SPUTTER-DEPOSITED PIEZOELECTRIC FIBER COATINGS FOR ACOUSTOOPTIC MODULATORS

All-fiber optical phase modulators were fabricated by coating standard telecommunication optical fibers with thin films of piezoelectric ZnO . Piezoelectric optical fiber coatings of PbZrxTi1-xO3(PZT) were also produced, and the actuation capability necessary for making optical fi ber modulators is demonstrated. Both the ZnO and the PZT fiber coating s were deposited by reactive direct current magnetron sputtering of me tal targets. The geometry of the sputtering system, fiber rotation, an d reactive sputtering processes that result in sufficiently high depos ition rates for deposition of axially symmetric coatings between 0.5 a nd 7 mu m thick were studied. Two types of piezoelectric fiber optic m odulator structures, Cr/Au/ZnO/Cr/Au and Ti/Pt/PZT/Au, are currently b eing investigated. Results on crystalline phase formation, microstruct ure, and piezoelectric and optical behavior of the coated optical fibe r devices are presented. Impedance and phase angle measurements are us ed to demonstrate how device geometry affects the resonance response o f ZnO coated devices. Interferometric measurements have shown that the ZnO-based modulators can produce optical phase shifts as high as 0.70 rad when the modulator is driven at the 196.5 MHz fiber radial resona nce. (C) 1996 American Vacuum Society.