Acoustic Beam Steering by an Interdigital Transducer for Wideband Bulk Wave Acoustooptic Deflectors

Abstract

An interdigital transducer method has been exploited for generating and s teer ing t h e acoustic beam on a LiNbOj bulk wave acoustooptic Eragg cell. The interdigital transducer, deposited on t h e x sur face of a ILiNbO crys ta l , is e f f ec t ive in generating longitudinal waves with the wavevector lying in the xz plane. The acous t ic radiation pa t te rn consists of two main lobes whose directions depend on the acous t ic frequency and l ie a t angles located almost symmetrically about t he x axis. The acoustooptic in te rac t ion geometry is such t h a t one of the s teered acoustic beams t racks the Bragg angle and reduces the momentum mismatch over a wide range of frequencies. Results a r e repor ted re la t ive t o two LiNbO cells operating in the frequency range 1.4 2.1 GHz and 1.05-2.0 GHz, with a d i f f raction efficiency of approximately 2% per Wat t of acous t i c power. 3 .