Design and Transmission Characteristics of Lensed-Taper Launching Coupler for Infrared Hollow Fibers

Abstract

A new scheme of launching coupler for hollow fibers consisting of a lens and a tapered hollow waveguide is proposed to increase the alignment tolerance between the incident beam and a hollow fiber. A series of experiments using the tapered hollow waveguide made of Pyrex glass were performed to investigate the properties and effectiveness of the tapered waveguide and to design the structural parameters of the lensed-taper coupler. We successfully reduced the attenuation of the tapered hollow waveguide with a silver iodide and silver film coated on the inner surface of glass taper. This new launching system has large alignment tolerance for the optical axis of the waveguide.