Fiber-optic acoustic sensor using the Fabry-Perot interferometer

Abstract

A highly sensitive and compact butt-coupled-type fiber-optic acoustic sensor has been developed based on the Fabry-Perot interferometer (FPI) for use in remote sensing or sensing in narrow spaces. The system consists of a sensor head, a controller, and an optical fiber transmission line. The sensor head is based on the FPI, and is formed from the high-reflectance-coated confronting surfaces of an optical fiber and a diaphragm. The sensitivity of the sensor head is related to the finesse of the FPI. As the finesse increases, so does the sensitivity. To ensure system stability and increase the dynamic range, the controller is composed of a DFB laser diode with a wavelength of 1300 nm, double optical isolators, an automatic temperature controller, and an automatic power controller.