Abstract: The present invention is a device which may be used to detect the presence of light in a single mode optical fiber while the optical fiber is in use, or to introduce light into an optical fiber. The device includes an identifier chip, and an associated, complementary shaped plate, each of which employ both microbending and macrobending portions. The chip and the plate are each formed of a single piece of material, although only the chip must be formed of an optically transmissive material. In use the chip is urged toward the plate with an optical fiber therebetween. Deformation of the fiber caused by the stress exerted by the chip and the plate will cause detectable light to be emitted through the chip if the fiber is live.