Cascaded Ferroelectrics Steer Light

The ability to electro-optically modulate the refractive index in ferroelectric materials promises to enable the development of ultrafast switches and scanners, but heretofore the scanning angles they offer have been limited. Now researchers at Pennsylvania State University, Los Alamos National Laboratory and the University of Delaware have reported in the Oct. 21 issue of Applied Physics Letters a cascaded ferroelectric system that demonstrates scanning angles of 25.4° at rates of 5 kHz for a 632.8-nm laser beam.

The researchers employed a LiTaO₃ crystal with two integrated domain-engineered scanner stages, each of which theoretically offered 13.04° of deflection for the light from a HeNe laser -- or 26.08° through the two stages. They attributed the loss of 0.68° in deflection to a lower-than-predicted maximum applied field from their voltage supply. By adding more stages of crystals to the setup, it should be possible to achieve angles of 90° or greater, they suggest.