Frequency characteristics of a semi-closed structure in a guided-wave optical pressure sensor for detection of tsunami formation: investigation based on numerical simulations and experiments

Our group is developing a guided-wave optical pressure sensor to detect minute pressure fluctuations occurring during tsunami formation. The sensor consists of a diaphragm as a pressure-sensitive structure and a semi-closed structure with a small hole under the diaphragm which provides a unique high-pass filter function. Cutoff frequency of the high-pass characteristic is an important factor to detect pressure fluctuations due to tsunami formation. In this study, investigations were carried out on frequency characteristics and cutoff frequencies, which vary according to the semiclosed structure dimensions and pressure vibration amplitude, by numerical simulations and experiments in order to further establish design details of the sensor