Abstract

For measuring high-frequency and intense ultrasonic fields, a miniature sensor with a tough structure has a great demand recently. The authors propose a new small acoustic sensor which has a micro optical cavity of 100 μm long at the end of an optical fiber. The deformation or me refractivity change of the cavity by sound wave can be measured by monitoring the reflected light intensity at another end of the fiber. In this report, the fabrication technique of the sensing part is first described. Then, we examine the basic properties for measuring ultrasound in water. It is shown experimentally that MHz ultrasonic field can be measured successfully by the proposed micro probe with a good spatial resolution.

© 1997 Optical Society of America