Optical Detection of Ultrasound using Two-Wave Mixing in Semiconductor Photorefractive Crystals and Comparison with the Fabry-Perot

Optical detection of ultrasound presents several advantages over conventional ultrasonic techniques; performed without contact and at a distance it can be used to probe parts at elevated temperature, in particular on a production line, and parts of complex shape. However, optical techniques are typically less sensitive than conventional piezoelectric-based techniques1. Hence, efforts have been done to improve the sensitivity of optical techniques while maintaining their useful features such as a large detection bandwidth.