Fiber-optical sensor for surface acoustic waves

A new sensor is presented for detecting surface acoustic waves (SAW). The probe is constructed using single-mode fiber components (two directional couplers, a polarization controller, and a phase modulator) with a laser diode and detector. This sensor has the advantages of being small and rugged and does not require an optical bench for stability. The sensor can detect acoustic waves over a dynamic range of 110 dB and has better amplitude sensitivity (0.0003 Å) than has been reported for other SAW sensors.