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Optical fibers have been involved in the area of sensing applications for more than four decades. Moreover, interferometric optical fiber sensors have attracted broad interest for their prospective applications in sensing temperature, refractive index, strain measurement, pressure, acoustic wave, vibration, magnetic field, and voltage. During this time, numerous types of interferometers have been developed such as Fabry-Perot, Michelson, Mach-Zehnder, Sagnac Fiber, and Common-path interferometers. Fabry-Perot interferometer (FPI) fiber-optic sensors have been extensively investigated for their exceedingly effective, simple fabrication as well as low cost aspects. In this study, a wide variety of FPI sensors are reviewed in terms of fabrication methods, principle of operation and their sensing applications. The chronology of the development of FPI sensors and their implementation in various applications are discussed. [ABSTRACT FROM AUTHOR]

A canonical problem configured in three different arrangements of periodic multilayered isotropic dielectric material layers with a dissipative dielectric defect, to guide multiple compound Tamm waves with Uller–Zenneck wave characteristics, was formulated and solved. The numerical solutions showed multiple Tamm waves guided at a fixed wavelength along the dissipative defect with same polarization state. These waves propagate with different phase speeds, different propagation distances, different field localizations, and different field profiles. The results identified excitation of symmetric and anti-symmetric solutions of p-polarized Tamm waves and p- and s-polarized waveguide modes. The high phase speed solutions ceased to exist beyond a certain limit of dissipative dielectric defect thickness, but the low phase speed solutions were computed for a wide range of dissipative dielectric defect thickness. The Tamm waves were compounded when the thickness of defect is very small and transmuted into waveguide modes for increasing thickness of dissipative dielectric defect because most of the energy is then strongly confined to the dissipative dielectric defect. The excitation of multiple Tamm waves and waveguide modes at a given dissipative dielectric defect thickness and fixed wavelength can be considered for multi-channel optical communication and sensing applications. [ABSTRACT FROM AUTHOR]