title: Serially multiplexed point sensor for the detection of high humidity in passive optical networks.
abstract: We describe a fiber-optic sensor capable of detecting high humidity. The device is constructed from standard telecommunications single-mode fiber and is compatible with deployment in a serial array, permitting interrogation by optical time-domain reflectometry for network monitoring. The sensors exhibit a reversible change in insertion loss between their dry (lossy) and humid (transmissive) states. The loss can be tailored to take any value; the current devices were designed to change by approximately 2.5 dB at a wavelength of 1.31 mum. The sensors are simple to construct and are compatible with installation in an existing passive optical network. The transduction mechanism is based on the humidity-induced change in refractive index in a polymer overlay on a polished half-block single-mode fiber device.
authors.forename: D C
authors.initials: DC
authors.lastname: Bownass
authors.forename: J S
authors.initials: JS
authors.lastname: Barton
authors.forename: J D
authors.initials: JD
authors.lastname: Jones