: The stranded optical cable 10 includes a plurality of stranded multicore optical cables 12 and a cable sheath 16 covering the multicore optical cables 12, each multicore optical cable 12 including at least two of optical units 13 as a pair and a unit sheath 14 covering the optical units 13, each optical unit 13 being formed by bundling a plurality of optical fibers. And, parts of the cable sheath corresponding to both ends of the stranded optical cable 10 are removed to expose the multicore optical cables 12 certain lengths so that the optical connectors 21 are connected to the multicore optical cables 12, respectively.

Abstract: The present invention provides an optical adapter, which can suppress electromagnetic waves from an optical communication module, is provided. An optical adapter comprises: a housing; an optical fiber which is housed in the housing; and a ferrule which is housed in the housing. The housing has a first edge to be inserted into a receptacle of an optical communication module, and a second edge for insertion of an optical connector plug. The optical fiber has a first edge to optically couple with the receptacle, and a second edge to optically couple with the optical connector plug. The ferrule houses the optical fiber. At least a part of the housing or at least part of the ferrule is formed of an electromagnetic absorption material.

Abstract: The present invention relates to an optical signal processor which can perform favorable optical signal processing even when there are environmental changes and the like. The optical signal processor inputs light emitted from an end face of an optical fiber, subjects the inputted light to processing according to its wavelength, and outputs the processed light so as to make it incident on the end face of the optical fiber; and comprises optical systems, a diffraction grating device, mirror reflectors, an optical path turning part, and a monitor part. The optical path turning part transmits therethrough a part of the incident light and reflects at least a part of the remnant. The optical system monitors the light transmitted through the optical path turning part.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1-n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: The present invention provides an optical adapter, which can suppress electromagnetic waves from an optical communication module, is provided. An optical adapter comprises: a housing; an optical fiber which is housed in the housing; and a ferrule which is housed in the housing. The housing has a first edge to be inserted into a receptacle of an optical communication module, and a second edge for insertion of an optical connector plug. The optical fiber has a first edge to optically couple with the receptacle, and a second edge to optically couple with the optical connector plug. The ferrule houses the optical fiber. At least a part of the housing or at least part of the ferrule is formed of an electromagnetic absorption material.

Abstract: The present invention provides an optical communication module and an optical subassembly which can suppress leakage of electromagnetic waves. An optical communication module includes: a receptacle section for insertion of an optical connector plug; a casing section which is connected to the receptacle section and houses a circuit board; and an optical transmission subassembly and an optical receive subassembly, which are optically coupled with the optical connector plug and are electrically connected to the circuit board. At least a part of the receptacle section, at least a part of the casing section, at least a part of the optical transmission subassembly, or at least a part of the optical receive subassembly is formed of a resin containing an additive which has electromagnetic wave absorption properties.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1-n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: The present invention relates to an optical fiber having a structure which allows further improvements to be made both in terms of lower reflectance and narrower bandwidth, and to a fiber grating type filter including the optical fiber. The optical fiber applied to the fiber grating type filter comprises a core region extending along a predetermined axis, and a cladding region provided on an outer periphery of the core region. The core region does not contain any photosensitive dopant which contributes to predetermined wavelength light photosensitivity as a glass property, but a part of the cladding region contain such a photosensitive dopant. By means of this composition, it is possible to form a grating, which has a grating plane slanted by a predetermined angle with respect to the optical axis, in a part of the cladding region surrounding the core region.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1–n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: An optical connector plug inserted into a receptacle of an optical communication module, having: an optical fiber; a ferrule having a tubular form, the optical fiber being provided in an inner hole of the ferrule; and a housing which is fitted into the receptacle, the optical fiber and the ferrule passing through the interior of the housing, wherein either one of at least a part of the housing and at least a part of the ferrule is made of an electromagnetic wave absorption material.

Abstract: The present invention provides a diffraction grating element that allows the temperature control mechanism to be dispensed with or simplified. The diffraction grating element of the present invention comprises a transparent plate having a first surface and a second surface that are substantially parallel with one another; and a diffraction grating which is formed on a first surface side with respect to the second surface and is substantially parallel with the first surface. At any temperature within a temperature range ?20° C. to +80° C., the sum of the rate of change in the period per unit length of the diffraction grating with respect to a temperature change, and the temperature coefficient of the refractive index of a medium that surrounds the diffraction grating element is 0.