The electromechanical coupling in piezoelectric materials has been widely studied however a unified view of this
interaction as function of frequencies using different measurement techniques has not previously been available. This
study examines and compares multiple optical based homodyne and heterodyne interferometry techniques for
displacement measurement over a wide range of frequencies and including a comparison made by using a commercial
Laser Doppler Vibrometer. Ferroelectric lead titanate PbTiO<sub>3</sub> with high ferroelectric strain is studied in this work.
Frequency dependence of the electromechanical displacement is obtained using multiple techniques and the emphasis is
given to near resonant frequency interrogations.