Patent ID: 9354387
Filing Date: 2016-05-31
CPC Classification: C03B,G02B,H04B

Claim Text:
1. An optical waveguide comprising: plural cores including a pair of adjacent cores with an identical core-structure; a cladding covering each of plural cores; a first surface on which one ends of the plural cores are disposed; and a second surface on which the other ends of the plural cores are disposed, the plural cores extending from the first surface to the second surface, wherein a minimum value D [μm] of center-to-center distance between the adjacent cores is a value in the range of 15 μm to 60 μm, and the optical waveguide satisfies any one condition of the following first to third conditions at a predetermined wavelength within a predetermined wavelength band, the first condition being defined by: an optical fiber serving as the optical waveguide; a difference of α a linear value serving as a virtual crosstalk in a 10-km fiber length between the adjacent cores at the center-to-center distance of the minimum value D, the linear value being not more than 0.01 where the optical fiber has bend in a predetermined radius of curvature of 30 mm to 200 cm; and the bending loss α the second condition being defined by: Expression (3) below being defined as Expression (1) from which a definition concerning a fiber length is removed in the first condition; and Expression (4) below being defined as Expression (2) from which the definition concerning the fiber length is removed in the first condition: the third condition being defined by: a bent portion of each of the plural cores, the bent portion being fixed in the radius of curvature R a crosstalk between the adjacent cores at the D serving as an adjacent core distance, the crosstalk being not more than 0.01; a bend supplementary angle falling within the range of 58° to 90°, the bend supplementary angle corresponding to a supplementary angle to an angle at a bending center side out of angles defined by straight portions sandwiching the bent portion in each of the plural cores; a plane serving as each of the first surface and the second surface, the plane enabling light entrance and light emission to each of the plural cores; and a height of the optical waveguide with one of the first surface and the second surface being defined as a bottom surface, the height being not more than 10 mm; wherein the optical waveguide satisfies the first condition or the second condition, and wherein each of the plural cores guides multiple spatial modes; wherein each of the plural cores comprises plural sub-cores and a sub-cladding having a lower refractive-index lower than the plural sub-cores, each of the plural sub-cores has an identical refractive-index profile structure, wherein the number of spatial modes of each of the plural cores is at least not less than the number of the plural sub-cores, and wherein inside each of the plural cores, a crosstalk between adjacent sub-cores is not less than 0.1.