Method for producing an optical power sampling device

Abstract

A method for producing a device for sampling optical power carried along a transmission medium. Capillary tubing, cut to a fixed length, is machined to uniform outer diameter. Its ends are machined to a smaller diameter to accommodate end caps. The outer cylindrical surface is polished, and a length of optical fiber is inserted thereinto. The space between fiber and capillary is filled with transparent cement. Caps are cemented to the tubing ends. Protective sleeving is slipped over the optical fibers, the sleeving being inserted within orifices in the caps and cemented thereto. Shrink tubing, covering the end caps and protective sleeving, is heated. The tubing, with fiber, is cut at an angle into two sections. Both cut faces are ground and polished. A discontinuity in the refraction index occurs at the cut faces by coating a polished fiber face with material having a refractive index different than the fiber, and aligning and cementing both sections together at their interface; coating the exposed face with a partially transmissive, partially reflective, metallic film, and aligning and cementing both sections together at their interface; or providing an air gap for index discontinuity, and separating the sections by a small spacer and cementing the sections so as to allow a small air gap therebetween. A photodetector receives reflected optical power from a cut face.