Fujikura Limited

Nippon Telegraph and Telephone Corporation

Osaka Prefecture University Public Corporation

Tsukasa Hosokawa

Makoto Yamada

Shoichiro Matsuo

Katsuhiro Takenaga

Kentaro Ichii

Hirotaka Ono

A manufacturing method for an optical fiber, includes: drawing, while heating in a heating furnace, a lower end of an optical fiber preform that is to be an optical fiber having a core consisting of silica glass containing a rare earth element compound. The heating furnace has a temperature profile in which a temperature of the heating furnace increases to a maximum temperature Tand then decreases from an upstream side of the heating furnace toward a downstream side of the heating furnace. The temperature profile has a changing point at which the temperature decreases more steeply on the downstream side from a position where the maximum temperature Tis reached. At the maximum temperature, a temperature of the silica glass is higher than or equal to a glass transition temperature and the silica glass is in a single phase.

Manufacturing method for optical fiber and manufacturing apparatus for optical fiber

An optical fiber for amplification includes a core having an inner core and an outer core surrounding the outer circumferential surface of the inner core. The relative refractive index difference of the inner core to a cladding is smaller than the relative refractive index difference of the outer core to the cladding. The outer core is entirely doped with erbium. The theoretical cutoff wavelength of an LPmode light beam is a wavelength of 1,565 nm or more. The theoretical cutoff wavelength of an LPmode light beam is a wavelength of 1,530 nm or less. The theoretical cutoff wavelength of the LPmode light beam is a wavelength of 980 nm or less.

Optical fiber for amplification and optical fiber amplifier using the same

An amplification optical fiber operable to propagate light beams in a plurality of modes in a predetermined wavelength range through a core doped with a rare earth element, wherein Expression (1) is satisfied, where a cutoff wavelength of a propagated highest mode light beam is defined as &#x3bb;max, under conditions in which the cutoff wavelength of the highest mode light beam is defined as &#x3bb;c, a shortest wavelength of the wavelength range is defined as &#x3bb;min, and a cutoff wavelength of a second-highest mode light beam to the highest mode light beam is &#x3bb;min.&#x3bb;&#x3e;0.5 &#x3bb;min+0.5 &#x3bb;max&#x2003;&#x2003;(1).

Amplification optical fiber and optical fiber amplifier

Growing community of inventors

Sakura, Japan

Tsukasa Hosokawa