title: Fiber loop ring-down spectroscopy with a long-period grating cavity.
abstract: We have successfully demonstrated cavity ring-down spectroscopy in a fiber ring with a long-period grating cavity. The cavity couples >99% of light from core to cladding, interacts with the environment surrounding the fiber, and then couples unabsorbed light back into the fiber core. This design provides a relatively large evanescent wave absorption area while maintaining a very low loss for the fiber ring. The effectiveness of this cavity as a sensitive chemical sensor is also demonstrated.
authors.affiliation: Department of Electrical and Computer Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada.
authors.forename: Sean
authors.initials: S
authors.lastname: Pu
authors.forename: Xijia
authors.initials: X
authors.lastname: Gu