Methods are provided for forming a plurality of permanent magnets with two different north-south magnetic pole alignments for use in microelectromechanical devices. Optional first and second variable delay devices delay the divided clocks. Optical energy from a single counter-propagating pump may traverse multiple stages while optical energy at the frequency of the signal to be amplified is permitted to propagate in the forward direction only. A control circuit receives a feedback signal derived from the detector output voltage, and uses the feedback signal to control a transition between urging a predominance of the contribution to the detector output voltage from one of the detector circuits to the other. Especially preferred are film compositions for hard gelatine capsules prepared from fish gelatin.