Measurement of the piezoelectric and electrooptic constants of GaPO4 with a Michelson interferometer

A new measurement system to determine the piezoelectric and electrooptic constants of gallium orthophosphate (GaPO4) by the inverse piezoelectric effect was developed, The change in length due to the applied voltage is measured with a Michelson interferometer. With this method the piezoelectric constants are determined without the knowledge of any other material constant and in a wide temperature range. The temperature dependence of the longitudinal piezo constant (d(11) = 4.5 pm/V) from room temperature up to 550 degrees C is very low. Therefore this new material is a good choice for piezoelectric applications in a high temperature environment.