Acoustooptic and electrooptic diffraction modulators for optical Information processing

Abstract

Acoustooptic (AO) and electrooptic (ED) diffraction modulators provide practical high-performance devices for optical information processing.1,2 AO modulators employ ultrasonic wave diffraction gratings which propagate in the device bulk or surface interface. These provide spatial and temporal optical modulation with continuous delay across the optical aperture. This is ideally suited to the pipeline/parallel signal processing of many optical processing architectures. In the linear EO TIR SLM, signals are applied through VLSI signal distribution chips to a long array of electrodes on the modulator. Optical modulation is provided through grazing incidence interaction with the quasistatic fringing electric fields near the surface. This modulator type is useful for wide-band recording and applications requiring programmable 1-D stationary phase gratings. Recent demonstrated performance in a lithium niobate EO TIR SLM includes 50% diffraction efficiency at 15 V with 4735 electrodes on 10-µm centers addressed at 256 Msample/s. High-efficiency AO modulators have space-bandwidth products of 2000 or less. Thus the characteristics of the AO and EO modulators are compatible and largely complementary.