Patent ID: 8175431

Claim:
A multi-core ferrule for holding an optical fiber bundle, said optical fiber bundle being optically connected to a single optical fiber held in a single-core ferrule, said single-core ferrule having a convex first end surface whose curvature radius is at least 50 mm and a circular first through hole penetrating the center of said first end surface, said optical fiber being inserted into said first through hole such that an end surface of said optical fiber coincides with said first end surface, said multi-core ferrule comprising: a second end surface being in abutting contact with said first end surface and having a convex surface whose curvature radius is in the range of 18.3 mm to 38.7 mm; and a circular second through hole penetrating the center of said second end surface, said optical fiber bundle being inserted into said second through hole such that an end surface of said optical fiber bundle coincides with said second end surface, said second through hole having a smaller diameter than said first through hole and aligning with said first through hole.