Methods of Measurement for Angle-Polished Optical Fiber Launching Efficients

Abstract

It is well known that single-mode fiber technology requires strict alignment tolerances to maintain coupling integrity. With acceptable bit-error-rates (BERs) of 10^-12 for telephony and as low as 10^-15 for datacommunication applications, even small link losses can render a system inoperable. Before standards can be established for in-the-field matings and products, it must be well understood how to measure coupling changes in the lab, as these are more easily controlled so that small changes may be observed. This paper discusses experimental techniques to measure the influence of small changes of the overall coupling efficiency between a laser diode and a single-mode fiber. Particular emphasis is placed on fibers with non-zero endface angles (i.e. angle-polished fibers). It is increasingly important to model and measure the effects of out-of-plane misalignments (OPM) and this paper will present some of the primary methods and concerns involved.