A 1.times.N fiber optic coupler is formed by assembling a coupler preform including spacer tube means surrounded by an outer glass tube that is concentric with the spacer tube means. A first optical fiber is disposed in an axial bore in the spacer tube means, and N optical fibers are disposed within a gap between the spacer tube means and the outer tube, the first fiber and the N fibers extending through the midregion of the coupler preform. The midregion of the outer tube is heated to collapse it about the fibers, and the central portion of the midregion is stretched to reduce the diameter thereof over a predetermined length. In accordance with the invention, the spacer tube means is glued to the first optical fiber and to the outer tube.