Optical fiber connector

In an optical fiber connector (20), an alignment sleeve (66) for holding two conically shaped portions (30-30) of plugs (24-24) each of which terminates an optical fiber (25) includes two conically shaped cavities (68,70) communicating through a common plane (72). A peripheral end portion of at least one end of the sleeve is provided with a notch (86). The notch is adapted to receive a key (43) which projects from a plug as the plug is inserted into the sleeve cavity. This locks the plug in the sleeve and prevents unintended rotation of the plug relative to the sleeve which could abrade opposing end faces of the fibers when a threaded cap in which the plug is mounted is turned into a coupling housing (57) which supports the sleeve and which already has another plug mounted therein . This connector improves insertion loss and performance repeatability by causing fiber core centroids (170,173) of optical fibers terminated by plugs received in the housing to be disposed in a common plane which extends radially from a longitudinal axis of the connector.