Abstract: Embodiments of the present invention are directed to a method of processing an optical fiber to match the optical field coming out of the fiber to that accepted into the optical waveguide to reduce the optical losses due to the optical mode mismatch of the interconnection. In one embodiment, a method of tapering an end of an optical fiber comprises providing a flow of etch vapor from an etch solution generally in an etch vapor flow direction, a concentration of the etch vapor decreasing with distance in the etch vapor flow direction; providing an optical fiber have an end portion with a tip, the end portion of the optical fiber including a core and a clad; and subjecting the end portion of the optical fiber to the flow of etch vapor from the etch solution to etch the end portion and form a taper at the end portion. The end portion is disposed generally along the etch vapor flow direction and the tip of the end portion points generally in a direction opposite from the etch vapor flow direction.