Highly sensitive optical hydrogen sensor using circular Pd-coated singlemode tapered fibre
A novel optical hydrogen sensor, based on the absorption change of the evanescent fields in a circular Pd-coated singlemode tapered fibre is presented. The proposed sensor is polarisation independent and its sensitivity is adjustable by means of the taper diameter, interaction length, and/or light wavelength. A simple light transmission measurement setup is used to test the sensor. The sensor is suitable for the detection of low hydrogen concentrations with high sensitivity and fast time response. Transmission changes as high as 60% are demonstrated.
Tunable chirp in Bragg gratings written in tapered core fibers
In this paper we present a technique to control the chirp of a fiber grating capable to produce positive or negative chirp in a single grating. The device is based on a uniform period grating written in a tapered core fiber, this grating has a positive chirp that can be reduced and removed by subjecting the fiber to mechanical stress, after some stress level the grating chirps to negative values. A chirp range of ±4 nm with respect to a central wavelength of 1546 nm has been experimentally achieved.
<title>Tunable chirp in Bragg gratings written in tapered core fibers</title>
In this paper we present a technique to control the chirp of a fiber grating capable to produce positive or negative chirp in a single grating. The device is based ona uniform period grating written in a tapered core fiber, this grating has a positive chirp that can be reduced and removed by subjecting the fiber to mechanical stress, after some stress level the grating chirps to negative values. A chirp range of +/- 4 nm with respect to a central wavelength of 1546 nm has been experimentally achieved.