Abstract: A method of manufacturing multi-mode optical fiber is disclosed. The method of manufacturing includes: a step of forming a first glass base material while controlling a supply rate of an additive for adjusting a refractive index to achieve a desired refractive index distribution; a step of drawing the first glass base material; a step of measuring a residual stress distribution in a radial direction of the multi-mode optical fiber after being drawn; a step of readjusting the supply rate of the additive in accordance with deviation of a refractive index, acquired from the residual stress distribution measured, from the desired refractive index distribution; a step of forming a second glass base material while supplying the additive at the supply rate after being readjusted; and a step of drawing the second glass base material.

Abstract: The present embodiment relates to a production method for matching a shape of a refractive index profile of a core preform with an ideal curve with high precision and in a short time. Prior to a glass synthesis step of stacking a plurality of glass layers including a refractive index adjusting agent of a predetermined amount on an inner peripheral surface or on an outer peripheral surface of a glass deposition substrate, glass synthesis actual-result data is created from production condition data of a glass preform produced in the past and refractive index profile data of a core preform obtained from the glass preform. In each glass synthesis section where the glass synthesis step is executed, a doping amount of the refractive index adjusting agent is adjusted on the basis of the glass synthesis actual-result data.

Abstract: A selection control method includes: acquiring configuration information of an assembled article; displaying a three-dimensional shape image of the assembled article based on the configuration information; specifying a first element group included in the assembled article in response to a selection of a range in the three-dimensional shape image, the first element group corresponding to the range; and selecting a specific element set as a unit when a ratio of elements included in the first element group among elements associated with the specific element set exceeds a predetermined value, the specific element set included in the assembled article, and selecting each element included in the first element group respectively when the ratio of the elements included in the first element group among the elements associated with the specific element set does not exceed the predetermined value.

Abstract: An embodiment of the invention relates to a GI-MMF with a structure for achieving widening of bandwidth in a wider wavelength range and improving manufacturing easiness of a refractive index profile in a core. In an example of the GI-MMF, a whole region of the core is doped with Ge and a part of the core is doped with P. Namely, the Ge-doped region coincides with the whole region of the core and the Ge-doped region is comprised of a partially P-doped region doped with Ge and P; and a P-undoped region doped with Ge but not intentionally doped with P.

Abstract: An embodiment of the invention relates to a MMF with a structure for enabling stable manufacture of the MMF suitable for wide-band multimode optical transmission, for realizing faster short-haul information transmission than before. In the MMF, when an input position of a DMD measurement pulse on an input end face is represented by a distance r from a center of a core with a radius a, a power of the DMD measurement pulse on an output end face with the input position r of the DMD measurement pulse being 0.8a is not more than 70% of a power of the DMD measurement pulse on the output end face with the input position r of the DMD measurement pulse being 0.

Abstract: The present invention relates to an MMF with a structure for relaxing wavelength dependence of transmission bandwidth. In the MMF, a doping amount of a dopant for control of refractive index is adjusted, so as to make each of an OFL bandwidth at a wavelength of 850 nm and an OFL bandwidth at a wavelength of at least one of 980 nm, 1060 nm, and 1300 nm become not less than 1500 MHz·km, make the OFL bandwidth at the wavelength of at least one of 980 nm, 1060 nm, and 1300 nm become wider than the OFL bandwidth at the wavelength of 850 nm, and effectively suppress increase in transmission loss.

Abstract: The present invention relates to an MMF with a structure for relaxing wavelength dependence of transmission bandwidth. In the MMF, a doping amount of a dopant for control of refractive index is adjusted, so as to make each of an OFL bandwidth at a wavelength of 850 nm and an OFL bandwidth at a wavelength of at least one of 980 nm, 1060 nm, and 1300 nm become not less than 1500 MHz·km, make the OFL bandwidth at the wavelength of at least one of 980 nm, 1060 nm, and 1300 nm become wider than the OFL bandwidth at the wavelength of 850 nm, and effectively suppress increase in transmission loss.

Abstract: To provide a practical infrared transmissive protective cover capable of detecting a heating abnormality of an internal heating element and the like by visual observation and by using infrared rays. The infrared transmissive protective cover includes a light transmission section, the light transmission section is made of a resin sheet containing a resin composition, and a total light transmittance of the light transmission section in a visible light region is 70% or more, and an average infrared transmittance in a wavelength range of 8 to 14 ?m is 5% or more.

Abstract: A method of manufacturing multi-mode optical fiber is disclosed. The method of manufacturing includes: a step of forming a first glass base material while controlling a supply rate of an additive for adjusting a refractive index to achieve a desired refractive index distribution; a step of drawing the first glass base material; a step of measuring a residual stress distribution in a radial direction of the multi-mode optical fiber after being drawn; a step of readjusting the supply rate of the additive in accordance with deviation of a refractive index, acquired from the residual stress distribution measured, from the desired refractive index distribution; a step of forming a second glass base material while supplying the additive at the supply rate after being readjusted; and a step of drawing the second glass base material.

Abstract: An embodiment of the invention relates to a MMF with a structure for enabling stable manufacture of the MMF suitable for wide-band multimode optical transmission, for realizing faster short-haul information transmission than before. In the MMF, when an input position of a DMD measurement pulse on an input end face is represented by a distance r from a center of a core with a radius a, a power of the DMD measurement pulse on an output end face with the input position r of the DMD measurement pulse being 0.8a is not more than 70% of a power of the DMD measurement pulse on the output end face with the input position r of the DMD measurement pulse being 0.

Abstract: An embodiment of the present invention relates to an MMF with a structure for reducing length dependence of optical characteristics while maintaining bend-insensitivity. The MMF has a trench portion provided between a core portion and a cladding portion and having a refractive index lower than that of the cladding portion. In a cross section of the MMF, the trench portion in at least a partial section of the MMF has a non-circularly symmetric shape with respect to an intersection between the optical axis and the cross section.

Abstract: An embodiment of the invention relates to a GI-MMF with a structure for achieving widening of bandwidth in a wider wavelength range and improving manufacturing easiness of a refractive index profile in a core. In an example of the GI-MMF, a whole region of the core is doped with Ge and a part of the core is doped with P. Namely, the Ge-doped region coincides with the whole region of the core and the Ge-doped region is comprised of a partially P-doped region doped with Ge and P; and a P-undoped region doped with Ge but not intentionally doped with P.

Abstract: An embodiment of the present invention relates to an MMF with a structure for reducing length dependence of optical characteristics while maintaining bend-insensitivity. The MMF has a trench portion provided between a core portion and a cladding portion and having a refractive index lower than that of the cladding portion. In a cross section of the MMF, the trench portion in at least a partial section of the MMF has a non-circularly symmetric shape with respect to an intersection between the optical axis and the cross section.

Abstract: The present invention relates to a GI-type multi-mode optical fiber in which the outer diameter of the core is 47.5 to 52.5 ?m or 60 to 65 ?m, or to a bend resistant multi-mode optical fiber provided with resistance against property fluctuation caused by the bending of the multi-mode optical fiber by providing a trench portion having a low refractive index at the outer periphery of the core. In the multi-mode optical fiber, both the maximum tensile stress and the maximum compressive stress in the optical axis direction remaining in the core are 50 MPa or less.

Abstract: The present invention relates to a multimode optical fiber provided with a region where a refractive index in a peripheral region of a core has deviation from an ideal shape of an ?-power refractive-index profile and where an absolute value of an amount of the deviation is not less than 0.005%, so as to generate radiation modes, and a refractive index of a cladding is higher than that of the deviation region.

Abstract: The present invention relates to a multimode optical fiber having a stably manufacturable structure as a transmission medium suitable for wide-band multimode transmission. In the multimode optical fiber, a core has a refractive-index profile a shape of which is defined by the exponent ? which varies along a radial direction from a center of the core and an average of radial variation of which is positive in a predetermined range in the radial direction.

Abstract: The present invention relates to a GI-type multi-mode optical fiber in which the outer diameter 2a of a core is 47.5 to 52.5 ?m or 60 to 65 ?m. In the multi-mode optical fiber, stress in the optical axis direction remaining in an outermost peripheral portion of the cladding is tensile stress of 0 to 25 MPa, the outermost peripheral portion of the cladding being defined as a region having a diameter of 1.8b or more when the diameter of the cladding is 2b.

Abstract: The present invention relates to a preform manufacturing method and others for effectively reducing variation in refractive index due to chlorine used in manufacture of an optical fiber preform. The manufacturing method includes a dechlorination step carried out between a point of an end time of a dehydration step and a point of a start time of a sintering step, the dechlorination step being a step of heating a porous preform after dehydrated, in an atmosphere containing no chlorine-based dehydrating agent, for a given length of time while maintaining a temperature lower than a sintering temperature, thereby removing chlorine from the porous preform after dehydrated.

Abstract: An estimating apparatus for estimating a degree of ease of parts removal, uses design data concerning an assembly that includes a given part as a constituent element. The degree of ease of parts removal apparatus refers to the design data and calculates the degree of ease of removal in a case of removing the given part from a given direction, based on a ratio of an area of the part when the assembly is seen from the given direction to an area of the part as seen from the given direction, without a visual field being blocked by other parts.

Abstract: A method for manufacturing a fiber fabric having a hard handle is provided without using, in particular, thick yarns, manufacturing a fabric in the high density which increases loads at stages of composing and organizing the fabric, or performing resin treatment for hard finishing. The method includes performing treatment on a fabric mainly including nylon fibers with a treatment liquid containing benzyl alcohol.