Sumitomo Electric Industries, Limited

Kazuhiro Yonezawa

Sumio Hoshino

Tadashi Enomoto

Tomohiro Ishihara

Manabu Shiozaki

Itaru Sakabe

Sotaro Ida

Saori Kubara

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.

Method of manufacturing multi-mode optical fiber

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.

Multimode optical fiber

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.

Multimode optical fiber and optical cable including the same

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&#xb7;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.

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.

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 &#x3bc;m or 60 to 65 &#x3bc;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.

Multi-mode optical fiber

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 &#x3b1;-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.

Multimode optical fiber including a core and a cladding

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 &#x3b1; 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.

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 &#x3bc;m or 60 to 65 &#x3bc;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.

The present invention relates to a multi-mode optical fiber having a structure enabling stable production and broadening of communication bandwidth as compared with the conventional structures. The multi-mode optical fiber has a core with a diameterthat is doped with GeOand chlorine. The chlorine concentration profile in the core along the diametric direction of the multi-mode optical fiber has a shape such that the chlorine concentration at a second measurement position within a range at a distance of from 0.9 a to 1.0 a from the center of the core in the radial direction thereof is higher than the chlorine concentration at a first measurement position at a distance of a/2 from the center of the core in the radial direction thereof.

The present invention relates to a multi-mode optical fiber having a structure which can be produced with good stability with a communication bandwidth broader than that in the conventional structures, and in which both GeOand chlorine are added to a core thereof, and chlorine is also added to a cladding thereof. The cladding contains chlorine such that the average chlorine concentration therein becomes higher than the average chlorine concentration in the core.

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Yokohama, Japan

Kazuhiro Yonezawa