Abstract: According to the present invention, provided is a connection structure for lensed optical fibers, which is configured to establish PC connection of lensed optical fibers (1) each including an optical fiber (2) and a GRIN lens (3) that has a rod-like shape and is coaxially fused to a tip of the optical fiber, wherein each of the lensed optical fibers (1) includes an end surface (31) subjected to spherical polishing, and wherein the end surface (31) has a curvature radius (R) satisfying conditions expressed by the following relations (1) and (2): (W/2a)?1??(1); and a=(R·F·(¾)·(1?v2/E))1/3??(2), where W represents a beam diameter, “a” represents a radius of a contact surface, F represents a pressing force at the time of PC connection, “v” represents a Poisson's ratio of the GRIN lens, and E represents a Young's modulus of the GRIN lens.

Abstract: In connecting between lensed optical fibers (1) in which a rod-shaped GRIN lens (3) is coaxially fused with a tip of an optical fiber (2), end faces of the lensed optical fibers (1) are spherically polished with a curvature radius R of 2 mm or more to crimp the end faces with each other, whereby a connection loss upon performing PC connection is reduced.