Low-cost connector-type optical terminators

It is often desirable to truncate an incomplete branch of a fiber-optic network in a way that minimizes back reflections which would otherwise contaminate signals in the active branches. If the incomplete branch naturally ends in a single-fiber connector engaged to an adapter (coupling), a connector-type terminator is used to suppress reflections; the terminator is simply plugged into the open end of the adapter. Because a polished optical fiber is embedded in the ferrule, the usual form of such a device is expensive. In this paper we present an inexpensive alternative. A solid ferrule (no hole, no fiber) is molded of a plastic whose index of refraction is close enough to that of the optical fiber that a reasonably low reflectance can be assured. The fundamental difficulty is that materials having the appropriate optical properties typically are very susceptible to creep. An adequate material has been found, and the performance of the derived product is here documented. In single-mode telecommunications applications, reflectance is found to be at the level of -50 dB. Also presented are details of the design which allow use of standard components and automated assembly as it applies to current manufacturing of connectors