Abstract: An optical module that has a structure ensuring reduction in size. The optical module has a structure where a part of a fiber block is protruded from a housing. By including a thin plate, this optical module can avoid entering of dust in the housing, allows a position shift of the fiber block due to a mounting position error of an optical component in the housing, a position shift of an opening portion due to a dimensional error of the housing, or a displacement due to a temperature change, and can reduce the coupling loss due to the optical axis misalignment.

Abstract: An optical circuit board which is mounted with a loop-back circuit for returning aligning light to the fiber array in the vicinity of the fiber array connection end. Since an aligning loop-back circuit can be formed in an optical waveguide pattern, a production cost does not increase in comparison to an optical circuit board of the related art. The aligning light combined from the optical fiber to the aligning port of the optical circuit board is returned to the optical fiber around the loop-back circuit. Therefore, it is possible to perform alignment using the returned light. That is, alignment can be performed while being mounted on a package without installing a light-reflecting film or mirror.

Abstract: An optical module that has a structure ensuring reduction in size. The optical module has a structure where a part of a fiber block is protruded from a housing. By including a thin plate, this optical module can avoid entering of dust in the housing, allows a position shift of the fiber block due to a mounting position error of an optical component in the housing, a position shift of an opening portion due to a dimensional error of the housing, or a displacement due to a temperature change, and can reduce the coupling loss due to the optical axis misalignment.

Abstract: An optical module that is connectable to an optical fiber array and that can be packaged in a high density. Two package modules are mounted on a board, and optical waveguides in a Si photonic lightwave circuit mounted on the package module are connected to an optical fiber array fixed to an optical fiber block. Moreover, output end surfaces of the optical waveguides in the Si photonic lightwave circuit are perpendicular to a mount surface of the package module. The optical waveguides in the Si photonic lightwave circuit may be tilted at an appropriate angle with respect to a direction perpendicular to a right end surface. Moreover, the optical fiber block fixes optical fibers with the optical fibers tilted with respect to a direction perpendicular to an end surface connected to the Si photonic lightwave circuit.

Abstract: An optical circuit board which is mounted with a loop-back circuit for returning aligning light to the fiber array in the vicinity of the fiber array connection end. Since an aligning loop-back circuit can be formed in an optical waveguide pattern, a production cost does not increase in comparison to an optical circuit board of the related art. The aligning light combined from the optical fiber to the aligning port of the optical circuit board is returned to the optical fiber around the loop-back circuit. Therefore, it is possible to perform alignment using the returned light. That is, alignment can be performed while being mounted on a package without installing a light-reflecting film or mirror.

Abstract: An optical module which is connectable to an optical fiber array and which can be packaged in a high density. Two 30 mm square package modules are mounted on a board, and optical waveguides in a 20 mm square Si photonic lightwave circuit mounted on the package module are connected to an optical fiber array fixed to an optical fiber block (15×10 mm). Moreover, output end surfaces of the optical waveguides in the Si photonic lightwave circuit are perpendicular to a mount surface of the package module. In the embodiment, the optical waveguides in the Si photonic lightwave circuit are tilted at an appropriate angle, for example, 20 degrees with respect to a direction perpendicular to a right end surface. Moreover, the optical fiber block fixes optical fibers with the optical fibers tilted at 20 degrees with respect to a direction perpendicular to an end surface connected to the Si photonic lightwave circuit.

Abstract: A tapered hollow shaft made of a fiber reinforced composite material, which comprises: (a) at least one angle layer consisting essentially of polyacrylonitrile-based carbon fibers having a tensile modulus ranging from 200 to 500 GPa and a tensile strength ranging from 4000 to 5600 MPa; (b) at least one straight layer consisting essentially of polyacrylonitrile-based carbon fibers having a tensile modulus ranging from 200 to 460 GPa and a tensile strength ranging from 3500 to 5600 MPa; (c) at least one reinforcing layer consisting essentially of pitch-based carbon fibers or polyacrylonitrile-based carbon fibers each having a compressive breaking strain of 1.7 to 5.0%, a tensile modulus ranging from 5 to 160 GPa, a tensile strength ranging from 500 to 3000 MPa and a density ranging from 1.5 to 1.

Abstract: Disclosed is a plate-like carbon fiber-reinforced composite material comprising carbon fibers, wherein that the carbon fibers have a strain at compressive break of 1.7 to 5%, a tensile elastic modulus of 5 to 160 GPa, and a density of 1.5 to 1.9 g/cm3 and further in that the composite comprising said carbon fibers cause no delamination by an impact energy of less than 1.4 J/mm in the test of compression after impact in accordance with JIS K 7089.

Abstract: The resent invention provides a carbon fiber which enables a molded article produced from a fiber-reinforced composite material using the carbon fiber to exhibit excellent flexibility and to be freed from defects such as bending. According to the method of the present invention the carbon fiber is produced by a two-stage infusibilizing process, namely carrying out a first-stage infusibilization of a pitch-based fiber, which is obtained from mesophase pitch having a softening point of 200 to 400° C. and a true density of 1.30 to 1.38 g/cm3, in a mixed gas atmosphere having a nitrogen dioxide concentration of 1 to 5% by volume and an oxygen concentration of 5 to 50% by volume, the balance being an inert gas or steam, at a temperature between 100 and 200° C. and then carrying out a second-stage infusibilization of the product of the first-stage infusibilization in a mixed gas atmosphere having a nitrogen dioxide concentration of 0.