Ultrasensitive fiber optic sensors and their applications

In this paper, a brief review on ultrasensitive fiber optic sensors and their applications, done recently at Penn State, is presented. Our discussions will mainly focus on two types of highly sensitive fiber optic sensors. One type is based on the combination of single resonant band long period gratings (LPGs) with the second refractive index matched polymer cladding layer. The other one is based on the LPGs fabricated in photonic nanostructured fibers and waveguides, It is found that a significantly increased sensitivity (two order plus) can be achieved by harnessing these approaches, which will benefit a variety of applications, in particular, low concentration chemical/biological agents detection.