Distributed polymer optical fiber sensors:a review and outlook

Aging degradation and seismic damage of civil infrastructures have become a serious issue for society,and one promising technology for monitoring their conditions is optical fiber sensing.Glass optical fibers have been predominantly used for the past several decades to develop fiber sensors,but currently polymer or plastic optical fibers(POFs)have also been used extensively to develop advanced fiber sensors because of their unique features,such as high flexibility,large breakage strain,and impact resistance.This review focuses on recently developed distributed and quasi-distributed POF-based sensing techniques based on Rayleigh scattering,Brillouin scattering,and fiber Bragg gratings.

Photonic gas sensors exploiting directly the optical properties of hybrid carbon nanotube localized surface plasmon structures

Weinvestigate the modification of the optical properties of carbon nanotubes(CNTs)resulting from a chemical reaction triggered by the presence of a specific compound(gaseous carbon dioxide(CO_(2)))and show this mechanism has important consequences for chemical sensing.CNTs have attracted significant research interest because they can be functionalized for a particular chemical,yielding a specific physical response which suggests many potential applications in the fields of nanotechnology and sensing.So far,however,utilizing their optical properties for this purpose has proven to be challenging.We demonstrate the use of localized surface plasmons generated on a nanostructured thin film,resembling a large array of nano-wires,to detect changes in the optical properties of the CNTs.Chemical selectivity is demonstrated using CO_(2) in gaseous form at room temperature.The demonstrated methodology results additionally in a new,electrically passive,optical sensing configuration that opens up the possibilities of using CNTs as sensors in hazardous/explosive environments.

Research at the University of Kent and Subsequent Research Activities

The author＇s research activities undertaken at the Applied Optics Group, the University of Kent at Canterbury are reviewed, during his time there from 1988-1992 and 1994-1996, followed by a summary of recent research. The areas of interest are high finesse ring resonators, tunable optical filters, novel optical fiber grating sensors in glass and polymer, femtosecond laser inscription and micromachining, environmental pollution monitoring, hydrogen activated Pd films on silicon and impurity measurement on silicon wafers.

Sensing Properties of Femtosecond Laser-Inscribed Long Period Gratings in Photonic Crystal Fiber

The use of near infrared, high intensity femtosecond laser pulses for the inscription of long period fiber gratings in photonic crystal fiber is reported. The formation of grating structures in photonic crystal fiber is complicated by the fiber structure that allows wave-guidance but that impairs and scatters the femtosecond inscription beam. The effects of symmetric and asymmetric femtosecond laser inscriptions are compared and the polarization characteristics of long period gratings and their responses to external perturbations are reported.