Abstract: An optical coupler comprises a rigid coupling element having a concave surface defining a desired bend profile for an optical fiber, a resiliently deformable bending element having a convex surface which is complementary to the concave surface of the coupling element, and means for urging the bending element toward the coupling element so as to conform an optical fiber placed between the bending element and the coupling element to the desired bend profile. The coupling element comprises a rigid body which has the concave surface, and an optoelectronic device which is carried by the rigid body at a position and orientation for optical coupling between the optoelectronic device and an optical fiber held against the concave surface so as to conform to the desired bend profile.

Abstract: In a method and apparatus for discriminating between a broadband unipolar signal having a component within one or more of three predetermined frequency bands and a narrowband signal within one of the frequency bands, a signal under test is amplified by a gain which is inversely proportional to the DC content of the signal under test to normalize the signal under test. The normalized signal is bandpass filtered to attenuate components outside of the predetermined frequency bands and the filtered signal is compared to a reference signal. The signal under test is deemed to be a narrowband signal within one of the predetermined frequency bands if the filtered signal exceeds the reference signal. The method and apparatus are particularly useful for detecting test tones on optical fibers.