Microlensed optical terminals and optical system equipped therewith, and

Abstract

The tip of a first optical fiber 8 is fused integrally to a second optical fiber 7, having a single refractive index and an identical outer diameter, which has a spherical lens 10 with the length and diameter to produce a beam expansion by Gaussian diffusion to at least 80 .mu.m or greater at the exit and a radius of curvature greater than 200 .mu.m. The spherical part of the second fiber is formed by thermal fusion; a spherical lens having the desired diameter at the optical fiber tip is formed by feeding the optical fiber tip into a thermal fusion unit to form the spherical lens. An optical fiber terminal for optical coupling composed of a single mode optical fiber, a non-doped silica fiber beam expansion segment, and a non-doped silica spherical lens, is connected to a polarization-independent optical isolator. A ferrule support having a rotatable spherical segment formed at the tip, in which the second optical fiber and an optical fiber protecting material are inserted and stabilized in a through-hole of the ferrule support, and a coupling unit consisting of a flange and a cap, which contact with the spherical surface of the spherical segment at opposite sides after the ferrule support has been adjusted into a position which produces an optimal beam converging function.