Optical properties of gadolinium molybdate and their device applications

Abstract

A practical electro-optic page composer has been constructed from single crystal gadolinium molybdate, Gd2(MoO4)3. The characteristic 'ferroelectric-ferroelastic' effect in Gd2(MoO4)3 is based on the existence of bistable states of the optic plane which can be rotated 90° by the application of an electric field E3 or a compressive stress X2 The following optical properties were observed for Gd2(Mo04)3:nc = 1.90, na ≈ nb = 1.85 and Δnab = - 4.08 × 10-4.Here Δnab reduces its value for E3 or X2 in contrast to KH2PO4 i.e., a clockwise optical hysteresis loop is observed. This suggests that the anomalous properties of Gd2(MoO4)3 do not arise merely from dielectric or elastic anomalies. By observing domain switching, a threshold field of E = 2 × 105 V/m was clearly established. The properties of the threshold field and the rotatable optic plane are those utilized in the present page composer. The page composer of Gd2(Mo04)3 can be operated at a few mili-seconds access time under 200 volts drive. Fairly good reconstructed patterns were obtained from the hologram written with this page composer.Ferroelectric-ferroelastics were classified by Aizu in Japan J. Appl. Phys. 8 1424-1434 (1969) as follows:A crystal belongs to a dielectric type f-f crystal whose properties arise from a dielectric anomaly when the following relation holds