Self-calibrated interferometric-intensity-based optical fiber sensors

Citation
A. Wang et al., Self-calibrated interferometric-intensity-based optical fiber sensors, J LIGHTW T, 19(10), 2001, pp. 1495-1501
Citations number
10
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Optics & Acoustics
Journal title
JOURNAL OF LIGHTWAVE TECHNOLOGY
ISSN journal
0733-8724 → ACNP
Volume
19
Issue
10
Year of publication
2001
Pages
1495 - 1501
Database
ISI
SICI code
0733-8724(200110)19:10<1495:SIOFS>2.0.ZU;2-K
Abstract
This paper presents self-calibrated interferometric-intensity-based optical fiber sensors, which combine for the first time fiber interferometry and i ntensity-based devices into a single sensor system. The sensor involves an extrinsic Fabry-Perot (FP) interferometric cavity. The broadband light retu rned from the FP cavity is split into two channels in such a way that one c hannel has a coherence length much longer than the doubled air-gap separati on in the sensor so the Fl? generates effective interference, while the coh erence length in the other channel is so short that no effective interferen ce takes place. As a result, the optical signal in the channel with a long coherence length yields information about the Fl? cavity length while the s ignal in the other channel is proportional only to the source power, fiber attenuation, and other optical loss factors in the optical path. To elimina te fringe direction ambiguity and relative measurement limitations associat ed with interferometric sensors, the sensor is designed such that it is ope rated over the linear range between a valley and a peak of one interference fringe in the first channel. Moreover, the ratiometric signal-processing m ethod is applied for the signals in the two channels, to obtain self-calibr ating measurement to compensate for all unwanted factors, including source power variations and fiber bending losses. Various pressure and temperature sensors based on the self-calibrated interferometric/intensity-based schem e are designed, fabricated, and tested. Experimental results show that a re solution as high as 0.02% of full scale can be obtained for both the pressu re and temperature measurements.