Optical fiber power tap

Abstract

There is disclosed an arrangement for tapping signal power from an optical fiber waveguide without requiring that the fiber be terminated or broken. An intermediate length of a fiber waveguide from which all or most of the outer cladding has been removed is sandwiched between first and second dielectric bodies, each illustratively in the form of a circular disk. The first body, which serves to couple optical power out of the fiber, is formed of a relatively compliant dielectric material, such as a soft plastic, having an index of refraction approximately equal to, or greater than, that of the outer cladding of the fiber. The second body is formed of a relatively hard dielectric material, such as a glass or hard plastic, having an index of refraction less than that of the first body. The two dielectric bodies and the fiber are placed in a specially designed holder and forced together so that the fiber deforms the first body providing a large area of contact therewith. A photodetector disposed adjacent to the first body detects the power coupled out of the fiber, converting it to a representative electrical signal suitable for utilization. The holder serves to maintain the proper pressure and alignment among the two dielectric bodies, the fiber and the photodetector during the tapping process. In a modified embodiment of the fiber tap, the second dielectric body is provided with a rounded surface which forces the fiber to bend into a radius sufficient to cause power to radiate out of the inner core of the fiber into the outer cladding. The latter embodiment can thus tap optical power from a clad fiber without requiring that all or most of the fiber cladding be removed therefrom in the vicinity of the tap.