Frequency-modulated multimode laser diode for fiber Bragg grating sensors

Author

Ferreira, L.A. ; Diatzikis, E.V. ; Santos, J.L. ; Farahi, F.

Author_Institution

INESC, Univ. de Tecnologia Optoelectron. e Electron., Porto, Portugal

Volume

16

Issue

9

fYear

1998

fDate

9/1/1998 12:00:00 AM

Firstpage

1620

Lastpage

1630

Abstract

A demodulation scheme for fiber Bragg grating (FBG) sensors is presented. It is based on the generation of an electrical carrier by using a modulated multimode laser diode to illuminate the fiber grating. The change in Bragg wavelength is measured by tracking the phase of the carrier at the detector output in either an open- or a closed-loop scheme. A theoretical analysis of the interrogation technique in terms of linearity and dynamic range is presented. Experimental data were obtained for both strain and temperature measurements. Sensitivities of 0.7 με/√Hz and 0.05°C/√Hz were obtained over a dynamic range of ≈60 dB. The application of this demodulation scheme to a multiplexed sensing system is also demonstrated

Keywords

demodulation; diffraction gratings; fibre optic sensors; laser modes; optical modulation; semiconductor lasers; sensitivity; strain measurement; strain sensors; temperature measurement; Bragg wavelength; closed-loop scheme; demodulation scheme; detector output; dynamic range; electrical carrier; fiber Bragg grating sensors; fiber grating illumination; frequency-modulated multimode laser diode; interrogation technique; modulated multimode laser diode; multiplexed sensing system; open-loop scheme; strain measurements; temperature measurements; theoretical analysis; tracking; Bragg gratings; Demodulation; Diode lasers; Dynamic range; Fiber gratings; Frequency; Optical fiber sensors; Phase detection; Phase measurement; Wavelength measurement;

fLanguage

English

Journal_Title

Lightwave Technology, Journal of

Publisher

ieee

ISSN

0733-8724

Type

jour

DOI

10.1109/50.712245

Filename

712245