Fujikura Limited

Osaka Prefecture University Public Corporation

Shimane University

Nobuo Kuwaki

Ryo Maruyama

Shoichiro Matsuo

Masaharu Ohashi

Hiroki Hamaguchi

Fumihiko Ito

A measurement method for measuring an effective refractive index difference between two propagation modes of a multimode fiber is provided. The method includes: measuring a first Brillouin frequency shift &#x3bd;by specifying a frequency having a lowest-frequency peak out of peaks in a first frequency spectrum of scattered light in a first propagation mode; measuring a second Brillouin frequency shift &#x3bd;by specifying a frequency having a lowest-frequency peak out of peaks in a second frequency spectrum of scattered light in a second propagation mode; and calculating an effective refractive index difference &#x394;nin accordance with &#x394;n=(&#x3bd;)/(2kV) with use of the first Brillouin frequency shift &#x3bd;, the second Brillouin frequency shift &#x3bd;, a predetermined wave number k of light in a vacuum, and a predetermined constant V.

Measurement method, measurement device, and non-transitory recording medium

An optical fiber alignment device includes an image-capturing device capturing images of end surfaces of two optical fibers; an image-analyzing device obtaining position coordinates of two or more cores in the end surfaces from the image captured by the image-capturing device for each of the two optical fibers; a calculation device substituting the position coordinates of the cores obtained for each of the optical fibers in a theoretical equation that represents a total sum of axial deviation losses at the time of splicing the cores to each other, the calculation device obtaining a positional relationship between the end surfaces of the optical fibers from the theoretical equation such that the total sum of the axial deviation losses becomes a minimum; and a driving device arranging the optical fibers such that the end surfaces of the optical fibers satisfy the positional relationship obtained by the calculation device.

Alignment device, splicing device, aligning method, and splicing method for optical fibers

Optical fibers Fp, Fn, included in a light transmission path, are two-mode optical fibers for propagating an LP01 mode component and an LP11 mode component contained in signal light, and a gradient d&#x394;&#x3c4;/d&#x3bb; of a mode dispersion &#x394;&#x3c4; with respect to a wavelength &#x3bb; in a wavelength band of 1530 nm to 1625 nm is |0.5| ps/km/nm or less. Symbols of mode dispersions &#x394;&#x3c4; of the optical fibers Fp, Fn are opposite to each other. The light transmission path can satisfactorily compensate the mode dispersion in a wide wavelength band.

Two-mode optical fiber and light transmission path

An optical fiber, including (i) an inner core having an &#x3b1;-power refractive index profile, (ii) an outer core having a refractive index of n1', and (iii) a cladding having a refractive index of n2 (n1&#x2032;&#x3c;n2&#x3c;n1), is configured such that a depth of a trench, defined by n2&#x2212;n1&#x2032;, is sufficiently increased.

Optical fiber and optical transmission line

An optical fiber () includes (i) an inner core () whose refractive index distribution has an &#x3b1; profile, (ii) an outer core () which surrounds the inner core (), and (iii) a clad () which surrounds the outer core (). In the optical fiber (), Rd is set to not less than 0.15, where Rd is a ratio of a refractive index difference between the outer core () and the clad () to a refractive index difference between a center part of the inner core () and the clad ().

Growing community of inventors

Sakura, Japan

Nobuo Kuwaki