ABSTRACT
This chapter reviews a few widely adopted and reliable chemical sensing platforms. It presents their working mechanism and importance in chemical sensing. This is because radiation with lower energy only changes the rotation of the molecules whereas radiation with higher energy can excite the molecule into a higher energy state and thus, not be feasible for the effective chemical sensing applications. Change in either one of these parameters proves to be the fundamental basis for the implementation of various optical fiber chemical sensors. The light propagates inside the optical fiber by a total internal reflection' phenomenon. For optical fiber, FP cavity might be located internally or externally and named intrinsic FPI and extrinsic FPI, respectively. For optical fiber case, the thin film is deposited at the end of the fiber tip forming a Fabry-Perot cavity.
