Electroptic diffraction modulation in ZnO film on sapphire

An electrooptic Bragg diffraction modulator with high diffraction efficiency which utilizes a low-loss epitaxial ZnO optical waveguide on a sapphire substrate is discussed. An interdigital electrode with a spatial period of 20 mu m and an aperture of 3 mm was fabricated directly on the film surface using a photolithographic technique. For the TE/sub 0/ mode at 6328 AA, a maximum diffraction efficiency of 98% has been obtained from DC to 100 kHz with an applied voltage of about 31 V. The unclamped electrooptic coefficient r/sub 33/ is estimated to be 5.8*10/sup -12/ m/V which is much larger than the clamped value of 2.6*10/sup -12/ m/V in the literature.<
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