Optical fibers are aligned in a jig of parallel apertured plates in which the fibers are inserted and positioned by the use of V-shaped or positioning ribbon actuators. The actuators are thermally actuated by a closed loop feedback system to center each individual fiber and its light output on an equivalent juxtaposed photodetector array. When the fiber is centered by this feedback technique it is permanently fixed in that position by potting, for example. The feedback control constitutes either a totally electrical system utilizing a processing unit or can be partially manually controlled by a human operator operating a joystick and viewing a meter or similar device which indicates an approach to a maximum output from a photodetector.