Abstract: The present invention provides a binder that can form a layer that does not reduce high-speed charge/discharge characteristics of a non-aqueous electricity storage element while improving adhesive properties with respect to a substrate such as an electrode or a separator. A binder for a non-aqueous electricity storage element comprising a binder containing a polymer represented by formula (1); a non-aqueous electricity storage element electrode, separator, or current collector in which the binder is used; and a non-aqueous electricity storage element provided with at least one of the non-aqueous electricity storage element electrode, separator, or current collector.

Abstract: An optical fiber comprising a core and a cladding region which covers an outer periphery of the core, having a zero-dispersion wavelength in a wavelength range of 1.4 &mgr;m to 1.65 &mgr;m, and being in a single mode in that zero-dispersion wavelength, wherein GeO2 is doped in the core in a quantity such that a relative refractive index difference of the core becomes not less than 1.8%, the cladding region includes first, second, and third cladding regions, and a refractive index of the second cladding region is smaller than those of the first cladding region and the third cladding region.

Abstract: A low-dispersion optical fiber provides both reduced chromatic dispersion in a used wavelength band and increased effective core area. The low-dispersion optical fiber is made by covering a center core (1) with a first side core (2), covering the first side core (2) with a second side core (3), and covering the second side core (3) with a cladding (5). When the maximum refractive index of the center core (1) is written n1, the minimum refractive index of the first side core (2) is written n2, the maximum refractive index of the second side core (3) is written n3 and the refractive index of the cladding (5) is written nc, then n1>n3>nc>n2 is satisfied. Relative refractive index differences &Dgr;1, &Dgr;2 and &Dgr;3 with respect to the cladding (5) of the maximum refractive index of the center core (1), the minimum refractive index of the first side core (2) and the maximum refractive index of the second side core (3) respectively are made 0.4%≦&Dgr;1≦0.7%, −0.30%≦&Dgr;2≦−0.

Abstract: A low-dispersion optical fiber provides both reduced chromatic dispersion in a used wavelength band and increased effective core area. The low-dispersion optical fiber is made by covering a center core (1) with a first side core (2), covering the first side core (2) with a second side core (3), and covering the second side core (3) with a cladding (5). When the maximum refractive index of the center core (1) is written n1, the minimum refractive index of the first side core (2) is written n2, the maximum refractive index of the second side core (3) is written n3 and the refractive index of the cladding (5) is written nc, then n1>n3>nc>n2 is satisfied. Relative refractive index differences &Dgr;1, &Dgr;2 and &Dgr;3 with respect to the cladding (5) of the maximum refractive index of the center core (1), the minimum refractive index of the first side core (2) and the maximum refractive index of the second side core (3) respectively are made 0.4%≦&Dgr;1≦0.7%, −0.30%≦&Dgr;2≦−0.

Abstract: A low-dispersion optical fiber provides both reduced chromatic dispersion in a used wavelength band and increased effective core area. The low-dispersion optical fiber is made by covering a center core (1) with a first side core (2), covering the first side core (2) with a second side core (3), and covering the second side core (3) with a cladding (5). When the maximum refractive index of the center core (1) is written n1, the minimum refractive index of the first side core (2) is written n2, the maximum refractive index of the second side core (3) is written n3 and the refractive index of the cladding (5) is written nc, then n1>n3>nc>n2 is satisfied. Relative refractive index differences &Dgr;1, &Dgr;2 and &Dgr;3 with respect to the cladding (5) of the maximum refractive index of the center core (1), the minimum refractive index of the first side core (2) and the maximum refractive index of the second side core (3) respectively are made 0.4%≦&Dgr;1≧0.7%, −0.30%≦&Dgr;2≦−0.

Abstract: An optical fiber comprising a core and a cladding region which covers an outer periphery of the core, having a zero-dispersion wavelength in a wavelength range of 1.4 &mgr;m to 1.65 &mgr;m, and being in a single mode in that zero-dispersion wavelength, wherein GeO2 is doped in the core in a quantity such that a relative refractive index difference of the core becomes not less than 1.8%, the cladding region includes first, second, and third cladding regions, and a refractive index of the second cladding region is smaller than those of the first cladding region and the third cladding region.

Abstract: A low-dispersion optical fiber provides both reduced chromatic dispersion in a used wavelength band and increased effective core area. The low-dispersion optical fiber is made by covering a center core (1) with a first side core (2), covering the first side core (2) with a second side core (3), and covering the second side core (3) with a cladding (5). When the maximum refractive index of the center core (1) is written n1, the minimum refractive index of the first side core (2) is written n2, the maximum refractive index of the second side core (3) is written n3 and the refractive index of the cladding (5) is written nc, then n1>n3>nc>n2 is satisfied. Relative refractive index differences &Dgr;1, &Dgr;2 and &Dgr;3 with respect to the cladding (5) of the maximum refractive index of the center core (1), the minimum refractive index of the first side core (2) and the maximum refractive index of the second side core (3) respectively are made 0.4%≦1&Dgr;≧0.7%, −0.30%≦&Dgr;2≲−0.