Compatibility of conventional ferrule with step-ferrule for angled convex optical connector

This paper describes the angled physical contact optical connectors (called the APC optical connectors) that provide the ferrule with an angled convex endface with respect to the optical fiber axis for greatly reducing backreflection light to the semiconductor laser diode from the endface of the optical fiber. The APC optical connector has extremely low backreflection of less than -60 dB when a slanted angle is more than 8 degrees. This paper describes the compatibility of the APC optical connectors of conventional type that consists of the conventional ferrule with a tapered chamfering at its endface and the improved type that consists of a step-ferrule with a short cylindrical portion at its endface. As the results, the shift of the vertex point of the ferrule endface from the optical fiber axis greatly affects the insertion loss and compatibility between the APC optical connectors in connection. Compatibility of the APC optical connectors with the conventional ferrule connected to the step-ferrule is achieved when the maximum insertion loss is specified as 0.5 dB when the rejection percentage is about 5%.