Abstract
A recently reported1 extrinsic Fabry-Perot interferometric (EFPI) sensor used a cavity formed by a single-mode fiber (SMF) end and a multimode fiber (MMF) end inserted into a hollow-core fiber (HCF) from its opposite ends. The EFPI lead insensitivity to random phase drifts results in an effective point sensor that is used extensively in strain, vibration, and temperature measurements. However, signal fading2 necessitates a stringent requirement of biasing the sensor at the quadrature point. In contrast to a quadrature-phase-shifted scheme,1 recent spectrum-analysis methods2,3 of phase detection provide a linear, direct, and self-consistent phase readout without phase bias, source stabilization, or polarization control. Detection by the J0·J2 method3 or other passive homodyne methods requires generation of a secondary phase modulation. The EFPI does not permit such a secondary modulation except at the sensor head itself, which is impractical in embedded sensors, or through source frequency modulation, which leads to instabilities. Herein is demonstrated the split-cavity cross-coupled extrinsic fiber interferometer (SCEFI), which eliminates the need for any phase bias, eliminates the effect of intensity variation with the air-gap change, permits secondary phase modulation, detects both static4 and dynamic phase shift, and leads to simple two/three sensor multiplexing3 on a single coupler.
© 1993 Optical Society of America
PDF ArticleMore Like This
Juncheng Xu, Gary R. Pickrell, Kristie L Cooper, Po Zhang, and Anbo Wang
CThL5 Conference on Lasers and Electro-Optics (CLEO:S&I) 2005
Qingguo Sun, Na Chen, Yuetong Ding, Zhenyi Chen, and Tingyun Wang
WL103 Asia Communications and Photonics Conference and Exhibition (ACP) 2009
Kent A. Murphy, Michael F. Gunther, Anbo Wang, Richard O. Claus, and Ashish M. Vengsarkar
P30 Optical Fiber Sensors (OFS) 1992