Single mode optical fiber coupler and method of manufacture thereof

The invention relates to a single mode fiber optic coupler and method of manufacture thereof. The coupler comprises two single mode fibers positioned side by side which are fused in a manner such that they taper down into a substantially circular cross-section coupling region wherein the two cores of the fibers run therethrough. The method of manufacture involves employing a laser source to heat the fibers and a ceramic member. The fiber pair is scanned over the ceramic member to cause the fusion of the two fibers into a single member. Thereafter, while continuing heating and scanning, an axial tension is applied by drawing apart the fibers to form the uniform substantially cylindrical region of coupling which is of reduced cross-section relative to the total cross-sectional area of the two individual fibers.