Optical waveguide and optical fiber transmission system

摘要

In an optical waveguide having plural cores including a pair of adjacent cores with an identical core structure, a minimum value D of center-center distance between the adjacent cores is 15 μm to 60 μm, each of the plural cores has a bent portion fixed in a radius of curvature Rb of not more than 7 mm, a bend supplementary angle of the bent portion is 58° to 90°, a height of the optical waveguide is defined as a height of not more than 10 mm, and a crosstalk of the adjacent cores is not more than 0.01.

主权项

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 the following first condition or second condition at a predetermined wavelength within the range of 1.26 μm to 1.625 μm, the first condition being defined by: an optical fiber serving as the optical waveguide; a difference of α90deg between cores having the identical core-structure, the difference being not more than 1 dB where the α90deg is defined as a bending loss per 90° of a predetermined core while the optical fiber has a 90° bend in a predetermined radius of curvature Rb [mm] of not more than 4 mm; 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 α90deg of not more than a value represented by Expression (1) below where a linear value serving as a crosstalk in a predetermined fiber length of not more than 10 km is XTw/oB and the optical fiber has bend in the predetermined radius of curvature of 30 mm to 200 cm, or, the bending loss α90deg of not more than a value represented by Expression (2) below where a cladding portion around each of the plural cores constitutes a trench-assisted type having a trench layer with a relative refractive-index difference of not more than −0.1% with respect to the cladding:
0.809 exp(6.64×10−2 D)√{square root over (XTw/oBRb)} [dB/90°]  (1); and1.42 exp(7.78×10−2 D)√{square root over (XTw/oBRb)} [dB/90°]  (2), 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:
0.809 exp(6.64×10−2 D)√{square root over (10−3 Rb)} [dB/90°]  (3); and1.42 exp(7.78×10−2 D)√{square root over (10−3 Rb)} [dB/90°]  (4).