Bulk-acoustic-wave reflection-grating devices in Fe:LiNbO/sub 3/

Reflections of bulk acoustic waves from optically generated holograms stored in iron-doped lithium niobate have been previously demonstrated. The reflection coefficients were shown to be large enough that practical signal-processing devices such as filters and resonators may be built utilizing this effect. Fabrication is simple and operation with bandwidths of several gigahertz and interaction times of tens of microseconds is feasible. This is an order of magnitude improvement in bandwidth over surface acoustic wave devices. Resonators, bandpass filters and dispersive delay lines are under development. Previous measurements of reflection coefficients for LiNbO/sub 3/ have been extended to several values of iron doping. The optimum doping has been found to be 0.015% by weight iron. The maximum reflection coefficient is approximately 10/sup -4/ per grating element which, because of the large number of reflectors in a typical grating, is sufficient for practical devices. Measurements of the effect of annealing in argon and oxygen are presented