Broadband acoustooptic deflectors: new results.
A new broadband acoustooptic (AO) Bragg deflector using acoustic beam steering to track the Bragg angle is described. It features, instead of the conventional stepped array acoustic grating to produce the steering sound column, a flat transducer grating made from a single piezoelectric platelet bonded to the AO medium, with the spatially periodic phase variations created by interdigitating the electrode configuration. The advantage over the conventional stepped array, for deflectors operating at frequencies above 100 MHz, is the ease of fabrication of the device, an advantage that far outweighs its somewhat reduced acoustic power available for light diffraction. An analysis is presented to show that the achievable half-power bandwidth from beam steering deflectors under optimum design considerations is over four times the bandwidth of fixed beam deflectors having the same transducer dimensions. Experimental results on lead molybdate deflectors confirm the predicted fourfold improvement.
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