All fibres Bragg grating sensors employing many-cycle directional couplers
Results of experiments on all-fibre passive demodulation of fibre Bragg grating sensors using a many-cycle directional coupler are reported here. The principle of operation is based on the fast wavelength response of a fused tapered 2x2 directional coupler pulled through many coupling cycles. The coupler's splitting ratio is then sensitive to small changes in the reflected Bragg wavelength. Ratiometric detection of the outputs of the coupler produces an electrical output linear with wavelength. Because such directional couplers may be readily tailor-made by choosing the number coupling cycles the coupler is pulled through during fabrication, this approach allows a range of sensitivities and wavelength ranges to be catered for, A design rule to allow the selection and fabrication of a coupler with the desired responses has been developed, and potential problems encountered with highly-sensitive, ie fast wavelength response devices, such as their polarization sensitivity, are also discussed. Suggested applications of such couplers to multiplexed Bragg grating sensor systems are also outlined.
Bibliographic Reference: Paper presented : Pacific Northwest Fibre Optic Sensor Workshop, Troutdale (US), May 8-9, 1996
Availability: Available from (1) as paper EN 39702 ORA
Record Number: 199610818 / Last updated on: 1996-08-30
Original language: en
Available languages: en