Phase- and intensity-modulated fiberoptic sensors

Abstract

Fiberoptic sensors can be categorized in several ways: as phase- and intensity-modulated devices; by the type and location of the transduction; etc. Transduction processes which result in a change in the path length within an optical fiber cause the light to be phase-modulated such as elastic deformations resulting in a length change of an optical fiber, sagnac effect, pockels effect, etc. Other transduction processes result in a change in intensity of the light transmitted through an optical fiber (intensity modulation) such as microbend losses, evanescent coupling, state of polarization, optical absorption, etc. The list of physical phenomena which can be detected is quite long and includes: acoustic, electric, and magnetic fields; angular and linear displacement, velocity, and acceleration; temperature, pressure, stress, and strain; radiation dosage and traces of gas; etc. Several types of fiberoptic sensors will be discussed below.Fiberoptic sensors can be categorized in several ways: as phase- and intensity-modulated devices; by the type and location of the transduction; etc. Transduction processes which result in a change in the path length within an optical fiber cause the light to be phase-modulated such as elastic deformations resulting in a length change of an optical fiber, sagnac effect, pockels effect, etc. Other transduction processes result in a change in intensity of the light transmitted through an optical fiber (intensity modulation) such as microbend losses, evanescent coupling, state of polarization, optical absorption, etc. The list of physical phenomena which can be detected is quite long and includes: acoustic, electric, and magnetic fields; angular and linear displacement, velocity, and acceleration; temperature, pressure, stress, and strain; radiation dosage and traces of gas; etc. Several types of fiberoptic sensors will be discussed below.