Torsional Actuators Using LiNbO₃ Plates with an Inversion Layer

Abstract

By utilization of a ferroelectric inversion layer formed in a LiNbO 3 plate by heat treatment at just below the Curie temperature, a piezoelectric torsional actuator consisting of a single-crystal plate with no bonding layer can be obtained. The optimal cut suitable for generating torsional motion efficiently without causing bending motion is theoretically examined. It is experimentally demonstrated that torsional actuators fabricated using 140°-rotated Y -cut LiNbO 3 plates with an inversion layer as thick as half the plate thickness exhibit no hysteresis and little creep. When an actuator with dimensions of 16×7.0×0.1 mm 3 is used as a light deflector, a light beam deflection angle as large as 2.08° is obtained at an applied voltage of 220 V p-p .