ABSTRACT
Fiber-optic sensors have been widely used in a number of fields, ranging from distributed sensing of strain at kilometer scale and biomolecule detection at micrometer or even nanometer scale. For Fiber Fabry Perot (FFP) sensors, they have mainly been used with miniature size for sensing of both physical and biochemical parameters. Fiber-optic temperature sensors can withstand temperatures up to 1000°C and have the advantages of immune to electromagnetic interference, and environmental vibrations. Rao and Ran developed Fiber-Optic Fabry-Perot interferometers (FFPI) strain sensors for high-temperature application by using laser micromachining technologies, including fs-laser micromachining, 157-nm laser micromachining, and also photonic crystal fibers (PCFs). For displacement measurement, a simple scheme was developed by Wang by using singlemode fiber (SMF) as both the input and output fiber. Fiber-optic gas sensors are special for flammable gas detection as they are inherently safe and unlike electric-based sensors, will never cause sparks during detection.
